All_Z_Way

I know the Vortec heads bolt with only 8 bolts and the LT1 heads with 12 bolts, but will the bolt holes line up.

I have a LT1 for a project I would like to carb, but I really don't want to spend the $260+ for a the LT1 carb intake....not to mention the rules I am building this for require a cast iron intake.

StudyTime

The holes don't line up. I held some LT1 intake gasket up to some L31 intake gaskets and the bolt holes were not close at all. The ports didn't seem to match too well either, but some port matching might take care of most of that (?).

You can always weld the holes on the intake up and have a shop or yourself bore you some new ones in the correct location.

I would mainly worry about the ports lining up. Do you find that they line up well enough to use?

You also have the whole reverse coolant flow hurdle to over come. The LT1 gaskets don't have holes in them, right?

I'm sure it can be done, but

I think it is a safe statement to make that it will not "bolt up".

Ben T.

Alvin@pcmforless.com

What about using a SBC intake?

They are converting LT1's to work on SBC's so you should easily be able to go the other way.

I thin you have to redrill 8 holes

SStrokerAce

The problem is the cast iron part.

What is the project?

We commonly change SBC intakes over for LT1 use, just got one ready for welding today.

THE HARD THING IS THAT IT HAS TO BE CAST IRON!

Bret

Alvin@pcmforless.com

what are you guys welding to get it to work?

I've been contemplating using a SBC 144 blower manifold instead of my modified LT1 intake on my roots blown car.


The floor is of the intake is much lower than the LT1's.. i think this would help in airflow since there is problally only 1.5 inches of height right now between the intake floor and the blower

WS6 TA

The ports won't line up. LT1 ports are closer to traditional SBC ports then vortec ports.

Welding cast iron will be easier to do without warping it then aluminum is, you don't have to put nearly as much heat into it to do it. Now for the life of me, I can't remember what the problem is with putting an SBC intake on an LT1 (I know that there is a hassle, but I don't remember what exactly the problem is), but it would seem to me that it would be easier to just drill the heads for the bolt pattern you want. Coolant and egr/heat riser passages shouldn't be an issue, since they're just not there on the LT1 heads.

I'm assuming that you're looking at some of the 4bbl marine intakes? Or the older (70's) passenger car intakes?

I'm curious, what are you building this thing for?

- mmp

OldSStroker

I've found just the opposite: TIG welding aluminum manifolds or heads is relatively easy for a good welder. Welding cast iron is difficult, expensive, and sometimes a good way to scrap some expensive cast iron.

I, too, am curious.

All_Z_Way

Well... I have a spare LT1 short block and I was looking to possibly put in my dirt track car.

The rules state I have to run cast iron heads and intake, but don't specify that I can't run an LT1 setup.

Since I had the short block, I thought this might be a fairly cheap way to use it.

My primary engine is just a 355 SBC with vortec heads and cast iron intake for vortec heads.

I was thinking that the vortec heads were closer to LT1 heads than the other way around.

I know some people cut a SBC intake to work on vortec heads, but the local machine shop said the ports don't line up very well this way.

Oh well... I guess it is buy a carb intake or just not use it all.

WS6 TA

The people that have problems welding cast iron (cast steels) are the ones that learned everything else first. If you overanalyze the situation/do everything "right" you get yourself into trouble. Make sure that the it's clean and cut so you can weld it, drill the ends of any cracks, get some filler a higher grade then the casting (mild steel works for cast iron, stainless works for almost everything, but in doubt get some 347, inconel or "cast iron" rod). Finally, set the welder (MIG and stick is actually easier then TIG) for about ˝ the power that you expect necessary for the piece and have at it.

The first iron/steel casting that I ever tried welding I just set it at the power that I expected to need and just blew away the part of the casting that I was trying to weld to

If you're really worried about cracking or other problems, throw the part in the oven for a few minutes and get it up to 300-400*

Good size iron castings are hard to warp, unlike similar aluminum castings (aluminum dissipates heat faster so you have to put more heat in it).

As far as the rest of this question, just get an iron, 4bbl sbc manifold (circle track guys sell them on ebay for $20 or so). The ports will line up, you just need to get the bolt holes to line up and block off anything that leaks…

Bersaglieri

True? I was confused on this, someone was telling me the Vortec ports were more similar to LT1 than SBC. Just curious for future intake options.

-Dustin-