[Joel78Vette]

I have a SBC 2 bolt-350 bored .030" over with 062 vortec heads (now 175cc intake runners and 60.2cc chambers) with stock valves (yes 3 angled), after-market springs (1.265" singles) set at 122#'s, 7/16" studs with guide plates; cast steel crankshaft, eagle rods, flat top, 4 valve relief, hyper-eutectic pistons; polished professional products cyclone intake (dual plane good to 5500 rpm's) topped off with a stock 650 thunder series edelbrock carb. The camshaft is a Howard's Race cam (retro roller)-214/[email protected]", .488/.495" lift w stainless steel 1.6 full roller rockers. Quench is about .057". about .016" in the hole with a .041" gasket (1003, I believe). Static compression sits about 10:1 at 1700 ft above sea level. I have a full 2 1/4" hooker exhaust with 1 5/8" - 3" ceramic coated headers. A level 2 700r4 w 2200 stall converter and 3.55 rear gears on 27" tires (255/60r15). The block mains have been aligned honed and have studs vs. bolts. Good Hp and TQ numbers would be appreciated. Thanks, Joel

 

[camaro355]

hp and tq estimation

probly somewhere around 375hp and 400ft pounds of torque

 

[techinspector1]

I'm seeing your static compression ratio at closer to 10.6:1 and would counsel you that the cam is too short and the squish is too wide.

I don't have the exact specs on that Howard cam, but a swag would put the intake valve closing at about 33 degrees ABDC. Adding 15 to that and plugging 48 into the KB calculator, along with 10.6, 3.48 and 5.7 gives a dynamic compression ratio of 9.42:1. This motor will not run on pump gas in my opinion. Cylinder pressure will exceed the ability of pump gas to prevent detonation. You'll need either less static compression ratio or more cam... or both.... to drop the dynamic compression ratio about 1 full point, down to 8.42:1.

 

[Joel78Vette]

The cam is 4 degrees advanced built in. I put it in straight up. The intake valve closes at 37 therefore bringing my dynamic up for better drivability and torque as a daily driver. Sorry I forgot to mention the use of vehicle too. So far it has ran quite well with 8-10 initial timing with a medium and a stiff spring in the distributor. I know 30-34 max total timing is what these heads like with higher compression. So far no pre-detonation. Hope this helps you all to help me out. Thank you so far gentlemen!

 

[techinspector1]

The cam is 4 degrees advanced built in. I put it in straight up. The intake valve closes at 37 therefore bringing my dynamic up for better drivability and torque as a daily driver. Sorry I forgot to mention the use of vehicle too. So far it has ran quite well with 8-10 initial timing with a medium and a stiff spring in the distributor. I know 30-34 max total timing is what these heads like with higher compression. So far no pre-detonation. Hope this helps you all to help me out. Thank you so far gentlemen!

Do you have the cam card?

 

[Joel78Vette]

Yes I do, Sir. LC is 112; Intake CL is 108; 264/270 Advertised; exh closes -9, exh opens at 47, intake open 4?? (washed off of card so guessing), and intake closes at 37. Gross lift is .325 (I), .330 (E), @.050 214/218. It's a 1000-5000rpm Cam.

 

[Joel78Vette]

It's the 110235-12 cam, FYI.

 

[Joel78Vette]

I'm seeing your static compression ratio at closer to 10.6:1 and would counsel you that the cam is too short and the squish is too wide.

Sir, can you explain also what you mean by the squish being too wide? Is there some rules about the squish in conjunction w/static compression?

I understand that the compression may be too high for that cam, but I couldn't afford the .051" thick gaskets at the time to bring me down where I felt more comfortable either. I know it sounds absurd to do all of the work I did for the sake of $60 or so and then not have the optimum motor that we all hope to build and enjoy.

 

[snakebit68]

torque and horsepower estimation

I agree with techinspector1 that your compression is too high for pump gas... and that cam is a bit on the short side.

 

[techinspector1]

Sir, can you explain also what you mean by the squish being too wide? Is there some rules about the squish in conjunction w/static compression?

I understand that the compression may be too high for that cam, but I couldn't afford the .051" thick gaskets at the time to bring me down where I felt more comfortable either. I know it sounds absurd to do all of the work I did for the sake of $60 or so and then not have the optimum motor that we all hope to build and enjoy.

Adding a 0.051" gasket to a 0.016" piston deck height would only compound your problems. It's a bad idea to use a thicker gasket to adjust static compression ratio because it widens the squish and the motor is more likely to detonate with the wider squish than it will from the decreased static compression ratio. The generally accepted range for squish on a SBC is 0.035" to 0.045", regardless of static compression ratio. You could do it with a 0.039"/0.040"/0.041" gasket thickness and a zero piston deck height or you could do it with a 0.026" gasket and a 0.014" piston deck height or you could do it with a 0.016" gasket and a 0.024" piston deck height.

Don't confuse piston deck height (zero to maybe 0.045") with block deck height (9.025" to maybe 8.980").
is
With 10.6:1 static compression ratio and the intake valve closing at 37, the dynamic compression ratio is 9.27:1. If you have not heard the motor detonating, then it's because you either have not had the motor under load or your exhaust system isn't allowing you to hear it.

 

[bygddy]

Sir, can you explain also what you mean by the squish being too wide? Is there some rules about the squish in conjunction w/static compression?

I understand that the compression may be too high for that cam, but I couldn't afford the .051" thick gaskets at the time to bring me down where I felt more comfortable either. I know it sounds absurd to do all of the work I did for the sake of $60 or so and then not have the optimum motor that we all hope to build and enjoy.

Read this....go from there....or search quench on here....tech knows his sht, listen to him.
"Proper" quench will help quell detonation, especially when your getting to the raged edge of pump gas....which it looks like you may be surpassing.

Piston Head Clearance Guide - Tech Article - Chevy High Performance Magazine

 

[vinniekq2]

Maybe tech can match your engine to a better set of heads and gaskets for your application.Then see what HP you can get?

 

[Joel78Vette]

First, the article and reply from both the "Inspector" and "BYGDDY" spoke volumes so far! Thank you!

I have been using Jeepstrokers.com/calculator instead of manually figuring out my compression ratio which is where I got 9.92 SC/9.25DC @1750 altitude. Correct me if it's off and I should stop relying on that please. My piston ring height is .282". I put my digital caliper micrometer on it to see what it was. Also, the best i could see I had .025 piston to wall clearance. Not 100% on that measurement!

Possible solution....I do have another set of 062 heads that may be about 63cc Chambers. Should I use those instead, Gentlemen? It seems to be the easiest and cheapest way to go to run this combo together and use this as a daily driver. I did have Howards 224/230 @.050", .501/.509 cam. Intake Valve closes at 38.5 degrees. That is two steps higher but I sent it back upon 2 out of 3 people recommending I run the smaller cam with this exact set-up.

I have a .015" shim head gasket but was warned about running only .031" quench. Another guy swore that he runs .020" ALL the time with these vortec heads and about slapped me through the phone multiple times explaining the quench preventing pre-detonation and that I would be fine running the .031" quench.

What do you think Gents about the head and/or gasket change as the easiest fix? I do have a set of one piece 7.3" push rods for the other heads instead of the 7.144" that I'm using now to make the transition go fast and easy.

Also, as of today I am brand new as a user vice a reader only on the forum. How do I simply "qoute" and "reply" instead of going to the bottom of the page to reply and having to re-log in every time? Thanks for any and all of your expert advice. MUCH APPRECIATED! You Gentlemen are Champions in my eyes. Especially you "Inspector"...I've read some threads w you in them and am impressed at your expertise. Again, Thanks. Joel

 

[vinniekq2]

Tech is truly a good guy here. Welcome to the forum,btw. he will likely do the math for you again,and he is one of the best here.The cam issue could be addressed at the same time. A small roller is always a good choice.
as they say in twilight zone
"please stand by"

 

[bygddy]

0.025 in the hole, flat tops 4vr we will say 7cc, 0.015 felpro head gasket, PN#1094, your 63cc heads (check and be sure, because they won't actually be 63) but assuming......this gives you 10.3:1 and 0.040 quench.....
You mentioned 0.016 in the hole at the top, then I believe said 0.025 further down? If the block hasn't been decked this is more likely...

 

[bygddy]

And i believe, with your current cam, and the 63cc heads and 0.015 gasket your still at 8.9dcr which is likely still to high for pump....the good quench will help, and depending on what fuel you have access to......maybe.....but not the safest choice.

 

[bygddy]

And last but not least, another very good read
Dynamic CR

 

[Joel78Vette]

I stated 63cc because they were very mildly "cleaned" up. Originally I know they are 64cc. Just hoping is all.....

 

[cdminter59]

Joel78Vette, What type pistons do you have in this engine? Flattop or dished pistons. Do you know the name brand or part number, or piston head volume? The cylinder head chambers are 60.2 ccs on the set of heads on the engine now correct! You also say you have another set with the chamber volume of 63ccs. These measurements need to be checked and correct! Has the deck of the block been milled, also did you measure from the top of the piston at TDC to the deck of the block. You said you have .016 deck clearance. Please post some answers.

 

[Joel78Vette]

0.025 in the hole, flat tops 4vr we will say 7cc, 0.015 felpro head gasket, PN#1094, your 63cc heads (check and be sure, because they won't actually be 63) but assuming......this gives you 10.3:1 and 0.040 quench.....
You mentioned 0.016 in the hole at the top, then I believe said 0.025 further down? If the block hasn't been decked this is more likely...

I cc'd a chamber on my 2nd set of 062 vortec heads and got 62cc's. Also I am in the hole .016". The .025" is the piston slap or piston to wall distance. I know that has little effect on the overall compression of the motor but just wanted to input all the data when jeepstrokers.com/calculator asked me for it. Also my pistons are H345ncp .030" with 4 valve relief (about 6cc's).