Thumpr cam question

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DusterDillon74

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I am running a thumpr comp cam on my 360. I am running it on a duel plane summit intake and it feels like its lacking power still. also on the edelbrock carb its leaking raw fuel while its running and has a diesel effect when i shut it off please help with any knowledge thar could do to fix the problems!:sith:
 
Verify the float settings on the Eddy carb. There was an issue with some being shipped wrong a couple years back. No other calibration means much until the float levels are set.

As for your fuel leak, exactly where is it leaking? Sounds like something you should fix.

Running-on or "dieseling" is a classic symptom of having a too high idle speed. Try reducing this.
 
The running on, or dieseling might also be caused by too much advance on the timing. You might post what your initial and total timing is.

Bill S.
 
the total timing is 35 and it is leaking from the vac secondaries its not a constant leak but almost a pulsing if this makes any sense. the car idles at 600 BUT when you put it in park it jumps to 1300 1500 ish
 
check the floats...also check that the metering rods are down while the engine is running...

remove the caps that cover meter rods...start engine and watch metering rods....if they are not down or going up and down...you need to change the spring that controls the metering rods ...you need a lighter spring.....the meter rod needs to be down in the jet while it idles
 
It is NOT leaking from the vacuum secondaries. As no such a device exists in your carb. If fuel is dripping from the secondary nozzles at idle, I would strongly suspect too high float levels, a sticking float, or excessive fuel pressure.

Remove the top of the carb, make sure there is no crud or something causing a float to stick and double check the levels.

The owners manual that came with your carb contains A LOT of good info. Give it a read.
 
DusterDillon74 said:
I am running a thumpr comp cam on my 360. I am running it on a duel plane summit intake and it feels like its lacking power still. also on the edelbrock carb its leaking raw fuel while its running and has a diesel effect when i shut it off please help with any knowledge that could do to fix the problems!:sith:
Click to expand...
which thumpr ? {thumpr , mutha thumpr ,big mutha thumpr } what gear ?? what trans/converter ?? gotta fix the gas drip issue before further tuning. An air gap intake would help . just my .02 :thumrigh:
 
as mentioned, fix the dripping carb or you are wasting time adjusting anything.

It's dieseling because the dripping fuel is giving the engine fuel when it shouldn't be pulling anything.

Also it may not have enough initial timing, throttle blades too far open. the big RPM drop is usually a sign of that issue.
 
Set the timing at 15° initial with the vacuum disconnected and hose to the carb plugged. Ignore total for the moment.
Slow the idle down to 700 out of gear and balance the mixture screws to the smoothest lean idle. See if it's still pulling fuel out the boosters at that point. It shouldnt be. Shouldnt deisel any more either.
 
DusterDillon74 said:
what air gap would you recommend?
Click to expand...

There's only one Air-Gap intake. Edelbrock makes a "RPM" manifold. They come in 2 styles. "Ait-Gap" and regular w/heat cross over cast in.

Other intakes by Edelbrock may also have a "Air-Gap" due to there racey design. AKA Victor series intakes. Big block Chrysler's are natural A-G designs from the factory.

Check the idle screw on the carb and the fast idle screw. Due note when you tap the gas, if the choke closes a tad in-acting the fast idle setting which would cause the idle to jump up.
 
There are actually two air-gap intakes, one is the Edelbrock Performer RPM Air-Gap and the other is the Professional Products Crosswinds, which has magnum/LA bosses (and splined plugs for the unused holes depending on install), and a significantly lower pricetag, but watch out for eBay scamsters, I just got sold something that has been backordered and now I'm fighting to get my money back. Summit has the Crosswinds as well but at a much more Edelbrock-level pricetag.

X5 on the "fix your dripping gas problem instead of looking at your intake manifold", there's nothing that you're describing as being wrong (the run-on and the leaking raw gas) that can come from a mischosen intake, only from problems inside the carb or problems with fuel pressure coming into it. "Lacking power" is a sideeffect of this misadjustment.

Are you running the mechanical pump or an electric? If it's a stocker mechanical, you're probably fine ,if it's electric, did you get a regulator? What pressure is it putting out? You want less than 7psi hitting your carb. Where did this carb come from, was it new or did you get it used? If it's new and leaking, take it back and get another one. If it's used, rebuild it with a quality rebuild kit, at minimum new floats and needles/seats, and adjust the fuel level carefully. Raw gas is a symptom of something bad, and a precursor to things that are even worse (like an engine fire). Once it's fixed, I'll bet you'll feel the pants to seat coefficient of power you are expecting.
 
Biggest power gain will be to ditch the eddy carb and go to a holley 650 double pumper. Put a 1" open spacer under it and call it good. A 750 can work well too, but the 650 will work better with your gearing/converter.
 
ou812 said:
Biggest power gain will be to ditch the eddy carb and go to a holley 650 double pumper. Put a 1" open spacer under it and call it good. A 750 can work well too, but the 650 will work better with your gearing/converter.
Click to expand...
i hear that i hate eddy carbs,even an 1850 holley would be better.and easier to tune....
 
I would run that late 70s Holley 2 barrel before I ran an edelcrap.
 
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