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Holley Carb Rebuild Experts - NEED HELP!

Posted By: PurpleBeeper

Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 07:50 PM

I haven’t rebuilt a carburetor in years and I’m confused. I have a 3310-3 Holley 750 vacuum secondary carburetor I just rebuilt and my car is “surging” like extra fuel is slipping in somewhere. I used a Holley “Quick Kit” which has several base/body gaskets and metering block gaskets. The original gaskets for this carburetor are long gone. How do I know which gaskets to use? HELP!
Thanks Everyone!
Posted By: Paul_Fancsali

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 08:11 PM

Every time I have had a surge it was from trying to lean out a carb too far , or the power valve is wrong . If you put under a 6.5 valve in you maybe surging due to that alone. Are the jets stock in front ?. Also be sure you have all ports closed, and make sure if you have a vac distributor that it is tied to a PORTED spot on the carb
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 09:35 PM

Maybe this will help... which base/main body gasket for a 3310-3?

Attached picture 7493096-DSCF1986Compressed.jpg
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 09:40 PM

Quote:

Every time I have had a surge it was from trying to lean out a carb too far , or the power valve is wrong . If you put under a 6.5 valve in you maybe surging due to that alone. Are the jets stock in front ?. Also be sure you have all ports closed, and make sure if you have a vac distributor that it is tied to a PORTED spot on the carb



Hey Paul, I'm 99% sure the carb isn't too lean since the tailpipes are black-sooty (plugs look decent though). I replaced the 6.5 power valve with a 3.5 power valve (I only have 9" vacuum at idle). The jets are #72 (I think #70 is stock) which doesn't seem too rich for this motor (272/284 duration cam). I'm running only the mechanical advance & blocked off all the un-used carb/intake ports. Any other ideas? Thanks!!!
Posted By: moparmarks

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 09:43 PM

I can't count how many 3310s I've re-built over the years and I couldn't tell which gasket to use. Match up the gasket to the body. Just make sure they both have all the same holes. Do the same with the metering block gasket and the metering plate if it has one. Can't remember if the 3rd series has a plate or block on the sec. Also the wrong P/V gasket will dump fuel. Make sure the A/P has the check valve.
Posted By: Dcuda69

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 10:28 PM

Was this carb on the car before or is it "new" to the combo? If new to the combo we may need more info to help figure it out.
Posted By: RapidRobert

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 10:33 PM

"surge" at a steady cruise speed? Then yes a lean misfire, a cyl or cyls is too lean to sucessfully fire making it slow down a perceptable amount which you are feeling. If not jetted too lean then a vac leak somewhere, carb or somewhere else (manifold/pcv/brake booster check valve)
Posted By: dogdays

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/07/12 10:34 PM



Recheck your float level, a lot of problems can result from a bad float setting.

A 3310-3 is a pretty early 750 cfm Model 4160 carb. It should have a metering block up front, a metering plate in the back, one accelerator pump and straight leg boosters.
You use the body gasket that lines up best with the holes.
Fuel doesn't get that far down in the carb anyway.

Holleys are generally rich from the factory so I'd go to stock jets if you are between sea level and 1600 feet.

Did you put the gaskets and spacers behind the metering plate?

R.
Posted By: RemCharger

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/08/12 01:26 AM

That should be a 4150. I always run 76+ for jets and 82-84 in the back if you get a metering block. make sure the power valve is not holding the metering block away from the main body. Check the airbleeds for restrictions too.
Of course make sure you have no vacuum leaks.
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/08/12 01:58 AM

Quote:

Was this carb on the car before or is it "new" to the combo? If new to the combo we may need more info to help figure it out.



I ran this carb on this engine in the early 80's and I don't recall a problem (long time ago). The car/engine sat for 20 yrs. and I rebuilt this carb to get it running again.

440 +0.030"
Six pack rods
TRW L2295 pistons with domes milled off flat
Comp Cams CL221-2224-4 274/286 488/491 cam straight up (was 292/509)
double roller chain
melling hi vol/press pump
1/2 pickup w/6-pack/Hemi pan
Hedmann 1-5/8" headers
MSD-6A w/DC distributor - mechanical only
906 heads w/Isky adjustable rockers
DC double springs
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/08/12 02:06 AM

Quote:

"surge" at a steady cruise speed? Then yes a lean misfire, a cyl or cyls is too lean to sucessfully fire making it slow down a perceptable amount which you are feeling. If not jetted too lean then a vac leak somewhere, carb or somewhere else (manifold/pcv/brake booster check valve)



This sounds very possible 'cause my idle vacuum is pretty low.... but how can I track down that leak? I've blocked off the PCV hose and power brake hose with no noticeable change in idle vacuum (have vacuum gage on motor) and I don't hear a "hiss" + I've sprayed all over with carb cleaner & don't get any increase in idle.

Also, when the the car surges (occassionally at idle, but mainly at cruising speed) the vacuum gage does not change & the tachometer spikes "up" instead of "down".

Still.... so far this sounds the most likely. It idles fine, when I floor it the car takes off like a purple striped ape, but at cruising speed it "surges" or "bucks". I turned down my fuel pressure from 7psi to 5psi and put a black vacuum secondary spring in and replaced the power valve with a 3.5 and it "seemed" to get better, but it still "surges".
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/08/12 02:15 AM

Quote:



Recheck your float level, a lot of problems can result from a bad float setting.

A 3310-3 is a pretty early 750 cfm Model 4160 carb. It should have a metering block up front, a metering plate in the back, one accelerator pump and straight leg boosters.
You use the body gasket that lines up best with the holes.
Fuel doesn't get that far down in the carb anyway.

Holleys are generally rich from the factory so I'd go to stock jets if you are between sea level and 1600 feet.

Did you put the gaskets and spacers behind the metering plate?

R.



You're description of my carb is exactly correct. I'm sure I'm below 1600 ft. in Chicago, but I think stock jets are #70 and it's only got #72's, but "maybe". You're idea on the spacer/gasket with the metering plate is a good guess! When I pulled the carb apart I didn't have those and the rear float was stuck, but I've fixed those issues now.... still a little surge.

Maybe it is lean??? Mystery vacuum leak??? I checked the driver's side plugs recently and three looked clean/light tan and one was slightly sooty-black rich (not oil wet). I'll check the floats again.
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/08/12 02:24 AM

Quote:

That should be a 4150. I always run 76+ for jets and 82-84 in the back if you get a metering block. make sure the power valve is not holding the metering block away from the main body. Check the airbleeds for restrictions too.
Of course make sure you have no vacuum leaks.



Hmmmm...."maybe" even the #72 jets are too lean, huh? I think your car is MUCH faster than my lil' ole' street car... but "maybe".

Also, is it possible for the power valve to hold the metering block off the main body? Wouldn't it leak like a sieve there? I did run a bread tie wire in all the air bleeds and used good carb cleaner, but I'll clean them out again.
Posted By: RapidRobert

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/08/12 02:35 AM

Quote:

but at cruising speed it "surges" or "bucks".

Just thinking out loud but that almost sounds like an ign related miss rather than a more minor up/down "surge" misfire from too lean. I would check rotor phasing. Post how things go with this issue
Posted By: PurpleBeeper

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/09/12 03:16 AM

Quote:

Quote:

but at cruising speed it "surges" or "bucks".

Just thinking out loud but that almost sounds like an ign related miss rather than a more minor up/down "surge" misfire from too lean. I would check rotor phasing. Post how things go with this issue



OK, dumb question.... What is "rotor phasing"?

If it matter, I have a DC distributor (new w/ new brass cap/rotor) with the out-of-the-box timing curve.
Thanks!
Posted By: Sixgun

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/09/12 03:39 AM

Rotor phasing:
Take an old but usable dizzy cap,drill a decent sized hole between the coil terminal and the #1 tower (say 1/2" or 5/8")and paint a white stripe(paint pen/white out) on the rotor from the center contact (on the plastic part, not the metal) to the outer end that "throws" the spark.Install this cap in place or your "good" one.Set up your timing light as normal.Run the engine up until the timing stops advancing (mine is "all in" at 3K) and shoot the light at the hole you made in the cap.You should see your mark pretty close to dead center in the hole.This means the mag pickup/reluctor/points/crank trigger/telegraph what-have you is being triggered at the approximate correct time for the ignition spark generated to have the rotor in line
with #1 spark plug terminal and fire that cylinder(as well as the rest)in a timely manner.
If it's way off, the spark is having to jump forwards or backwards to fire that terminal, savvy? I won't go in to how to correct this, unless someone asks...
Rapid, feel free to add in here if I missed anything.
Bear
Posted By: RapidRobert

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/09/12 03:44 AM

Perfectly normal question. You would drill a 1/2" hole in the top flat of the dist cap 2/3 of the way fron the center terminal to the #1 cap terminal (closer to the #1 terminal) and aim your timing light down in the hole which will "freeze" the rotor like a strobe light freezes people on a dance floor. Let it idle & check with vac advance connected and disconnected & we want the rotor to be near dead on with the cap terminal. If too far away it will miss especially under load & at WOT the vac adv will be near zero & rotor phasing will be where it's at when you pull/plug the dist vac hose. This hole you drill is productive even when done testing as it lets ionized air out of the cap which can promote crossfire but if it looks unsightly to you just use a junk cap to drill on & can also cut a rectangle out of a junk cap on the side to check the rotor tip distance to the cap terminal when not runing which is related to rotor phasing but is not the same but can also cause missing as both contribute to an air distance greater than the spark can jump. If the dist bushing/shaft radial play is minimal you can go as low as .010" on that distance and NAPA offers an Echlin Mopar rotor with a .060" longer tip MO3000 for $8 & change out the door. If the rotor phasing is way off the best solution is to redrill a new slot for the roll pin like Andy did way back with his machined reluctors. Holler with any news. EDIT Hey Bear we posted at (nearly) the same time. If Ida known you were going to I would have saved myself the effort
Posted By: Sixgun

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/09/12 09:10 AM

No sweat RR, I honestly felt you could express this one a little better than I.With my DC cast iron tach drive, I carefully slotted the pickup mount holes, and re-phased the assembly thata way until I got the rotor where I wanted it.
But RR, shouldn't the rotor be centered in the hole when the mech advance is all in?(This came from Dvorak years ago).Open to discuss, not arguing.
regards,
B
Posted By: RapidRobert

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/09/12 05:05 PM

Quote:

shouldn't the rotor be centered in the hole when the mech advance is all in?

Actually the rotor is phased in the same position from idle all the way to max mech advance/RPM cuz when the weights shift the reluctor the rotor is tied directly to the reluctor firmly with the locating tang so when the reluctor is moved 5 degrees the rotor moves 5 degrees and the only thing that changes it is the amount of vacuum advance because it moves the magnet. Ideally you'd want the rotor arc to be centered on the cap terminal so it swings the same distance to either side of the center of the cap terminal but required voltage is the greatest at WOT when the vac adv is retracted so at that point if your arc ain't perfect you'd want the no vacuum position to be a bit closer than it is at the full vacuum position. Note that vac adv shifts the rotor phasing clockwise on a BB and CCW on a SB from the no vac (at rest position) and (8) stamped on the can arm is going to swing the rotor in an 8 degree arc. The cap terminal and the rotor blade are pretty wide so you have alot of leeway & the Echlin MO3000 rotor is a good deal as it lets you have more of a mismatch on the phasing without misfiring as it's the total distance of the arc phasing difference plus the rotor tip distance from the cap terminal that either causes it to misfire or not and any spark jumping a gap outside of the spark plug gap is wasted energy/increases required voltage/needlessly stresses the coil & the rest of the ign system. Hope that helps.
Posted By: moparmikethree

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/20/12 10:21 PM

wrong power valve. if too small 3.5 instead of a 6.5. will that dump fuel or be lean
Posted By: RobX4406

Re: Holley Carb Rebuild Experts - NEED HELP! - 12/21/12 02:06 AM

Power valve doesn't do crap at cruise speed.

Sounds like a comp XE274H camshaft. The vacuum you have at idle is pathetically low for that camshaft. It should be pulling at least 11" and more likely 12-13 at idle of about 850 rpm.

My favorite question for this stuff. What's the initial timing on the engine?

Please don't say it's total timed at x,xxx rpm... cause that doesn't mean squat. Put a light on it at idle and see what you have. If it's less than about 15* BTDC, it needs to be around 15-20. You'll have to open up the distributor to limit mechanical advance to hit your total number in most cases.
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