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Little back ground on the current engine.
416 with the deck cleaned up .003
TFS 235 milled .060
felpro .041 HG
Anyway im trying to get this lower part of the manifold to line up with the ports. Im thinking with the engine decked, milled heads and thinner HG the manifold doesn't want to sit down all the way on the intake ports of the heads. One side will but the other side hangs up on the ledge right by the edge of the manifold. Doesnt sit flush here Port lines up pretty well considering some ive seen posted here. Right side of manifold could use some blending.
Has anyone used a fel pro intake gasket between the head and manifold to help? Either that or I'm going to grind down the edge of the manifold on both sides that are cloarst to the valve covers.
What are your thoughts?
Last edited by 65LSXNOVA; Aug 7, 2024 at 02:27 PM.
Is the lower section torqued down to the heads that would drop it a tiny bit. what fasteners are you using on the valley cover.
My LSXR didn’t line up well to my 235’s. I ended up port matching the heads removed some material and added some also.
Yeah I bolted the lower section down to the heads with all the bolts. I had all the bolts removed from the valley cover so it wasn't the bolts holding the lower manifold up. I then removed the valley cover all together and it helped a little bit. I think I might try grinding the ribs down on the bottom of the underside of the manifold and get some counter sunk fasteners for the valley cover. I'm sure the valley cover was sticking up some not being bolted down.
Originally Posted by jasons69chevelle
Is the lower section torqued down to the heads that would drop it a tiny bit. what fasteners are you using on the valley cover.
My LSXR didn’t line up well to my 235’s. I ended up port matching the heads removed some material and added some also.
I ended up grinding most of the ribbing on the underside of the lower manifold down as it was still hitting the valley cover. I also rounded over the furthest edge closest to the valve cover to allow the manifold to sit flush against the intake surface of the cylinder head. Almost done.
Had a hell of time trying to get this thing to idle with the holley term x. Never had a issue with the TBSS intake and current combo.
now the engine is making a very loud whistling noise at medium throttle above 3000 rpms. Almost like its sucking air in somewhere. I tried carb cleaner around injector ports and all around intake. All vacuum ports are capped off and zip tied to insure they can't come off.
Maybe try clear silicon or a heavy application of dielectric grease around the outside gasket. Just because you are spraying it w/ brake cleaner and no result does not mean it's not leaking. Keep in mind, it's plastic, it's going to move around some when it's under load. The dielectric grease works for testing, but is not a perm cure, fyi. With the amount you shaved off the heads, plus thin gaskets, I guarantee the intake is bowing some down the middle when tightened down.
Maybe try clear silicon or a heavy application of dielectric grease around the outside gasket. Just because you are spraying it w/ brake cleaner and no result does not mean it's not leaking. Keep in mind, it's plastic, it's going to move around some when it's under load. The dielectric grease works for testing, but is not a perm cure, fyi. With the amount you shaved off the heads, plus thin gaskets, I guarantee the intake is bowing some down the middle when tightened down.
more I work on this manifold the more I've been thinking I should have taken your advice and gone single plane. I definitely could give up some low end TQ. But what's done is done for now. Siliconed the runners to the lower manifold. Then siliconed the upper to the lower. If its got a gasket or seal or vacuum port its getting siliconed. Ill probably silicone the manifold to the heads also.
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LSXRT 102 & TFS 235 alignment issues 
