As far as replacing the excellent factory cast iron intake with a Performer, waste of time/funds. You are putting a smaller intake on the engine so no power waiting for you anyplace. So like the millions of folks before you who own a Pontiac or other Detroit based V-8 engine about all you've done best case scenario is spend a couple hundred bucks to take 27 pounds off the front of the vehicle......

I disabled the egr on a `79 301. That motor pinged till I put it back.


The `79 400 didn`t. But, it had a larger cam.

I was just following orders.:)


I would have left it alone if it was mine. Low miles, numbers matching `79 SE, W72, WS6. What`s that car`s production? Maybe 1700 or so?

If you're keeping it very close to stock using the original log exhaust manifolds and Y-pipe (or true duals), I wouldn't go with any new HFT cam larger than the 2800 myself. You'll only have very low 8's compression like Cliff said, even after a resurfacing. Here are the dyno sheets for the '79 W72 with the original Y-pipe and then with 2.5" mandrel bent head pipes...FWIW. Dan also dyno'd it with RA manifolds to see what improvements they made.

Dennis

Thanks so much for all the responses. This W72 is 4-speed is all stock, including the intake. As for the exhaust, using the stock exhaust manifolds, but then the 2.5” stainless Pypes X-pipe, along with their down pipes (so, no factory Y-pipe) and then the Pypes Turbo Pro mufflers.

Interesting comment, Cliff about the loss of power above 5200 rpm. Since all stock, but rebuilt Quadrajet with the larger 800-CFM carb, standard on the W72, agree some power capacity should remain, though not more than would be expected from a low compression 400, such as this one.

Leaning toward the recommended Crower 60240, as it does seem to have a bit more power down low than the Summit 2800. Good to hear that the 60240 has a smooth idle and has a hint of a larger cam in tone. Would still like to hear one though, a recording of it, if anyone is running this cam on their car. Kindly advise.

Thanks so much!

OK, so not to hijack, but I have a related question. I know one should not choose a cam based on idle sound. But I also know that people do like the car to sound a little spunky. So usually, if someone wants that sound they go with more duration. What if you did a custom cam and kept the duration low but went with a tighter LSA, more overlap? What would that do? Would it help anything or just make your dynamic compression even lower and run like crap?

EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA) HERE:

https://www.compcams.com/cam-timing-...paration-angle


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Excellent info, Steve - thank you!

Choosing the cam for the power - relative with these low compression 400’s, I know - but would like some idea of idle, mindful the exhaust note dependent of the exhaust system chosen, etc. Want it to sound smooth and close to stock.

So what do people think about doing something like the '79 W72 cam but on a 110 LSA instead of the factory 113.5? Seems like it might have some benefits for what the OP is looking for without the negative effects of a bigger cam in a low compression motor. Would that be correct or am I missing something?

And to correct myself, I said that it would decrease dynamic compression but I had that backwards.

The tighter lobe separation might be helpful for a lower compression. But in the OPs situation wanting the 'smooth idle' it would be negative because the Idle quality would suffer.
That said a slightly rougher idle might be tolerated by many.

Another topic of interest might be changing to lobes with the same, or very similar, .050-duration but with less seat timing.
And with the same or similar lobe lift, or even adding additional valve lift.

Example, I suspect if you look over the lobes listed here at Bullet you might find something that has the same duration at .050", but with less advertised duration. And again with the same lift.

https://www.bulletcams.com/Masters/HFlobes.htm

This does not necessarily represent any endorsement here, its is offered for general interest only. Also keep in mind Crower, Comp Cams or others will grind custom cams to fit your needs.


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Thanks Steve, I appreciate your expertise. I thought the OP also said he wanted a little hint of cam in the idle too, that's why mentioned it. Maybe I got that wrong. Anyway, good thread.

Example, using the intake lobes for conversation in comparing the Crowers tiny 60240 cam to one at Bullet Racing, their HF260/300 lobe.

The Bullet lobe has less advertised duration with 260 degrees but the same 210 degrees duration at .050" lift. It has .450" lift vs Crowers .422" lift, beneficial if it can be utilized.
The only unknowns here is at what tappet lift are the two lobes advertised duration rated at and the .200" duration numbers.

https://www.bulletcams.com/Masters/HFlobes.htm

Using the calculators available at Wallace note the affects of the reduced seat timing.

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

A similar situation could be applied to the exhaust lobes. And again noting any lobe separation desired could be utilized with a custom ground cam.


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Actually, the '79 W72's custom Comp Cam was ground on a 110 LSA. It made great vacuum and idled very well. The idea was to build cylinder pressure with only 8.1 compression. Here are the specs.

Dennis

Just to add my 78 W72 cam to this thread, I picked a XE268 cam for mine before I read about other options or opinions on the XE cams. It runs very good in all situations with no tuning issues, pinging or being soft off the line, pulls great to 5000 with no hesitation etc. Its a basic build at .030 with TRW/Speedpro pistons on stock rods, 6x-4 heads milled about .025-.030, comp is estimated around 8.75ish. 1.52 comp roller tip rocker with no problems or "blueing" from heat. its a 4 speed.

The carb was set up by Cliff so Im sure that helps a lot, but I dont have any of the problems some claim on this cam, its ran mid/upper 13's at 103+mph, taking it easy on launch due to a newer street clutch & not wanting to hurt the engine or car, just a fun test & tune day to see what it would do. Hard BFG street tires & not very good track prep. Sure does run good for a turd cam. ;)

Nice. The results you got for both of those motors was very impressive.