Porting Intake Manifold or buy new?
Thread Starter
Drifting
Joined: Sep 1999
Posts: 1,411
Likes: 1
From: Wylie TX
Porting Intake Manifold or buy new?
All of this manifold talk from Clink69 has gotten me to start thinking what I'm going to do about my manifold problems.
I have an intake manifold (Weiand #7525) which matches to a 1204 gasket and heads (AFR 195) that match a 1205 gasket. I'm thinking of either:
Porting (or having it ported) my existing manifold or
Buying a Weiand #7530, running a spread bore carb adapter and a 2.5" filter element (replacing my 3" element).
The other components of my engine are Q-Jet carb, Comp Cams (XR274R) solid roller with 236/242 duration @ .050 and a redline at/about 6500 RPM.
Also, the heads have been milled (and the block decked) and although the manifold goes on w/o leaks, it makes me nervous how difficult it is to get the bolts in, so I'll probably need some machine work either way I go.
I have an intake manifold (Weiand #7525) which matches to a 1204 gasket and heads (AFR 195) that match a 1205 gasket. I'm thinking of either:
Porting (or having it ported) my existing manifold or
Buying a Weiand #7530, running a spread bore carb adapter and a 2.5" filter element (replacing my 3" element).
The other components of my engine are Q-Jet carb, Comp Cams (XR274R) solid roller with 236/242 duration @ .050 and a redline at/about 6500 RPM.
Also, the heads have been milled (and the block decked) and although the manifold goes on w/o leaks, it makes me nervous how difficult it is to get the bolts in, so I'll probably need some machine work either way I go.
Drifting
Joined: Nov 2000
Posts: 1,361
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From: Honolulu Hawaii
Re: Porting Intake Manifold or buy new? (Chris A)
Take this as a grain of salt, I don't think a 1204 to 1205 port size is a big concern. A 1204 to 1206 is something to wonder about. 1204 intake being a restriction in a big port head is the big issue to me, not fuel atomization. If your carb doesn't make a good mixture then fuel distribution to individual cylinders would become a greater concern. I wouldn't fix the mixture by changing the intake first. I would work the carb first.
Regarding the use of a smaller air filter on a 7530, make sure you are not bringing the air cleaner lid too close to the carb mouth causing a restriction.
Regarding the use of a smaller air filter on a 7530, make sure you are not bringing the air cleaner lid too close to the carb mouth causing a restriction.
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Re: Porting Intake Manifold or buy new? (Chris A)
Chris,
I my memory is correct the 7525 is an open plenum manifold.Use it! Port match but leave the floor of the runners on the manifold alone or not port matching would be ok also.Use the 1205 gasket.Small to large = velocity.I think you really need a Holley 750 double pump list#4779.It will distibute fuel better than the Q-jet at high RPM and the pulses from the intake tracks won't affect the secondarys.Have you tried header bolts in the difficult spots?
I my memory is correct the 7525 is an open plenum manifold.Use it! Port match but leave the floor of the runners on the manifold alone or not port matching would be ok also.Use the 1205 gasket.Small to large = velocity.I think you really need a Holley 750 double pump list#4779.It will distibute fuel better than the Q-jet at high RPM and the pulses from the intake tracks won't affect the secondarys.Have you tried header bolts in the difficult spots?
