Alright here is the problem I want to get the 383 shortblock sale that is currently offered by AP engineering:
I will be adding a forged crank to the list also,4 bolt splayed.
383 LT1 SHORTBLOCK

$2,300.00
EAGLE ESP CRANKSHAFT
DIAMOND FORGED PISTONS / FLAT TOPS OR DISH
DIAMOND 4130 CHROMEMOLY WRIST PINS
DIAMOND PRO SELECT RINGS
EAGLE H BEAM CONNECTING RODS
MICHIGAN 77 MAIN BEARINGS
CLEVITE CONNECTING ROD BEARINGS
CLEVITE CAM BEARINGS
ARP MAIN STUDS
MACHINE BLOCK
BALANCE AND BLUEPRINT
ASSEMBLED

NO CORE CHARGES

CUSTOM PISTONS ADD - $150.00
Splayed 4 BOLT CAPS AVAILABLE ON LT1 BLOCKS - $550 (Includes caps, ARP Main Studs and Labor)

So my Question is I need to find out the Chamber size of head or
Flow #'s for the head?
So I can match the correct Piston offered (Flat or dished) to make a
CR of 10.5 to 1 or close.
The original owner does not know and someone from Arizona Speed and marine did it, but now has passed away.

So I'll need an educated guess as to the numbers my heads will produce, here is a list of my mods:
Engine: .030 overbore(355 CID) .030 over pistons, Manley rings, stock rods, Clevite bearings.
Comp Cam 112 degree cam profile 224/226 with 515 lift. Comp Cams roller lifters.
Heads: hand ported ,blended, portmatched w/ Manley Proflow stainless steel valves, 2.02 intake, 1.56 exhausts. 3 angle valve job,Erson springs, neoprene seals, Harlan Sharp aluminum 1.5 roller rockers.
Exhaust: Magna flow mufflers,
Exhaust manifolds ExtrudeHoned, port matched.
Fuel: 24lb SVO injectors,adjustable fuel regulator, stock in-tank fuel pump
Chip: Z-industries
Throttle Body: 52 MM TPIS
Intake manifold: ExtrudeHoned, port matched
TPS recalibrator
Ram air system w/K&N filter

These are stock LT1 heads with the above modifications

Please give me some options? Forget the existing heads? Buy New which Brand?
I am looking to make as much HP as possible even if I have to change the current Cam.

Thanks I am all Chad

 

Know one can Guess?????

What is stock flow #'s of LT1 head?

Thanks, Chad

 

Know one can guess on the #'s????

Also what is stock flow #'s for a LT1 head?

Thanks, Chad

 

58cc /170 intake.
Stock flows 180 @.300
214 @.500
Check;
http://www.chevyhiperformance.com/te...98/index4.html

www.fierolt1.com/lt1_lt4_headflow.htm

 

rodj: Thanks for the help those sites are informative

Q on the stock LT1 heads it says the Combustion chamber is 58cc and on the other site it gives examples of some LT1 heads:
TPIS ("cleaned up") LT1
67.0cc
TPIS-Ported LT1
63.0cc

So what does it take to get this result and since I am using bigger intakes and exhausts valves does that change the combustion chamber? by how much?

Thanks Chad

 

ttt

 

Get what result?

Jake

 

How can you get the rated cc increase(63cc and 67cc) over the stock 58cc?

By just porting the stock head? or by changing the intake/exhaust valve sizes?

Thanks Chad

 

ttt

 

Changing valve size won't do anything to effect combustion chamber volume if they are properly installed.
I've seen new valves installed higher in the chamber which decreases camber volume, be this leaves the edge of the valve exposed to the heat of combustion and can create a hot edge resulting in detonation.

If you want to increase the combustion chamber volume from 58 ccs to 63/67 ccs you can either use a thicker head gasket or have a porter open them up enough to give the 5 to 9 ccs. There should be enough meat in the heads to get 5 and that's the way I'd go if it were me.

The other option, which is even less desirable, would be to install a new set of pistons to increase the piston to block deck clearance. There's one other, but it's even more crazy.

Jake

 

You cant increase the combustion chamber size without grinding out the chamber itself. it is a lot of work. if you are building a custom shortblock just have them put the piston in for the comp ratio that you want. stock lt1 pistons have about a -7 cc dish. for a 10.25 comp ratio. if you want more compression then get a -3 or -4cc piston but you need to compensate for a 0 decked block, ap can calculate the piston height for you in there comp ratio calculator. they charge an extra $150.00 for custom pistons. if you give them your head combustion chamber size and what comp ratio you want they can figure it out for you..

about your heads.. where they professionally ported? if they were you will be fine with flow # anywhere from 260 to 300 depending how much they were ported. if they were not done professionaly i would recommend it on a 383 ci. and they are 58cc chambers...

 

Arizona speed and marine had them done by a company called Air flow research but this was done in 1993, the recipt said 2.02 intake, 1.50 exhaust, ported and matched with big cut valves.
I called AS&M but they cannot give me any estimates of course

So for me to correctly GUESS my CR for my 383 would be combustion chamber size of 60cc???

AP just needs total combustion chamber # or flow #'s, so they can calculate proper CR.

What if my guess of the combustion chamber is off what is the results??
Thanks Chad

 

air flow research would not have flatmilled the heads unless you told them to. so your combustion chamber size would not have changed from stock. so id stick with 58cc. as for needing flow #s to calculate comp ratio, not possible, flow #s will have no effect of comp ratio at all.

comp ratio will depend on many things
1- bore
2- stroke
3- piston volume
4- piston to deck heght
5- head combustion chamber size.
basicly thats it, i may of forgotten something.

 

So my combustion chamber (58)cc number would NOT have changed from the mods I had done to it?

Really thats all the information needed so they can match to get the correct CR for the pistons being installed.
Thanks Chad

 

I thought porting the head increases the combustion chamber number?

 

unless they actually did work on the chambers themselves, which a doubt with a basic port job, no it will not affect combustion chamber cc size.even if they did some minor bowl blending it will not change the cc enough to make a difference.

 

here is an example of how you calculate cr ratio.

1- boresize- 4.030
2- stroke- 3.75
3-standard head gasket bore size-4.160
4- standard head gasket compressed thickness- .039
5 combustion chamber size- 58cc's
6- piston volume- -10 cc's
7-piston deck clearance- .025 -stock lt1

with those numbers you will have a 10.56/1 cr

the only thing that i dont know about your motor is what the actual piston volume is and the piston to deck clearance.
an example is if your deck clearance is 0 and all else the same you cr will be 11.22/1.

use this link for c/r calculations

http://www.classicar.com/garage/shopmathcr1.asp

 

mos90: thanks for your replies.

Next Q assuming my above calculations stay the for the 383 motor, and the motor was built for a 58cc combustion chamber hence stock,
HOW would a change in the heads later on down the line to a AFR 195, 64cc combustion chamber. Would I lose HP?

Also how would this change my CR? UP or DOWN? and by how much?

Some of my problems are that I am unsure of the condition of my current heads and IF there damaged from my spun bearing I probably will not use them, But I don't have the time yet to pull the motor and see. I wanted to get this motor build up deal and add as I go

Sorry for the rammbling, Thanks Chad

 

Compression ratio is only one of the things that goes into creating power in the engine.

Even if you lose a half point or so in compression by going with AFR 64CC heads compared to your current 58 cc heads, you will make more power because the AFR heads flow so much better than what you have now.

So I wouldn't be concerned about the slight loss in CR.

A spun bearing doesn't hurt the heads either.

Jake

 

i ran into the same issue with my dart heads. they were 64 cc also and my stock heads were 58cc. my 91 was 10/1 cr and i wanted close to 11/1 so basiclly i needed to get my combustion chambers to 54cc because i was using a stock short block. so i broght my heads to a local machine shop and they angle milled them to 54cc's for $100.00. then because a milled the heads so much they needed to match the intake to the heads. all they had to do is take off the .070 that they took off the heads off the intake end rails. so it would have enough clearance between the block. so for 150.00 i bought my heads to 54 cc's and they work great. i think my final cr came to 10.85/1

if you put 64cc heads on your 383 it it had a 10.8/1 cr with your stock heads. it would drop it to 10.1/1 which would be a loss of 5hp. but the difference in head flow, like someone else mentioned, would make up 3 times that. the general rule is 1 point in cr is = to 10hp.