The Ford Barn

Ol' Ron · 05-26-2015, 07:34 AM

Because the intake ports are machined at the factory, they are very accurately sized and located. Using a flow bench I found the for a street engine, increasing floe was done by just cleaning up the opening, not inlarging it. Stragening out the top and radiusing the entrance into the bowl. Next where the port floor enters the bowl remove aprox 1/8" material. Then blend in the port to the bowl. With practice this can be done in just a few minutes with a carbid burr. Do not polish the port.
What you want to accomplish is a hi velocity flow with little interferance in the port. The Chevy valve has a very poor bottom. For a street engine I undercut the valve (any valve) with a 20 degree angle from the minor diameter of the seat to the stem. The edge of the valve should have a small radius, THis prevents cracking from heat.
There are as many ways to port a block as ther are guys that do it. The method I discribed is just something that works quite well up to ???RPM. Nobodys ever done any dyno testing on the affects of porting an engine.
Now with that done transfer the finished ports to the intake manifold.

Tom Walker · 05-26-2015, 05:13 PM

Thanks Ron that's great stuff!

chap52 · 05-27-2015, 07:17 AM

Mikebishop has it right...Great picture...Wish I had known that relief notch trick before I built mine. Spent a lot of time getting the adjusting tuned in when I added a cam. Fortunately the engine was on an engine stand and not in the truck.
Again, enjoy the adventure.

05-26-2015, 07:34 AM	#21
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: 51 Flathead 8-How Far to Take Rebuild? Because the intake ports are machined at the factory, they are very accurately sized and located. Using a flow bench I found the for a street engine, increasing floe was done by just cleaning up the opening, not inlarging it. Stragening out the top and radiusing the entrance into the bowl. Next where the port floor enters the bowl remove aprox 1/8" material. Then blend in the port to the bowl. With practice this can be done in just a few minutes with a carbid burr. Do not polish the port. What you want to accomplish is a hi velocity flow with little interferance in the port. The Chevy valve has a very poor bottom. For a street engine I undercut the valve (any valve) with a 20 degree angle from the minor diameter of the seat to the stem. The edge of the valve should have a small radius, THis prevents cracking from heat. There are as many ways to port a block as ther are guys that do it. The method I discribed is just something that works quite well up to ???RPM. Nobodys ever done any dyno testing on the affects of porting an engine. Now with that done transfer the finished ports to the intake manifold.

05-26-2015, 05:13 PM	#22
Tom Walker Senior Member Join Date: Aug 2012 Location: Leicester. UK Posts: 404	Re: 51 Flathead 8-How Far to Take Rebuild? Thanks Ron that's great stuff!

05-27-2015, 07:17 AM	#23
chap52 Senior Member Join Date: Jun 2013 Location: Marana Arizona Posts: 1,776	Re: 51 Flathead 8-How Far to Take Rebuild? Mikebishop has it right...Great picture...Wish I had known that relief notch trick before I built mine. Spent a lot of time getting the adjusting tuned in when I added a cam. Fortunately the engine was on an engine stand and not in the truck. Again, enjoy the adventure.