My 500hp 454,s Ran Holley 850,s With 82 Primary And 84 Secondarys With Power Valves Front And Rear .my New 540 Has A 950 And Likes 80,s And 82,s.go Figure

Thanks z.zuperboat and I'm looking for the post TPC Racing. Well had a bit of an oil leak at the remote oil plate, you know, the one underneath everything that you can reach without taking the exhaust risers off. Anyway, got that handled. Ran both of them, set the initial time at about 16 degrees at 1000 rpm. Had #86 in the primaries and 92's in the secondaries. Ran the engines about 2 minutes (in the driveway, no load) and the plugs are black as they come and dry, first time I've seen them black since the intial re-build. Changed the primaries to #80's, change plugs, ran it about 2 minutes, plugs are Gray/black. I think I'll run them there for now, better safe than sorry and I'm running low on boat money according to the wife! Will post after an in the water run this Saturday. Thanks again guys.

I have a 540 bull dog with 89prim 91sec, 34deg @3400rmp elevation 4500ft
One question, When checking the plugs for a sweet tan color, which plug to check, do you check them all or is there one cylinder that will run leaner that you need to watch for.
Bryan

Formulaz583, what makes the #5 & #7 run leaner than the others? Seems like I remember someone telling me that these dual plane intake manifolds (that's what's on these engines) would cause #7 & # 8 to run very lean if the engine was already on the lean side, is that true and if so, why? What is it about a dual plane manifold that causes that? Thanks.

formulaz583 sounds good to me and since the intake valve I lost was in #7 I guess I can attest to which one goes lean first, #7! Putting it in the water tomorrow, will let you know how I make out. Won't have smaller than #80 jets for primaries till Tuesday but I'm going to see what the 80's look like under a load.

When your done jetting those motor lets make a EFI map for those motors and get rid of those carbs. Hah just kidding you.

A fellow boater and I have both installed egt's in our exhaust. We have never pulled a plug and can tune a motor to a T. They take the guess work out. Money well spent.

As a pilot and flight instructor, I couldn't agree with you more. At night I could look out through the cowling's of a Cessna 421 I flew and watch the red glow of the exhaust pipes through the vents as the EGT's went up. While beautiful, peak EGT was not a good place to be for long. Not a bad idea. Where did you find the system for your boat, how much trouble to install and about how much $$$$ did it cost you? Thanks for the thought, that's a great way to go for those of us who don't have dyno's.

I have a similar power motor to yours and my jetting was all screwed up. I have a dart manifold like the 500hps (staggered tubes) so all my jets needed to be a different size. I used the 500hp carb specs and now it runs, idles and top ends better. I ganed 3.2 mph also. I don't know what your manifold is. My carb is an 830 holley. Here's the specs.

Primary - Port 81, Stbd 75, power valve 6.5
Secondary - Port 89, Stbd 93, power valve none

Alcor--Call Livorsi or look at their catalog. They have everything you need up to 3" guages. Toughest part is that you need a bung to attach the probe to.