Race car wont idle

Tom Hillabrand · Jan 5, 2021

Ok, I have a fresh 446 wedge NSS motor heres the breakdown 440 motorhome block .030",13:1 ross pistons, aluminum rods,comp cams 320°/650 lift solid cam, triple springs,Hughes rockers and push rods, edelbrock aluminum max wedge heads, A&A crossram, pair of new edelbrock carbs, MSD ignition, race headers. Started it up to break in the cam with just one valve spring for break in. Ok break in is done but it only wants to run at high rpm 2,000 or so but cant get it to idle and it acts like a vacuum leak but we cant find any. We were meticulous in our assembly practices. Basically you have to crank it a long time and it just wont idle on its own. SUGGESTIONS PLEASE?

493 Mike · Jan 5, 2021

Tom Hillabrand said:
Ok, I have a fresh 446 wedge NSS motor heres the breakdown 440 motorhome block .030",13:1 ross pistons, aluminum rods,comp cams 320°/650 lift solid cam, triple springs,Hughes rockers and push rods, edelbrock aluminum max wedge heads, A&A crossram, pair of new edelbrock carbs, MSD ignition, race headers. Started it up to break in the cam with just one valve spring for break in. Ok break in is done but it only wants to run at high rpm 2,000 or so but cant get it to idle and it acts like a vacuum leak but we cant find any. We were meticulous in our assembly practices. Basically you have to crank it a long time and it just wont idle on its own. SUGGESTIONS PLEASE?

Have you tried (assuming lash is correct now) varying the lash?
Mike

66Satellite47 · Jan 5, 2021

Just a WAG here, but sounds like a combination of the intake design, carb tuning and distributor advance curve. Seems like that style intake would take a while to warm up. How quick does the advance come in on the distributor?

33 IMP · Jan 5, 2021

Whose throttle linkage? The edelbrocks have a different throttle shaft hookup location than the original carters, and if you set the edelbrocks for correct full throttle opening , they wont come down to idle, not enough "throw".
I would disconnect the throttle linkage, and try to get it to idle.
The center to center of the throttle shaft to linkage mounting hole is 1.5" on a max wedge carter.

Don Frelier · Jan 5, 2021

Sounds lean to me.

Jeremiah · Jan 5, 2021

Are the metering rods seated at idle? If you don't have enough vacuum to seat the step-up/metering rods it will be way fat. Do these carbs have chokes? Can you manipulate the choke to get it to idle?

Don Frelier · Jan 5, 2021

Agree with above. What do the plugs look like?

Fran Blacker · Jan 5, 2021

How's the manifold to head fit. Could be a vacuum from inside bottom of manifold. If the suggestions above don't work.

33 IMP · Jan 5, 2021

There is a hidden manifold plug at the very back of the real max manifold (i dont know about the A&A) that will be a huge vacuum leak if it isnt there. Pretty hard to miss, but i managed to miss it on mine for a while.

super-bee_ski · Jan 5, 2021

66Satellite47 said:
Just a WAG here, but sounds like a combination of the intake design, carb tuning and distributor advance curve. Seems like that style intake would take a while to warm up. How quick does the advance come in on the distributor?

Funny you should say that, as a friend of mine has a perfect #1 clone 63 Max wedge
That is exactly how his runs for the first 5 min
So "finicky" that it takes time to "settle in" so to speak.
But, what do I know...
That is an extreme engine...

dvw · Jan 5, 2021

I've run plenty of cross rams with close to stock Eddys and Carters. Even with big cams they idle fine. Does it idle poorly or just to fast? As mentioned check for interference with the carb linkage at the ends of the throttle shafts and the manifold. I've also had loose secondary throttle blades that hung up in the bores.
Doug

theman440 · Jan 5, 2021

Check your vacuum at idle, if you have less than 6 inches it wont be enough to make the idle circuit(s) work. Try setting the timing at 35 degrees (at idle) and see if it will idle. You may need to lock the distributor.

66Satellite47 · Jan 6, 2021

dvw said:
I've run plenty of cross rams with close to stock Eddys and Carters. Even with big cams they idle fine. Does it idle poorly or just to fast? As mentioned check for interference with the carb linkage at the ends of the throttle shafts and the manifold. I've also had loose secondary throttle blades that hung up in the bores.
Doug

Doug, good point on the throttle blade position/alignment. Had 1 Holley that was just slightly off, loosened the blade screws & re-set. Worked perfect. Lots of small things to check.

Fran Blacker · Jan 6, 2021

When I first started my x ram with holleys wouldn't idle. Guy sold them to me adjusted secondary screw to be open a crack.

HEMI-ITIS · Jan 6, 2021

I would start by disconnecting the linkage at the carb to be sure the blades are closed. Step by step,you will get it.

Race car wont idle

Tom Hillabrand

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493 Mike

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66Satellite47

Well-Known Member

33 IMP

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Don Frelier

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Jeremiah

Well-Known Member

Don Frelier

FBBO Gold Member

Fran Blacker

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33 IMP

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super-bee_ski

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dvw

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theman440

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66Satellite47

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Fran Blacker

FBBO Gold Member

HEMI-ITIS

STREETER on LI

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