95zsean

What is the best LT1 casting number? I'm looking for a good used set but want to make sure I get a good cast number for a engine project to come in the next year.

Thanks

chevyowner02

The best for porting? Or just a good all around head.

speed_demon24

643 or 374 for porting.

95zsean

I'm looking to port and polish them. What years do these cast numbers come on?

rskrause

For practical purposes they are the same. I wouldn't be too concerned about which specific casting number unless it's going to be a real wild port job. If it's not DIY, ask the person who is doing the porting if they have a preference.

Rich

95zsean

There is a really good shop in my local area but they have never worked on a LT1. They have a flow bench and a engine dyno and I've seen some wicked engines out of this shop. They say bring them a set and they will make them flow. I just want to give them a good set.

aboatguy

I agree those are the best choices for porting.