I am going to port match the heads and intake on my lt1 to the gasket my question is what is the biggest I can go without welding the inatke and still get a good seal.

As far as gaskets I have seen widths: 1.24" or 1.25"
and heights: 2.040", 2.060", and 2.250"

so which is the largest I can use, I need to have to the machine shop that is doing the work ASAP.

thanks for you help.

 

if your only running the cc306 then I'd just gasket match the regular felpro gasket.

 

I am having the heads ported as well as GM847 w/1.6 nsa rr and quite a few other mods since I am building my second engine, so I would like as much flow as possible.

I have measured up the fel-pros, and there isn't much difference at all, I also plan to move up to either the lt4 or the edelbrock lt4 in a few months but would like to have the heads ported to match already(if not as close as oem manifolds allows) and they said that they would match the intake for free with everything they are doing, so I might as well.

I would like to match to the intake size of some SCE intake gaskets I wanted to buy which are 1.250" x 2.250", but I don't want to have to mess with welding the intake to aloow it to be ported that far as it would be expensive and I want to replace later.

 

"I am going to port match the heads and intake on my lt1 to the gasket my question is what is the biggest I can go without welding the inatke and still get a good seal."

Why do you want to do that? What is the smallest cross sectional area in your intake manifold runner? What cross sectional area is best for your setup? What is the cross sectional area of the pushrod pinch area of your head?

Point I'm leading to is you can screw things up if you are not carefull. I think some more research might be in order. With to big of a port the flow can become lazy and you can have a dog of a motor.

 

just like you never see intake runners with a mirror finish. it creates a drag.

 

Bigger isn't always better...

 

so what do you guys recommend, I am trying to have the gaskets to my machine shop before Thursday because I am going on vacation and want to assemble my engine when I get back.

I know too large a port affects velocity, I am just looking to get the most airflow I can right now out of the motor, I did not know that the oem LT1 intake could be ported to the point it would be too large. SO what size would you recommend doing for my combo.
to help a little here is what I am having done:

3 angle valve job
w/back cut valves
pocket port and radius work
match porting on intake
guideplates and studs 7/16"
Comp cams gold 1.6 NSA RR
GM847
and also new valvesprings if the PAC springs I have on cc306 will not work on GM847-machine shop will test these first to make sure they will work-if not new possibly
and are milling the heads for flatness they said that they might be a little warped on one head(I had oil in water) so it might need to be milled more.
Impala head gasket, *depending on how much is milled maybe thicker or thinner
42# injectors
tune(possibly LT1 edit????)
4.10's
as far as short block I am going to rebuild with a summit kit with speed pro forged flat top (.030" over/+6.10cc) pistons

I already have hooker super comp LT
ORY
3" exhaust
SLP cold air

Also in the next 6 months or so I plan to go to either the LT4 or edelbrock LT4 intake and I do not want to have to have the heads off the car again to match them to the new intake.

thanks in advance for the help, if there is anything else you need to know to recommend a port size I will check this tommorrow on my lunch hour.

 

Generally speaking you want a constant taper from where the air inters the runner in the intake manifold all the way to the valve chamber in the head. In other words a funnel shape so to speak. Someone with a program such as EA Pro would be able to figure out what is best for your motor.

 

would I need to find it(EA Pro) from someone on here or a machine shop/engine builder