Hi, i have a 351 with a 700 mechanical secondary (double pumper) holley. Lateley it has been running like a pig, and a friend of mine assisted with installing a genuine rebuild kit on it to stop fuel leaks etc. These leaks were eliminated, but i still have the same problem as before.

At idle there is a heavy smell of fuel and a stinging sensation from my eyes when it is just idling, . This same friend borrowed a machine which plugs into my exhaust pipe and gives an accurate reading on what it is doing, (similar to a dyno). The readings showed that it is running ritch at idle and extremely lean when under load. (this explains why i blew a head gasket.) He had played with the idle when it was observed with the machine. The reading has slightly improved but nothing significant.

I would like to know if anybody can assist me with achieving an efficient reading at idle and under load to be feeding the amount of gas required for it not to be lean. Could there be a problem with my metering block? Vaccumes? or are the primary jets too high/secondaries not enough?

I am posting a new thread because i have no idea what i am doing when it comes to the fuel system on the damn car, and wether i do it myself or not, it would be benifitial to understand what i need to do so i dont feel like an idiot.

 

If I'm not mistaken, the idle circuit, which is rich, is different from running under throttle. You can change the jets to a larger size to make the mixture rich while running under a load. As for the idle....check the metering plate gaskets and make sure you have them installed correctly. Make sure the floats are adjusted correctly.

Have you checked the vacuum with a vacuum gauge?

 

Hi, thanks for your reply! i have checked the metering plate gaskets, and all the holes on the metering block seem to match up to the plates on the gaskets. They appear to be installed correctly. As for testing with a vacuum gague, i havent done that as yet, but i have performed a little test that made the mixtures on idle go a little better.

I had unplugged the the vacuum from the distributor (vacuum advance) and the mixtures semmed to have IMPROVED! what does this mean? i understand that the distributor wont be advancing, but obviously my timing wont advance. Is it better to pull vacuum from the manifold itself rather than the carby?

My rear jets are 78, and my front are 68. What jets do you recommend i try? I'm not sure if this is any help but my discharge nozzles are (front) 28, (rear) 32.

If it isnt a hastle how does a vacuume gauge work? what does it plug into?

 

You want to hook the dizzy to the carbs timed vacuum port, not the manifold.

 

The dizzy should be hooked to the port on the side of the metering block.
Go to 72 jets in the front. Then readjust the idle mixture with the screws in the metering block.
How large is the camshaft? Stock?
Hook the vacuum gauge to direct manifold vacuum. Adjust the mixture screws until you get the highest vacuum reading, then turn them both in about 1/4 turn. This will get the idle about perfect.

 

Hi Jimmy, My carby does not have a port on the side of the metering block. It only has a vacuum port on the plate where the butterflies are. that's where i have pulled vacuum from.

I dont know the specs on the camshaft, but its not standard. It is a "mild" thing. The motor was run before and 'apparently did mid to high 13's down the quarter mile'. (351 Cleveland 2V)

Im still in need to buy a vacuum gauge, and a friend suggested that my powervalve is not setup right. I have a 65 in it at the moment, and since i have a mild cam i should be running a 45, or even try a 50. Does this make sense to you? its all pig latin to me. (well at least its fun learning what all this stuff means!)

PS i dont see why i should go larger jets in the front? wouldnt that just allow more fuel to come through? hence, making the 'fueling up' smell heavier?

Cheers.
Dim

 

i agree with tying the 72 jets and that will richen you under load and adjust the mixture screws till the motor idles the smoothest. you need to some how find a ported vacuum for your distr. cuz your advancing to much and leaning the motor out. i think youll be find after this.

 

You must have an OLD 700 Holley. The ported vacuum would be on the passenger side in the base plate just in front of the throttle linkage.
Unless it is a very lopey idle, the 65 powervalve should be fine. This means that it opens 6.5" of vacuum. When you get a vacuum gauge, check the idle vacuum when in gear. The powervalve should be about 1/2 of the idle vacuum. So if you had 12 or 13" of vacuum, you would want a 65.

 

for the fuel smell you need to readjust the idle mixture screws and make sure that the throttle linkage is allowing it to fully close.