My son is attending school at the School for Automotive Machinist in Houston. I sent him my Nailhead as a school project for two reasons. #1, my son gets to rebuild my engine for me (with the supervision of some of the best engine builders in the field) #2 the school can use it to teach more indepth, since they primarily use SB Chevy and Fords in their lessons since thats what a majority of the market is out there for in racing, I wanted to give them a chance to look at a unique engine and teach how to approach something from scratch. They have the engine torn down and we were discussing numbers the other day. The valve spring pressure is only about 100lbs, which you can almost do with your fingers. This leads to alot of valve float at higher RPMs. More other V8 engines have valve spring pressures upward of 200lbs. What have you done, replaced yours? left them at the 100lbs rate? Is there an issue with upgrading them with the unique rocker arrangement we have?
I think it ok for the stock rebuild. If you are upgrading your cam you need the springs recomended for the cam. Lots of defferant ways to go. Mine is a comp cam with ls1 behives among other changes.About 115 and 275 and works good for the rpm my nail sees. I read about that school all the time, they are always placing high in the engine masters comp. Are they doing a stock rebuild?
The valve spring pressure is either 88# or 96# according to Buick.... but,,,, you also have a inner spring that is added to that... so the pressures vs compression spec's will add up very fast... and , also ,,, the way a nailhead's valve gear is arranged make it not very apt to float the valves at the rpm's a nailhead operates at.....looks like real good engineering to me... run the lowest pressures possible to cut friction but have the pressure come up only when it is needed..... I have had nailheads that would not float the valves,, they would just run up to where they would just level off.... just north of 6000 rpm.....
Not doing anything massive, like I said the bore is already .040 over, the heads will get port work done. My son was showing me how they calculate the surface areas and try to get the same surface area through the ports. Everything will get balanced and if I can get my hands on a bellhousing so they can get it on the dyno, it will be dyno tuned before the crate it and send it back.
