Hi all. I am looking for some advice. I have just built my 2nd engine and first stroker engine, a 383. I recently had my engine on the Dyno at VACA Performance in Downey, CA. I made 407 HP and 409 Lbs of torque. My compression ratio is between 8:1 and 8.1:1. I am wondering what you guys think of this and if I should do any more tuning to it? I am running 750 Demon CFM carb with 76 and 85 jets at WOT 40 degrees. NGK plugs at a .035 gap with an MSD S.F. HEI. My engine will also be in the July issue of Chevy High Performance, which comes out in May. Let me know what you think and if you have any questions at all free to ask. You can check it out on my resto page. Talk to you all later.

I would expect that motor to have more torque. Also I would gap plugs at .045. What number is between 8.1 and 8.1?

What cam?

Sorry, I meant 8.1:1 to 8.05:1 ratio. My cam is an Edelbrock Performer RPM. P/N 2204.

8.x is not enough compression to run that cam, you need more like 9.5 - 10.0, and I hope you have some good gears/converter.

Lunati 60111 would probably be better matched to your CR.

What do you mean not enough to run that cam? It made like 13 lbs of vac at 1000 rpm. The guys at the dyno shop were quite impressed at the power it made with it being such low compression.

You're leaving a lot on the table, that's all I'm saying - a cam with that much duration does not belong in an 8:1 compression motor.

Here are the specs in case anybody else wants to chime in:

Duration at 050 inch Lift: 234 int./238 exh. Advertised Intake Duration: 296 Advertised Exhaust Duration: 300

Yep, A little more compression would really wake up your engine with that particular cam...but I bet it really lopes at idle...

Just to stir the pot:DMy 383 has 10.7-1 with similar cam specs(mine is a hyd.rlr) and it idles at 750 with 16-17 inches.

Well, I kept the compression low because I will evetually install a nice pro-charger/paxton on it. I could bump the compression up if I bopught some 64cc heads, but being in the military I dont have that much lying around. The current heads I have on there are Edelbrock performer Rpm heads, p/n 6703. They have 70cc chambers.

The guys at the dyno shop were quite impressed at the power it made with it being such low compression.I'm also impressed with the power considering the compression ratio. The c.r. is definitely not ideal but considering that your putting a Procharger on it in the future, I think you're in really good shape.

Your original question seems to be whether we think it's tuned well enough. How much tuning did they do on the dyno? Did they have an AFR meter in it?

Well, we started off with stock jets on the Demon. It made like 390 HP and 393 Lbs of TRQ. Timing was set at 38 degrees WOT. We dropped the jets down two sizes on the primaries and secondaries. It made less HP and TRQ, 383HP and 387 TRQ. Timing was the same. We then went two jet sizes above the stock configuration, 76 and 85 jets. Timing was still at 38 WOT. It made 403 HP and 406 LBS of TRQ. For the final run we advanced the timing to 40 at WOT. It then made 407 HP and 409 LBS of TRQ.

And, they did have an AFR meter on it. I do not have the sheet with me so I can not tell you what the average number was. I think it was around 13.7 or so.

Since they did spend some time on the dyno getting the tune optimized I would say go ahead and drop it in. If it needs more fine tuning for driving then you can make more adjustments.

Since they did spend some time on the dyno getting the tune optimized I would say go ahead and drop it in. If it needs more fine tuning for driving then you can make more adjustments.

I would love to drop it in and fire it up, but my car is in pieces. Thanks for the advice though. It is what the dyno shop said too.

curious what your cranking comp was-are you using dished pistons? i ran 9.4 comp on a 383, and used to run 18 lbs boost thru it with a procharger- i never got into the real low comp, unless a roots blower
prob a cam ground on 114-115 l/s might have built a little more cyl pressure, would have been neat to try a couple diff cams
i ran a perf RPM cam on one of my blower motors, def made more power than a custom cam i had ground(it was the hyd roller)
at least you can run a lot of timing, cheap gas, should be crisp

I do not know what the cranking Compression was. Yes, I am using dished pistons. Here is a run down on the kit I bought:

Rotating Assembly:
Eagle Specialty Products
p/n 12106

Forged 4340 Chromoly Crankshaft
Stroke 3.750
Displacement @ .030 383cid

Forged 4340 Chromoly H-Beam Rods
Rod Length 5.70

Forged SRP Pistons
-31cc Dish
8.5:1 cr @ 64cc

Clevite77 Race Bearings

Perfect Circle plasma-moly rings