Cam Suggested Compression Ratios..

[bigcam406]

Do you have some basic details on that engine? Did you ever have it dynoed or ran at the track?

motor was never dynoed.was installed in a 72 chevelle,turbo 400,456 gear,4500 stall,29.5 tall tire,all steel except the hood.weighed approx 3800lbs.went consistent 10.80's.basic stock short block(factory crank,rods,pistons),heavily modified 990 heads,edelbrock victor r intake,850 holley.worked alot better than i thought it would.

[F-BIRD'88]

1. That car is and always will be a snail with a powerglide trans in it.

2. that motor has something wrong with it. I can make 560hp with a hyd cam and 10:1cr in a 454.

Did you leave a shop rag in the manifold?

3. The cam is too small.

4. This 454 is makeing 150hp to 200hp less than it could at 11:1cr

5. How do you make a 69 BB Camaro with aluminum heads weight 4000 lbs.?
What do you have in the the trunk.

I have a whole different aproach 11;1 cr and it should run on pump gas too.
But the power glide has to go.. Get a Th350 or th400.

A new .710" lift roller cam that will make a lot lot more HP @11:1 with your new AFR heads.
The 5200 stall is just right. the gears look OK for now.
The new engine should make well over 650hp... with the AFR heads and 11:1 and a new .710" lift roller cam
that makes HORSEPOWER.

Does this Car have tiny headers?

Powerglides are for 2300 lbs 700 hp 505 CID Supergas cars. A power glide has no place in this car unless you can loose 2000 lbs.

Did you ever track test this car. I bet its about as much fun as watching paint dry.
ET MPH? 60ft.

[F-BIRD'88]

The AFR heads are capable of very good power.

There is a basic issue with your motor thou. It is way down on power.

I have a cam in mind for you. It is a UD Harold Cam. (Ultradyne) UD Harold is the right guy to talk to
about this cam and your motor. It is not a custom cam. It is a off the shelf cam. But Harold may want to adjust it.
He is a cam expert and this is his cam. 11.12:1cr is plenty compression for this specific camshaft.

The power glide has to go. Everything about your car will be better once the glide has a new home.
Your car will never be fast with a power glide.

You can contact Harold by Phone or email.
The intake manifold will need some sweetening too.
You have the basics and 11:1 is plenty.

[BlackoutSteve]

1. PG shows a tenth quicker than a TH400 on Maxracesoftware ET Analyst. See quotes below, we've already covered this in another thread..
2. Those heads do not flow as much as required, hense the swap.
3. Given the weight of the car, gearing and intended max rpm, that cam was chosen. This stock LS7 bottom end is not going to 8000.
4. Yes, I am well aware that it is below it's potential, see #2.
5. Air con, power steering, power windows, full interior, plenty of sound deadening/insulation, all steel, me (170lbs), fuel.

@ 4000lbs the power glide is killing you.
You are really doing it the hard way by ignoreing that and chasing power to reduce the ET.
You need leverlage to get 4000 lbs moving. The 1.76 gear is not enough of a lever.
Get a th 350 or th 400 trans..
The heads you have can be improved with some work.
If your car was 2300lbs the glide would work. But its not. It is leaving like a snale
with that trans. And its still going to leave like a snail even if you improve the heads flow.
Get a 3 speed or loose 1000++lbs.

Using the existing 570hp540tq engine, PG (1.76/1:1), 5200 converter, 4.56 gears, tire dia and 4000lb race weight..
60ft 1.631. 10.90/125.57.
No changes except for the addition of a TH400 (2.48/1.48/1:1), same shift points launch rpms, weight and so on.
60ft 1.617 10.988 / 125.39
Better 60fts but nearly a tenth slower overall.
Edit: numerically lower rear gear to ~3.9 results in quicker 10.916 than the 4.56 gears, but at a slower 124.85 ..and still slower than the 'Glide on both.
That's on Larry's MaxRaceSoftware ET Analyst program.

So unless I see real gains and not actually going backwards, I'm not going the effort and expense on a TH400..

[F-BIRD'88]

The soft ware is lieing to you. The new heads are great and the cam is too small.
You will never go slower with a th400 in a 4000LB Big block car. I don;t need soft ware to know that.
I have been track tuning these types of cars for 30++ years. Have had to grab guys by the scruff about power glides in street cars
more than once. It will always be a snail with a glide. It will leave like a snail and it won't get better as you go down the track.

Get a th350 or a th400. Gllides are for dragsters and supergas cars that weight 2300lbs.
And you won;t be reving it 8000rpm.
Th gears are fine but with the added horsepower of the heads and the new right camshaft the MPH will be much higher so you may need a taller 29.5" tire.

[F-BIRD'88]

Did you wound this 12:1cr motor on pump gas before the dyno test?
It is way down on power... Or are the Edelbrock BBC RPM heads that lame?

Or is that dyno test on water injection?..... or....

I can make over 660hp @11:1 cr using ported big valve chevy oval ports.
I don't use the Vic Jr manifold (not saying its a bad manifold) and the cam is a lot different, but is .700"+lift

[bigcam406]

imo,i think the heads are a restriction.the new AFR 300's will be a good addition to reach your goals.i'd also recommend a cam that has a narrower lsa than the one you are using,108-110 should suffice.this will build torque through your rpm range.

[bigcam406]

sorry,i just went over the specs on the cam you were questioning,didnt clue in to the lsa of 106,been a long night at work....

[novadude]

The power glide has to go. Everything about your car will be better once the glide has a new home.
Your car will never be fast with a power glide.

If he is driving around on 14" polyglas tires, I don't think he could even use a deeper 1st gear.

Steve... nice car... I love the "pseudo resto" look!

[Strange Magic]

Those Edelbrock heads have ~106cc chambers after 0.043" milling, and I feel thiat milling them was a mistake. I really don't want to mill the new heads.
The new heads, AFRs that I am looking at buying have 113cc chambers. If I simply bolt these new heads on,

Here are some basics that you should understand. Whenever you are dealing with a dome, which is the case here, you must always check that the dome configuration fits that of the cylinder heads chamber that it was designed for. It is understood and very common that many cylinder head manufactures like to make alterations to their chamber design to better their cylinder heads and even though a cylinders head cc's could be more than what you have removed, it does not mean that your current dome will fit into that chamber without interference. the slightest interference will beat the rod bearings out and possibly cause piston damage/cracking as well. I will tell you this, that a Dart and a Brodix do not share the same chamber design. I will tell you that a AFR does not share the same chamber design as a Dart. The Edelbrock also has a little difference to it as well. Each cylinder head manufacture has there own design engineers and each manufacture has there own belief in what that shape should look like.

Thats one heck of a pretty car to be sitting it out this summer, because a rod is hanging out the bottom from a piston that was crashing the head. Whenever it comes to anything other than a flat top or dish, it is important that the head be bore scribed on the block and the pistons be fitted into the chamber to make sure that you have the green light to continue. If there is interference, the engine builder has to make one of three decisions. Those decisions are to either remove slight material from the piston. Remove slight material from teh chamber or make a decision that if the material is too much to be removed, than to provide that customer with the correct pistons to match the chamber properly.

I will mention the following below:

1. There is no replacement for displacement
2. Compression is king when it comes to making torque output and HP.

[Strange Magic]

If I simply bolt these new heads on, I will go from 12 to 11.15:1 and am concerned that power may be (overly) adversely affected.

This is a catch 22 here. Personally I believe that your weak dyno power output figures are strickly related to detonation, and even when an end user reduces timing or reduces cylinder pressures (camshaft intake opening and closing events) thats only a band aid. I did not read anywhere herein, that you tested this engine, on the dyno two ways. The first with teh fuel which you made a decision to use, and the second with a fuel that has the correct grams of lead, correct octane and correct spec gravity for the application at hand. With this said, and if you decide to lower the compression, you might not see that loss. This is all dependant on how you band aided it with your tune up as it was. When an engine is in detonation it gets very, very fvckin mad to say the least. To truely determin if it is really pissed off, is to hit it with the correct fuel and tune accordingly. That is the true method to evaluate what is going on. If your going to continue with higher that normal compression for the fuel at hand (yes I understand about your water injection) than your decisions are not as simple and cut and dry as you might think, and thats why this situation is very tough to put a finger on. To answer your question: Assuming it is in detonation from my 30 years of building engines, than by lowering the static compression will allow you to drive additional timing into it (only compared to how your tunned to band aid it before) so that it makes up for the torque output loss that comes from reduced compression. You will re-achieve that same detonation area/magnatude.

My question is how much the lower ratio will hurt that cam's ability to make it's intended power and will if hurt that cams ability and do more harm than simply expect 3% less from the missing point..

The camshaft events need to be taken into consideration with the following factors: Pump size, piston speed, compression ratio and fuel of choice. In a case such as what is expressed, I would highly reccommend that you rid the engine of some of the cylinder pressure to combat your number one enemy, which is detonation. On the flip side you have a counter productive issue going on. By reducing your cylinder pressures, you've just taken air speed/velocity away from that engine at low to mid rmp range and combined with a power glide which operates over a 1400 rpms curve, your doing yourself more of an in-justace than any good. I don't want to burst your bubble, but I do want you to understand the hard facts. Your application is a band aided nightmare and the increase in intake port volume combined with reduced compression and the powerglide, could and most likely will, make it even worse.

Your best asset in camshaft design considering what you plan to do, is to highly consider reducing valve lift, which will increase port velocity and signal the boosters which will increase and broaden that torque curve. Thats one small aspect of many, regarding the camshaft design.


P.S. When looking at this beautiful car, and i've seen many just like it before, it seriously craves an engine that has mega power (which is what you want) and the ability to run on that pump gas without issue. With that said, the appropriete engine for what you crave would be a 582 or 598 that has 10.5 compression. That would be a 4.375 x 4.600 or a 4.500 x 4.600. I know this is not in the cards, but I thought I would throw it out to you. Does it baffle me as to why your engine had issues or had a lack of power? Not at all. Detonation will produce significant heat into the oil and the oil will break down real fast. Excessive heat absorbed into the oil will kill camshafts and lifters first and foremost. It's the first items to fail under stress when you have excessive heat absorbtion. The converter/trans is the second item which usually absorbes heat directly from that engine. If you had the oil temp gauge hooked up when dynoing and knew exactly what to look for, your oil temps would be an indication that something is not happy.

[BlackoutSteve]

On the dyno, the engine was using 100% VP and Mobil aviation. Not at the same time, but the aviation was easier to obtain and much cheaper. I am well aware of the 100-130 cruise/take-off octane ratings but that fuel still is around 104 from memory. We tried the VP on that same day as it's what the dyno had and wanted to try, not sure which VP, but plenty octane and it made slightly less power than with the Av. A small tune could have fixed that, but they were on par.
There was no pinging at all with the timing at 40°. (Might talk about the timing..)
On the car, I have a knock sensor that does work, and the H2O does work as far as that is concerned with premium pump. Besides, there are no bearings that show detonation, no broken rings or lands and no glittery spark plugs.

The existing pistons were custom made with Edelbrock domes to suit those heads. The deck is zero with a 0.039" gasket and the rods are steel. There is no interference. I checked that during the build and there is no evidence inspecting the parts.
I am STILL waiting on a response from AFR as to the design of their chambers. If I go new pistons, do I just whack in off-the-shelf "open chamber" domes. Will the Edelbrock domes interfere with them if I don't?

Whatever issue this engine has, I know that it's in the heads, ...with that cam choice. The cam would not be (so much of) an issue if the heads were flowing what the engine was asking for.
I had a smaller Crane mech flat tappet (134781) with no other changes to the current, and the car ran 122mph at 3660lbs with the 'Glide and 4.11s. It was also chassis dyned on 3 different DynaPack dynos and showed 510 at the wheels. So, I think the new roller cam effectively made the Edelbrock heads undersized as I doubt the larger roller cam would have ran the 122.
(Roller interface dynos were useless with traction and repeatability for tuning is crap. I had no success with 2 of them.)

OK.. let's say the 'Glide is way wrong.. I'll worry about it later. It's got nothing to do with comp, cam & heads. ..or H2O injection for that matter.

Thanks a heap for all your help guys..

[F-BIRD'88]

How did this car get from 3660 lbs to 4000 lbs. Your whole story is convoluted.
Start over. Build a 660hp 11:1cr 454. The engine you built has something wrong with it.

I have no experience with the edelbrock heads but.....
I do not believe the edelbrock heads are that lame. Something else is wrong.

I get a matching 513HP at the wheels with 122MPH in a 3660hp car.
That matches your 510hp @ the wheels.

122MPH @3660lbs with the glide. Why no mention of the ET of that run.??
Cause it stunk...

And this motor got damaged between that point and the dyno test you posted.
There is more to this story. and the glide will never work.
and you could have and should have made 510 @ the wheels at 10:1cr. and the small crane cam F314-2 NC cam and edelbrock heads.
That makes sense.
No need for this water injection BS and 12:1.

[F-BIRD'88]

Did you ever flow test the edelbrock heads. Are they stock or modified/ported?

Something does not add up here.

[Strange Magic]

On the dyno, the engine was using 100% VP and Mobil aviation. Not at the same time, but the aviation was easier to obtain and much cheaper.

The story is a litle confusing and contradictive. If you dynoed it on vp and aviation as well (had enough time to do these tests) than why would you choose either of those fuels to dyno with, if thats not the fuel your going to run it on, and if thats not teh fuel you ran it on anyway? I would assume your dyno sheet posted would be that of a sheet where it has made the most hp. Why would you list a sheet that shows less? You wouldn't.

I would suggest you get through the first issue, first. That first issue is the mis-match of a dome configured for an Edelbrock cylinder head that is not the same dome configuration that would be used in teh AFR cylinder head. You need to physically bore scribe and place the piston into that chamber to see if it has issues, as mentioned before. You've already mentioned exactly what you plan to do and you might already have that camshaft in hand as this discussion takes place. The question really is, if wrong are you willing to change it? If not, than there is no discussing it any further. I get a strong impression that you have made your decision already, of which is not going to change, and your just curious for some input.