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BB 915 head valve size #2462413
03/07/18 02:46 AM
03/07/18 02:46 AM
Joined: Jan 2003
Posts: 1,202
Nebraska
4
4406bbl Offline OP
pro stock
4406bbl  Offline OP
pro stock
4

Joined: Jan 2003
Posts: 1,202
Nebraska
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.
Re: BB915 head valva size [Re: 4406bbl] #2462415
03/07/18 03:02 AM
03/07/18 03:02 AM
Joined: Aug 2003
Posts: 32,288
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
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Joined: Aug 2003
Posts: 32,288
Bend,OR USA
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 up You can never have to much airflow devil work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: BB915 head valva size [Re: 4406bbl] #2462425
03/07/18 04:04 AM
03/07/18 04:04 AM
Joined: Jan 2003
Posts: 1,202
Nebraska
4
4406bbl Offline OP
pro stock
4406bbl  Offline OP
pro stock
4

Joined: Jan 2003
Posts: 1,202
Nebraska
These are the 1.60, so at minimum the 1.74 exhaust need to be done.

Re: BB915 head valva size [Re: 4406bbl] #2462435
03/07/18 05:40 AM
03/07/18 05:40 AM
Joined: Jan 2007
Posts: 1,660
Mi,U.S.A.
M
mike s Offline
top fuel
mike s  Offline
top fuel
M

Joined: Jan 2007
Posts: 1,660
Mi,U.S.A.
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
Re: BB915 head valva size [Re: 4406bbl] #2462591
03/07/18 03:05 PM
03/07/18 03:05 PM
Joined: Jan 2003
Posts: 11,738
So. Burlington, Vt.
F
fast68plymouth Offline
I Live Here
fast68plymouth  Offline
I Live Here
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Joined: Jan 2003
Posts: 11,738
So. Burlington, Vt.
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
Re: BB915 head valva size [Re: mike s] #2462594
03/07/18 03:08 PM
03/07/18 03:08 PM
Joined: Mar 2008
Posts: 857
Affton MO
Q
qwkmopardan Offline
super stock
qwkmopardan  Offline
super stock
Q

Joined: Mar 2008
Posts: 857
Affton MO
I put .100 long-2.125 sb chevy intake valves in mine. They also had 5/16 stems. Exh was 1.80 ford 351 cleveland with 11/32 stems. If you are installing new guides you can use any stem size. Smaller means less weight. Engine made over 650 hp at only 10.5 to 1, on a 449/383 engine--4.28 bore x 3.900 stroke. 9.02 at 150mph 1/4 mile-in 2500# car.


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