1970 350 mods
 

Hi, new to the forum. My dad and I bought a 1970 Lemans Sport with a 350 and 3-speed auto trans. Currently the only aftermarket thing we have done to it is cherry bomb mufflers. my dad and I want to beef it up this winter and Get it to 300-350 whp. We were already planning on putting some new headers and a qudrajet carb, what else would help it get it to those numbers? Thanks.

Also we were thinking about 4-speed manual swapping it.

A 3 speed auto or a 4 speed does not matter anywhere near as much to your future plans as does the rear gears the car has.
If the car does not have AC and currently has a 2bbl carb then you likely have 3.08 rear gears and that will need to change FIRST so you can cam the motor to get to 300 hp no less top 300 Hp.

You 2bbl motor was rated at 255 Hp.

The highest hp 350 Pontiac ever made put out 325 Hp.

That was in 1969 with heads that not only breathed better than yours but gave the motor near 2 full points more of compression than you have with your 1970 heads.

Also the 4 bbl cam that 69 motor had was 3 steps bigger then your 2 bbl carb 254 cam.

If I am not mistaken the rear gears that cars with the 325 hp 350 came with where 3.55.

Just incase it's worth mentioning, a transmission swap will not net a single extra horsepower - but it may make the car more fun to drive around.

To be brutally honest, you're going to need to do a LOT to get 300-350hp;
That engine as it sits is 2 barrel carbureted, it has 8.0:1 compression and a factory rating of 255(b)hp;
So you're looking for roughly 20% to 40% power increase.

Let's compare your car's engine against 70-72 GTO's - because they have the horsepower level you're hoping for);
1970 GTO "base" 400: rated at 350(b)hp; 400-4bbl; roughly 10:1 compression; uses large valve cylinder heads; has a larger cam (067); same exhaust manifolds
1971 GTO "base" 400: rated at 300(b)hp; 400-4bbl; roughly 8.5:1 compression; uses large valve cylinder heads; has a larger cam ('067; same as 1970), same exhaust manifolds
1972 GTO "base" 400: rated at 250(n)hp; 400-4bbl *other than casting numbers, this was in essence the same engine as used in 1971)*

A four barrel swap may yield a seat-of-the-pants power increase when going from the primaries to the secondaries, but I'd wager any power increase would be minimal.

Headers will net a gain, but will probably massively outflow your engine as it is set up (or as it will be post four-barrel swap).

Some people may knock the 350 (for 1970 those would be casting #11) heads, but I am guessing that you can leave them installed as the small valve configuration won't be the "power bottle-neck" that some might suggest.

I'd instead suggest you look at a camshaft upgrade to compliment a four barrel carb swap;
I believe that the two barrel carb you have is rated for 500cfm;
Most Quadrajet 4 barrel carbs have a 750cfm rating.

If you swap cams, and don't want to mess with cylinder heads, stick to a grind with factory lift ratings - for most Pontiac grinds the rating (with 1.5:1 ratio rockers) was around 0.406" lift.

If you went to a '067 type camshaft, and a GOOD dual plane intake, you probably wouldn't hit your aspired horsepower level, but odds are you would see a sufficient enough increase to be quite pleased with the net result.

I'd suggest a factory 1968-1972 4 barrel intake manifold, but if you are dead set on an aftermarket one, I believe the one which comes closest to flowing as well as a factory unit would be the Edelbrock Performer RPM;
Any other dual plane intake manifold will actually flow WORSE than a factory cast iron intake manifold.
If you chose a factory intake manifold used after 1972 you will need to change your valley pan (the part below your intake) to accommodate the EGR protrusion on the underside of 1973-1978 Pontiac intake manifolds.

Summary of my suggestion (with a bit more info):
- leave heads
- leave exhaust manifolds
- swap to a 067 Pontiac grind camshaft
- swap to a 1968-1972 Pontiac cast iron intake manifold
- swap to a 1968-1972 Pontiac 4bbl carb (with choke mechanism to match intake)

My opinion is that headers will only help the engine if you do a cam swap to compliment the 4bbl swap;
Headers alone won't get you near what you're looking for.

There are older articles comparing intake manifolds, and exhaust changes - those might be worth reading.

I hope this helps.

A 350 that can put 300 to 350 to the wheels is a pretty hot 350 that will require a lot more than the usual cam swap, intake, carb and headers.

Honestly I’d start looking for a 400 or better yet a 455 to swap in there since you’re going to spending quite a bit of money in your pursuit. A 350 is a nice engine but the wrong one to start with when you’re wanting 350 horsepower to the rear wheels.

A 350 horsepower 350 will put around 280 to the wheels, making one horsepower per cubic inch with a 350 won’t be cheap or easy and forget about 350 to the wheels.

Let cubic inches get you closer to your goal without the need to build a high-strung 350 which won’t be all that street friendly. A near stock 455 will make 400 horsepower without much fuss and be fairly docile around town, so there’s your 300 to 350 to the wheels. Bonus it will pull a tall rear end gear easily so no need to swap to numerically higher gears.

I echo what everyone else is saying here. 300-350hp at the rear wheels is going to be a tall order for your engine. is it possible to build a 350P to make that kind of power, yes. But it's not a bolt-on endeavor.

With the engine you have, you've got to contend with very low compression, cast pistons that won't hold up to much abuse, cast rods that won't want to spin as fast as you'd need this engine to and an oil pump that isn't really up to the task either.

In it's stock build configuration, doing a 4bl swap, with a small cam upgrade like a factory 067 cam or maybe something like a Comp 250H and headers with an upgraded exhaust is probably the limit. You're probably talking somewhere around 275 crank hp.

Now, going to a more performance oriented rear gear is also going to help you out a bit here, and the torque the engine makes will make it feel like it has a bit more pep.

If your goal is 350 to the ground, streetable and reliable, I like others agree that a swap to a 455 or stroked 400 is a good option. Depending on what your budget is, I'd probably go to somebody like Len Williams and have a basic 455 made. He markets a 425hp stroked 400 that is a nice piece and will get you to your 300-350 wheel hp target.

Or, if you want to get a little hairy and mess around with your reliability you always have this option. https://www.youtube.com/watch?v=izBrYc7LI7Y

I doubt an engine like the one referenced in the YouTube video above would hold up for very long. But it would be cool while it held together.

If you want to make good hp swap to a 68-70 pontiac 4 bbl intake. All part will be a swap from the donor engine to your 350. Oh and bye the way your engine is a 354 cid Pontiac rounded down to make it simple for people to remember. Get a 4 bbl Quadra jet from the same period and fine tune it. It will work great when you adjust the secondary flap to open correctly. Next will be the headers try to find a set with I believe 1 5/8 primary tubes. If you are going to which from an auto to 4spd trans you can install the 068 cam if you stay with automatic then the 067 is you best bet. You could save money by changing the rocker arms from the 1.5 to the 1.65 on one side I don’t remember intake or exhaust side. If you can find an old H-O catalog check which to change on your year 350. Nunzi’ catalog will have the same recommendation. Recurve the distributor and you will be happy. Should you want more get big valve heads # 12,13, or # 48 from 1970 if you have the extra cash

Thank you for the input, we'll probably start with the new carburetor, cams, and intake manifold. I figured the manual trans swap wouldn't add any power (just bored from dailying an auto) but when we do the trans swap, we'll change the rear gears. Again, thank you so much for the input.

You might find that doing some of those small things and making sure the car is right and tight is all you need.

My wife had a 1970 Chevelle with a basic Chevy 350. It was one of those Gm Goodwrench crate engines. With the intake and headers, it maybe made 225hp.

That said, because the car was well sorted, had a nice sounding exhaust and a more performance oriented gear set. It was a blast to drive. It wasn't "fast" but it never left you wanting for more.

If you decide to try and run headers with your car, it is possible it has a set of heads that do not have the outer most bolt holes drilled. This makes sealing up a set of headers difficult it not impossible. Before buying headers, check to make sure those holes are drilled and tapped.

Good luck with the project!

A lot of guys are going to suggest you “find a 455”; depending upon where you live this could prove nearly impossible. I live in the Ohio Valley, just northwest of Louisville, KY. Pontiac 455s, as well as 428s, are nearly impossible to find within 4-5 hours of me. Bart’s suggestion of a 400 makes all kinds of sense; good Pontiac 400s are still relatively easy to find. To make 300-350hp at the rear wheels you are going to have to make 400-450hp at the flywheel. 450hp out of a 400 is a pretty “hot” street engine, but installing a stroker crank kit in a good 400 block will make it achievable. I would love to see you do it with a 350, but you are looking at major expenditures to achieve it with a 350 unless you install a stroker kit and modern aluminum heads.

I think 350's are good street engines and respond to modifications just like any motor. I think one needs to be realistic about power numbers and I prefer flywheel dyno numbers or quarter mile times instead of RWHP. Way too many variables with a chassis dyno. I've had 720 HP engines show 480 RWHP and 680 HP engine show 550 on the same dyno. I've also tested parts that pick up power 15-30 on a dyno and at the track but show no difference on a chassis dyno.


With that being said if, you'll see a nice performance gain with a good cam, headers and improving the intake tract and possibly changing heads to raise the compression.... and replacing the cherry bombs with a good flowing muffler. If the engine needs a complete rebuild and it's the original engine, it'd be a good idea to keep it. At that point you could install a 4.00" or 4.25" stroke crank, and spend some money to improve the heads. There's 350's out there making over 500 HP and 400 is achievable pretty easily with a sensible plan.

It sounds like your looking to pep up the current motor without a rebuild. A good cam, headers, Performer intake manifold with a Q-jet or vacuum operated secondary carburetor will make a big difference. Enough so that you'll be needing to address the differential with a posi (assuming it's open now) and possible up the gear a little to a 3:23-3:55 depending on your driving style.

A realistic goal for doing some bolt on modifications to a 1970 350 would be something in the neighborhood of 220-250 rear wheel horsepower.

Doing a head swap to aluminum aftermarket heads, a pretty hot cam in the region of a factory RAIV cam and headers along with a calibrated Quadrajet on a stock iron intake would get you close to your original goal of 300-350 RWHP and it won’t be inexpensive.

After you get your stick shift trans in there you’ll need a 3.90, 4.11 or 4.33 rear gear to go along with the big cam and heads.

A 350 with 350 to the wheels is certainly doable, but not with a few bolt-ons keeping the stock 1970 #11 heads.

Do a lot of research before throwing money at that 350. Either be more realistic about what it’s able to produce within a tight budget using a few of the usual hop up tricks or get serious and set yourself up with a 400 or 455 and go from there.

Those Cherry Bomb mufflers are a neat blast from the past but you’ve already chosen the wrong mufflers for an engine that’s going to meet your lofty expectations.

Hi B-man, thank you for the input. Originally we were planning on getting a muffler delete and h pipe but the guy working on the car said it was too loud (buzzkill lmao) so he threw on some cherrybombs. the current whp goal is 220-250 with my new list upgrades.

Can aluminum heads even work on the 350s? Isn’t there some kind of valve shrouding or some such performance deterring issue going on?

Unless you’re dead set on hopping up the 350, I’d follow the advice of searching for a 400 block, then going to town.

Can research info, gather parts as required, take time to assemble, etc. etc.

If you’re dead set on giving your butt dyno a workout, and plan to build a different engine, can always drop a couple hundred dollars and go to the David Freiburger school of quick and cheap power. Be warned though, that school is an enter at your own risk one, lol.

After getting input from everyone else I threw out the 300-350 whp goal. It's a lot cheaper to just throw on some bolt-ons instead of swapping out the block.

KRE offers a 260 cfm head with smaller valves on the order of 2.06/1.66 or something close to that with a 65cc chamber that’s ideal for 350 builds so they’re readily available.

It’s not so much the small bore not able to make power it’s trying to get more than 1 horsepower per cubic inch without spending close to 3k on aluminum aftermarket Pontiac heads to achieve that no matter the displacement.

The LS1 has a bore (3.90”) just about the same size as a Pontiac 350 (3.875”) so with the right size valves and a high flowing head (260 cfm LS1, maybe 170 cfm #11 350 head) getting one or more horsepower per cube is not a problem with a small bore size.

I might as well throw my hat into the ring…lol…with my thoughts on hopping up your ’70 350. I would follow the ’69 350HO recipe by adding ’70 #13 heads with their 75-78 cc chambers to keep your compression in the low 9’s (#12’s would get you 9.5-ish compression), add a cam like the Summit 2800 (204/214/112 @ .422”/.444” lift…kinda like a high-lift 067 cam), add a factory 4-bbl intake (’68-’71 to work with the exhaust cross-overs) and a suitable Q-jet. Replace the standard oil pump with a 60 lb. unit and the HD driveshaft. I would keep the log exhaust manifolds and add Pypes 2.5” mandrel headpipes followed with a complete 2.5” system with Magnaflow/DynoMax UltraFlo mufflers. 350HO’s came with 3.55 gears standard, so add that and a new limited slip diff and you’d have a very strong combination. I would keep the convertor near stock for better drivability and cruising performance if you keep the TH350. I always go for the hot stock factory looking sleeper.

Here is a ’69 350HO dyno sheet run with log manifolds with 2.5” mandrel bent headpipes, 067 style cam, and 10.6 to 1 compression. It was .030” over and a fresh rebuild, so maybe a bit more work/cost than you want to tackle. With a full point (+) less compression it would be in the 300 hp range. But all the pieces would work well together on a short block in good condition.

Dennis

If for whatever reason(s), you have the motor out of the car and torn down to the short block, you're not too far away from a Butler 4.25 stroker kit. That gives you 400+ cid with a 4.25 stroke (more torque than a stock 400). That, plus a set of aluminum heads would kick a$$.. Obviously that means a full rebuild, but it would get you pretty much everything you want in a fresh motor that you can have confidence in.

I think I would just put a supercharger on it.

When my 557 block gives out I’m going with a blown 350


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So would you spend a pretty good amount of money to supercharge a 350 in unknown used condition or would you completely rebuild it first using a few upgrades like forged pistons and rods for starters?

It seems pretty clear after reading the responses from the original poster that he’s not interested in or able to afford a supercharger, aftermarket heads, stroker rotating assembly nor a top of the line fully blueprinted 350 HO Pure Srock engine.

All fine suggestions and examples but unfortunately none of that’s in the cards here.

A 400 block and a set of pistons would pretty much solve the issue.Tom

Along the same line as Tom has suggested here searching for a used good-running 400 in your local area would likely be the same cost roughly as the hopping up the 350.

You mentioned your mechanic suggested the mufflers so I’m guessing he’s doing the major work so the engine swap might be out of your purview as far as room or equipment is concerned. But again still worthy of consideration, cubic inches are your friend when it comes to street performance.

Let me ruffle some feathers in terms of running aftermarket heads and their impact on drivability as compared with your current heads.

A base line 1970 400 4bbl motor will make peak torque at 3000 rpm, your 354 motor with the same heads and cam will make peak torque at 3200 rpm.

With these facts in mind you need to think about what your average street rpm in terms of drive time will be.

Now if you slap on a set of aftermarket heads with port volumes a little smaller then the norm aftermarket head you’re still going to increase your peak torque rpm up to 3600 rpm .

With a combo like that if you had let’s say 2.93 rear gears you would need a minimum of a rear gear ratio of 3.34 to keep the same throttle response feel at 2850 rpm that you had with stock motor.

Take a very close look at the dyno test of that motor in post 17 and notice that the dyno pull did not start off until 3000 rpm.

Just like the rule of thumb for cams is that it’s better for a street motor to be somewhat under Cam’ed , the exact same rule holds true for cylinder heads!

Pretty much all the parts except the block and pistons from his 350 will go into and on a 400 block.If necessary a set of custom pistons will get him too the CR he would want to run.JMHO,Tom

I would have to get the engine rebuilt in order for it to comfortably handle the supercharger

Listen the Pontiac 350 has a longer stroke then any other 350 cid motor that was in GMs divisions back then, so it has superior torque available for great street driving.

Build for keeping that advantage up to 4000 rpm or so with changes you make for the motor and in rear gearing and you will be nice and happy.

As usual, late to a thread.

Your original request IS possible, however: I could NEVER have afforded the process without being able to trade out a bunch, and deduct more as advertising. You do not want to know what it cost.

It also produces an engine that is an absolute handful on the street, and more so every year I age!

I did it for a reason, and not sorry that I did, but it truly is NOT a practical street cruiser.

I have now read the entire thread (twice). The pretty much stock 400 is an excellent idea (opinion).

There are other "add-ons" not yet mentioned in this thread worth considering:

(1) Gearing - a number of folks have mentioned higher ratio rear gears (helps acceleration, kills gas mileage). Possible alternative: different transmission gear ratios. Memory is fuzzy, but I think low gear in the transmission I settled on is a 2.62:1. Better acceleration than standard ratios, but still have 1:1 4th gear and I still use a 3.08 rear drive. Gas mileage is very good; engine RPM's are quite manageable at any legal speed limit.

(2) Weight reduction - most folks talk about power adders, but few talk about weight reduction. Other than alloy wheels, and aluminum-cased 4-speed (mine came that way), I cannot tell you what weight reduction is possible on your Firebird, as my weight reduction campaign was on a 1974 GTO. Without going totally crazy; it was possible to change wheels, transmission case, water pump, rear drums, intake manifold, etc. Going totally crazy resulted in aluminum flywheel, elimination of the "5 mile/hour" bumper system, and some other mods I won't talk about.

How does it run? Low gear is virtually useless if driven in anger unless one likes buying rear tires!

Consider the 400, you will be glad you did.

Jon

Milage differences really only come into play at steady highway speeds as this chart shows, it also shows the other side of the coin.

That other side is the fact that around town driving dealing with stop lights and such that a 3.40 something rear gear will give the fuel mileage of a 2.41 rear gear, but with far better acceleration, as in fun.

The difference between what we believed was a 2.73 to the 3.42 that we put in my wife's chevelle was night and day.

Not that we recorded mileage on the car, but it seemed somewhat the same and highway cruising wasn't terrible with the 27" tire combination. Around town where the car was really used though, it was so much more fun.

Unless you have a 350 Buick. ;)

True .100” longer.

350 guy here.

I've done a couple of iterations on 350 motors.

The first iteration was a very basic 69 350, #47 heads. This was the 1969 equivalent of your 1970 350. I put a Summit 2800 cam in it, with 4 barrel intake. I ran both Qjets and Holley carbs on it. The Qjet was a better all around carb, but Holleys were simpler, and did fine too when that is what I had. I ran an HEI ignition, with dual exhaust. This was a very basic, fun street cruising combo that did not require any exotic build elements or parts. The 2800 cam works great with stock valve train parts. It is similar to the previously suggested 067 cam. This was all in a 67 Firebird with 3 speed auto and 3.23 mid level performance street gears. In retrospect, it was a wonderful blend of cost effectiveness, simple tech, performance, and drivability. It broke just under 15's in the quarter when I decided to chase after more power and performance in iteration number two...

Iteration two is a 350 with forged parts (planned on doing a turbo build that never happened), and Ram Air big valve #12 heads. This was a compression bump, which gave more power, but kept it pump gas capable. I run a Lunati 702 Voodoo cam, HEI, headers, 3.73 gears, and a 2000 stall converter. This cam required careful selection and upgrade of valve train and head parts, because too much lift with big valves on a 350 WILL cause valves to contact the cylinder. I also run a FiTech system, because I wanted to play with some modern style fuel delivery. All of this cost significant money, and made the car less street friendly (3600-ish rpm on the highway).

Here in the Phoenix area there is only one drag strip in town, and every time I went I would have to take a day of vacation, lose sleep, and spend a good $100+ just to get one, maybe two runs down the track in a night. Most of that time was spent pretending I was part of a cool drag race culture while the track spent an hour cleaning up somebody's oily breakdown, pretending they cared.

Not my thing anymore.

I'm not going to undo what I built engine-wise, because it is no doubt a blast to drive. But what I will do is go back to a simpler time, with better street gears and street manners. I will go with a quieter exhaust, and stop making life goals of burning down the Dairy Queen parking lot while pretending "Street Outlaws" has ANYTHING to do with me.

Make your car reliable. Make it affordable. Make it fun but not crazy. Enjoy the time with your dad. Get a stereo in it with bluetooth, and tell dad to throw on his playlist that probably had a lot of spandex and hairspray involved. See how many different hamburger places you can visit in one summer, and how many burnout strips you can leave on that one almost deserted road that everybody has nearby.

To put it in very simple terms, I have now arrived at a point where I lean more toward "Roadkill" or "Vice Grip Garage". It saves money and sanity.

4 barrel intake and carb? Yes.
HEI ignition? Yes.
Headers and reasonable exhaust that doesn't make you an enemy of the state? Yes.
Good wiring that doesn't catch on fire? Yes.
Brakes that can stop you? Yes. Front disc/rear drum are fine.
Seat belts, preferably 3 point? Yes. After breaking my neck in a car with air bags and 3 point belts, I am a fan of some reasonable safety gear.
Cam swap to something like the 067 or 2800? I like it. Best time to do this is when the intake is off.
Changing rear gears or adding a limited slip differential? This is not a lightweight diy project. Best saved for later as money and/or skill develops.

Wow. I've turned into such a "square".:D

Thanks for the input! My dad and I are getting this done by a shop cause we don't have the time or tools to work on it sadly but I'll bring up the cams. The shop said they recommend getting an aluminum intake cam, 4 barrel carb, and headers since we don't know the integrity of the block. Going down Woodward in the Le Mans with my dad and my buddies has to be my favorite times in this car. Also doing burnouts on Woodward with my dad with Atomic Punk blasting has to be the most kickass thing I've ever done lmao. At this point with the car, my dad and I wanna be able to beat at least a Prius.

I took a bone stock 70/350 2bbl 4speed 3.31 gear and put in a 204/204 - 110 Erson cam and quadrajet and that made a big difference... you dont have to follow standard big cid. cam recomendations a small single pattern cam will fill cylinders just fine with modest bump in .050 duration and single pattern keeps low rpm torque up due to less overlap

A factory iron intake is perfectly fine for what you’re doing, they can produce far more HP than what your motor will be making.

If you can turn up a used Edelbrock performer then that’s a good choice also.
Do not get a performer rpm intake.

Agreed. I think your suggestion for a Performer is a good one. I like the dual pattern intake for the flexibility to run square or spreadbore carbs. And it saves your back if you pull it off.

Remember the "Crosswind" intakes that you could get on ebay years back? It's a knockoff of the Performer RPM, but better IMO. They used to be $150. They are now $290 as a "Speedmaster" brand. But hey... the economy is in great shape!:rolleyes: I use them on both my cars, and they fit better than either the Performer or the RPM. I like all the open space between the intake and the valley pan cover. Lots of room to "conceal" hoses and wires!:D

Imperial, sounds like you might be near the Motor City? I'm from Michigan originally. Cars are in our DNA!

I was gonna guess Motley Crue, RATT, or AC/DC were on dad's play list. But Van Halen fits perfectly too!

Those are my current playlist...what are you saying?

I'm saying "Well played, sir. Well played.";):D

I spent this week burning up some Def Leppard (Pyromania), Scorpions (Blackout), and a "best of" collection of Tesla.

yep I live in the Metro Detroit area, my dad used to wake me up with Van Halen blaring as a kid lmao

classics.... 👍

Here’s the old yet still valid HO racing recommendations for camming and gearing a 350.

The gearing recommendations are probably even more valid today with the under 10 to 1 compression that needs to be run.

What's a 524886 cam? Assuming it's Pontiac, where was it used?

I went the Butler 4.25" stroker kit route with my 350, Comp XE276HR cam with 1.5 roller rockers and 6X-4 heads. Torker-I intake (I know that some think it's a mushy choice, but there's sentiment attached) and 800cfm Quadrajet. CR calculated at 9.3 with Ross flat tops set at 0.0 on the deck. On the dyno, torque was 442 @ 4300 and HP 453 @ 5600. With the add-ons like ignition and Hedman headers, the build was about $9000. With the lighter piston weight of the 350, I think there's plenty of RPM capability to take advantage of the big valve head.

The 524886 was known as the number 6 hydro cam .
It was only used in 58 thru 62 motors and is a tad hotter then the 067 cam.

The 886 has 60 degrees of overlap while the 067 has 54.

I’m looking to stroke my 350 with a 4.00 kit from butler. Is there a way I could contact you for info?


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You should be able to message me through my member profile page.

I see no one commented either positively or negatively on my reduce the weight comment.

While lots of folks are concerned about power, one can easily pull a quarter of a second off a quarter mile time, and with some careful planning and purchases, more than 1/2 second while EVERYTHING else is left alone.

Easy reductions:

Aluminum wheels
Aluminum intake manifold

Less easy reductions:

Aluminum transmission case
Aluminum rear drums (in some cases)
Distributor housing (both CI and AL used)
Water pump housings same as above

And you can go overboard if you have a mind to do so (an AFB weighs less than a Q-Jet or Holley, and a TQ weighs even less).

Not going through everything, but I took almost 500 pounds off of a 1974 GTO. That is 8.6 percent of the shipping weight for the car.

Jon

This is a very good point. There's even more areas that you can look at that will save weight without effecting quality of life with the car.

-Fiberglass/Carbon Fiber hood and trunk lid.
-Wilwood replacement calipers to replace the iron units
-Aluminum radiator
-Gear reduction mini-starter

Not all of these are cheap, but between those 4 items, there's an additional 50-75 lbs of weight off the vehicle without touching anything that would start to make the car suck to drive.

If the car has drums all around, I'd swap to 4 wheel 11" discs with the Wilwood d52/d154 calipers. More repeatable stopping power and much less unsprung weight on the car.

Headers are sometimes lighter than manifolds, but I didn't specifically include them because they can at some points start impacting quality of life via ground clearance and added noise.

Sure you can pay for some lightweight components, some cheap and some crazy expensive.

And you can strip out insulation, power accessories, comfort accessories like air conditioning and heating etc, etc, etc.

I stripped over 300 pounds out of my 1964 GTO 455 HO powered bracket car by removing seats, carpet and floor insulation, inner fenders, radio, heater, wiper assembly and such. Mostly to reduce drivetrain stress and breakage, less to improve performance because I was bracket racing not class racing.

I eventually put almost all of those things back when I was done racing the car.

Honestly when you’re starting a build and going to be down on cubic inches just to prove a point I just don’t see the point of that. Just build more power with a larger engine to begin with for pretty much the same money.

Buying a bunch of lightweight body parts and taking weight out of the car is much more expensive than just upping the cubes from 383 or 388 to 461 or 467.

On the street cubic inches are your friend. I’d rather have a lightly modified 455 than a heavily modified 350, less stress and lower RPMs required with more inches.

Back about 45 years ago one of my younger brothers friends had a very nice 1969 Charger with a 318. He did end up with a 440 in it, and eventually stripped several hundred pounds out of it by removing most of the interior, air conditioning, heating and whatever else. Took what was a decent cream color original paint job and primed it flat black.

It was a teenager’s hot rod and we really didn’t know that this car would be so valuable today. But even back then I had to just shake my head knowing he had essentially ruined what started out as a very nice car. :(

Just add cubic inches during the build, it’s free horsepower. Being a Pontiac there’s no big block or small block so almost all the same engine parts interchange between small and large cube engines, we should consider ourselves lucky that it’s easy to take advantage of more cubes in the same package. :)

B-Man - I will completely agree about the cost of building an ultra high performance 350 and a mildly modified 400 to get the same power. In my neck of the woods, 455's have been "son, haven't had one of those for years" for decades; while obviously the power potential is greater, not sure about the cost.

Much of my weight savings was because I NEEDED different parts, and the aluminum was not that much more:

Steel wheels were insufficient width for the tires I wanted
Desired wide ratio transmission
Using original RAIV intake with no crossover

I still have all inner fenders, insulation, seats, uphostery, etc.

When different parts are going to be used, why not lighter parts.

The problem I now have is the low first gear, the reduced weight, and the power is too much for the tires; I guess I went overboard ;)

Jason - I looked unsuccessfully for years for someone with an English wheel to do hood and deck lid; is fiber even an option for a 1974 GTO?

Jon