Was wondering if this would help out any or just be a waste of time. I seen this tbi spacer. And thought I could just bascially cut that into the stock manifold with the mill at work. And maybe make a open type spacer to help add more volume to the manifold. What do ya think?

 

Or you could just enlarge the already existing hole.

https://www.thirdgen.org/forums/post...38-post14.html

 

Good question guys. I have bored many, many, many SBC manifolds and you MUST be very careful in doing so.

You should be able to bore most, if not all of them safely to 46mm. It's when you bore them to 50mm where you can get in to trouble. There is NO rhyme or reason to GM and their intakes. I have recently taken 4 intakes with the same casting number and bored them sucessfully to 46mm. Now, i took those 46mm intakes and bored them to 50mm. Only one was sucessful. The other 3 were ruined and opened into passages.

So, to machine between the bores in your intake as Scott has done with his "Powerplate" is a possibility and a great idea. I have been wanting to take those manifolds that I have "ruined" to see if I can do that. Some intakes have a port between the two bores so becareful of that as well.

I'll be honest with all of you. I have had two vehicles on the dyno and have seen no significant change in ANY of the "spacers". Three dyno pulls on each vehicle prior to the installation of the spacer/s and then three dyno pulls after installation on each vehicle.

1-2hp gain and a little increase in torque. Torque was the biggest increase. Vehicles used 92 Firebird stock 305 and a 1991 5.7L pickup with basic ultimate TBI mods.

 

I was going to enlarge the bores while I had it off. Was just wondering about cutting maybe 1" deep and across the center. And smooth off the center into a ramp. I didn't know if this would help or hurt fuel distribution.

 

Great idea. I don't see why it won't work well if the casting will allow you to do that.

 

Aight guess i'll give it a try, just don't have anyway to prove if it affected anything tho lol. cause with it off i'm gonna do a cam and head swap.

 

It will help for sure.

 

I'll let ya know how it goes and post some pic when it gets done.