Cam selection based on availability
 

Starting a new post since a lot changed since I started this one last year.

https://forums.maxperformanceinc.com...d.php?t=843418

Need cam advice based on actual availability due to current cam shortage from lack of cores.
Have:
70 GTO
5 speed
400 block
4.25" stroke Eagle crank
#12 heads reworked by Butler with Crower 68404 springs and 7/16 studs. All new Ferrea valves, etc. 72 cc

Plan to have block done 0.035 over with Icon forged 30 cc dished pistons. ~9.5:1 compression. Forged rods will also be purchased.

The heads limit power as they are unported, but that is OK. They are original and I plan to keep them as is. The springs limit lift to 0.520. Budget calls for HFT.

Looking at what's out there in stock, there is the Melling SPC-8 041 Ram Air IV clone that I could use with 1.65 rockers but will I need to elongate pushrod holes?

The Lunati 704 has a little more than 0.520 lift and probably wants a little more spring pressure than the 68404 springs provide to control its aggressive ramps.

I am willing to sacrifice a little power for reliability/not modifying the heads further.

Would you do either one of the above or wait on another cam option in 6 months or more?

RAIV with 1.5:1 rockers, no need to grind for pushrod clearance.

Fairly gentle ramps and .470” lift should be pretty easy on parts and have longevity. Heads with stock ports don’t really need more than .470” lift in this instance, the cubic inches will do the work.

It’ll be a fine street engine that you can drive anywhere with plenty of power.

Thanks, Bart. Makes good sense.

What we did when using the Lunati 704, was shim the Crower 68404 spring to install at 1.550" with stock length Ferrea valves. This puts them around 125-130 lb on the seat and 310-315 lbs over the nose. The 68404 spring coil binds at .950", so this still leaves around .075" before coil bind with the Lunati 704 camshaft using a 1.5 rocker.

The 68404 springs are good for more than .52” lift. Would be my first pick for springs in your combo for either cam. FWIW, I would only shim the intakes with the Lunati. And only if it has 30* intake valves. I know sometimes Butlers change the intakes over to 45*. Depending on how the springs are set up they can run upwards of .54”- 57” lift.

I would rather do the 704 Lunati if you can find one. It will have a stronger mid range than the SPC-8, well suited for a manual tranny set up with the gears are space closer together. I would not expect much difference in max power though between a SPC-8 and a 704 with stock heads, but would think the 704 would out perform the SPC-8. But it will come at a price, I think you will find it will be pickier on fuel than the spc-8.



I agree with Bart too. If the spc-8 is what is available, it will work fine. The summit 2821 is the same cam if you can’t find a melling spc-8.

I had just ordered a Lunati 702 directly from them a few weeks ago and got it last week. It took about 26 days, so you might be all right just ordering what you want at this point.

You may want to consider am Ultradyne/Bullet cam and talk to Tim Goolsby. I used their 278/286 112 LSA cam on a similar/mild 400 rebuild (.030 over) with stock 13 heads that dyno'd 400+/480+ without extensive tweaking.

https://i.imgur.com/g8niqGE.png

RA IV "copy" SUM-2821 is in Stock.

Slight updates as I found the cylinder head paperwork. They are 73 cc chamber volume and the valve seats were ground 30° on intake and 45° on exhaust.

Might check with ClaySmith cams.Built custom cams for a past pontiac racer.Had him do a custom hyd roller for me a couple month ago.Came very fast.Tom

HIS, thanks for the heads up. I ordered one friday. BLUE TA

What about a Crower 60211? Seated seat pressure looks ok with the 68404 springs even though Crower does recommend the 68405 springs. I know my unported heads will not take advantage of the lift but possibly better overall than the 041 clones. The 108 LSA might make for a little lumpy idle and higher power band.

What is your total low gear ratio? Thats first gear times (X) rear end. And has the car got vacuum assist power brakes"

For about the same power and a bit more street friendly... Think I'd want the 60244 more than the 60211.

Clay

First gear 2.80, rear 3.23. So, 9.044 overall. I would be concerned about vacuum for power brakes so the 60211 may be an issue. The 112° LSA on 60244 would definitely produce more vacuum and low end.

RA manifolds will be hamstringing the 60211. Wouldn’t be using the extra overlap very efficiently. Be a good choice with headers, and a vac pump or some Rhoads.

Per Summit's Q&A/reviews on the 60244:

Will this Cam work with Power Disk Brakes without a Vacuum Canister?
Asked by DANNY on 2/5/2017

1 Answer:
It will depend on displacement. In a 350" Pontiac, doubtful. In a 455, most agree it will work. I had one in a 76 TA with a 400 and it worked, but not as well as stock, with my power brakes in a standard transmission and 4:10 gears.

The 041 cam is one of the worst cams they ever put in a Pontiac intended for street driving... Don't make the same mistake the factory did.. That cam is strictly for drag racing and will take all the fun out of driving your Pontiac..

"The 041 cam is one of the worst cams they ever put in a Pontiac intended for street driving"

And how many cubic inches is this statement intended for ?

Some specifics should be involved. 400 ? How about in a well build 455 ? How about here:

This application its not too shabby. Yes not a factory 041 but the cam here is considered by MANY as very good substitute for the 041 !

https://pontiacstreetperformance.com...d455MikeG.html


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As info:

Crower just shipped my cam that was ordered three weeks ago. Looks like they are catching up.

Just FYI, Crower has no HFT Pontiac cores and no ETA. Left voicemail with Tim Goolsby at Bullet last week but no call back.