Building confidence, it is always the little things (LONG)



Well it's been about two months since I last worked on the car. I have been very busy.

It was prior to the crash of FSP and I was having trouble with overheating and a dying idle during warmup. The car starts fine, runs through about a minute or two of warmup and as it begins to warm up the car starts to die down and sputter, cough and chug, then after a few minutes of this as it warms up some more, boom it pops up to normal RPMs and runs fine the rest of the day. It only does this if the engine is cold.

So in the last post I was told to try a dozen different things and narrow down the list of possible problems. I was also having trouble with overheating and advance issues on my new DII conversion.

Well I tore the car apart this weekend and here is what I did, what I found, and what the current story is.

First ran the car and gave it a good tune up. I plugged all of the vac lines and checked for leaks. I found a leak in the carb, not at the base but at the first level on this CarterYF the screws were lose and the carb was wiggly around that gasket. I torqued them down and leak was gone.
PCV valve was clogged, put in a new one. (I swear you have to change those things like every three thousand miles.)
I got the timing and advance set by way of my new dial-back light.
Set the mixture and the car was still surging a little, but it was smooth.

Here is the fun part.
After I did that, I tore the whole thing apart.

Drained everything, pulled everything - hoses, carb, alternator, fan, radiator, thermostat, water pump.
I had it down to block and head distributor and fuel pump.

I found the thermostat in backwards, (OVERHEATING) it was not timing related, that turned out to be fine.
I put in a new water pump, 195degree stat, hoses, 3-row radiator. I also installed my sanden compressor and dryer filter for the AC to be finished in the spring.
I put in a new Powermaster 100 amp 1-wire alternator. (the external regulator on the engine was lose and the plug slipped right out.)
installed everything checking for leaks and pressurized the system.
I cleaned all of the gasket surfaces and put the carb back down after pulling the screws on the loose level and using loc-tight on them.

I got everything back together and it fired right up. Ran smooth and I had no problems.

The surge was electrical, since I replaced the system almost totally I cannot tell you if it was the regulator, alt, or wiring or all three. I noticed before that at night the lights would pulse with the surge with the engine, and I could never get the RPM's down and steady. Now it idles warm right at 900 and in drive right at 600.
The heat problem was the therm, in all of the test drives today it ran a nice even temp between 195 and 215 degrees (I let it sit in drive for about 20 minutes to get that high.)

But I still have the warm-up problem. So it has to be internal. I am thinking I have one or more stuck valves that lock up cold, and as the RPM's fall with the choke the car pops and heaves more and more the lower the RPM's fall, then the valve opens and everything runs up nice and fine?

It has to be something like that. Nothing outside the engine is causing this problem. And since it has done this since I have owned the car I think it will live for a couple of months more, but if anyone has any ideas I would look into them.

And from now on, I am the final mechanic on anything I can do with tools and two hands. NO MORE SHOPS FOR THE EASY STUFF, I am going to do everything myself unless I cannot do it myself for some reason, then I will take the chance.
More on the warm-up trouble above.

Today I pulled the air filter and watched everything while the engine was having this trouble, tomorrow I am hooking up all the scopes to see what the gauges do during this event.

But I noticed today that while the engine is dying there is little to no air flowing in the top of the carb. As the event stops and pops into a normal RPM range you can hear the air flow into the carb open and begin to take air.

Any thoughts.
Just a thought, I couldn't get my engine to idle decently below 1000 rpm, and I ended up pulling off the carb and cleaning it out with methylated spirits. The fuel bowl had a bit of rust scale (microscopic) in the bottom from the fuel tank. I think petrol/shellite might have been better to wash/spray it out with but I reassembled everything with the same gaskets and seals, ensuring everything was to spec and reinstalled it.

I ran the engine and it was actually idling at 300 rpm! (shaky but it didn't stall.) So I played with the idle fuel mixture and idle speed until it idled at 600 rpm. It's much more smooth now (for a 270/280 cam) and I went and bought a fuel filter as a band-aid solution to the rust contamination.