I recently purchase 2 800cfm dp holley carbs from a board member. They are HP 500s take offs and appear to be factory stock. Jetting is staggered 75 sb primary, 81 port primary, 93 sb secondary and 89 port secondary. Has single power 6.5 power valve.

These carbs are going on 425 to 450hp 454s. Actually dyno 2000 says my engines should be 500 hp but I find that hard to believe. I need advise on which way to go with jetting as I am in the process of freshening the carbs now. I'd like to start somewhere in the ballpark. Should I run the carbs with factory hp500 setup first?

Engines are: 468cid, 8.5:1 compression, rect port al edelbrock rpm heads, 226/234 @050, 544/564 comp cams, edelbrock rpm dp intakes, eickert headers. Planning to spin to 5200rpm.

Looking for specific jet combinations, power valves, squirters and accel pump selection advice

Dave

Dyno and SuperV are currently running these carbs on similar engines as yours, just with a point more c/r and a slightly larger cam and Merlin oval-port heads. Maybe one of them will pop in here and post.

Thanks Crazyhorse. Do you by chance know the theory behind the staggered jets in the hp 500s?

Dave

The staggered jets are necessary with some intakes. What intakes are you using?

Edelbrock rpm performer, dual plane. What did the HP come with?

Dave

Dart single plane I think.

So Tom, you think I should have even prim/sec jetting due to the dual plane? Maybe 81 prim, 93 secondary? Gotta start somewhere.......

Dave

I am not familiar with those carbs, if they were 3310's (780 cfm) I could tell you exactly.

Thanks F31. I guess I will just put my qjets back on and forget it. It was probably a dumb idea to switch to holleys anyway

Dave

Well, Im gonna try my Quads again this year after I change manifolds and get them set up. There should be quite a few people on here who know the jet setup for those 800's. Ive never been able to get the quads to put out top end like the holleys but Im gonna need fuel economy and engine reliability for a while so thats why Im gonna try and go back.