help calculating head gasket thickness, compression 403
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
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help calculating head gasket thickness, compression 403 hey guys-
looking for some assistance putting together the details for my 403 that is going into my vette. short block details:
LS2 403" Stroker Shortblock
4.000" Stroke CompStar Crankshaft
6.125" CompStar H-Beam Rods w/ARP2000 Hardware
4.005" Bore -28cc Dish Diamond Piston Set
Total Seal Piston Rings w/Steel Top
Melling high volume oil pump
Billet double roll timing set
Comp cam
Spec card #06751604
Grind # LS1 3726/3728
281/285 adv
232/236 @ .050";
.595/.601" lift;
114 degree LSA, ground with a 114 degree intake center line.
i plan to use my c&c-ed 853 casting heads and a ported FAST 90/92...not sure on what thickness headgasket i'm going to need, or if i will need to mill the heads to up compression. shortblock was built for boost but i want to keep the car NA...i got a killer deal on the shortblock.
suggestions? thanks
looking for some assistance putting together the details for my 403 that is going into my vette. short block details:
LS2 403" Stroker Shortblock
4.000" Stroke CompStar Crankshaft
6.125" CompStar H-Beam Rods w/ARP2000 Hardware
4.005" Bore -28cc Dish Diamond Piston Set
Total Seal Piston Rings w/Steel Top
Melling high volume oil pump
Billet double roll timing set
Comp cam
Spec card #06751604
Grind # LS1 3726/3728
281/285 adv
232/236 @ .050";
.595/.601" lift;
114 degree LSA, ground with a 114 degree intake center line.
i plan to use my c&c-ed 853 casting heads and a ported FAST 90/92...not sure on what thickness headgasket i'm going to need, or if i will need to mill the heads to up compression. shortblock was built for boost but i want to keep the car NA...i got a killer deal on the shortblock.
suggestions? thanks
That is going to be a real soggy set up. The cam needs to be advanced a ton to get your dcr up and better to drive. I would use the thinnest head gasket you can find while keeping the quench around .035"-.040". What heads are going on that engine?
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
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853's that have been cnc-ed...what do you mean by soggy? would a different cam be more beneficial?
Last edited by andy9743; Jun 12, 2013 at 02:18 PM.
With that set up, a head gasket isn't going to bump your compression enough to put you in the ball park. With a 66cc combustion chamber, and a .045" thick gasket with a 4.060 bore, your sitting at 9.05:1 static compression and a 6.72:1 dynamic compression. That is crazy low for a NA car
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
Likes: 0
With that set up, a head gasket isn't going to bump your compression enough to put you in the ball park. With a 66cc combustion chamber, and a .045" thick gasket with a 4.060 bore, your sitting at 9.05:1 static compression and a 6.72:1 dynamic compression. That is crazy low for a NA car
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I'd *personally* go with a -2cc piston, 4.005, either Wiseco or Diamond. Both are shelf pistons.
Vendor: pick your poison. Texas Speed, WS6Store, Vengeance, BrianTooleyRacing.... They're all listed to the right of this paragraph.
Vendor: pick your poison. Texas Speed, WS6Store, Vengeance, BrianTooleyRacing.... They're all listed to the right of this paragraph.
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TECH Senior Member
Joined: Mar 2004
Posts: 14,620
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From: BFE
With stock chambers 66.67and .052 gaskets,that would get you 11:1
^^ That's the man I was hoping would show up in here!
OP, listen to Pred-Z... Guy doesn't beat it around the bush and will smack you in the face with fact and reality.
OP, listen to Pred-Z... Guy doesn't beat it around the bush and will smack you in the face with fact and reality.
thats not what hes asking for....he's asking for the relative difference between your deck and piston when at TDC. You can backcalculate the deck height once you know this difference since the compression height is known.
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
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does .005 sound correct?
Last edited by andy9743; Jun 13, 2013 at 08:15 AM.
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
Likes: 0
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Yes I meant just that. Piston position at TDC with respect to block deck. So are you assuming .005 or is that measured? See that makes a difference in the compression calculations.
IMO -28cc dish is too much for NA setup. -2 cc valve reliefs would be enough.
Cam is a bit small, but would make a nice driver with plenty trq; are you considering a swap?
I would choose more overlap, something around 11* positive to 15* positive.
IMO -28cc dish is too much for NA setup. -2 cc valve reliefs would be enough.
Cam is a bit small, but would make a nice driver with plenty trq; are you considering a swap?
I would choose more overlap, something around 11* positive to 15* positive.
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
Likes: 0
Yes I meant just that. Piston position at TDC with respect to block deck. So are you assuming .005 or is that measured? See that makes a difference in the compression calculations.
IMO -28cc dish is too much for NA setup. -2 cc valve reliefs would be enough.
Cam is a bit small, but would make a nice driver with plenty trq; are you considering a swap?
I would choose more overlap, something around 11* positive to 15* positive.
IMO -28cc dish is too much for NA setup. -2 cc valve reliefs would be enough.
Cam is a bit small, but would make a nice driver with plenty trq; are you considering a swap?
I would choose more overlap, something around 11* positive to 15* positive.
predator z check your pm's
thanks
Thread Starter
Staging Lane
Joined: Nov 2012
Posts: 56
Likes: 0
suggestions on what direction to go with pistons? idk if i really need to go with forged pistons for what i'm looking to achieve. whats out there in the 4.005 bore? what is cost effective for a dd type status? i'm not going to race the car, the current crank rods were set up by the po, it's most likely overkill for me. hyperutectic an option in 4.005 bore? thoughts on that? i found some wiseco's for $700 but idk if they would be overkill for my application. i know the c&ced 853's are going to hold me back but that's not the end of the world, i just want a well put together combo that makes respectable power. if i need to change the cam i can, if i need to change the pistons i can, if i can save the cam great...i think the pistons have to be swapped though from what i'm feeling here. intake is a mamo ported FAST unit, with an ls2 tb.
