I've got big block large port hi perf heads (L71). In additon I've got the L71 exhaust manifolds. Unfortunately the manifolds have the holes for the A.I.R system. Because I don't need them the holes are pluged. If I look inside the manifold I think that the rise around the holes is distubing the air flow. Can someone tell me if it's necessary to grind this material away? I can imagine that without removing it there are a lot of wirls which are bad. Thanks, Markus
-
-
RED FLAG
I sent a pair of 901/902 exhaust manifolds to Brezezinski along with about $300.00 to have them "ported" and modified to conform with their latest dyno information that claimed more horsepower and torque. I installed the finished work and noted a definate deterioration in over-all performance.
At 7000 RPM I'm sure my engine made more power BUT at the rpms where I use it most of the time it became soggy. I shot myself in the foot! The unmolested manifolds scavenge exhaust gases much more efficiently where I need the torque!Leave things alone unless you think you can improve on the work of hundreds of GM engineers. Also, I'm sure you don't have acces to dynos like they do!
As far as the tips to your plugs are concerned, yes, I'd grind them off a little and not worry about it!
The Rev. -
Re: "Porting" BB exhaust manifolds
You could also match the manifold openings to the heads, which shouldn't take much grinding.
DukeComment
-
Re: "Porting" BB exhaust manifolds
But Duke, shouldn't we deliberatly have a mis-match there? How about anti-reversion assistance?
The Rev.Comment
-
Re: "Porting" BB exhaust manifolds
If the boundary of the manifold port is at or beyond the port boundary in the head, it's okay; but it the manifold port boundary is inside the head port boundary at any point, it should be ground back.
DukeComment
-
Re: "Porting" BB exhaust manifolds
Of Course!
Dale.Comment
-
Re: "Porting" BB exhaust manifolds
Hehehehe!!! you guy's are great ,lol,Comment
Comment