Too much exhaust duration
 

I’m building a 454 with l29 heads,air gap intake and 496ho exhaust manifolds. Should be 9.5 compression

the cam I’m looking at is 539/539 lift 228/238 @.050 on a 114 LC

In an auto application I now it would run well but my concern is will the manifolds flow enough. Am I look at to much exhaust duration for my combo?

kieth eikhart used a duration like that on his 675 + 725hp motors

well that answers that question thank you

just my opinion but I would bring the compression down a little. I try to stay at 9.2 or less with iron heads as the fuel you get is not always what you want and that is a bit too close to the edge of detonation for me. I had one customer not long ago that was 9.2 and told him to always run at least 91 octane, well he got 89 on a poker run and detonated a hole in one piston. in a boat always error on the side of caution. thats just me any how.

thank you

Many used cans like that. No biggie.

Flat tappet ? Be careful with wear….

That's a very good point and a great reminder for those of us running cast iron heads ---- Thanks!!! 👍 🇺🇸⚔️

Always better to have reasonable compression, vs always having to retard ignition IOT avoid detonation. Retarded ign timing will heat up the exh valves.