They came off a B-body and have 1.94 intake valves. Would they fit my '87 305? I have an LT1 intake so this would be ideal.

 

under LT1 heads

https://www.thirdgen.org/techbb2/sho...ight=lt1+heads

 

With the dished pistons in your LB9 ('87-up) you may be better off using L99 heads. They are similar castings, are plentiful, and have even smaller chambers. Deck and head preparation would be the same for either.

That iron head had a casting number 10208890. The valve spacing and chambers were sized to fit the 3.74" bore of the L99, which is strikingly close to the 305 bore.

 

1. They'd sort of fit. The valve size isn't an issue, you'd lose some CR (fixed by milling), but you need to deal with the cooling. LB9GTA gave you the link you need to read. The issue is the cooling passages on the head/block aren't compatible without modification.

2. The aluminum LT1 heads will work more easily in doing what you want, because welding is fairly easy. Welding cast iron (the head you have) is not, but it can be done. The cost for that special welding work might not be worth it given that you can find used aluminum LT1 heads. HTH.

 

I'm not sure how any static compression ratio would be lost by going to the LT1 head. The chambers are 54cc, whereas the LB9 chambers are 58cc. The chambers I checked on my '94 LT1 were actually close to 53cc. The L99 chambers are really tight - in the 47cc range.

Aluminum heads can be plugged and welded, but may require truing to eliminate twist after the welding. Iron heads can easily be TIG welded with nickel filler and the welds will be stronger than the aluminum or even the cast iron. Aside from that, the iron LT1 heads are known to flow better than their aluminum counterparts. The only penalties are the extra mass of the iron and potential heat soak problems of any iron head.

 

What $'s would it take to weld the ports on either alum or iron LT1 head?

 

Talk to ME Leigh. He runs LT1 heads on a 305. He has a pretty nifty cooling setup, too.