stevejohns

Thanks for all the help guys. Im starting to see how much work it takes to get just a few mph. My 502 has som decent parts on it , dart heads and intake , holley 800 , and now the gil manifolds. The only part I dont have info on is the cam. Its a hyd with single valve spring and the max hp was at 5300, So Im guessing its not too radical. Im thinking of going to a hyd roller cam and new spgs etc. Most of the info Ive seen is in the .600 lift 112 sep and 232 dur range. Any idea on whose to go with and what gains maybe seen. Im assuming mine is prob in the high 400s or low 500s.
Thanks again sj

Cord

I'm thinking crane 631. If you had a tubular header (ie CMI elbow top) you'd be over 500hp with that cam. Unfortinatly, your exhaust is going to be holding the motor back.

stevejohns

Hi Cord.... according to the dyno run by the builder... John Lingenfelter. The Hp was 490 at 5300. Im sure that was with dyno headers on. So Im guessing Im close to that with the gils. Are you thinking over 500 at the prop?

Cord

Yea. You'd be around 530hp. The gils are a excellent manifold, but they won't be providing enough scavange for this engine. That could put you back down to the low 500's.

Lingenfelter is such a engine expert, that I'd try contacting him for his cam recommendations.

Tinkerer

Dyno headers will give you a very high HP output- any exhaust manifold or marine header that is not full length tubular will give a lesser HP reading. The other thing is I think you should have at least an 850 HOLLEY not a 800.

KAAMA

SteveJohns.

John Lingenfelter is an excellent engine builder. I think he helped Merc develope their EFI systems for their engines. Other than that he's not much into building marine engines. Sounds like the Gils helped you out a bit over the stock TRASH manifolds. . You didn't mention if the heads were ported at all or how big the intake runner volume is. Being that you have Dart heads and depending on the size of the intake runners then by adding a hyd roller cam you will see a definate increase in performance---especially if you had the heads pocket ported.

DanB has a 27' Warlock with a 509", 308cc Merlin cast iron heads---NON ported, dual plane Air-Gap intake manifold, Holley 950 carb, and he's running a pair of Lightening Headers at about 9.0 cr, and a Crane #139741 hydraulic roller on 112* lobes and his engine dyno'd out at 563hp @ 5500rpm.

Also, I think you'll be fine with the 800cfm carb, but certainly wouldn't go any smaller.

BTW, Bruce Wolff used to work for Lingenfelter years ago. Wolff builds about 98% of marine hi-perf engines. His shop is in S.W. Michigan about 20 miles north of the Michigan/Indiana border. Wolff's # 616-422-1090

stevejohns

Thanks again guys.. Im not sure about all the specs on the parts due to buying it used. I do have the origonal invoive with the part #s. Ill do some researsh and find out what I can. I called J.L. when I bought the boat and they still had a copy of the work order but the cam was the only item with no # . sj