Puck

iTrader: (17)

Did nobody actually look at that dyno? It is not the parts or the tune. You're not magically losing 40rwhp from changing a cam.

Again, while not ideal there is nothing "wrong" with the heads or cam. Look towards opti, coil, or even ECU. I'm guessing during the cam install either the Opti rotor came loose, or it got drenched in coolant.

clarkkei96

Original order form.

ACE1252

I'm thinking the same thing given the break up from 55-6500.

The order sheet is interesting....was the 74cc special ordered or something? AFR only shows one size for the 1031 head....65cc. 54cc is the 1032 head. Wonder if this is a case of GEN I principles being applied to the GEN II?

clarkkei96

This was ordered ten years ago, might have changed since then for the 1031. Or a special order?
Engine probably has 25k to 30k in the past ten years, if that.

From what I was told, it was running fine before cam swap. Has electric water pump, no coolant spillage. It is an old opti though. I do have a MSD on the shelf.

transbird95

iTrader: (4)

Nice to see another MN guy on here! I see you had it tuned at hi tech. Guy didnt want to touch my car for some reason. Said lt1 pcms are too "unstable" now. I had my cam off a tooth once and it was down about 30hp but it still had a smooth curve just less power all over. It also peaked very early. 6100rpms instead of 6800.

ACE1252

I'm not trying to be an a$$ towards that shop, but given that statement, I'd be glad he didn't want to work on it. Nothing but BS coming out of that dude.

Given your experience and the dyno graph, makes me wonder if it's off a tooth and has an ignition issue. Wonder what the graph would look like if it was down a cylinder? I guess the thing would be shaking bad enough not to want to take it up too far in the RPMs.

clarkkei96

When you installed the cam correctly, what type of gains did you make? 20hp, 40hp? Did you have a before comparison?

transbird95

iTrader: (4)

The first pull was 20 or so hp right away. He got another 10 or so adjusting the tune. Not sure if its your problem or not just what happened with me. Hope this helps.

clarkkei96

Thanks for the responses guys! I'm sure we're all back to the work week grind but thinking about driving our cars!
I did talk with Elliot Lloyd, he can custom grind a cam to better suit the 74cc combustion chambers, basically trapping a little more cylinder pressure. But that is only a bandaid fix till I can afford better heads. Should be close to 400whp. Still not bad!
Couple last questions for you folks.
1. How much can I get for used AFR 195/74 cc heads. About 25k on them? I was told they would be a great head for nitrous or supercharger with the 9 to 1 compression.
2. What vacuum lines should I be checking for pressure? If I understand correctly, this also affects brakes and transmission?
3. Transmission shifts hard at 1-2 and 2-3, shop did a fix that worked for a couple weeks. Would the above mentioned vacuum affect? Any ideas? Tranny cooler recommended?
Please post thread links if needed.

Thanks guys!

BALLSS

vacuum can be measured at any port on the intake or vac line going to it

If you have a big cam that can cause low vac and yes affect braking especially at lower rpm. you can run a external vac pump in those situations

Puck

iTrader: (17)

New H/C wont fix this issue. Get the car running right before you dump expensive parts into it.

Heatmaker

Exactly. LT4 AFR 195cc heads are more than enough. They're the 4th best head you buy for the motor next to the 210's, 220's and 227's. On a 383 they're fine if you were running a 396 - 400+ or above then they'd be a problem because you need every bit of air that motor can breathe. The CC 306 isn't a slouch either it's been a go to cam since forever. Guys run that with un-ported stock heads, ported stock heads, 383's etc. etc. and hit some impressive 1/4's with it. Something is wrong with one of your engine and you have to start taking things apart to figure out why it's not running properly. Heads and cam aren't a thing you consider to be the problem when you have a graph like that. If your graph showed your car smoothly making HP and then just hitting a flat spot when it peaked then you could say your maxed out your heads or want a better cam to dig into the RPM's but that's not what your graph is saying.

clarkkei96

I get what you are saying, AFR 195's are great, but not the 74cc. They don't even make the 74cc. The troubled curve on the graph is most likely my factory opti that's been in there since day 1.
The 74cc AFR 195cc heads don't get the compression needed to make power. For example, stock heads are 54cc with a flat top piston. Running a cc306 with stock heads would even be better! 74cc would only be complimentary on a nitrous or blown application. 64cc AFR 195 would be killer, once I install my MSD opti.

Heatmaker

With a flat top piston the drop in compression is not going to be that dramatic until you go domed. SBC wise it's an old argument as old as dirt between 64 and 74 chambers it's not a foreign chamber size to the block the heads are sitting on though it just comes down to your preference and plans for the motor. It's not a setback or a handicap on your motor at all when it's set up right. Right now though it's blaming parts that are not the cause of your problems. Find out what's actually going on with your motor first and then decide what setup you want and then open your check book. You're going to spend at least 2,600 on heads and cam just to get a 20hp advantage.

KW Baraka

iTrader: (7)

The engine's not setup right.....not with those heads and that cam.

If there are other issues with the engine, fine.....get 'em fixed.....and the engine will STILL be down on power.

KW

clarkkei96

I can't say for certain but doing research on the original cam specs, it's looking like it MIGHT have had specs similar to a cc503. Smaller lobe durations which would of trapped the air mixture for a little better cylinder pressure, thus the missing 40hp.
The 5500 to 6500 was most likely the original opti.
Before doing any work, I'll be checking cylinder pressure. Pending a passing grade, I plan on installing a cam that better suits the heads under recommendation from Lloyd Elliot. I know I can get back the missing 40!
Last idea, might not matter, but I know the previous owner had problems with the fuel pump which has since been changed to a Bosch 550.
The car runs great, it will roast the tires off the line, I'm not thinking it's a dire engine situation. Just some missing ponies.
I'll post my results when I swap the cam.

Puck

iTrader: (17)

I disagree, that dyno chart is obviously a dire situation. 306 isn't the best cam, but it has always made good peak numbers. It has very lazy lobes and a weak low to mid range, but rips up top. Your car has likely ignition issues causing it to not make power past 5k when it should be pulling clean to over 6500rpm.

The compression difference you are looking at might get you 15-20hp tops. A smaller custom cam more tailored to your combo would make similar power to the 306 but with a stronger mid range and easier to tune. While going to a *larger* cam that should have picked up 15hp or so you are more then 40hp. 1-2pts more compression and a smaller cam isn't going to make up 55+hp.

First fix your ignition issues to get a nice clean dyno graph, then if you are not happy explore a better cam for your combo. With the new cam, heads can likely be milled to get you at least 1pt more compression and better quench. They already flow great.

Or, throw thousands at a smaller head and cam setup, make less power with the same issues, then have to diagnose and fix the same issue again in a month after lots of time and money (opti, coil, ECU, ICM, too wide plug gap, etc).

ACE1252

I advise you to do some more digging on the car before you start throwing parts at it. You are assuming that the cam is the problem with no hard data to back it up....other than 40 missing hp. I know that may sound like a wtf statement but consider this.....

The problem I see is that it appears you didn't dyno the car before the cam swap....so you don't know what it was doing before the swap. It clearly has some kind of issue looking at the CC306 graph. I don't think the cam is causing the instability in the graph up top. I think I'd work on trying to solve that then go from there.

Degree the cam. See if it lines up with the cam card.

Get it to a track and get some times on it if it's running good enough to make a few passes.

What happened to the old cam? Did they throw it away? You really need to know the specs of the old cam.

Did you ask Lloyd if he thought the cam could cause that kind of power loss?

Looks like to me, if the CC306 was bleeding down the cylinders that much, we would see the same type problems on a stock headed CC306 swap.

Puck

iTrader: (17)

If those same heads made 390+ on a baby cam, why do you think they are inadequate for a larger cam? I would be the first to say too low compression and a cam with lazy lobes isn't the best NA combo at all, but its not going to hurt you 50+hp. This is a 383 as well, so it's not as bad as too low compression and lazy cam on a 350 would be.

Puck

iTrader: (17)

Agreed. Wish I had a copy of my old dyno to show him...looked identical. Was a bad opti that seemed fine during normal driving - car shredded the tires, pulled hard from a light, etc.