[462ta]

running crower 60916 221/229 cam in a 406 with home ported 13's, never been able to get the power out of this combo--275rwhp 315 tq that it should, since that dyno i have home ported the heads added tri y headers (tried adv cam--lost power on same dyno), question is im only at 9/1 comp would bumping that up to high 9,s be worth the hassle and cost. im going to add 3.73 gears--have 3.23 now with 28in tire so it should feel better.

[71 Ventura II]

Automatic transmission I'd expect to see in the neighborhood of 286 HP to 296 HP at the rear wheels. If your at a fairly high altitude then 275 RWHP is all you can expect. JD

[Cliff R]

With unported heads on a zero deck shortblock we've made 419hp/453tq at the flywheel.

We've got customers running mid to high 12's in street driven FB's and GTO's with that combo, so the track numbers support what we saw on the dyno.

Something fundamentally wrong someplace? Even at 9 to 1 compression it should make more HP than what you are seeing. Torque may be down some do to the lower compression, but I'd still expect 380-400hp/420-430tq at the flywheel with that cam in a 400 engine with 9 to 1 compression.

One negative I've seen with that cam, without exception every single one has needed to be advanced at least 4 degrees, some more than that, to get them down to 108-109ICL......Cliff

[462ta]

Thks Cliff, any idea where to start looking for the lost power, i tried adv cam with just putting it on the 4 deg keyway and put it on the same dyno and it was down to 240 rwhp so i put it back straight up, tried deg cam with a buddy but we kept getting some scewed up numbers so eventually we gave up, i need to do it again with someone who knows more about it. with the cam straight up it cranks 150 and when i put it on the 4 deg it cranked 165 on compression check.
built a pretty good bottom end with 5140 rods and KB forged pistons 14cc dish, 13 heads at 78cc ported using Jims book but did not go crazy, gasket match, ran the cutters down the bowl and blended, smoothed out runners and pushrod bulges,unshrouded valves.Built quadrajet using your book on stock 69 intake with tri y headers and 2 1/2 mandrel bent full exhaust.
Do you think deg cam properly will make a difference in finding some of the lost power im down 60-80 hp from what others are seeing.

[Cliff R]

78cc plus 13cc is 91cc. I don't know how you get up to 9 to 1 compression, should be closer to 8.2 to 8.4? Nothing mentioned about zero deck height and gasket thickness?

In any case, with that much area above the piston, a smaller cam would be a much better choice, something down around 214/224/112.....Cliff

[chiphead]

According to the CP website, 91CC on a zero deck shortblock is 9.3 compression. That's about what I have, with 70CC heads and 20CC dished pistons.

If you don't degree the cam with a degree kit, you don't really know where you are. +4 on the timing chain gear isn't always really +4. You can still be way off in the weeds with cam timing.

What are your ignition timing settings? What carb, intake, etc?

[Cliff R]

Might be 9 to 1 depending on deck height and gasket used. In any case, not enough compression for that camshaft, IMHO. I've never even tried one below 10 to 1 compression, most were 10.2 to 10.4 to 1 or so, and we prefer the 60243 for manual transmission and any more compression than that.

+1 on the 4 keyway set, could have moved the cam just about anyplace, at least from what I've seen here with those set-ups.....Cliff

[462ta]

zero deck with 038 gasket
36 deg all in by about 3000 near as i remember
quadrajet on 69 intake
i guess where im at is do i remove the heads and bump comp keeping the 60916 cam or just leave that alone and go with a smaller cam, best bang for the buck in other words

[71 Ventura II]

Originally Posted by 71 Ventura II

Automatic transmission I'd expect to see in the neighborhood of 286 HP to 296 HP at the rear wheels. If your at a fairly high altitude then 275 RWHP is all you can expect. JD

Originally Posted by Cliff R

With unported heads on a zero deck shortblock we've made 419hp/453tq at the flywheel.

We've got customers running mid to high 12's in street driven FB's and GTO's with that combo, so the track numbers support what we saw on the dyno.

Something fundamentally wrong someplace? Even at 9 to 1 compression it should make more HP than what you are seeing. Torque may be down some do to the lower compression, but I'd still expect 380-400hp/420-430tq at the flywheel with that cam in a 400 engine with 9 to 1 compression.

One negative I've seen with that cam, without exception every single one has needed to be advanced at least 4 degrees, some more than that, to get them down to 108-109ICL......Cliff

Originally Posted by chiphead

According to the CP website, 91CC on a zero deck shortblock is 9.3 compression. That's about what I have, with 70CC heads and 20CC dished pistons.

If you don't degree the cam with a degree kit, you don't really know where you are. +4 on the timing chain gear isn't always really +4. You can still be way off in the weeds with cam timing.

What are your ignition timing settings? What carb, intake, etc?

Hello guys, remember "He's" reporting +- 275 RWHP not crankshaft! 275 RWHP is equal to +- 357 HP at the crank when running a traditional 3 speed automatic. A full point of compression equals +- 8% difference in HP. So, for you guys who found +- 405-419HP at the crank running @10.0-1 compression in a similar combo try the math. Drop the power by the 8% accounting for the drop to 9.0-1 compression you get, 372-385 HP at the crank or expected +- 286.44-296.45 RWHP .

Accounting for the 8% loss due to compression drop the 372-385 will yield a RWHP of 286.44-296.45 as stated. That's only 3-7% below expected return, Not a fundamental issue, more like a fine tuning reward.

Factors in play effecting results: Lower compression and driveline parasitic loss. He's not far from expectation for the combination of parts in the environment. He lives only 627' above sea level which is cool! JD

[Cliff R]

The power loss for compression formula doesn't hold water, never did. We choose the camshaft based on the compression and CID. A cam that works well for 400cid at 10 to 1 compression is NOT as good of a choice at 9 to 1. For every full point of compression the cam needs to be about 10 degrees smaller, to keep idle quality, off idle power, and torque production in the lower rpm range on par with the larger camshaft in the higher CR engine.

What we are seeing here is typical of choosing a camshaft that is too big for the application. It would be a LOT happier with something closer to an 068 grind...IMHO.....Cliff

[mechanic17]

"tried deg cam with a buddy but we kept getting some scewed up numbers so eventually we gave up"

Sounds like you may have been trying to degree the opening/closing events, which can be a real PIA whether at the seat (.004-.006") OR @.050". Next time, go for the intake (ICL) center line of 108 like Cliff says--which I believe should be the +4 keyway. Then double-check the exhaust centerline (it's more of a beginner's method, I admit, but you're far less likely to get head-tripped doing it.)

What Ventura says makes sense, but even so I'm damned if I can figure out how you LOST power advancing that same cam 4 degrees, with less than optimal SCR. The tested rise in cylinder pressure shows you should have gained, as well as computer sims I did in another thread, and Cliff's experience. Assuming you did really receive the stated cam (someone else suspects his cam was mis-boxed for a 60919 as he got 230 intake duration when degreeing,) I'd next investigate if your timing set is off, or the valvetrain is maladjusted--maybe too much or too little lifter preload?

**EDIT** after writing that last paragraph: Aww, hell, I made a mistake here for those who care about computer sims. I'm rerunning them, and FWIW, the peak numbers are very close to Cliff's real-world dyno numbers of 419hp/453tq, IF you use 10+ SCR.

I try to use these things in a very responsible way--that is, to compare changes in variables like raising or lowering CR, or advancing or retarding a cam, or comparing one cam to another in the same engine.

Okay, it seems the computer predicts this cam (60916) likes to be retarded, not advanced, which would seem to jibe with the OPs experience of a 35 hp loss at peak when advancing on the dyno. In fact, there seems to be very little loss lower down in the curve, even with a 4 degree retard, and the hp peak rises considerably (tq does not). But Cliff has found advancing it (again, at a more optimal CR) to be better. I'm at a loss to explain that conflict, even with a CR change.

[mechanic17]

Hey Cliff, I see you're an "early riser" like me (aka insomniac in my case). In response to the comment you just made, would you say the factory 744 cam is a good example? 'Cuz I bought the Wolverine version awhile back, and reading all the threads on it where 50% of users love it and others hate it, I'm torn. I'm running computer sims on it, and I just cant seem to get a power curve out of it that impresses me (compared to either the 068, the 041, or any decent aftermarket cam), no matter what variables I change--which is weird because dragstrip tests have shown it going 13 flat in mildly modified GTOs, and I find it hard to believe Pontiac engineers just produced a "dog" anyway). So would you say that's a cam (like the 041) that DEMANDS a high SCR (and low gears) to function properly? How high?

[462ta]

Ventura--is 30% drivetrain loss really that accurate with a TH350 most ive read or talked to said more like 20-22%, were going to put the car back on the dyno and do some tuning before i tear anything apart to see if we can find some HP, sticking witha quadrajet so im going to find/borrow couple diff set ups to quicken up the down times.

[BruceWilkie]

Originally Posted by 462ta

Ventura--is 30% drivetrain loss really that accurate with a TH350 most ive read or talked to said more like 20-22%, were going to put the car back on the dyno and do some tuning before i tear anything apart to see if we can find some HP, sticking witha quadrajet so im going to find/borrow couple diff set ups to quicken up the down times.

That seems about right for t350 and stock convertor. Chassis dyno with a non stock convertor and things can change drastically. Best bet with chassis dyno is to tune with it. Then make a few passes at the track and compare MPH with weight. Then use one of the calculators to see if you are near where you should be.

[chiphead]

I've always heard that an automatic has ~20% drivetrain loss. I assume that is through the TQ, tranny and rear end. That's 80 HP on a 400 horse engine and seems high. I also question if it is always 20%, no matter the HP of the engine. A 700HP engine would be losing 140 HP in the same theoretical driveline, which seems insanely high.

Whatever the driveline losses are, I would expect the majority of that to be in the torque converter and then the rear end (once TH350 is in direct drive). So if you have a very loose TC and a Ford 9" rear end, you're going to be wasting more power than a lockup converter and a lightweight rear end.

BTW, what is the idle vacuum? My 400 makes 8-10" at 750 RPM with XE274 cam. Lumpy idle.

[462ta]

vac 15-16 can idle it down to 500 or so
how do u like the 274 cam buddy just put one in his 400 with 4 spd and says it pulls real hard but i have not been in his car yet

[71 Ventura II]

Originally Posted by 462ta

Ventura--is 30% drivetrain loss really that accurate with a TH350 most ive read or talked to said more like 20-22%, were going to put the car back on the dyno and do some tuning before i tear anything apart to see if we can find some HP, sticking witha quadrajet so im going to find/borrow couple diff set ups to quicken up the down times.

The Inverse of the loss is what's used. I did not use a loss of 30% but did use 23% by using the inverse factor of .77. Ex. 386 HP X .77= 297.22 RWHP.

As a general rule I use parasitic losses of 23% for traditional 3 speed automatics and 15% for a manual transmission applications. Use inverse of .77 for auto and .85 for clutch. (As a disclaimer some of the lock-up automatics can be slightly more efficient and the exotic race clutches can be extremely efficient but for the norm these are good "Median" numbers to work with).

FWIW I would speed up the timing curve or lock it between 34-36 degrees. Keep in mind with the lower compression and unknown "squish" or "Quench" area for the combustion don't rule out more total timing in the 38-40 range and conversely trying 32-34 if the return is not rewarding while increasing total. I'd speed up the curve and try adding one degree at a time until the power drops off then back up.
WARNING: If your distributor does NOT have positive stops installed to limit the mechanical advance above 4000 rpm's it will kill your HP!!! Without the stops the springs will stretch allowing additional timing sometimes 7-10+ degrees! If you don't have it limited get it done ASAP. JD

[71 Ventura II]

Originally Posted by 462ta

running crower 60916 221/229 cam in a 406 with home ported 13's, never been able to get the power out of this combo--275rwhp 315 tq that it should, since that dyno i have home ported the heads added tri y headers (tried adv cam--lost power on same dyno), question is im only at 9/1 comp would bumping that up to high 9,s be worth the hassle and cost. im going to add 3.73 gears--have 3.23 now with 28in tire so it should feel better.

Real data from my car:
Both Ken Brewer and the Kauffmans proved that the #16 cam, in a 400, with unported d-port heads can produce 400+ HP!!! I will say Ken, the Kauffmans, and myself ran 1.65 rocker arms. With that said, if your heads don't have the elongated pushrod passages it will be perfectly acceptable to run the 1.5 rockers, just expect +- 8-15 less HP.

IIRC
Ken Brewer results 405 HP @5400 rpm and 470 ftlbs TQ @4000 rpm.

Kauffmans results 419 HP @5400 rpm and 470 ftlbs TQ @4000 rpm.

My results had to be in the same ballpark based on track testing. I ran my Ventura II with the 400, Hughes GM25 converter, and 3.70 gears with super TALL 29.5" bias slicks to easy 12.50-12.70 ET's pulling 105-107 MPH. Stock unported heads!

After porting my heads the same combo picked up big time running 12.20's @109 mph!!!

I am a big fan of the #60916 cam in the Pontiac 400! It will give you a strong "Muscle Car" exhaust note, pull hard to 5500-5800 rpm, and still pulls great vacuum of 15 lbs @1000 rpm idle.
My combo: Top down...
Holley #4779 750 DP
Edelbrock "Performer" w/1" adapter from the spreadbore to square bore carb.
1968 #16 heads w/Crower #68404 dual springs, Crane Energizer 1.65 roller rockers
Stock 1971 bottom end w/Milodon rod bolts, 60# oil pump, and cast pistons. With the rebuilder pistons I used the actual compression was 9.70-1.
Hooker "Competition" headers 1 5/8" 4 tube

TH350 w/Hughes GM25 converter and 3.70 gear. The GM25 converter is one of the most efficient converters I've tried. Converter contribution was 7.5% Not bad at all especially in the price range. The Continental will be tighter with a Converter contribution of 3-5% with a higher investment ratio.

My 3.70 gear running the 29.5" tire is the same effective gear as a 3.63. Inversely if your running a 3.42 gear with say a 28" tire you have the effective gear of a 3.54 or if your running a 27" tire your looking at effective 3.66 ratio. Gears are engineered assuming a 29" tire so for every inch lower you gain gear and every inch taller you lose gear. Bottom line your in the same operating range as my car... JD

[71 Ventura II]

Originally Posted by Cliff R

The power loss for compression formula doesn't hold water, never did. We choose the camshaft based on the compression and CID. A cam that works well for 400cid at 10 to 1 compression is NOT as good of a choice at 9 to 1. For every full point of compression the cam needs to be about 10 degrees smaller, to keep idle quality, off idle power, and torque production in the lower rpm range on par with the larger camshaft in the higher CR engine.

What we are seeing here is typical choosing a camshaft that is too big for the application. It would be a LOT happier with something closer to an 068 grind...IMHO.....Cliff

Here's an example of over camming an engine for return. Above I posted all the major details of building a 400 w/#60916 cam running 12.50's @107 mph. I tried changing the #16 cam to a Crower #60311 w/1.65's, Torker II intake w/1" spacer, and 3800 converter in an effort to go fast. WELL RESULTS: The damn car ran the same ET! I mean there wasn't more than .01 difference between them. But with the larger solid cam combo I had to raise my shift rpm from 5600-5800 to 6500 rpm's to get it to respond!!! Now that was a diminished return on investment by grossly over camming. LOL

[chiphead]

Ventura, those are some stout numbers with the 60916 cam. You sure your compression wasn't more than 9.7? My 400 will just break the 12s on motor with the XE274. 3750 race weight. Cranking compression is 165 PSI with the cam adv 2*. 38* total timing. Don't get me wrong, it's fast and fun. But I'm trying to maximize the combo, so I'm wondering if a Crower would work with 9.3 compression.

It seems like the OP has a similar setup, so I'm curious why it's so down on power. I'd love 15" of vacuum at idle. Sounds like this cam really needs to be degreed, to eliminate that as a problem.

Are they checking AFR on the chassis dyno?

Should a 60916 cam be making 15" of idle vacuum at 9:1 compression? I'm at 8-10". Yes, I've got idle fuel.