ADJUSTING A 4 BARREL HOLLEY

[man-of-war]

Hi,<br />I had the 23' Wellcraft on the lake today to add some hours to the break-in process but I never went past 3500rpm until today. I took it up to 4000rpm and back down and when the secondary opened on the 1410 Ebelbrock it was missing/surging. It felt as if it wanted to go but couldn't because it was flooding OR lacking fuel. My fuel pressure was 6.5 psi. The two month old Ebelbrock was serviced two weeks ago because we thought this was the cause of fuel being dumped into the crankcase. I have had enough with this Ebelbrock quadra jet carb. I'm going back to the Holley 3310 750 cfm carb. This Holley was rebuilt last year and used for one month this summer, (only one metering block on this carb). My question is how do I adjust the air/fuel needles? I have a vacuum gauge permanently in place on the Ebelbrock intake. At idle (500rpm) the reading on the vacuum gauge is +-10. Am I supposed to get the highest possible vacuum reading? How would I know if i went too lean? THANKS

 

[Boomyal]

Re: ADJUSTING A 4 BARREL HOLLEY

Originally posted by man-of-war:<br /> How would I know if i went too lean? THANKS

Not sure about the vacuum ideal at idle. There are probably too many variables, such as cam, to state a universal value. There may be a known ideal for your setup but I don't know how you'd find out.<br /><br />I would start with both needle valves open one full turn. (The book will tell you 1 1/2)<br />I would also run down to the AutoParts store and grab a set of Moroso clear plastic float bowl observation screw replacements.<br /><br />Crank 'er up, set the timing, let it warm up. make sure your linkage is adjusted good (for idle etc) then start slowly turning each needle valve back and forth, 1/4 turn at a time to see where she smooths out. If it smooths out at a higher than ideal idle then turn the idle screw back down.<br /><br />Too high a float level can affect all this that is why the see thru screw replacements are good. If you intially don't see in gas in the window, rock the boat back and forth a little. If you just see it slosh up on the windows you are good to go. If not, raise the floats a little.<br /><br />Good luck.

 

[man-of-war]

Re: ADJUSTING A 4 BARREL HOLLEY

I installed the Holley today. I did not get those observation screws yet. By far the sound and the performance of this Holley proves it is the better choice verses the Ebelbrock 1410. I did the adjustment on the air/fuel screwes but I did not want to lean it out yet. I left the original setting of 1.5 turns from shut. The engine is still in the break-in stage, the mechanic that rebuilt the engine said that going too lean can crack or break pistions. I checked the plugs after my trip today and the plugs were grey in the centre (the part where the spark jumps to). The outer piece on the opposite side of the threaded part was black and dry. Around 2 plugs were damp with fuel. How do I fix this problem?.......Thanks

 

[Boomyal]

Re: ADJUSTING A 4 BARREL HOLLEY

Can't say for sure. Sounds like it might be a little rich. Unfortunately carbs are not as consistant per cylinder as FI. At what rpm did you take the reading? You really do need to confirm the float level. You can unscrew the original float bowl screws and if gas pours out your float level is too high. That as well as the air fuel screws can make a difference. Also did you let the motor come up to temp before you shut it off to take a plug reading?

 

[man-of-war]

Re: ADJUSTING A 4 BARREL HOLLEY

yes,the engine was hot after a 45 min run,at 3000rpm.thats when i took the plug reading.i will check the float level today.when i first adjusted the float level,the boat was on the trailor and i used a level to level the boat.but on the water the level of the boat is way off.good call Boomyal.....thanks

 

[man-of-war]

Re: ADJUSTING A 4 BARREL HOLLEY

you were right Boomyal,the level was to high i fixed that problem.the next task was the fuel/air mixture,i adjusted then until the idle went up then adjusted the idle,i got the highest vacume reading.I took it out for a run at 3000 rpm 34 mph for about a half hour then checked the plugs,they were all clean grey in colour.im not sure if i took it to lean but i backed off a 1/4 tuen on the fuel/ air mixture.bought the boat home today ,i removed the plugs and they were brown/black colour.not to mention the gas that's siting in my crankcase.is 7 psi to high at idle?....THANKS

 

[Boomyal]

Re: ADJUSTING A 4 BARREL HOLLEY

Originally posted by man-of-war:<br /> you were right Boomyal,the level was to high i fixed that problem.the next task was the fuel/air mixture,i adjusted then until the idle went up then adjusted the idle,i got the highest vacume reading.I took it out for a run at 3000 rpm 34 mph for about a half hour then checked the plugs,they were all clean grey in colour.im not sure if i took it to lean but i backed off a 1/4 tuen on the fuel/ air mixture.bought the boat home today ,i removed the plugs and they were brown/black colour.not to mention the gas that's siting in my crankcase.is 7 psi to high at idle?....THANKS

I don't think so on the fuel pressure MOW. Usually mechanical pumps are what they are but the plug color sounds good.