Grinding 351w heads

[Pops]

Does any body know what the potential power increase would be by
port matching and removing the air injector mounds inside the exhaust
ports on 95 351w heads?

Thanks in advance.
Pops

 

[noreasteb]

A while back i did some reading on this and from what i read the exhaust humps should not be ground because it slow the exhaust gass velocities and could potentially result in torque loss. I am not an engine guy so this could be totally false. I have read that port matching intake and exhaust with their respective manifolds proves to be beneficial.
Hope more people chime in on this ... got a motor build coming up in Sept.

 

[Bronco_69]

more like a power loss. dont do it.

 

[Broncobowsher]

Anyone can randomly hog material out. Tricky part is carving the right amount in the right places. Shape of the port is important. The real tricky part is getting all 8 ports the same shape so they all flow evenly. It is not as easy as it sounds.

Simple port work, gasket matching and blending the match an inch into the port is fairly easy to get right. When you get deeperinto the head where stuff bends around, then it gets touchy.

The bump in the exhaust port is usually refered to as the EGR bump. Generally good to remove for performance.

More is not always better. There is a difference between cleaning up and carving up.

 

[bmc69]

Simple port work, gasket matching and blending the match an inch into the port is fairly easy to get right. When you get deeperinto the head where stuff bends around, then it gets touchy.

The bump in the exhaust port is usually refered to as the EGR bump. Generally good to remove for performance.

More is not always better. There is a difference between cleaning up and carving up.

all true, including the removal of the 'bump'. I've done a lot of 302/351w performance heads (probably in the hundreds?) and when I learned all of that (way back in the olden days..back when all you ahd to work with wre stock castings), we had a flow bench to work with too. The exhaust side of the 302/351W heads is where the 'wheezer' nickname came from..and they can really benefit from the proper exhaust port work when combined with the correct valve sizes and other port/bowl blending and mods. FWIW, when talking about a decent truck head, that usually means 1.85 or 1.94 intake valves and 1.60" exhaust valves, with appropriate bowl work in each case. The intake side requires little of nothing for the RPM of interest for a truck engine, excepting the bowl work to accomodate the larger valves properly.

 

[Wyflyer]

I did extensive head work on my 400, ground off the thermactor humps, port matched to intake, port matched to exhausts, and also cut off the valve guide boss and shortened valve guide O.A.L. Lots of shaping, heavy polishing on the exhausts.
It made an amazing difference. The most you can lose is a set of heads and some time.

 

[broncnaz]

Probably easier to just get a set of earlier heads without the bump. Also as was said bigger valves would really help more than removing the bump. If your exhuast system is not upgraded also the efforts are lost.

 

[Pops]

Thanks guys for the replys, bmc69 great info on valve sizing. The original plan for this motor was a set of AFR heads but cash is running low. So a little
do it myself is in order. Just going to port match and remove humps.

So far the motor is getting Performer-plus cam and intake, MSD dizzy with
#6 box, High volume Melling oil pump,7 qt Milodon oil pan and aset of BC Broncos Ceramic coated Headers.
Thanks again
Pops

P.s. If I ever get my Pay Pal account straightend out I'll post pics

 

[Bronco_69]

this is some of the best infor for DIY porting and the E7 heads.

http://www.diyporting.com/
http://www.diyporting.com/E7prj.html

 

[Pops]

Bronco 69
that site is awsome, thanks for the link!!!!!!
Pops

 

[Canuck]

I,m running a stock 302 block&cranck & rods. I picked up a set of 351w heads from a 1970 mustang , planed.030 off. ported & polished and put in flat top pistons . and an edelbock 650. its got sick power . I love it