Fuel dribbling out of the boosters or vents when idling will cause run on. This would be caused by too high idle speed/throttles open too far or too high fuel level in bowls.

Got jets switched out today and yes, I do have provisions for power valves in all four blocks. Now that I know what to look for I can see they are blocked. Don't know what shop was talking about. Ran out of time to run it today, will get it tomorrow. Also, I'll try to get the afr readings from shop next week. Thanks all for all the advice.

I'm sorry I just gotta put this out there I've been following your post for the last few days but whoever dynoed your motors did absolutely nothing for you. I mean with the end product what was even the point of dyno ing them? Will the motor come off the dyno and be 100%...? No, but it should be alot closer than where you are at right now.

Black Bajax I'm starting to see that as well. This guy definitely can build them but it seems as if he rushed the dyno.

All, I understand that I should be adding more fuel by increasing secondary jets and adding per valves but wouldn't this also increase the BSFC numbers and make them even worse?

Generally i would never enter into a conversation of this nature...but soo much money and intelligence has been been shared...perhaps some thought is needed. First i have been rebuilding carb's since 1968 and gleefully thought they were things of the past....anyone who ever thought they were a godsend is mentally deranged. Get some new carbs and then jet...there was a reason they were on ebay or craig's list......Plz someone of high credibilty come in and post as to how all the circut's work and how one can be overlooked by the best...messing everything up...carb's are extremely complex.

It would be a lot of typing to get into the works of a Holley. For a good overview, go to Holley.com. Go to the technical page. They have a section called A Look Inside Your Carburetor. There is some other good info on the site as well.

There are some decent books for Holleys out there. One of them is by Dave Vizard, How to Tune and Modify Your Holley. This book was published in 2013, so it should get into the newer technology. I have an older version of a similar book and have from personal experience found that the basics are well explained, but the technology has changed drastically since the book I have was published.

I have yet to see a Holley book for Marine applications.

Once you learn to understand the functions of the circuits, Holley carbs are pretty simple to work on.

I got to the lake early yesterday to tune everything before "Sunday fun day" started. Idle is set to right around 800 pulling 13-14in vaccuum. Initial timing is 12 with total of 36 coming in at 3800. 32 degrees at 3000rpms. 85 jets in primary with 6.5 power valve and 92 secondaries. I found the power valves and a local Orielly's but I didn't check for jets. Here are #2 plugs from each motor. Think I'll step down the primaries to 80 and see if that cleans up the plugs some.

[ATTACH=CONFIG]525748[/ATTACH][ATTACH=CONFIG]525749[/ATTACH]

Make sure you put in a new set of plugs and check. Doesn't take much to foul a plug and a fouled plug will give you a bad reading... What rpm were you at when you shut the motor down and pulled the plugs?

My carbs are old Barry Grant's that were built off Holley's. They do have "BG" cnc'd on them. If you go by Holley #'s they are 750's. But, my unscientific experiment says they are larger. http://www.offshoreonly.com/forums/g...-saturday.html

When Tom Earhart dyno'd my engines, that's when I learned about BSFC. I was originally in the 0.63 range and he was telling me I needed to pull some jetting out of it. These just came off my 420's. I guess with my new heads and cam upgrade the carb signal was greater and pulling harder on the jets at different throttle positions.

A friend of mine must have spent half the summer piddling with plug readings on his 502. With the oxygenated fuels we have to run in our area it is nearly impossible to get any color on the plugs. You have to make a full throttle run and then immediately pull the sticks back and shut her down. He even swerved around the opposite way to keep his own wake from inundating us. Letting it idle for any length of time will give you a false reading. This is one of the reason that so many have moved on to installing bungs and taking A/F readings with a wideband O2.