63 _ Engine dies after warm up _Part II

[Steve D.]

Re: 63 _ Engine dies after warm up _Part II

After the last round of testing, the starter and solenoid both quit working. Direct jump to the S terminal or to the motor pole produced nothing. Same result after cool down. Tested again after removing starter, same result. I can't see how this could be related to the problem at hand, but it seems a strange coincidence, especially since both went at the same time.

I replaced the starter, and started the engine. This time it ran 20 minutes, somewhat short of the previous run. It restarted easily enough, but backfired when starting. The only times I have ever had a backfire were when I was reinstalling the distributor, before I got it positioned correctly. This is the first time I have ever had a backfire after the timing was set.

[Duke W.]

Re: 63 _ Engine dies after warm up _Part II

I had bad luck blocking both heat riser passage sides on my '63 340 HP engine. I had a very bad stumble starting off from a dead stop for about 20 minutes in mild temperatures. The problem no doubt was exacerbated by the CR trans and 3.08 axle.

I suggest you make shims out of stainless steel stock - no more .010" thick, and leave enough material sticking out that you can grab them with needle nose pliers and extract them after loosening the manifold bolts.

In the past I have suggested just installing one shim. This will allow some exhaust gas heating under the carb, but since it's a dead end passage, there is no net flow, so heat transfer is significantly reduced.

I don't know what kind of choke system you have, but for those that have heat stoves on the right hand side of the inlet manifold heat riser passage, I recommend blocking just the driver's side, and this should allow near normal operation of the thermostatic spring.

It sounds like the issue may be percolation related. There have been many threads on this subject, including one started by me as I recall asking for IR gun readings from the chassis fuel pipe that runs along the top of the RH frame rail to the carb. Since this pipe runs very close to the exhaust manifold, the fuel entering the fuel pump can be close to 150 degrees, and several found that placing insulating sleeves on this area of the pipe significantly reduced down stream temperatures, including the carb bowls.

Measure exhaust manifold temperature with a IR gun - after idling for a few minutes after being warmed up from driving. If they are more than 500F there's something wrong with the spark advance map.

Try idling with and without the air cleaner installed. With it installed excess fuel vaporization will likely be pulled into the engine creating an overly rich mixture. With it off, especially with a breeze, it's likely to dissipate. Look for any fuel bubbles coming out of the vents, both when idling and a few minutes after shutdown, and listen for the sound of boiling fuel in the bowls. There have been legitimate reports of fuel boiling that ejected liquid fuel from the bowls vents and you could actually hear the boiling after the engine was shut down.

Also try adjusting the idle mixture screws a bit on the lean side and raising the idle speed.

What is the basic engine configuration - 300 or 340 HP, and other than the Edelbrock manifold and carb are there any other modifications? What is your target idle speed and manifold vacuum at that idle speed? What is the number of the installed VAC, and does it pass the Two-Inch Rule. Is the PCV system the OE '63 design, and what PCV valve is installed? A photo might help.

When the engine stalls does it do so quickly from the normal idle speed, or does it slowly loose RPM and then stall?


Duke

[Steve D.]

Re: 63 _ Engine dies after warm up _Part II

340, LT1 cam, B-28 can. Idle drifts from 900 down below 800 and then stumbles and dies. This morning's measurements: at TOD (time of death) carburetor body temp was 110, fuel bowls 120, inlet fitting to fuel pump 155, pump discharge fitting 135. Also at TOD, no fuel coming from air vents, no wetness on either primary or secondary plates, no gurgling sounds from carburetor and no puking from expansion tank. This occurrence is not carburetor specific; the result is the same with the Edelbrock or the Holley that I replaced it with for test purposes. Total timing at 900 after warm up (before stumble) is 30 deg (initial 12, 16 can, centrifugal 2). On this morning's test, when it started to stumble, I increased the advance and it did not die and idle returned to 850-900. I checked the timing and it was about 35 deg. After a while, it started to stumble again so I increased the advance (39deg) and it returned to idle. After a while, it started to stumble again so I increased the advance (43deg) and it returned to idle. After a while, it started to stumble and this time I let it die. The observations and temp measurements above were made immediately after TOD.

[Duke W.]

Re: 63 _ Engine dies after warm up _Part II

The spark advance map sounds okay, but I'm perplexed that increasing total idle advance temporarily delays engine stall.

You report that the fuel pump inlet nipple is 155 and the outlet is 135. I can't get my arms around that data, either.

Since you've checked just about all possible electrical items and the problem occurs with either carb, that implies it's a fuel issue ahead of the carb, so everything upstream of the needles and seats is suspect- hoses, pipes, pump, and filters including the intank filter sock.

The first thing to do when the engine is cool and running well, shut off the engine and slightly move the accelerator pump. You should see fuel discharge from the nozzles immediately. Then run the same test after it stalls. If it takes more movement to see fuel flow at the nozzles it indicates a low fuel level in the bowls, which could be caused vapor lock or restriction in the lines or something amiss in the fuel pump. If this is the case run the fuel pump delivery test in the '63 shop manual both warm and after stalling.

The fact that it will keep running if you increase revs could mean the fuel pump just won't deliver enough fuel at idle speed due to some internal problem,like a check valve not properly seated or leaking. If the main diaphragm was ruptured or even leaking there would likely be liquid fuel coming out of the top vent hole. Another possibility is an internal delamination in a fuel hose, which is temperature sensitive and blocks fuel flow when hot.

You should also report idle vacuum at 900, and provide the details I requested about the PCV system.

Duke

[Leif A.]

Re: 63 _ Engine dies after warm up _Part II

Sounds distributor related... I do not know exactly how. You can advance the timing and momentarily everything is OK, as it starts to die you advance timing a bit more and everything is OK, then it starts to die again...until you can"t advance the timing any more. If this were a DeLorean I would say you need a new flux capacitor (weak attempt at humor). This is a bit of a mystery.

[Steve D.]

Re: 63 _ Engine dies after warm up _Part II

With a new FC I would need to upgrade the wiring to handle the 1.21 Jigawatts!