Need advice on a cam for Pontiac 350
 

Hi everyone, I have a 75 Pontiac 350 that I’m looking to swap a cam into. It has 6X heads which I assume to be 6X-4 heads since it is a 350 and is from 75. I’m also almost positive it has screw in rocker studs. I’m trying to decide on what a good cam would be for this engine, I think I’ve settled on the summit 2801 cam kit which comes with lifters. I’ve been reading that this is similar to the 068 cam. My question is would this be a good cam for my engine? I have a 4 speed manual with 3.08 rear gears (according to the build sheet) and I’m looking for something that has a good idle sound and pick up a decent amount of power. Would I need to swap the valve springs with this cam? Also, how hard is it to access everything needed considering the engine is in the car? I know I’ll have to remove a decent amount of stuff to do what I need to do. This will be a first cam swap so any advice is much appreciated. Thanks

If your 6X heads are original to the motor then its a 1976, but either way if you have -4 type heads then your compression is only a meager 7.6.
In that case a Sum-2800-1 is the cam I would use+ it’s lift will work better with your stock valve springs.

You will of course need new lifters and timing chain and gears.

You will need to remove the radiator to get the old cam out and the new one in.
It will the help of a second person to guide the old cam out and the new one in without harming the cam bearings.

I was looking at the summit 2800, but I’m worried it won’t be worth the effort of swapping the cam. Like it’ll be too similar to the stock cam and won’t have much difference. While my main goal is to increase power I do want it to have a nice cammed idle sound. I know the 2802 is way too big for my set up, but figured the 2801 might be a good choice since it’s between the two. Unless I’m looking at it all wrong. What would the main difference be between the 2800 and the 2801? I know different lift and duration but I’m not sure what these differences really do. I talked to a summit tech, and he recommended me a set of comp springs 988-16. If I changed to these valve springs would the 2801 be a good choice?

The 2801 has too much duration for a 350 that’s lucky to have 7.6:1 compression, it likely has less.

I had a 1976 400 with a 068 cam, it was in a 1976 T/A equipped with the original 6S-8 heads which were the AIR version of the 6X-8.

It was okay but really lackluster in performance, that 7:6:1 400 just didn’t have enough compression to be happy with that cam. I used it because I was strapped for cash and already had it on the shelf, thinking back the 066 cam that the factory originally used in that engine would have performed much better.

If you’re set on running the 2801 I’d advise cutting the heads for compression or better yet swap them for a set of ‘68 -‘70 350 heads after converting to screw in studs. It’s going to be hard to cut those 6X-4 heads enough to raise your compression by on point.

Good valve springs are great for controlling the valves and should be part of most any cam swap but when you put the wrong cam in your engine they won’t help resolve that.

The 2800 is a far better fit for your engine as it sits.

Ok so the 2800 would be a better fit for the engine as it sits, and as Steve said it would also be ok with the stock valve springs. Would this 2800 pick up a decent amount of power and give it a better idle sound too? I’m just trying to figure out if it is or isn’t basically like the stock cam that’s in it.

Your problem is you’re wanting a choppy idle or powerful sound. You’re not going to be able to use a very radical (long duration) cam in a low compression engine and have it run well.

Sure you can stick a big cam in it and it will have a rough idle, but it won’t get out of its own way.

Nothing’s worse than a car that sounds fast but isn’t.

If you want a powerful lopey sounding cam then you have to build an engine that will support it.

Your stock springs could very likely be worn out and have lost their tension. Have them checked or simply buy new so you don’t waste time and money.

Your stock cam if it’s a 4 bbl motor only has a advertised intake duration of 269 with a exh of 277.
Lift is .388”/ 424” respectively.

Compare these numbers to the 2800 and you will see that the 2800 is a good amount bigger then your stock cam!

Picking a cam for its idle tone will leave you very unhappy!
A Pontiac 350 has a lot longer stroke then a Chevy 350 and as such makes a bunch more torque which is more fun on the street then Hp when you have a car with only 3.08 rear gears.

Don’t cam the motor to defeat what it has going for it!

It is a factory 4bbl, thanks for the stock cam spec I couldn’t find that information anywhere. I definitely don’t want to pick it just for the idle sound, the 2800 is sounding like a good choice. Should I bet a timing set that’s the factory design?

Do you guys have an estimate for how much the 2800 might increase the torque and horsepower over the stock cam?

KJ223 Info Only
2801 cam in a 355 Pontiac with 8.3 to 1 comp note :(compression with Stock 6x-4 will be around 7.4 to 7.5 to 1)
Heads flowed: 206 @ .450" Intake / Exhaust flowed 164 @ .450"
Made 325 Hp @ 5000 rpms (corrected)
384 Ft lbs @ 3700 rpms w / Exhaust manifolds
Never Dynoed a 2800 cam ... but lots of people have,,, maybe someone will share

Your stock motor was rated at 165 hp, with the change to the 2800 you should pick up 20 to 25 hp once the Carb is recalibrated as needed.

"Sure you can stick a big cam in it and it will have a rough idle, but it won’t get out of its own way.

Nothing’s worse than a car that sounds fast but isn’t."

+2

Even with the tiny stock cam in it you'd just about have to drop it off a floor jack to do a decent burnout! Compression and CID are your friends for making power (torque). To get these "little" engines to run you need to look at raising the compression ratio, not putting bigger cams in them when they don't have much compression in them.

The 2800 is dubbed by the Chevy crowd the RV camshaft. It's a "turd" in a Chevy 350 with 7.5 compression, the factory 350/300hp will outrun it at ever RPM and it's only 196/204, .393/.410" lift.

The rule of thumb is to increase the static compression ratio one full point for every 10 degrees more duration you put in it or you loose vacuum at idle, throttle response off idle, low end power, and power in the normal driving range as it jut pushes peak VE up in the RPM range. In the case of the little 350 engine it's already hard pressed to make any power (torque) with those specs so there isn't a magic bullet for a cam out there going to help that scenario......IMHO.......

is this an application that might benefit from an XE grind with short seat to seat duration?

Yes, if the owner wants a little "attitude" in the idle quality and quick power right off idle it's a good place for one of those cams. They make the engine "feel" strong as all the power is early and in a narrow RPM range. The XE256 would be the one to use here, not the large XE262 or 268......IMHO.....

I

The Voodoo 700 or 701 should work here, also. 701 being the max here [maybe even too big here], with this low compress 350.


https://www.lunatipower.com/voodoo-h...8-250-256.html


https://www.lunatipower.com/voodoo-h...8-256-262.html

The 4 speed and 3.08 gears might save you here with the 701. Most folks try to cam these low compress 350`s with auto trans with stock stall and 2.41 to 2.78 gears.

Summit 2800 v. Lunati Voodoo 10510700

"Any thoughts on which cam will make most usable power for a stock 1974 Pontiac 354? It's a stock bottom end with some 4X heads milled to be about 8:1."

" The Lunati for sure. I have even used the 213/219 Voodoo in a 326. It idled good and ran strong. It was 9.2:1 compression, but the 354 with 8:1 won't be a problem for either of those 2 Voodoo cams.
Don't let the fast ramp thing fool you. It is much slower on the closing side."
Paul Carter

https://forums.maxperformanceinc.com...ghlight=Voodoo


.

I don`t remember, at what lift, where the retainer to guide clearance problems pop up on stock heads. But, the 701 has 468 lift. I suspect one would have to have the guides machined, for safety, with this lift.;)

I appreciate all the replies I’m still learning all this, but from what I see it looks like it comes down to the 2800 or the voodoo 700, and also possibly the comp xe cam? I don’t really know which one to pick over the others based on these options

Being as Harold Brookshire designed the Voodoo series, the 700 gets the nod for my 350.

It looks like the voodoo cams 700 and 701 are out of stock everywhere I look.

Maybe worth the wait?


If you`re gonna tear it down, make it count.;)

These are computer dyno simulations so you what you want or don't want from them. The only difference is the cam used. It is show in the yellow box.

Stan

These all use the Voodoo cams.

Stan

Definitely more torque on those Voodoo`s.

One can see the torque vs hp swap on those shorter seat timing cams. It is a sim, but some sims are pretty good.

Awesome thank you, I’ll keep an eye out for the voodoo 700 to come back in stock. Like you guys stated earlier the 2800 would be a good upgrade from the stock cam, but based on what you guys have also said, along with these simulated dyno sheets the voodoo 700 seems to be my best bet

X2 on the ‘68 -‘70 350 heads or as this year 350 should have large valve heads stock, maybe 16 / 62 / 12 / 13's. Only thing about these heads is there is no upper boss on the heads for the stock alternator / power steering mounts of the '75. So the accessory mounts would need to match the heads. Your going to tear off the front & top of the engine anyway so...:)

KJ223 - If you are only swapping the cam, Cliff has the best suggestion with the XE256 cam and new valve springs to handle the fast ramps.

Dennis

It sounds like you do not want to swap heads but if you do, I'd remove 70 350 heads (#11) from your list as there are better options for increasing the CR. #11 heads have been discussed on here before and the reality is they're estimated to deliver maybe 7.9 CR in stock form, not the advertised 8.8.

I put a Summit 2800 in my stock 350 but haven't driven it since the swap so can't comment on power increase over stock, nor alternative cams. I do know that I'd replace the heads if I wanted significantly more grunt, and I also know I chose not to spend that time and money until I drove the car. The simulations predict increased power with my swap and that's better than less!

When I drove the car with the original cam and 2bbl, it still had a lot of low-rpm torque for what it is. Not tire-burning torque, but it felt like more power than some other V8 cars I've owned, especially considering it is pushing a heavy car around pretty well...and that was at 5200' elevation.

So I'll be interested in what you learn and what others are saying in this thread.

Mike

These simulations are interesting, thank you.

Was the stock cam in a '75 or '76 350 the 66 you show in your comparisons?

This would surprise me, given the cam in a 70 350 was a 54 and they did not increase CR in later years, but perhaps with a 4bbl they did install a bigger cam?

I'm not sure these are accurate, but they are the only specs I found for an 054 cam:

http://forums.maxperformanceinc.com/...1&d=1690573601

The only 350 that was factory equipped with the 066 cam was the 320 hp 1968 350 HO auto trans engine, manual trans 350 HO got the 067 cam. Both were equipped with #18 heads unique to this particular engine with 1.96/1.66 valves and had likely a true 10:1 compression at best.

The 1969 325 hp 350 HO stepped up to the big valve 2.11/1.77 #48 heads and up in cam to the 067 auto and 068 manual trans, probably the only 350 with over 10:1 true compression. The ‘68 and ‘69 350 HO were the only 350 engines with 4-barrels until the later ‘70s smogger 4-barrel low-compression and low-performance performance 350s appeared.

All of the comparatively mundane 2-barrel and later ‘70s 4-barrel smogger 350s had the mild 254 cam. The later ‘70s (all non-HO) 4-barrel 350 engines went from the earlier Rochester 2-barrel to the Quadrajet 4-barrel as standard carburetion simply for better emissions, they really weren’t a performance engine.

All those later Quadrajets on the smogger 350s were 800 cfm units as well, grab it if you come across one as they’re some of the best performance carbs after some calibration work.

I ran a 2800 in a 350P with 8.8 compression and it ran excellent. This was a “temporary “ ending while I redid original 400 motor. Ran very well. I have the cam and matched lifters saved (broken in right) and an Elgin timing chain and gears. I was happy with that cam in a 350

I made my own version of a 69 HO. I had a 69 350 and some 48s, put a 2801 in it. Topped off with the intake and Q jet from my 69 WT 400 GTO engine and some 3 tube headers.
Ran nice. Sounded like a old hot rod should. At 3500 RPM the engine took off.
Threw that block away and kicking myself for it.

Sorry but the 066 was the smallest Pontiac cam I had a file for. I have found some specs for the 254. It produces better number than the 066. Remember I have run these simulations with a CR of 7.5:1

Stan

My brother, Dan, has a ’69 350 HO Firebird (100% stock) and I have a ’69 350 HO Custom S 4-dr sedan (also 100% stock) that each have measured 9.7 to 9.9 to 1 static compression ratio cold and 10.0 to 10.2 to 1 hot with the Whistler box. The Firebird is a 4-speed car, so has the factory 068 cam, and the Custom S is an automatic car, so has the factory 067 cam. Dan ran both engine set-ups on the DeskTop Dyno, and the 067 cam made the same hp as the 068, but with 10 lb-ft more torque. So, don’t over-cam your 350. Both cars have the std. 3.55 gears with the optional HD Safe-T-Track limited slip.

Dan built and dyno’d a ’69 350 HO intended for the Pure Stock Drags way back on 2006 with 10.6 to 1 compression and a 067 inspired custom ground cam (201/217/110 at .413”/.424” lift) that made 342 hp (@5300 rpm) and 403 lb-ft torque (@ 3700 rpm) through the log exhaust manifolds and 2.5” mandrel head-pipes.

Your ’75 350 4-bbl needs 9.0 to 1 compression minimum to run well with anything more than the 2800 Summit cam, which requires different heads like 16’s, 62’s, or 13’s with a chamber around 78 cc’s.

Dennis

Thanks for posting! That's a lot of solid info. How do these cars perform in the 1/4?

The Firebird (4-speed M20) has run 14.30's @ 98+ mph. The 350 HO is still std. bore, but with a re-ring and new bearings, new Ferrea SS 1-pc valves and CC springs (115 lb. seat/275 @ .450") shifting at 5000 rpm. It weighs 3560 lb. with driver, full tank of fuel, and spare tire/jack in the trunk. (It has somewhere around 50,000 +/- original miles).

The Custom S hasn't had a chance to see any action yet as we just acquired it this past January and are trying to finish up the interior and exhaust. It likely will weigh in the 3900 lb. range race weight (w/driver, full tank of fuel, and complete spare tire & jack in the trunk). The 350 HO was rebuilt back in 1975 when the nylon timing gear sheared and must have bent some a valve or two, because there is a picture of the original owner standing in the engine bay in 1975. We aren't sure how it was rebuilt way back then, but it does run well and now has 72,000 miles on the odometer. There is a thread in the 68-69 GTO Tempest & Lemans TECH forum called "ebay 1969 4 door Custom S 350 H/O?" that follows the work we've been doing on it. If I had to guess, I think the Custom S could turn 14.5's at 95 mph once dialed in.

Dennis

I have a 350 at the machine shop now,going .030 over,eagle rods and getting balanced,number 17 heads and going with the sbc 2.02 intake valve and having a warpath classic muscle car cam ..445/ 468,likely the white box 214/224-2801 cam, hopefully i can report back and let you know how it performs in a month or two

I have used a couple 2801s in 350 60 overs.Ran good,one was a 2 speed auto.Tom

The 2801 is a fine cam for a 350 with 9:1 compression.

Not so fine in a 7.5:1 350.

Sure it will run, but you might not be all that impressed with it in a low-compression 350.

After all the time in the hobby this is a first for me, someone actually having taken a 350HO stick car down the strip. Thanks for the info I'm grateful! My 68 350HO car was an automatic and made a best pass at 14.1 - 99mph. The engine had a 0.030 overbore, longbranch manifolds, TH350 and a 2800 cam over stock. Very interesting comparison!

Sounds great! Any porting to go along on the heads? What was your chamber size on those #17s?
I did a set of #17 heads and mine were mid 80s CC chamber, but responded well to porting even with stock valves. I'd do the 2.02 or 2.05 valves like you if I did it again.

Based on the simulations that Stan provided the Voodoo 703 outperforms all other cams discussed.

Maybe on paper, but realize that dyno simulations do NOT tell us how well a cam will work once placed in service. Idle quality, vacuum production, throttle response, power right off idle, and good power and efficiency in the "normal" driving range is NOT well reflected by peak and average power numbers.

From what I've learned from actually doing this coming up on 50 years now is that compression is your friend with these things. Higher compression makes MORE power (torque) at every RPM, all else being equal, and it allows for larger cams with more seat timing and offsets losses in dynamic compression from going tighter with the LSA as well.

I've never built a Pontiac 350, but if I did the FIRST thing I would do was to obtain a late 60's set of small valve small chamber heads (grocery getter variety) like 1969 #46 castings. I'd do some good valve and seat work, better springs, screw in studs and mill them so my "little" 350 engine was closer to 10 to 1 compression than 7.5.

At that point I'd cam it similar to what I do with my 350 SBC builds (the exact specs depending on application/use of the vehicle). Then I'd enjoy closer to 1hp/CID or even a bit more, with good idle quality and street manners vs trying to defy the laws of physics and build a strong running 350 with no compression and too much cam in it trying to push around nearly 2 tons of vehicle without a lot of gearing or converter......FWIW......

I had an Elgin copy of the Summit 2800 cam in a low compression Pontiac 400 and it ran great. It had Very good low end torque.

FWIW…The simulators like Stan gave a screen shot of generates symmetrical cam profiles. I have a similar program. If you want an idea of how a cam like a 702 or 703 Lunati act on a simulator like that retard the cam timing about 6* and run a sim and that will mimic how that Lunati cam will actually run, then run it again with the rated advance and take the highest HP and TQ from both. That is what I have found anyway, it’s because they have such long closing ramps on those cams, they are not symmetrical. The XE isn’t either, but the programs is closer on them than the Lunati Voodoo. The program represents the Summit cams pretty close though, they have some slight assymetric’s in their profile, not much compared to the others mentioned. Not that I have seen anyway. 2800 would drop in with the stock valve springs.

Even at .050” the Lunati voodoo cam shows a couple degrees of negative advance compared to the nose. It is one of the only flat tappet hydraulic profile that does that, degreeing the cam .050” down off the cam nose or from .050” off the base circle move the ICL quite a bit on those, just by measure from different points. Those also have 5* more seat timing than what is shown on the cam card, so they are much less aggressive than a Comp XE.

Comp’s XE is pretty hard to beat for building compression on something that is extremely low on compression. If you want the rough idle and big mid range push the XE’s do that pretty well. You could even go as big as a XE268 if it has a lower gear than 3.08s, more like a 3.73. With 3.08s you probably need that XE256 just like what the other guys mentioned.

I think the mid 70s 350 probably has more compression than 7.5, because if I recall right, it does not have the all the cylinder scallops and valve releifs other 350s have. It may have exh scallops on the bores? It is probably just under 8:1 if it has never been apart. If I was bothering with a cam swap I think I would use new valve springs and run the 702 Lunati, then advance it to 106. It would be a decent match up of street manors and top end power in a low compression 350 with a 4 speed and 3.08s. Probably no reason to go with the smaller 701 unless it was taller gears yet. The 702 would not care than much about the lower compression with a bit more advance.

I've witnessed a few dyno runs with Pontiac engines using iron heads and Comp XE cams. I've also had a good many customers (thousands actually) that used XE cams in their engine builds and many had dyno'd them. This would include a of other brands, Chevy, Olds, Buick, etc. They suck horribly in a Buick build but not sure why? I had discussions with Jim Weise years ago when he tried them in Buick builds and had to go back to the T/A cams he'd been using. Although they superficially showed some promise coming up thru the RPM range the Buick valve train didn't like them much and the engines went "dead" past 5000rpms and he even experienced rocker arm breakage. Power not only came right back no more parts breakage when he went back to T/A or factory cams in his engine builds.

Ya before you remind me I know that's not related to Pontiac stuff so I'll add this tid-bit about XE cams. I'm NOT fond of them and that's common knowledge on here. I can make a LOT more power with a similar size Crower cam in the same application without having to run a LOT of spring pressure or experiencing "lifter crash" at high RPM's. I'm never seeing as much power from Comp cams with iron heads, at least those with 30 degree intake seats. That shouldn't be surprising as the flat chamber floors and 30 degree seats thrive on low lift flow.

With all the bad rap I've given those cams over the years I have observed one success with them in a Pontiac engine and a few success stories here, so I'll add to them. It was a 455 set up for "stock appearing" drag racing. They "worked" the factory heads pretty hard (not even sure they were legal) and they used 45 degree intake seats. They also used super light valve train parts, titanium retainers, stamped steel rockers, etc. That engine cranked out pretty hefty power numbers and made nearly 90 MORE HP than a 455 another customer built using the same heads and XE cam a few years earlier.

I don't remember all the numbers or specific details from each engine other than they were both 455's, both used iron heads, about the same compression, same cam, factory intake, Q-jet and factory distributor. As good as the XE cam did in that one build I would still never use one. I do NOT like having to use a butt-load of spring pressure on a flat cam to keep things happy. It's just a personal thing, and why would I when I can make PLENTY of power with closer to stock spring loads and cams with a LOT less aggressive ramp profiles........FWIW.......

Cliff,
I have never seen loses in dynamic (cranking) compression from tighter LSA. What I have seen is loses in idle vacuum from tighter LSA

Stan.

Cliff,
You answered your own question. Drag racing. Find someone running a "stock" Pontiac in NHRA and see what spring pressures they are running, along with tool steel lifters.

Stan

Wasn't talking about NHRA SA, the engine in question was going to be raced in factory Stock.

I'm well aware of what goes into "max effort" SA race engines as I build carbs (or used to) for them.

As far as cranking pressure from what I've seen here it's pretty much meaningless in the big scheme of things. My own engines have ranged from 150 psi to 200 and ALL of them made good vacuum at idle speed and excellent street manners.

What is HUGE in this deal is how much initial timing is required to get decent vacuum or the engine to even want to try to idle. Basic rule of thumb here is about 10-14 degrees. IF you aren't making at least 10" vacuum (hopefully more like 12-15") without running the timing clear off the scale at idle speed your engine isn't overly happy with the cam choice. I'm talking street engines here, not full race stuff.

At that point out come all the "crutch" fixes we get to read page after page of on here, my Forum, and just about every other Forum out there related to this hobby, when none of that would have been needed if the engine builder knew how to pick cams for the CID and compression ratio of these engines in the first place.........FWIW......

JMO but with an automatic and stock converter and 3.08:1 or higher rear the 702 might be a better cam.

Stan