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FAO Gary P re: your old jenvey 48's inlet manifold

820 views 11 replies 5 participants last post by  DarrenH 
#1 ·
hi, how are you today allllrighty then. I know you did some port grinding on the inlet manifold, did you just match it to a standard inlet man gasket ? The only reason i ask is, i was standing there (with my engine in bits) offering up my current gasket to the head, and the mating face of the jenvey manifold. The gasket is only a eeeency bit too small, yes you read that right, too small for the jenvey manifold AND the ports on my head. I was expecting to have to open my head inlet ports out slightly to match the work you did on the manifold, but no, they are a perfect match. If anything i will have to make the gasket holes slightly bigger, especially at that rounded "nose" shape section on the gasket holes. So, whats the crack ?
 
#5 ·
My SBD inlet manifold looked like it was made to use 45mm TBs as so much has to be cut away to fit the head and the TBs smoothly. Not only that, bit MrF opened up the head a bit and enlarge the maniflod even more.

Also, where there is the bend in the manifold, loads was taken away from the inside edge so that the flow of air was straighter.

There is loads of work to be done on the inlet. How do your TBs match up?
 
#9 · (Edited)
using my old gasket to eye up each mating surface, i deduced the following. Head ports + mating ports of inlet manifold = spot on, inlet to throttle bodies = spot on match. The only thing as i said earlier, is the standard inlet man gasket will need a wee bit of shavage so it doesnt protrude into the flow.

I still dont understand how the enlarged and flowed inlet manifold matches perfect with my standard head, i'm not complaining mind you.

I presumed gary englarged the head ports and the inlet man ports.
 
#10 ·
cos your head is identical to mine odders - and it's a well know fact that opening out the inlet ports is bad for gas speed, hence low down torque, so I left em, save for gasflowing - seriously porting the inlets is for race engines only.

the theory is nice and big at the rams, tapering down evenly to the chambers.
 
#12 ·
splendid, i suppose i should have just asked ages ago. That was the one main thing i was worrying about, do i disturb the head and enlarge the ports. But now the head has to come off anyway, but i dont have to enlarge the ports. Weird how things turn out. :D
 
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