Help with manifold matching
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Re: Help with manifold matching
I know that everyone (including me) port-matches heads and intake manifolds by scribing our chosen gasket size onto the port openings. Its always bothered me that head & intake manufacturers develop a port to the best of their ability. Then we come along and change possibly vital airflow dimensions based on what a gasket manufacturer builds...
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Re: Help with manifold matching
That's just it. They don't develop it for all combinations having various and differing airflow requirements. It's a happy medium based on market shares. On the plus side.. there's almost always room for improvements on more highly developed parts combo's.jsgarage wrote: ↑Wed Mar 21, 2018 7:46 pm I know that everyone (including me) port-matches heads and intake manifolds by scribing our chosen gasket size onto the port openings. Its always bothered me that head & intake manufacturers develop a port to the best of their ability. Then we come along and change possibly vital airflow dimensions based on what a gasket manufacturer builds...
Ever measure gasket openings of all stamping before starting the layout/scribing? I've seen mismatches of gasket openings exceeding .040" difference in widths. Seems rather silly to go to all the trouble of blueprinting an engine and porting heads and inductions to gain more consistency.. then piss it all away by matching a $2 gasket.
Re: Help with manifold matching
it doesn't take long to use a ball peen hammer to tap out a cardboard pattern to transfer exact dimensions from head to manifold or vice-versa, rather than grinding an 'aneurysm' into the joint to match an oversize and/or mis-located gasket....
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
Re: Help with manifold matching
By no means am I a real head porter, but knowing that I have a pushrod pinch further down stream from my intake face I always make the intake and head as small as the castings allow. If my heads are sized pretty close to begin with I try to match up the ports so there are no hard lips without any issues in the head or intake. I hate the idea of port matching to a huge gasket and then have a pushrod pinch that is much smaller. By keeping it smaller before it I can keep the pushrod pinch as smooth as I can. But then again I am a backyard hack that has the time to do it this way. I can see how guys doing this as a profession have to do things to maximize their time and dollars.
Paul
"It's a fine line between clever and stupid." David St. Hubbins
Re: Help with manifold matching
I do this same thing. I focus on the actual pushrod pinch as being the actual narrow point so I try to widen it rather than the port opening itself in order to get a straighter line. Widening the opening along with the pushrod pinch seems to in my mind at least to be working against youFC-Pilot wrote: ↑Thu Mar 22, 2018 3:39 pmBy no means am I a real head porter, but knowing that I have a pushrod pinch further down stream from my intake face I always make the intake and head as small as the castings allow. If my heads are sized pretty close to begin with I try to match up the ports so there are no hard lips without any issues in the head or intake. I hate the idea of port matching to a huge gasket and then have a pushrod pinch that is much smaller. By keeping it smaller before it I can keep the pushrod pinch as smooth as I can. But then again I am a backyard hack that has the time to do it this way. I can see how guys doing this as a profession have to do things to maximize their time and dollars.
Paul
Re: Help with manifold matching
I also don't see any thing in ,his, on this motor. Other than increasing the chance of a gasket leak at the manifold.
Raising up the manifold a bit, as said is as far as i'd go with this one. There is more in the cam and carb.
Raising up the manifold a bit, as said is as far as i'd go with this one. There is more in the cam and carb.
Re: Help with manifold matching
A dual plane on a jet is kinda odd to start with...unless it's a really low rpm big block in a heavy boat with something like an A2 or bigger cut impeller, a single plane is always better
Look for a single plane and chuck that dual plane ...or you will kill all the good flow in those heads
like you said, the impeller acts like a small diameter converter.
Ive run mild small blocks in jets with single planes ...that's the ticket
Look for a single plane and chuck that dual plane ...or you will kill all the good flow in those heads
like you said, the impeller acts like a small diameter converter.
Ive run mild small blocks in jets with single planes ...that's the ticket