How can you tell if a set of heads are Lt1 or Lt4? Is there casting numbers on the heads that tell you? If they are lt4 heads, will a Lt1 intake work with the Lt4 heads? If not, why? Any info appreciated

Brandon

 

casting numbers. Lt4s are 10239902

The lt4 heads are a raised port design. thats why the lt4 intake was made to match up to it. I remember reading something saying you can bolt them together, but its not the ideal thing to do. (dont quote me on the last line)

 

Are the last three numbers on the Lt1's 576?

Brandon

 

Also found 12555690 as a possible lt4 casting number.

The lt1 numbers that i know of are...
10128374
10205245
10207643
10128649

Also iron lt1
10125320

 

Thanks man, ill check the number on mine when i get home and let you know the exact one.

Brandon

 

I checked the number and it was 12551561. Lt4 head. I can also tell by the underside, it has a lot more bulk to the casting than the lt1. I am happy that it is an lt4 head but the guy that bought it from Cmotors said it was an Lt1 casting, but i think he was wrong. Wish i would of knew it sooner before i sent my stock Lt1 intake off to get ported. These are a beautifup let of heads though, someone at Cmotors really knew what they were doing and spent what looks like countless amount of hours on these heads. I guess thats why the peak numbers on these heads were 278/199. I matched up the intake to the lt4 head though and i didnt see where there would be any problems with the runners lining up. Maybe since so mych material was gutted out of my Lt1 intake there wont be any restrictions in air flow . Let me know what you think.

Brandon

 

My LT4 heads have LT4 stamped on them.

 

Yea mine also say GM 4 on the top

Brandon

 

12551561 on the net brings that up as an lt1 casting. LPE says that casting number isnt acceptable as a core for their stuff, not sure why.

 

Well im confused then. Oh well there goin on my block no matter which they are.

Brandon

 

Where exactly on the heads does it have the casting number? I want to look at mine when i get home. Do you have to take anything off? I was just on another board asking if i had an LT1/LT4 intake manifold becuase a few people have asked (becuase its a red manifold) but i'm not posative. (Could of been powdercoated)

 

That is not an LT4 head.

 

The valve cover. Once you determine the head is an LT4, the intake manifold will come very close to the ridge (or machined step) on the head, under and close to the valve cover mounting surface.

 

Do regular valve covers fit the LT4 heads? i was under the impression that they ran the composite "raised" cover.