Re: Big block exhaust valves
[Re: RoadRunnerJD]
#2550989
09/17/18 11:59 AM
09/17/18 11:59 AM
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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The old 426 Stage III had 1.88’s. How come those are not being used in the race heads today? As mentioned, depends on the heads. A smaller exhaust valve leaves room for a larger intake valve.
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Re: Big block exhaust valves
[Re: RoadRunnerJD]
#2551096
09/17/18 03:27 PM
09/17/18 03:27 PM
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Joined: Jan 2003
Posts: 2,077 Oklahoma City
Jwilli500
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top fuel
Joined: Jan 2003
Posts: 2,077
Oklahoma City
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Correct me if I'm wrong didn't the 426 notch the top of the cylinders a little on those because the 1.88's got too close? I know we had to on my 383 with 1.88s (Same basic 4.25" bore) This is one of the reasons I wont consider 1.88s, not worth the aggravation plus not much benefit. The old 426 Stage III had 1.88’s. How come those are not being used in the race heads today?
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Re: Big block exhaust valves
[Re: Jwilli500]
#2551265
09/17/18 09:23 PM
09/17/18 09:23 PM
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Joined: Aug 2003
Posts: 43,097 Bend,OR USA
Cab_Burge
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I Win
Joined: Aug 2003
Posts: 43,097
Bend,OR USA
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[quote=Jwilli500]Correct me if I'm wrong didn't the 426 notch the top of the cylinders a little on those because the 1.88's got too close? I know we had to on my 383 with 1.88s (Same basic 4.25" bore) This is one of the reasons I wont consider 1.88s, not worth the aggravation plus not much benefit.] You are correct on the larger 1.88 exhaust valves in the 4.250 or smaller bores
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Big block exhaust valves
[Re: RoadRunnerJD]
#2551784
09/19/18 01:57 AM
09/19/18 01:57 AM
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Joined: Jan 2003
Posts: 1,908 Nebraska
4406bbl
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Posts: 1,908
Nebraska
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Put your heads on a non chamfered .030 over bare 440 block, turn it over and tell me what you see. Even some 1.74 heads could benefit from a small notch. When machine shops put 2.14-1.81 valves in they usually unshroud the head making it worse. Put heads on block, turn over, scratch bore circle on head, mark heads left and right, tell shop do not go past this line, if they do you need a notch, unless a ledge in the flow path helps, it may I do not know but doubt it.
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