P 350 for towing
 

OK, I'm building a P 350 to go in my 84 Chevy Truck because the crate stroker 383 is junk. I'm going to use either the 46 heads that came with it or some 670's I have that are already built. ( I know about the notches in the block). The question i have is cam choice. I'm thinking about Summit 2800 204-214. I want this motor to be smooth, quiet and super torque output for towing. Looking for about 320-350 HP.

Steve

If you want great torque from off-idle to highway cruising, then forget about HP. Look at the International Harverster V-8's, used in school buses and dump trucks. HP is blah, but they can pull HEAVY loads from a dead stop with no problem. They used reversed split, exhaust about 10 degrees smaller than the intake duration. Something like the old Comp 260 would probably work very well for what you are talking about.

Regarding heads i would drop the 670's on the block first with checker springs to see max lift before a valve hits the edge of the bore its a limitation on other large valve 4bbl heads

The 2800 wont be a bad choice but to help low end torque dont skimp on compression not saying push the limits

To get 320-350hp you'll need the CR the 670's will provide.

BUT, as mentioned, you don't need hp for towing. You need low end torque, AND gearing.

I had several one ton tow trucks, which I used to pull one & sometimes 2 cars to the track. Most of these had wimpy low CR 350 sbc engines. Some had 300ci inline six Ford engines. But, they all had 2 things in common: a 4-speed manual trans with granny low, and at least 4.10 rear gears. All these trucks made good tow trucks & got us safely to & from lots of races.

Also drove 2 ton milk trucks with these same type wimpy sbc engines, and a couple of 292 inline six engines. These trucks hauled 20,000# & more, most every day. They got their power from gearing, supplied by the manual 4 & 5 speed trans & 2-speed rear ends. Guessing that the high speed gear ratio was well into the 5's, if not closer to 6.00. When loaded heavy, and pulling a steep hill, we'd either downshift the trans or the rear end.

SO, IF you got enuff gearing from your trans & rear end, you can get by with a low CR P350, using the #46 heads. I would make sure you have screw-in studs. I've read that the early '73 model #46 heads had press-in studs. But, they can obviously be converted, for a couple of hundred bucks or so. I've read that all Pontiac heads built after about mid May of '73 had screw-in studs. So, most late '73 & 'all '74 #46 heads should have 'em.

I suppose that many will say the press-in studs are just fine for the small cam you'll be running. But, I experienced a pulled stud on one of those wimpy 350 2-ton truck motors. Just pinned it, in the truck, & kept on running it.

If you run the low CR #46 heads, you can use the small 250 Voodoo cam. It will increase cyl pressure and power. Probably make more power than the 2800 Summit.

http://www.lunatipower.com/Product.aspx?id=1773&gid=287

https://www.summitracing.com/parts/s...xoCnDwQAvD_BwE

If you have press-in studs & don't wanna switch, it might be a good idea to go with one of the low lift factory clones, like the 066. I think the Melling SPC-4 might be one of these.

https://www.ebay.com/p/Melling-SPC4-....c100005.m1851

I believe the Sealed Power CS-641 is also one of these.

https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds

https://www.summitracing.com/parts/s...w/make/pontiac

Butler also shows that the Melling SPC-5 is one of these low lift clone cams--maybe the 067 ?.

https://butlerperformance.com/i-2445...tegory:1234841

https://www.amazon.com/Melling-SPC-5.../dp/B000C4KLDK

https://www.ebay.com/itm/Engine-Cams...4383.l4275.c10

If you wanted to use mostly stock parts, this cam or the voodoo 250 with the 46 heads should work. It looks like a healthier version of the stock 350 cam.

http://www.lunatipower.com/Product.aspx?id=1757&gid=258

Butler performance make a stroker kit to take that up 388 cid and that's where I would start!

Me and a buddy were thinking the same thing. A Pontiac 350 in a chevy truck for "truck duty`s". A better working engine than the sbc. Stronger block, more space between bores, [better cooling than the 400 or 455], stronger crank, longer stroke, longer rods, longer runners in the intake, and a high velocity head. All on 354 cubes. Torque with decent mileage. :cool: Even an auto trans with a 2.78 to 3.42 gear would get most jobs done.

I see nothing wrong with your plan. I've used the 2800 on a 350, and had no complaints when used as designed. Gobs of vacuum at idle. And the 2800 will go with everything else, like press in studs, etc.

Tough call on which heads to use. 46's are small valve, so you would have less shrouding. If it were me, I'd use the 46's, but would still be curious how 670's would perform on a 350.

I agree with Steve. 350 cubes is not really enough cubes....I'm very aware of the stroke/bore advantage of a Pontiac over a Chevy, but it still doesn't make up for the grunt needed you are looking for.
One of the biggest problems with Pontiac 350's is getting the compression ratio to a respectable number to help the power production, BUT you don't want to go too far in a towing situation, with the engine being under a constant load situation. 9:1 would likely be the max for your deal...
A stock low compression 400 would get you to where you want without much added expense....

Any truck chassis that was designed to work with half the torque and HP of a moderatly prepped P350 should shine with the extra power of a P350

I agree. We used to have a `66 Chevy pickup. It had the "High Torque 250" decal on the valve cover. Hardly a big engine.

Back in the day, I`ve seen the Chevy C60 series 2 ton trucks powered by 2bbl chevy 350`s. Big ole truck with 350 cubes. A Pontiac 350 could have done what those engines did in those trucks.

In other words, one doesn`t HAVE to throw away any Pontiac 350 or automatically stroke them. They have a place for use if you have one.

Wonder what stroke most 383 sbc`s are? 6 inch rod [vs 5.7] with a 3.75 stroke? Hmmm.

which version of the 46 heads are these? 69 or 73/74. if they are 69, i would install harden seats on the exhaust and go with the small valve head. The 69 version have smaller chambers, around 72cc. I would run something like a SPC-5 cam (066).

Keep it simple and use the 066 cam, used in the '68 320 HP 350 HO auto trans applications.

Here's the perfect time to clear this up.

I assume that the Melling SPC-4 is an 066 clone, and that the Melling SPC-5 is an 067 clone. If this is NOT the case, will somebody please post the correct info.

Also, please list all brands & part numbers for 066 & 067 clones, and links to this info.

Thanks !

Butler shows some specs for the SPC-5, but don't say what it's a clone for.

https://butlerperformance.com/i-2445...tegory:1234841

This list on the Wallace site shows some specs for factory cams.

http://www.wallaceracing.com/camcode1.htm

Here's some more specs. As always, not all online info agrees.

http://ronspontiacpage.com/reference...ckcamspecs.htm

http://www.pontiacpower.org/PontiacCams.htm

http://www.classicalpontiac.com/restoration/cams.html

http://ronspontiacpage.com/reference-pages/crane.htm

Paul Spotts says this cam is "...factory blue printed 9779067 - 066...". Don't see how that can be possible in one cam, since the two are SLIGHTLY different. :confused:

https://www.ebay.com/itm/Pontiac-sto...sAAOSw0e9UwqDI

Also says "...Made by same company that supplies Melling, and others - US made!..." So, I assume it is exactly the same cam as either the SPC-4 or SPC-5.

Here are the Melling specs. Pontiac cams are near the bottom of the page. SPC-4 & SPC-5 are similar, but different.

https://www.melling.com/wp-content/u...ck-294-304.pdf

The 2800 has slightly less seat timing and slightly more off the seat duration and more lift than either 066 or 067 cams and having actually experience with it in a 350 it basically acts like a entry level 4bbl camshaft torque coming in not long after idle and it doesn't feel like it runs out of breath on the top end also it wont stress valve train much as its not a far departure from bone stock cams its hard to beat in a 9.2-9.6 compression P350

I have a stock 350 1977 Chevy 3/4 ton truck with a 4.11 rear, I may be doing the same thing soon myself.

Sounds like a cool project to me. Good use of a P350.


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Good point. I forgot that the 73/74 heads might be a possibility. I just assumed it had the heads from 69 swapped on. Those would make for a low compression engine. A bonus would be if they were screw in stud versions.

I would stash away the 670's. Or sell them to fund the project. If the 46's were the 70's heads, mill them for a compression bump. If the 69 400 heads, then use as is. Cast pistons, 2800 cam, and get on it. This is for a towing rig, and sounds like a "build with what's in the garage" thing. It doesn't sound like an all out performance effort, so I think it's ok to not go after every bit of ideal compression.

My 16 year old son wants a pre-87 GM truck, or possibly a 70's Nova. I told him that he has his choice of a few 350P's to drop in. One of them currently has a 2800 cam.

You’re talking about the 549. The block alone weighs nearly as much as a complete Pontiac engine. Not overly powerful, either. IH never had one that was rated over 250hp. Parts are difficult to find on a good day.

Truck has a crate 383. Same stroke as the P350.

I'd be curious about engine specs on the 383 (HP & TQ curves, CR, etc.,) and what is junk about it. Need to know exactly why it's not getting the job done.

Less cubes with the same stroke sounds like a step in the wrong direction.

The stated HP goals is gonna take a lot of compression to get the idle quality and off idle power the OP is looking for. IMO that compression requirement will be all wrong for an engine with 2~3 times the cruise load a car would have. That will make for a bunch of heat which is a problem with higher CR's.

Need to hear more about this truck and what kind of load it's got to tote...transmission rear gears and the like.

Clay

In addition to the above, this may be one of those ideal combos for an SP2P intake.

I guess I'll be the only one that thinks your crazy :D

The amount of money involved to make all this work just doesn't make any sense to me. The headache of trying to get all the accessories to work, the transmission, Cruise, Air, PS etc.... For a Pontiac 350??? switching brands like that opens up a ton of obstacles to overcome in an 84 chevy truck for what I see as no gain at all.

If you really want a tow vehicle, I'd be selling the 84 and looking for a nice used diesel. Even a BBC version of that vintage truck would serve you better and not break the bank.

If none of that is an option for you, I'd stick with the chevy engine in a chevy truck idea and save yourself a ton of headache.

Wonder how many headaches were had putting chevy engines in Pontiacs in the past? It would have been easier to keep a Pontiac 400 in that black `68 Pontiac Firebird 400 instead of that sbc I saw at a show.

Nice black Firebird 400 vert. Till I got up to it and walked away. Many headaches like that we all have seen.;)

I get your drift, in this case, about keeping a chevy engine in that truck. But, he`s got that engine laying around already. AND, piss off the chevy guys.

A classic is easier, plus switching from what was a Pontiac to a chevy engine is cheaper and easier to find the parts for. Talking about an 84 chevy pickup, it has a computer, AC, Cruise control, a 700R4 overdrive trans that becomes useless. etc...

To swap to a different brand engine in a chevy truck "properly" and have things work like they should will be a fairly expensive adventure that simply just isn't worth it. There is no gain.
I can see butchering the job and doing it on the cheap, hack half the wiring harness, forget about emissions controls, shove a Pontiac 350 turbo behind it, get a driveshaft made, and forget about trying to get the accessories hooked up, but then you're going to be stuck with a truck you now hate to drive and gets horrible gas mileage, and likely won't pass an EPA visual or sniffer test. Why?? It's not going to tow any better either after all that trouble.

Get yourself a better tow vehicle to start with. Nice used 3/4 tons are everywhere for little money. Or just keep your chevy engine in the chevy truck, fix what's broke and save a ton of money and headache.

Better yet, buy a nice little SBC crate motor with a warranty, drop that in and be done with it and save yourself the trouble.

Plenty to choose from to suite anyones price range. There are even 383 crate engines out there in various forms of power.

I`ll give you that. But, if he wants to endure the headaches... :)

That is the path of least resistance.:cool:

Here's a quick and easy solution that is cheap.

https://blueprintengines.com/collect...er-cam-1pc-rms

Roller cam, decent power, vortec heads will require a new intake but most everything else is a simple swap over and done type of deal. Not to mention 30 month 50k mile warranty.

Not sure how the computer and electronic controlled Q-jet would like the camshaft (it is a mild cam however) but since the OP was running a 383 already I'll assume he has the ability to tune it accordingly.

So if the truck is nice, well maintained, and worth keeping, this would be a viable option for $2500.


Where's Pontiakr when you need him, he's better at googling this stuff and could probably find something like this cheaper ;)

Junk 383 crate is what the OP has now. And appears to be tired of it.

Looking at the OP's sig quote...I suspect he knows what he's doing.

What one might see as a challenge, could be a cake-walk for someone else.

Clay

Are we back full circle to junking the Pontiac 350?

No specifics on the crate 383 as to who or why so I won't speculate. I don't pay attention to sig quotes, it's the internet after all. But if he does truly have the abilities then I guess it's safe to assume he was able to tune the factory computer to accommodate the 383 and we can rule that out as being a cause. Or has this thing been gutted and converted to something more simplistic already?? Just not enough details here.....

This ain't that, and I didn't think I came across that way. Nothing at all wrong with a Pontiac 350.

Trying to swap one in an 84 chevy pickup for towing that already has a chevy in it however throws up several red flags that I've already mentioned. None of which stated a Pontiac 350 was junk.

A computer in a 1984 Chevy truck?
The 84 we had was without computer and overdrive.

3/4 or 1 ton?

computer controls hit in 81, with computer controlled Q-jets and distributors.

82 was the first year for the 700r4 overdrive and would have been in 1/2 ton trucks with 350's.

Heavier 3/4 ton trucks and the big blocks of that vintage were still getting 400 turbos as GM did not have a heavy duty overdrive (4L80) until about 1991.

The '84 GMC I had, was equipped with a Q-jet & a 4-speed manual, with granny low. Don't think there were any computers on board.

I assume that the auto trans 1-ton trucks would have had a TH400 that year.

Guessing that the sbc equipped 1/2 tons would have come with a TH350, and that all BBC equipped trucks would have come with a TH400.

That's a 1-ton. Little different deal. At that time they didn't have to meet the same emissions restrictions that the smaller 1/2 tons did. If over 9000 GVW they didn't even put converters on them.

My 79 1-ton 454/400 turbo never had cat converters from the factory, even still has large fuel tank filler neck openings for leaded gas pumps with larger nozzles, even though in 1979 that was just about phased out at that time frame.
If you read the fuel gauges in these trucks, the heavier GVW trucks also won't say "unleaded gas only" on the fuel gauge.

3/4 ton.

That's why. As I explained in post 34, GM wasn't putting overdrives in the 3/4 ton and up trucks as they didn't have anything strong enough at that time. Had to wait until 1991 for the overdrive in anything 3/4 and up.

That would have no CCC. Even better place for that P350...

"...82 was the first year for the 700r4 overdrive and would have been in 1/2 ton trucks with 350's..."

Here's an online quote about the TH350 in trucks. Obviously, I can't say if this info is right or wrong.

"... Chevrolet/GMC trucks and vans used the THM350-C until 1986..."


According to online info, the 700R4 trans can be used without a computer. Pontiac guys do it all the time.

https://www.google.com/search?q=how+...hrome&ie=UTF-8

Here's more online TH350 info, saying that the TH350C was used in some 2-wheel drive trucks & vans thru 1986.

http://gmautomatictransmissions.com/...plications.php

http://wildaboutcarsonline.com/cgi-b...=9950419968967

Hope he doesn't plan on towing any heavy equipment.

OK, the heads are 73 #46 with press in studs and 1.96/1.66 valves.

Next, I have 4 - 455's, 2 - 400's, 1 - 301, 3 - 350's. and maybe another 428 and 455 on the way. I am not looking for all these engines, they just "show up".

So I restored 1- 84 chevy truck and just ran the reman. 305 that was in it till it started to knock, I did not want to put a Pontiac in it at first because of all the accessories and mounting brackets...SOoooo..I bought a Blueprint 383 crate motor that for the truck. It had ample power but the cam loped too much and vacuum was too low for the power brakes and shook the truck at idle with the a/c running. No more big cams for an everyday driver!!!! Last year I was towing my Firebird home from racing and it started to slowly lose power, I figured I may not have tightened the distributor holddown screw and the timing was backing off. Made it home and the next morning fired it up and it sounded like hammers in the block. I'm figuring a broke wrist pin maybe a bearing but oil pressure is still good and no debree in the oil. No more Chevy engines in my vehicles.
I have since restored a 1984 GMC 2500 LWB truck also and it will get a pontiac motor too, after the 305 expires.
Gas mileage is a consideration as the factory tanks are about 16 gallons.

Steve

Back in the day, a friend of mine built a few 400 Pontiac powered late 70s Chevy Trucks. It was a pretty straight forward swap. I think I would definitely use a 400 or 455 if was going to go to all of the trouble, especially for a towing application.

Formulajones, you mistake me for a regular guy!!!!!!!!! I ain't scared of cutting frames, mounts, etc apart and "fixing them"
I restored a Trans Am and ripped out a perfectly good A/C system, smoothed the firewall and installed a Vintage A/C system for a Camaro because they did not make one for a Firebird, Try Building A/C brackets with a Procharger system too.
I welded extra tabs on 700-R4 transmissions to bolt right up to Pontiac motors, so simple almost anybody could do it.

Steve

ALSO, I have a Ford F250 for towing/working and a 28' enclosed trailer but sometimes I like to go retro and pull my Firebird open trailer with an old Truck, I think it is too cool.

awesome i say go for it

Back in the 90s I had 78 chevy shortbed 2wd. Had 428 Pontiac in it. Was a blast to drive and had plenty of power. This October I'm putting 350p in my 3/4 ton 83 chevy. No ac or overdrive. My ac is 60mph with windows down. 350 chevy crate motor in it now wont fall off a cliff fast. bought 350p from a friend rebuilt for 500 bucks. Has the 47 heads which are the pressed in rocker studs but I'm going for economy and not hp. Has the 320hp cam in it but wonder if #48 or #64 would make it a little stronger? Decisions never end.

Or some 18 heads or '70 16's.

I don't understand the dis-like for SBC truck engines?

Since I discovered that GM makes and sells a 4 bolt main roller short block with "N" crank and powered metal rods that's all I use here for what you are doing.

The block doesn't have a cam, front cover, oil pump or timing set, but does have a provision for a mechanical fuel pump rod.

Install a set of Vortec or even better 64 cc aftermarket heads, CS-274 cam or upgrade to a roller set-up, the block with go either way.

Light years better than any Pontiac 350 set-up and it will be dead solid reliable for at least 100,000 miles. I have some out there with the roller cam upgrade that have went further than that and still no issues anyplace.

One is in a 1 ton service truck used by a friend of mine to do HVAC work and it has PLENTY of power despite moving around over 10,000lbs on a daily basis. I have another in a 1991 Chevy 3/4 ton backed by an NV4500 5 speed and 3.73 gears and it is used to haul a 24' horse trailer and has to be over 12,000 loaded and it does fine. The owner says it is much stronger and more efficient than the original early Vortec 350 it replaced.....FWIW.....Cliff