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·I have not been messing with m
I have not been messing with my 308 for the past couple of months because im trying to finish a HUGE project on my 911S. Full race suspension, exhaust, lightweight body panels and interior blaaaaaa blaaaaa blaaaaaaa
However, Im now compelled to finally finish the 308. Its all back together and runs/drives pretty well.. except for one issue.
It has a maddening and pronounced stutter at certain times. It does not do it in first or second gear at all, only in 3d, 4th and 5th. When I shift into 3d and revs drop back, if I give it full throttle it goes WaaaWaaaaWaaaaWaaaa in rythmic stutters. It feels almost like its not getting steady fuel or spark. Very rapid hesitation. Once revs build back to 5k or more it tends to smooth out and pull hard. Its bad under full throttle. If when I shift to 3d I only give it slight throttle until the revs build and then slowing increase to full throttle, its fine. If I shift to 3d and floor it, its WWHHHAaaaaa WHHhaaaaa Whhaaaaa Whaaaaaa waaaaaaa waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Maddening!
Im running a Millermon distributor. When installing it, I really thought the mechanical advance appeared to be advancing very little and the "spring" effect seems very weak. Im now wondering if something is indeed not right with the advance? It seems that under hard acceleration in the lower gear, the centrifugal force exerted on the mechanical advance is plenty to ensure it does advance properly, but in the higher gears where it is not advancing as quickly, perhaps the timing is not keeping up with the fuel? I just got a timing light with an advance tester, but have not tried it out. I worry that testing timing and advance without the engine being under load would not reveal the problem outlined above.
I have thought about this being a fuel issue, but if its the carbs how come it runs like a bat out of hell in 1st and 2nd gear. Accerations is really strong in the lower gear all the way to the rev limiter at 7k. Its only the higher gears where the problem is noticed.
I thought that perhaps its related to fuel percolating or vapor lock? In the lower gears the engine is revving faster and thus burning fuel faster, keeping fresh and cool fuel flowing through the lines and bowls. In the higher gear the fuel is moving slower and thus could get hotter? This seems a real stretch.
I keep coming back to the distributor and an advance mechanism problem. Ben Millermon has always been great to deal with.... when you can find him. He is not exactly easy to reach and getting any parts or supplies is always extremely slow.
Ideas? Im planning on spending time on it this weekend. I am signed up for a track day at Road Atlanta on the 23d. Despite working on it all I can, the 911 just isnt going to be ready
If I can get the 308 running sweet, ill put in some super blue fluid, perhaps put some track brake pads in and drive it on the track! Either that or Ill sell it. There is a local Gentleman who is very interested, but I dont want to sell it until Ive had a chance to drive it some with it really running perfectly.
Thanks!
Terry
I have not been messing with my 308 for the past couple of months because im trying to finish a HUGE project on my 911S. Full race suspension, exhaust, lightweight body panels and interior blaaaaaa blaaaaa blaaaaaaa
However, Im now compelled to finally finish the 308. Its all back together and runs/drives pretty well.. except for one issue.
It has a maddening and pronounced stutter at certain times. It does not do it in first or second gear at all, only in 3d, 4th and 5th. When I shift into 3d and revs drop back, if I give it full throttle it goes WaaaWaaaaWaaaaWaaaa in rythmic stutters. It feels almost like its not getting steady fuel or spark. Very rapid hesitation. Once revs build back to 5k or more it tends to smooth out and pull hard. Its bad under full throttle. If when I shift to 3d I only give it slight throttle until the revs build and then slowing increase to full throttle, its fine. If I shift to 3d and floor it, its WWHHHAaaaaa WHHhaaaaa Whhaaaaa Whaaaaaa waaaaaaa waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Maddening!
Im running a Millermon distributor. When installing it, I really thought the mechanical advance appeared to be advancing very little and the "spring" effect seems very weak. Im now wondering if something is indeed not right with the advance? It seems that under hard acceleration in the lower gear, the centrifugal force exerted on the mechanical advance is plenty to ensure it does advance properly, but in the higher gears where it is not advancing as quickly, perhaps the timing is not keeping up with the fuel? I just got a timing light with an advance tester, but have not tried it out. I worry that testing timing and advance without the engine being under load would not reveal the problem outlined above.
I have thought about this being a fuel issue, but if its the carbs how come it runs like a bat out of hell in 1st and 2nd gear. Accerations is really strong in the lower gear all the way to the rev limiter at 7k. Its only the higher gears where the problem is noticed.
I thought that perhaps its related to fuel percolating or vapor lock? In the lower gears the engine is revving faster and thus burning fuel faster, keeping fresh and cool fuel flowing through the lines and bowls. In the higher gear the fuel is moving slower and thus could get hotter? This seems a real stretch.
I keep coming back to the distributor and an advance mechanism problem. Ben Millermon has always been great to deal with.... when you can find him. He is not exactly easy to reach and getting any parts or supplies is always extremely slow.
Ideas? Im planning on spending time on it this weekend. I am signed up for a track day at Road Atlanta on the 23d. Despite working on it all I can, the 911 just isnt going to be ready

Thanks!
Terry