‘79 W72 Y84 4-Speed New Cam Search
 

In progress with re-build on a stock W72 and want to keep it close to that with the refresh. Have read all, if not almost all, of the threads on the plethora of cam choices. Heard the videos capturing the idle on the Summit 2800 and 2801 cams, as well as the Lunati.

Seems wide support for the Crower 60240, though have not been able to find any videos of its idle. Realizing the choice of exhaust will affect the tone, would like to hear the idle sound to see just how smooth. Anybody running that 60240 cam in a 400 and have a vid to share? Kindly advise.

Thanks so much!

How is your car geared?

Does it have AC?

The factory put a lot of thought into the 402 cam that was fitted to the 78 and hence the 79 W72 motors.

It’s been found over the years that your motors stock 402 cam performed the darn near equal of the factory 067 cam, but for maybe a 4 Hp difference on the top end .

To this day I am surprised that no one has ground up a high lift version of the 402 cam.

Peak Hp with the 402 cam was at about 4300 rpm which even with 3:23 rear gears was a real good place to be.

Don’t make yourself crash on a rocky shoreline by picking a cam by exh sound when you only have a 8.2 comp motor at best.

I had a Summit 2800 cam in my low compression 400 w 4 speed. Very good low end torque and a kick to drive. Summit sells it for 243 Bucks with lifters and you can use stock valve springs.

My brother, Dan, rebuilt two different W72 400 engines, a ’78 and a ’79. The ’78 W72 was the original engine in his ’78 WS6 TA which was modified in an earlier life, then removed for an SD-455 engine. The original 400 (completely torn apart with original rods missing) was already .030” over and needed .040” over pistons to clean up the cylinders properly (so new custom forged pistons and Eagle H-beam forged rods, but ignore this if your short block is good). With rebuilt stock 6x-4 heads minimally cut for trueness, new Ferrea 1-pc stainless valves, CC springs, etc., the static compression worked out to 8.75 to 1. He installed a Summit 2800 cam with old (never used) Crane hydraulic lifters, old factory RA exhaust manifolds, original factory cast iron intake manifold and original Q-jet rejetted for more power on the dyno. With the small 2800 cam, it made 360 hp/456 lbft torque (at 5000/3600 rpm respectively).

The ’79 W72 was a stock std. bore rebuild (new rings on original cast pistons) with minimally cut 6X-4 heads, new valves, etc., stock manifolds (intake & exhaust) & Q-jet. The static compression was 8.10 to 1. Dan had a custom cam (CC) made with 201/219/110 @ .050” with .420”/.450” lift to try to emulate the original ‘402’ cam specs as much as possible from their standard lobe selections. It made 329 hp/413 lbft torque (at 4900/3400 rpm respectively). This was through stock exhaust manifolds and 2.25" headpipes (not mandrels bent pipe).

Steve25 is right on with the ‘402’ cam being a pretty good grind and the Summit 2800 and the Crower 60240 cams are good replacements. The 60240 would probably like more compression in the 8.5-up range, however, we’ve never used one yet.

Dennis

Cam Quandary

An In-Depth Look at the '77-'79 T/A 6.6 Camshaft Specs

https://www.motortrend.com/how-to/hp...-cam-quandary/


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Steve C. - thanks so much for the article, very helpful!

Steve25,

Thanks so much for your suggestions. My car is all stock and that gearing for the stock 4-speed transmission is 3:23.

The car does have A/C.

Not trying to make the car more than what it is just want to have a smooth idle and decent power, mindful of the low compression of these late ‘70’s blocks.

Thus, just trying to choose the right cam.

I don`t have a vid but, I did install the 60240 in a bone stock PWH `79 400. It had Doug`s headers and a Performer intake. Still had the stock heads and springs. Car ran well. When cold, one could hear the cam. As it warmed, pretty smooth. This is with headers. With manifolds, I doubt if the "cam" sound would be there.


Seemed to pull to 4800 to 5200 and fall off sharply. Could have been the stock springs but didn`t hear anything bad going on.


It does have a lower lift and gentle lobes that one could use stock springs.


I put the intake and headers on as it wasn`t my car and that`s what the owner wanted. The engine had 48,000 miles and was un touched.


`79 black/gold SE with WS6. Nice car.

Did the above still have its EGR and stock carb ?

Me? Stock carb and no egr. Did add Comp 1.52 roller rockers and poly locks. A little tidbit I should have added above.:)

Guy was actually a mopar freak. He said he would never sell that Poncho. That`s what happened. All classic cars got sold except the T/A. Last one to go was a `70 Challanger R/T. 440, 4 speed, dana 60. Red with black vinyl top. Amazing. He sells a car just under a hemi E body and keeps a low compress poncho.:eek:


True story.


I`m guessing the looks AND the handling was too much for him go go back to old mopar handling.

I did have fun for around 6 months driving that thing around with the stick and having the kids checking it out at red lights in mom`s suv.. Brought it to a few car shows. Painted the intake blue. Could hear some folks at the shows talking to each other about the "big block'.:rolleyes:

Dennis,

Thank you for that history - interesting real world examples! Fascinating too about the “402” recreation vs. the Summit 2800. Seems that the Crower is good too, but apparently runs out of steam above 5000. Cliff says that this 60240 is the one that has been the most overall successful with these lower compression 400’s, though the data on the 2800’s sure is impressive. Would still like to hear what the Crower sounds like, though it is reported to be smooth on idle.

Interesting to see the 0.050 specs on the W72 cams. 0.050 close to what my '97 Vortec 350 truck motor has!

The Summit 2801 in the 93cc 6X-4 heads on the flat top piston 400 in my 81 TA is about the same idle as my 78 TA had. Decent power RA exhaust manifolds into 2./5" dual cats(they were still smog testing here when I put it together.

Stated... "Seemed to pull to 4800 to 5200 and fall off sharply. Could have been the stock springs but didn`t hear anything bad going on."

Might of been nose diving due to inadequate pressure to control the valvetrain mass.

"The valvetrain is one of the areas where properly matched parts are vital to ensure that the engine functions properly and the valve springs are the key to this."

Valve springs often loose pressure over time.

To the OP. If the springs are old. Replace them.

Not a place to cheap out !


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After running a 2800 and 2801 and a 068 cam in a 350, The 2801 shouldn't be to much cam in your 400 with a stick it has more low end torque than a 068 and will have more legs than a 2800

Agreed.

A reality check is in order here. IF you cam one of these late model low compression 400's with enough duration to pull HARD to and past 5000rpms you are going to have to drop it off a floor jack to spin the tires from a stoplight! Compression is your friend with these things, and your enemy. Unless you have 6X-4 heads that have been milled down a bit, flat top two valve relief pistons close to zero deck, and a thin head gasket to get the squish tight and compression up to at least 9 to 1 looking at cams with enough duration to make strong upper mid-range and top end power is a complete waste of time.

The 4 speed and 3.23's help some here but it doesn't appear we're going to have much past 8 to 1 compression when it's all said and done. It also appears that idle sound is on the list of requirements. You just can't have your cake and eat it to with a 400 build at 8 to 1 compression pushing around a car weighing 2 tons. Big cams with a lot of overlap are not on the list with these builds.

I have typically avoided "low" compression 400 builds over the years as most customers I've had were wanting a stroked version or going to early heads to get the compression up some. They already knew those engines were turds right out of the box and had owned the cars long enough to want to up the power considerably. The few that I got involved with early on educated me to stay away from larger cams in them. One was brought here to custom tune that had the Summit 2801 cam in it. It was really "soft" off idle and didn't start pulling well till 3000rpms or so. Had another in here with a Comp XE262 cam in it, what a gutless turd that was. Even got involved with one that supposedly had the compression raised some and Comp XE268 cam, it was even a bigger turd! I've also been around a few with the Summit 2800 cam in them and they were remarkably smooth at idle compared to the Crower cam. That would be a close second choice for one of these engines if I were building it here and the customer wanted stock type idle and good street manners.

I'm mentioned several times on here over the years that the first engine in my Ventura had 6X heads on it and the Crower 60240 cam, 210/221/112 LSA. Idle quality was decent, just a hint of a larger cam going on in the idle note. Strong mid range power and pulled really hard to 5000rpm's, and excellent street manners.. With 2.73 gears, TH400, and a stock converter it ran 14.0's @ 99-100mph at the track on BFG street tires. Best run ever in really good air and track conditions was 13.87 @ 101mph. That's getting it done pretty good for a pretty much stock late model 400 build with unported 6X heads on it......

My question about the removal of EGR to run the performer and the use of a stock carb From a EGR motor is due to the leanness that will take place when the EGR system is made inoperable and then responce from the motor will ping and surge.

I cringe when hear that on any car be it Pontiac or whatever that someone has disabled the EGR system and now has ping and off idle carb response problems.

I disabled the EGR on my old stock 180 HP 78 motor when I swapped on a 72 HO intake no pinging. The 400 in the 81 has a plain performer(although I have an EGR one if we ever get that much govt inspections!) and no pinging.

One more note on the pull hard to 4800-5200 rpms then drop off sharply.

CLASSIC symptoms of sucking the bowl dry on the carburetor. More times than not that's going to be the issue vs weak valve springs or something not up to par in that area. I usually look there before diving into the engine to see if there are valve train related issues......

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.