Recently bought a sand rail with a 2.0 pinto motor in it. So far I have upgraded to a mallory unilite electronic ignition, new coil, full tune up, new electric fuel pump, fuel filter etc.
My questions are the following...
1. The motor is using a offenhauser intake with a new Holley 390cfm four barrel, is this carb to big for my application?
2. No matter what I do, the idle won't come down unless I retard the timing so far that it has a hard time starting, could this be due to the size of carb as well?
3. What should base timing be?
Thanks in advance for all of your help.
The back barrels are also adjustable, remove the carb and look on the bottom side, there is a screw to adjust the back throttle shaft, you may have to close them up a little. Make sure the diaphragm spring for the secondaries is still there. Maybe an air leak. Get out the trusty carb cleaner in a can or a semi safer method is an unlit propane torch. Spray around the manifold & listen for changes. Time it until it kicks back while starting or pings while its under load and back it off a touch is what I say.
A sure and easy way to tell if the carb is to big is to check the plugs for excessive carbon which would make the car pop because of missfiring. Set the timing to the stock specs. If the carb is to big an adiquate velocity is not achieved though the carb base throat.
The factory sets stock timing specs to a stock engine running on crappy gas and below 3000 rpm not to mention to keep the emmissions down. I havn't see a carbureted car yet that didn't improve by advancing the timing a bit. My 460 truck is at 8 more degrees then stock. I've set the hotter v-8 engines at 34 to 36 total and then adjust the total advance down to where the engine starts hot without Kicking back.
We also ran a 2.0 with a 390 double pumper and it idled fine. The main problem was the 4 banger has some kind of issue with pulling gas through the accelerator pump shooters but there is a fix for this. Don't ask me what it was, we just lived with it until it was sold. If any of you are from the so. Ca. and attended Norton AFB drags, maybe you remember the pinto powered Old Farts Racing Team roadster. That car always had a passenger when driven down the track, It was hilarious & fun at the same time.