What is the stock bore of the performer tbi? I want to bore my tb to 48 mm then put in some 48mm tpi blades and I need to know does the manifold have to be bore also?

 

I think that manifold only needs to be bored if you run the GM 7.4L or Holley unit.

 

43mm

 

43mm? I dont understand. I thought a stock tbi was 46mm.

 

I mesure 45mm the stock one and 42-43mm the edelbrock tbi. I just double cheked the 3704 new in the box.

The 3704 that I put on my lo3 I chamfered to 46mm. I actually have some doubts about the 3704 helping my lt1 cammed lo3 make more power then the stock one would.

 

Yeah, people say it doesent help much. If I dont end up getting vortec heads, its gonna be the stock intake FTW. I like my EGR capability.

 

Yea I had to drill out a hole for the egr. Does it help much to bore out the manifold a little bit?

 

I would match it to the throttle bores. You could do it with a die grinder or something.

Just take the gasket that you are going to use, make sure it matched pretty good with the bottom of the throttle body, then position it on the intake manifold using the bolts to hold it in place. Then you can use a marker, or pencil, to trace out the bigger circles around the existing bores. Then use the grinder and go to town.

Just make sure you clean it out really well afterwards. Metal shavings getting sucked into the motor would be bad.

 

Only thing you need to drill the 3704 for is the front a/c bracket.
You are talking about the cilinder heads? U using world products?

 

Im asuming it's the 3704, maybe it wasnt the egr but there was somthing that it didnt have. My dad marked a spot on it and told me it needed to be drilled out, I was like 15 at the time so its been a while, now that I think about it Im pretty sure it was a sensor or somthing I'l look when I get out of class I'm curious now.
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O by the way, I use the 083's.

 

Doesent the EGR mount to a machined flange or somthing, with a gasket? I didnt know it was just a hole...

Maybe I was thinking of the GMPP Vortec TBI manifold. I also found out that for whatever reason, vortec heads are not compatible with EGR, so that would make sense that the intake didnt have provisions for it. If I did ever get those vortec haeds and intake, I guess I could delete the EGR system all together. Though, I would miss the extra gas milage it gives me.

 

Slow, GMPP tbi vortec has provision but the exhaust gasses come from the exaust manifold troug a heat resistent hose that bolts in on the left/front and the egr is bolted to the right/front of the intake manifold.
Should not be to complicated to pull a extern plumbing from the exhaust manifold or headers.

 

Oh, I didnt know that. On my car, I can see the factory EGR valve is on the passenger rear of the intake manifold, with the vacuum hose going to it. What I couldnt find, was where the exhaust gas came from, to get to the valve. I will have to look more tonight.

 

It comes from the cilinder head directly in to the manifold.