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BB 915 head valve size
#2462413
03/07/18 02:46 AM
03/07/18 02:46 AM
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Joined: Jan 2003
Posts: 1,908 Nebraska
4406bbl
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,908
Nebraska
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Is there any reason not to use 2.08/1.74 valves vs 2.14/1.81? I am stuck with factory exhaust and 6bbl intake so would bigger valves actually hurt? I need to buy valves and have seats cut on a serdi so cost is not an issue, pistons have reliefs and are .001 in the hole. Heads are 79cc now, .039 head gasket. Intake side gasket matched, pushrod pinch is .080 wider, and will minor blend below the serdi cuts, and widen a little beside the intake guide. I put the heads on the block and scratched the cylinder wall edge on the head, and feel the bigger valve will not do much good on this engine. I also must use a streetable cam, nothing crazy.
Last edited by 4406bbl; 03/07/18 04:02 AM.
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Re: BB915 head valva size
[Re: 4406bbl]
#2462415
03/07/18 03:02 AM
03/07/18 03:02 AM
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Joined: Aug 2003
Posts: 43,228 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,228
Bend,OR USA
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Put the bigger valves in now, the 915 heads could have came with either 1.60 exhaust or the HP head size on the exhaust with 1.74. Go with bigger on both and have the shop machine match the bowls to the new seats You can never have to much airflow
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: BB915 head valva size
[Re: 4406bbl]
#2462435
03/07/18 05:40 AM
03/07/18 05:40 AM
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Joined: Jan 2007
Posts: 1,668 Mi,U.S.A.
mike s
top fuel
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top fuel
Joined: Jan 2007
Posts: 1,668
Mi,U.S.A.
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Another way to go is to cut the 2.14 intake valves to 2.10-2.11.More costly but you won't shroud the int valve so much. Also you can put the valve at original height in the cyl head. The more the valve is sunk the less the flow. 1.75 exh valve will work fine.A little bowl work will help alot. I do this on the smaller bore engines and have had very nice results.Also saves heads from seat inserts.
Leave the gun.......take the Cannoli's....Mike
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Re: BB915 head valva size
[Re: 4406bbl]
#2462591
03/07/18 03:05 PM
03/07/18 03:05 PM
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Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,506
So. Burlington, Vt.
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If a decent amount of blending(by someone who knows what they're doing) isn't part of the plan with the addition of the big valves, then I'd recommend sticking with the stock 2.08/1.74 valve sizes.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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