Automatic 66 GT 350. Rebuilt LIST 3259(by Drew). Engine is in time, good vacuum, nice idle, strong acceleration without hesitation/dead spots, no pinging, no starter drag when restarting after engine is warm.
At red light/stop signs, when in DRIVE rpm drops off and engine dies. Any suggestions how to fix? Thank you, Paul.
Aftermarket torque converter? Might need a higher idle setting.
Was a dashpot added to your 3259?
No dashpot on carb now. Had one on it that was falling apart when I sent it off for rebuild and it came back without it. I asked Drew about it and he was under the impression it was not normally used on a LIST 3259. It was returned in the box but doesn't look serviceable, boot disintegrated and spring showing. I'd be willing to put one on if I could find a source.
I will bump up the idle a bit. I believe the engine and transmission have never been out of the car. I'll do some research and see if any work has been done to the transmission/torque converter.
Thanks for the input, Paul.
Perform a manifold vacuum test on a warm engine, idling, and in park. I don't know the altitude of where you reside, but I would expect approximately 16 inches of manifold vacuum. If it is 14 inches or less, I would expect that you might have one or more vacuum leaks that you need to hunt down, like maybe the rubber hoses that connect the vacuum line from the manifold to the vacuum modulator. If it has never been changed, the modulator could be your source also. There could be other sources of leakage but try the easiest first. It is a simple diagnostic test to perform.
I hope this helps.
Frank
Quote from: paul on April 30, 2024, 01:15:09 PMNo dashpot on carb now. Had one on it that was falling apart when I sent it off for rebuild and it came back without it. I asked Drew about it and he was under the impression it was not normally used on a LIST 3259. It was returned in the box but doesn't look serviceable, boot disintegrated and spring showing. I'd be willing to put one on if I could find a source.
I will bump up the idle a bit. I believe the engine and transmission have never been out of the car. I'll do some research and see if any work has been done to the transmission/torque converter.
Thanks for the input, Paul.
It was typical for a dashpot to be used on S2MS 3259 list carbs when used on Automatic GT350's in 67. 66 automatics typically used 4100 carb after approximately vin
900 800 something.
When I got the carb back from Drew, I adjusted it to the engine and set the timing using the max vacuum as target. It is pulling about 16.5 inches now from the PCV port at the back of the intake.
I will check the lines to the transmission next. Could the vacuum lines to the transmission and/or the modulator be leaking and still allow the 16.5" of vacuum at the PCV port?
Drew does excellent work, the carb performs exceptionally.
Thanks guys, Paul
Sending a couple of pictures of an automatic 67 GT350 3259 carburetor. Have a copy of a letter from SA
saying that all cars after 6S800 will be equipped with the Autolite carb.
Texas Swede
Would anyone know where I could get a dashpot. Even if not original, if it improves reliability/road worthiness, I'd be ok using one.
Thanks
Quote from: texas swede on April 30, 2024, 02:36:52 PMHave a copy of a letter from SA saying that all cars after 6S800 will be equipped with the Autolite carb.
Texas Swede
Bo,
Could you post a scan of that letter? I'd love to see it. Thanks.
Quote from: paul on April 30, 2024, 02:36:15 PMWhen I got the carb back from Drew, I adjusted it to the engine and set the timing using the max vacuum as target. It is pulling about 16.5 inches now from the PCV port at the back of the intake.
I will check the lines to the transmission next. Could the vacuum lines to the transmission and/or the modulator be leaking and still allow the 16.5" of vacuum at the PCV port?
Drew does excellent work, the carb performs exceptionally.
Thanks guys, Paul
Paul, you want the pcv active when you perform the manifold vacuum test. I would suggest installing a temporary tee in the connection where the transmission vacuum line connects to the intake manifold. The pcv is, by definition, is a vacuum leak. You want to determine if there are additional vacuum leaks.
Frank
Here is the letter from SA.
Texas Swede
Interesting, I just posted a thread about that carb and stalling at stops in the '65 4 speed I just got. When I adjusted the idle to 1200, it doesn't stall anymore at stops but the idle does still drop off a bit. I can drive it now without worrying at least. I am sure the idle is way too high however.
Try bumping up the initial timing a few degrees and then re-adjust the carb.
Quote from: paul on April 30, 2024, 02:41:44 PMWould anyone know where I could get a dashpot. Even if not original, if it improves reliability/road worthiness, I'd be ok using one.
Thanks
I picked up an NOS one years ago on Ebay. You might start there, unless someone here has one.
NPD sells a repro early style dashpot.
I have had similar issue as well as lack of shifting gears that both turned out to be faulty old cracked vacuum hose. Leaks too small to see on inspection but changed the hse and clamps and problems solved.
8)