DSM PImp

I have a 383 LT1 with mods listed in signature. I am planning on purchasing headers and a 58mm TB. Now will it be worth my money to get my manifold ported? Also if I do get it ported, do you think the machine shop is going to want to take it off since their going to want to see the cylinder head port sizes so they can port mach the intake manifold?

Stoopalini

Yes, you'll need to take the manifold off to have it ported; and yes, you'll at least need to have the TB opening ported out to match the 58mm TB. The stock opening on the intake is 52mm.

Might as well have them gasket match it while they are doing port work. No need for them to see the head ports, as they'll use an intake gasket to do the port matching.

Thomas.

30AnvZ28

Why have a 58mm throttle body when you only have a 52mm stock intake opening?

The obvious answer here (as far as throttle body) is a definate yes... and if your running a 383, I cant understand why the rest hasnt been done yet... your robbing yourself of some serious power.

And yes, the intake has to be taken off to port it... I would sent it to LE to have him port it. Ive had mine professionally ported, but since he built my heads, I want him to go over it and see if he can improve it any.

JP95ZM6

Gasket matching is common, and easiest. However, it is better to match the intake ports to the head ports. The last think you want in the intake tract is a step to trip the air, and gasket matching may result in this. In my case, with LE2's and Felpro intake gaskets, it turned out to be the other way around; I needed to trim the gaskets a bit in the center wall areas to remove them from the air stream. Either way, it is better to port match rather than gasket match, and should cost about the same.

Intense_Spence

I might ad it would be best to have the ports matched to the heads as long as they don't end up being bigger than the gasket, then your air/fuel will be catching the gasket.

DSM PImp

I havent had it done yet because I havent had the money to do it yet. I also did not no the specs on the manfiold eaither. With the LE1 heads, is it easy to port the manifold runners larger than the head ports? Better yet how much bigger is the manifold gasket from the LE1 head ports?

Also how much have you guys paid to get the port work done on your heads?

engineermike

I wouldn't worry so much about gasket match as I would the "ski jump" on the roof of the runner. It really is a big problem area for the LTx intake manifolds. I found that I could remove .100" from the roof of my LT4 runners and still not break through (leaves about .050" wall thickness).

Mike

1989TransAm

I agree. A far as gasket matching goes try to get the top port close to lining up. I would not worry about the sides or the floor.

Wild1

I pulled my intake this week and my factory intake gasket was shorter than the base of the intake manifold floor by .126". I'm looking into possibly enlarging the gasket to match the port without compromising the print-o-seal. I'll unpack my gasket and check it out later this week.

1989TransAm

Having the gasket protrude into the intake track is not good. Either a bigger gasket or cut the one you have.

Godchsr

Out of curiosity, do you know how much expansion takes place on the gaskets as well?
IE: How much MORE should you take off the gasket in order to make sure after torquing the gasket doesn't reenter the intake stream.

dangalla

i cant give you the technical answer i think your looking for, but i just held my gaskets in place and opened them up with a dremel and a sanding disc and after they matched the heads i opened them up just slightly larger, maybe a 1/16 or so. i dont really think you have to worry about expansion of a paper gasket to much

Godchsr

Cool... I wasn't too sure about the material we use on these manifolds.

JP95ZM6

If you have enough material to make the gasket holes a bit oversize, it will make alignment less critical. I did not, so alignment was critical.

Keeping the gaskets aligned repeatably was tricky for me. My heads didn't have any alignment pins for the gaskets (I don't know if any LT1 heads do). The bolts didn't seem to align the gaskets very accurately, so before trimming the gaskets, I assembled everything. I then drilled 2 SHALLOW 1/8" diameter holes into each head's intake gasket surface, right through the intake 'tray' and the gaskets simultaneously and them maybe 1.16 into the heads. This let me use pieces of 1/8" welding rod to make my own temporary aligment pins. I used the holes and rods to keep the gaskets aligned to the intake while I enlarged them. I used the rods again during assembly to locate the gaskets, but I removed them after the first torque sequence.

I wish I could have found a bigger gasket instead - I have mystery oil consumption now, and the hogged out gaskets is a potential reason, I guess. But I think the LE1 ports are smaller, so you should have more material to work with. Good luck!

engineermike

That's weird, my stock heads and AFR 210's both had gasket alignment holes on them. I'm using the GMPP LT4 gaskets (with the large ports) from Thunder Racing and they have plastic alignment dowels built into them. Works perfectly.

Mike