I won't run my shorties open. The exhaust is too close to my fuel line. I would need to buy collectors then weld on flexable pipe (short down pipes might work too. But it makes no sense that the exhaust would let it breathe normally only until the engine gets warm.
Did you use the same coil on the dyno? I know it’s easy to make suggestions and throw parts at the problem but I had a similar situation and it was the coil. When the coil was hot it would work as if there was no problem until I really got to higher RPM’s. My car didn’t nose over just flattened out and would not rev. I changed to a bigger coil and picked up 4 TENTHS and the motor did not feel like it was laboring any more. Just one more thing to look at. Good luck finding the problem.
Yes. And what good will a passenger do? All they would say is Yup, noses over at the top. We've ruled out everything except exhaust, charging system and transmission. I doubt it is the charging system and I don't see how the exhaust would be bothered by engine temp. I have access to a lift, a worked over trans and another 3000 stall converter. I've chased this for 2 years and I'm done. If the trans swap won't cure it then I'll weld up extensions for the shorties and see if it is the exhaust. I can R&I a trans in 3 hours (less with a lift). So this is no big deal.
Sometimes an experienced hand will pick something out, be it fuel, timing, valve springs, or ?? Tell us again about your entire fuel system. I don't like the pressure drop. Have you tried more timing? 28 seems a little low. Never mind the dyno for now. It's cold out and maybe you could spike your fuel for diagnostic purposes. When is all the timing in at? In my opinion, NOTHING is ruled out until it's fixed! When the results disagree with the theory, you change the theory. I feel the problem is something simple that you have either overlooked or looked at incorrectly. These are simple engines (or so it would seem).
Valve springs were checked day of the dyno as well as valve tip height. All well within spec. It noses over at 28*, 30*, 32* and 34* of timing. Electric Aeromotive fuel pump plumbed just ahead of and below the tank. New 3/8" line from tank to carb. Aeromotive regulator. It nosed over with the old fuel pump and fuel line as well. While the engine hit a wall at 5000 on the dyno with the B4B, this is the same exact problem I've been chasing for 2 years or more. As far as overlooking something... Nick Serwo (Ivyland Collision) and I have tuned and retuned this car. The entire ignition system has been replaced. The entire fuel system has been replaced. We have adjusted everything we know and checked even more. I'll swap the trans and see what happens. Maybe I'll borrow another Holley, but I don't think it is carb related because it did it with my last carb as well.
I could never feel my fuel delivery problem unless the car was up to temperature, then it would nose overhalfway through 2nd gear. I hooked up a fuel gauge to it, and saw that it was starving for fuel even when it was cold...but it never nosed over cold. I am still mistified about that one.
What type of fuel line did you use? Is there a return? Have you double- checked the fuel line routing (ie away from exhaust, nice sweeping bends, etc)? What type of fuel pick-up? Can you by-pass the fuel pressure regulator for testing purposes? Would you like to borrow my Innovate LM1?
I used push-lock fuel line with -6AN fittings wherever I had to make a turn or a connection. No return. Car never had one and the pump is a dead-head pump. No return is necessary. The pickup is a 3/8" tube with no sock. I just sent my spare sending unit to Tri Starr Radiator to have it modified and rebuilt. Unable to bypass regulator because pump puts out too much pressure. But with the old fule pump, line and regulator it still nosed over. Like I said, I have ruled out pretty much everything by rebuilding or replacing every component. I guess my only other option is to put my engine and trans into a donor car and see if it still lays over.
That's what I would expect a fuel delivery problem to feel like. I've had them before when the stock electric pump couldn't keep up. So I know fuel starvation feels like. And what it is doing now isn't the same thing. I've had and seen faulty ignition systems. Had a bad coil once and under load it would buck and pop. Saw a bad coil-to-cap wire and under load it would buck and pop. My car just stops pulling at the top of 1st gear. I always shift at 5000 when racing, but when I have decided to wring our 2nd gear to over 5000 it soes NOT lay over. It is just at the top of 1st gear. I suppose I should go to the highway and make a full run and see if 2nd gear lays over like 1st gear does.
I'm too lazy to go back and read this whole thing... What are you using for power to the coil? MSD box? I remember Larry H having a problem with the box wanting to retard the timing, and he had a video of it where you could hear the lag/bog at WOT. But I don't remember what the cause was...I'll do some searching.
Found it... http://www.v8buick.com/showthread.php?t=136682&highlight=MSD+timing Doesn't seem to be the same symptoms, unfortunately.
This is the same transmission through all this time, right? Just "rebuilt?" I would be swapping that thing out today with a different one if that is the case.
New trans altogether. Recap. I bought a PAE trans several years ago. About 3 years ago I bought a B&M Holeshot converter and within 60 seconds it chewed up the input shaft of my front pump. Nice. Had Mark Diconti rebuild the trans. Lost 3rd gear within 5 minutes. He sent me another trans and I sent him mine as an exchange. Again I lost 3rd gear within 5 minutes! He traced it to 2 little "screens" that he/nobody uses anymore yet he put in mine. He removed the screens and John Jr. has been running it ever since. So I bought a Transmission Specialties transmission. And again Ilost 3rd gear within 5 minutes. Swapped the trans for another and it had a cracked bellhousing. So they rebuilt the 1st trans they sold me and I lost 3rd gear within 5 minutes yet again. Then I lost 2nd gear. Turns out the case was broken inside somewhere. So this is the 4th attempt from them. 4 attempts, 2 trannys, one rebuilt twice, one with a cracked bellhousing (that I'm sure they knew about but were just trying to push off on someone - there is no way a tech can rebuild a trans and NOT see a huge gaping crack in the bellhousing). Their previous track record with me doesn't leave me with the warm fuzzies. I'm wondering if something inside is broken and it is able to hold line pressure only until it warms up?
Oh my, what a nightmare - get rid of that tranny just for karma....... I am worried mine broke just buy reading that :shock: Good luck!
