Raising compression on a 455
September 14th, 2018, 09:29 AM
#1
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Location: Whittier California
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Raising compression on a 455
I'm looking to raise the compression on my 455, can I get some recommendations on some good forged pistons and rings? I currently have the l2323-030 18cc dished pistons, I'm looking for something like a flat top piston, aiming for 10:1+ compression with 85cc heads (guessing 85, big valve C heads, extensive porting and chamber work) and a .060 thick head gasket.
also would it be possible to just replace the pistons and rings with no machine work? The motor has maybe 5000 miles on it.
68' toro 455 030 over, 520/520 lift 292/292 adv 240/240 @ 50 solid cam, 72 cutlass, th400, 3200 stall, 3.73 rear.
thanks,
also would it be possible to just replace the pistons and rings with no machine work? The motor has maybe 5000 miles on it.
68' toro 455 030 over, 520/520 lift 292/292 adv 240/240 @ 50 solid cam, 72 cutlass, th400, 3200 stall, 3.73 rear.
thanks,
September 15th, 2018, 02:04 PM
#2
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Location: So. Ca.
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Cometic sells a .027 thick head gasket. http://www.cometic.com/i-24769361-ol...q%3Doldsmobile
September 15th, 2018, 03:09 PM
#4
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Location: Central Fl
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Use the Wiseco 15cc 455 piston. Then check how far in hole it is and use a .027 as mentioned if the deck height allows.
From there mill the heads to 78-80cc and you’ll be at 10.0:1 or so.
After that invest in a wideband O2 to tune it right. Should make a noticeable difference.
From there mill the heads to 78-80cc and you’ll be at 10.0:1 or so.
After that invest in a wideband O2 to tune it right. Should make a noticeable difference.
September 30th, 2018, 10:58 AM
#5
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Location: Whittier California
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Anyone know if those cometic head gaskets are compatible with a O-ringed deck?
Is it possible to have the heads milled fully assembled or am I looking at a valve job as well?
How much do I have to have taken off the heads and intake per CC?
If im doing my math right I have about a 8.7:1 static compression ratio and 6.6:1 dynamic with a .081 quench distance.
(85cc heads, 4.155 bore x 4.25 stroke, 18cc dish 1.735 height pistons .021 in the hole, .060 x 4.4 gasket, 72 intake closing point currently 2 advanced (292/2=146+108=254-2=252-180=72))
If I use that cometic .027 x 4.2 head gasket, mill the heads to 77cc and advance the cam to 10 degrees ill have 9.9 static, and 8.00 dynamic with a .048 quench distance. If I change the pistons as well (15cc dish, 1.75 height) Im looking at a 10.5:1 static and 8.45 dynamic with a .033 quench distance.
Is it possible to have the heads milled fully assembled or am I looking at a valve job as well?
How much do I have to have taken off the heads and intake per CC?
If im doing my math right I have about a 8.7:1 static compression ratio and 6.6:1 dynamic with a .081 quench distance.
(85cc heads, 4.155 bore x 4.25 stroke, 18cc dish 1.735 height pistons .021 in the hole, .060 x 4.4 gasket, 72 intake closing point currently 2 advanced (292/2=146+108=254-2=252-180=72))
If I use that cometic .027 x 4.2 head gasket, mill the heads to 77cc and advance the cam to 10 degrees ill have 9.9 static, and 8.00 dynamic with a .048 quench distance. If I change the pistons as well (15cc dish, 1.75 height) Im looking at a 10.5:1 static and 8.45 dynamic with a .033 quench distance.
Last edited by redbaron442455; September 30th, 2018 at 09:16 PM.
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