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


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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.