Carb'd edel. 1406, 350 bored 30 over, lopey aftermarket cam.

Seems like it stutters but has good performance to an extent. Any ideas? I just have basic handtools to work with ie: no money

 

What kind of cam? and it could be a vacuum problem, or a vacuum problem caused by too much cam.

 

You thinking maybe a vacuum canister is needed?

 

It is due to reversion that builds up in the intake manifold and causes misfires. You can observe this by the jumping of the needle on a vacuum gauge. It is caused by camshaft being extremely inefficient at the low idle RPM.

You can tune some of it out by using an adjustable vacuum advance unit on your distributor and adding more vacuum advance at idle, and limiting the total amount vacuum advance so you won't spark knock when vacuum increases as the RPMs increase while driving.

Luckily the adjustable vacuum advance units and tuning kits for the mechanical advance are not expensive and relatively easy to work with.

Exactly what type of distributor are you running now? Not looking for an answer like "GM" or "HEI".

 

My distributor is a vac advance Mallory. I dont know the specifics on the cam, it came with the engine from Phoenix engine builders, where I bought the long block.

I have a vacuum guage and have got it as steady as I could with it setting at 14-16


I thoroughly checked for vacuum leaks and there are none.


I have also adjusted it to the point where spark knock occurs and then backed it off. It is setting at 10 degrees. I had it set by a "professional" and then later moved it myself.

Now I do know this engine should purr. Is there some component I need to improve like the intake manifold or carb or something? What could be holding it back?

 

Well, now that I know more about what you've got, it points to another issue besides simple reversion. I still do not know what type of intake manifold you have, but if it is a square-bore dual-plane, then you should have no problems originating from that.

It sounds like you have set your initial timing to 10* without the vacuum advance hooked up & the vacuum port plugged. That should be fine.
What is your timing at idle with the vacuum advance unit plugged up to full manifold vacuum?
I'm assuming you did not hook your vacuum advance to a ported vacuum source on the front of your carb, but to full manifold vacuum.
Is that correct?

By the way, when was the last time you thoroughly cleaned out your carb?
If you are using 10% Ethanol fuel with an aluminum carb, then you will likely need to clean your carb a couple of times per year or more to prevent air-bleeds from getting clogged with oxidation.
Regular carb cleaner in the can, mineral spirits in a sprayer, and compressed air will do a good job of cleaning out the air bleeds.

Have you visually checked all of your spark plugs to look for signs of misfires? fuel fouling? Inspected the plugs and wires for cracks?

From how you described the problem it seems likely that you would see some signs of misfire and fuel fouling on at least some of your plugs.

Compression test on cylinders?

 

I have the distributor hooked to one of the two ports on the front of the carb. The one with constant vacuum. It is getting the same reading on the vac. tester as the port the brakes are hooked into. I have checked the all the plugs and wires (which all have less than 2k miles on them) except #8. I dont want to take the headers off. They were fine. ]

You mentioned losing compression in one of the cylinders. It might just be that. After I rolled the car I had to drain oil from #3 and #5 spark plug holes. I removed them and turned it over to blow anything out.

 

Not an expert, but I read some where recently doing research on pushrods, that pushrods could cause this problem. What kind of Rocker arms do you got? If you got roller tips and someone didn't get a perfect fit with the pushrods it can result in something similar to what you are reporting.