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Moody Blu'
08-20-2002, 11:21 AM
Well guys ever since I moved the location of the fuel pump overflow hose the surging has completely dissapeared.

now I have one little tuning problem to overcome.

a little past half throttle(3700 rpms) and up to 4500rpms I get a popping sound. when I go past 4500 rpms it stops sputtering and popping. it sort of sounds like a motorcycle thats breaking up.

I read my edelbrock book and it says if there are any stutters or surges that the motor is running lean.

should I go to a smaller needle to richen it up? or do I have the change the secondary jets?

I'm pretty sure my timing is right on, I could advance it a bit to see if the sputtering stops, but its been running flawless every where else in the rpm range. I kind of want to leave the timing alone.

by the way im running a 750cfm edelbrock performer series.
Griz, I think it has the offroad kit installed.(the spring needles)

so whats the consenuous?
lean or rich?
needle swap or jet swap?

Ralph Savarese
08-20-2002, 11:33 AM
I had that problem sorry to say it was a bad exhaust manifold letting water get in and eroded over time the valve seat. Check your spark plugs for splash sighns.
Ralph

MOP
08-20-2002, 02:04 PM
Not sure but I think a bad power valve or needles dropping may also cause that condition. You need a good Holley Man!

Moody Blu'
08-20-2002, 02:28 PM
hmmm maybe the spring needles are to soft?
im sticking with the edelbrock(carter afb)

KMLFAMILY
08-20-2002, 07:10 PM
I think to correctly answer your question someone would have to be familiar with the performer model carb. I was just reading the ad for one. It states two step metering rods are used instead of failure prone power valves for custom tuning of cruise and power circuits independently.They have a tech line @1-800 416-8628 7am-5pm pst.m-f Maybe this is why not many replies.

Moody Blu'
08-21-2002, 12:43 AM
yes the carb has a cruise and power circuit. they each one is on the same needle, depending on how hard you open the butterflies depends on what "power mode" you go into....

with that said, Im thinking the cruise mode is where it starts sputtering. but I am asking if anyone knows if it could be a lean condition or a rich condition.

MOP
08-21-2002, 01:16 AM
Popping is usualy a lean condition, have you taken vacuum readings to make sure you have no leaks? Can you fiddle with the heigth of the rods? You may need a little more fuel for the transition. Still you may also have some other gremlim.

THESCOOTER
08-26-2002, 06:25 PM
moodyblu , what color are your spark plugs? run the boat hard and shut the engine down and pull the plugs after running the boat hard,no idling. is your engine timed properly for example is your timing marks correct. are you sure its not electrical, what makes you think if is fuel. you can pull the carb and take it to a good hi pro card shop.let me know how you do. sometimes its not where you start but where you finish fixing a problem. the scooter

HyperDonzi
08-26-2002, 06:38 PM
just turb the key off so the carbon dosent have time to re cover the plug and if it is white, there is water in the cyl.

Moody Blu'
08-27-2002, 08:57 AM
welll I changed the metering rods yesterday and the popping is less severe.(its still lean)

I had .071x.47 metering rods in there .071 for cruise mode and .047 for power mode.

I changed to a .068 x .047 and the popping/ hesitating is not as severe now. I may go up 2 sizes on my main jet to richen up the entire powerband but I will see if i have a .065 x .047 metering rod.
I will play with my timing a bit after this, but I seem to be going in the right direction.

I will advance my distributor a bit if I still have a slight popping/hesitation after I change the rods again. I think I will change the metering rod spring too, im going from a silver(stock)8" spring to a pink 7" spring.

I havent done a WOT run because the boat is fine at WOT I am concerned with above 4000 rpms to about 4500 rpms this is where the hesitation mainly takes place. So A plug chop wouldnt do much. Unless I ran it at the throttle position where it hesitates and then cut it off.

ill keep everyone posted how the metering rod change goes.

Moody Blu'
08-27-2002, 05:55 PM
well, I played with my timing and got a extra 150 rpm out of her today.
im at 4950rpm's now

I changed metering rods from a .068 x .047 to a .065 x .047 and there is no hesitating now.
I aloso changed my metering rod springs to the yellow 4"hg springs.

I do feel very slight surges/hesitation at 3/4 throttle I may richen up my secondaries.(it may be the carb switching from power mode to cruise mode)

should I richen my secondaries up?

or should i richen up my mains?

im running a .407 main and a .413 secondary.

im 1 stage lean on my power mode and 1 stage rich on my cruise mode...

Im really happy everything I am doing is giving me positive feedback. It is making me more sure of my engine tuning expertise.

Should I leave my mains alone since I fixed the popping/hesitaion?
I'm positi ve I can squeeze some more rpms/HP out of this baby..

mains or secondaries that is the question! wink :D

tmdog
08-27-2002, 06:09 PM
Moody, sure are getting good rpm.wWhat prop and size are you running?

Moody Blu'
08-27-2002, 10:53 PM
a bone stock bronze 14 1/2 x 24p elephant ear prop.
I found a 25p cleaver for a volvo ill be trying that next year with my new drive (wiith trim and tilt)

I have no clue what speed im hittin people say im in the 60's but my gaffrig speedo says 50mph ???

I will have a gps gaffrig speedo next year so now more wondering what speed im really going.

See I use to have a gps that I could use but my dad hardwired it into his boat :o

dont matter though, I always will have a big grin on my face no matter what the speedo says....
as long as the boat moves.... wink