427/390 th 400 shifts fine at low speed, under load...will not!!!

[Michael B.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Did this just suddenly become a problem? Can you get it past 4000 RPM with moderate throttle?

Not at all common, but a stuck stator in the torque converter will cause RPM to fall flat about 4000 RPM. I have only seen that once in my 40 years of working on cars. Another possibility is restricted exhaust.

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Did this just suddenly become a problem? Can you get it past 4000 RPM with moderate throttle? Not at all common, but a stuck stator in the torque converter will cause RPM to fall flat about 4000 RPM. I have only seen that once in my 40 years of working on cars. Another possibility is restricted exhaust.

It was never a problem, until the new carb was put on...That said, the carb that was on the car when I bought her had a carb that never had the secondaries open....The car will reach 4K on a rev...and, just recently, she shifted into second WOT.....but, not to third. I don't want to keep pushing things until we get it figured out. The very fiste time I took her out with the new carb, she ran up fine..then the second time, there was a little hesitation when hitting the higher RPM's..but nothing like it is now. I left the car with the mechanic for other work...when I picked it up a week later, that's when the problems were very obvious. I'll have to hold the car in second to see if she hits 4K under moderate throttle, and I'll be back

Thanks,Bob
(9944)

[Jim T.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Did you make it to 4,000

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Did you make it to 4,000

Jim,

Haven't tried to "Edge" her up to 4K, but she did shift into second, WOT the other day, but NOT when going from Second to Third...Just hung there. She'll be back in the shop this week

Thanks,

Bob

[William C.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

If the engine isn't pulling the rpm under full throttle, the trans won't shift. You have an engine problem to diagnose before even thinking about the trans. The 390 should run to 5500-6000 rpm STRONG without hesitation. Have you looked at the advance curve?

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

If the engine isn't pulling the rpm under full throttle, the trans won't shift. You have an engine problem to diagnose before even thinking about the trans. The 390 should run to 5500-6000 rpm STRONG without hesitation. Have you looked at the advance curve?

Hi Bill,

The car just had a new Rochester Carb installed, and work was done on the distributor. I know the mechanic questioned the carb at first, but then said he didn't think that was the problem. (Never checked it) Still feels it's fuel starved, though. Car will be going in this coming Sat. Car ran fine, (but for the secondaries not opening) now with the new carb and distributor work, I'm having this problem. He did tell me that the distributor was 4 degrees off..and that's the best he could do. (Forgive me, I'm a bit mechanically challenged) so maybe he said something else PERTAINING to the distributor was off. I DO know that leaving something "off", (even by four degrees, is not like him). He said "Four degrees isn't bad out of 360."

When I first brought the car in for a rear end rebuild and new carb, I told him I wanted the timing curves. Another member led me to the article by a fellow member....He refused.....What can I tell ya!?

Car runs fine, just under full throttle...she dies....

I'm lost

Thanks,

Bob
9944

[William C.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

With all due respect, it tells me that he is not qualified to work on your car. Start with has he verified the timing mark with TDC on the engine? Has he run out the distributor to check the curve? has he checked fuel pressure @ rpm? Carb float level? Fuel filter? As I said, a 390 hp '67 should tear your head off up to about 6000 RPM, no hesitation, just a strong pull to the redline...! Anything else in unacceptable and must be addressed before you can evaluate the transmission performance.

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

With all due respect, it tells me that he is not qualified to work on your car. Start with has he verified the timing mark with TDC on the engine? Has he run out the distributor to check the curve? has he checked fuel pressure @ rpm? Carb float level? Fuel filter? As I said, a 390 hp '67 should tear your head off up to about 6000 RPM, no hesitation, just a strong pull to the redline...! Anything else in unacceptable and must be addressed before you can evaluate the transmission performance.

Yeah, we've ruled out the transmission...runs fine at normal speed...just when you get on it, it dies at around 4K

I hear ya, but he's a master judge and well known Corvette expert. I sold my '62 and '63 Split Window about 7 years ago. Thought that was "it" on my Corvette Fever...had six all together..but, recently..well...You know


Went back to his shop after all these years....Pretty tough to deal with these days. You ask for something, and he'll either say, "Yeah..I'll do that, or..."NO! I'm NOT doing that!!!" Not like I'm asking him to lower the car, and paint it orange, or anything...Very tough to deal with.


I know it sounds like he doesn't know what he's talking about, but his reputation precedes. The car was there for two weeks, and over 4K spent...I left the place, and when I accelerated on the On Ramp of the Freeway, she died...I came back, he went out with me, and the car stalled out and died in traffic. He removed the metal distributor housing and she started. Back to the shop, he and his employee worked on it for a while....Was not happy with the strength of the spark, but then said, "It's OK"


I had to pick up my daughter, so I left..and again, she drove fine.....WOT? Died!


Back to the shop a few days later, and he took it out..."Fuel Starved" Changed the line coming from the Tank because it was old and crimpped...Nothing! So, he was off to Corvettes At Carlisle, and is just now back.


According to him, it could be the Fuel Pump, screen in the tank, (He looked in and said it looked OK) Possibly the Fuel Filter, and, lastly....Maybe the Cam...(Don't know the name of the actual part) but, the part that operates the Fuel Filter
I get the feeling he doesn't want to do any work for nothing..I HOPE that isn't it, because he's always been honest, this is now a problem.


Sorry this is such a long post, but I'm baffeled

[Paul D.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Bob, I know you seem to be happy with your mechanic, but I think you should investigate other shops on this one. If he thinks four degrees of variance on initial advance setting is insignificant, refusing to recurve your distributor was a blessing in disguise! I'm not saying you NEED to recurve your distributor. You can realize some real performance gains over stock with some adjustments, but you need to get it running as good as stock first before attempting to improve. Someone with experience in centrifugal advance distributors needs to be looking at your car. It's hard to believe that most cars have not had distributors PERIOD since the 90's. You may need to look for a guy with some gray in his beard. Chip.

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Oops...Sorry...this post was meant for Chip...but, if it sheds any more light on the subject....Please let me know...

Thanks,

Bob
9944

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Bob, I know you seem to be happy with your mechanic, but I think you should investigate other shops on this one. If he thinks four degrees of variance on initial advance setting is insignificant, refusing to recurve your distributor was a blessing in disguise! I'm not saying you NEED to recurve your distributor. You can realize some real performance gains over stock with some adjustments, but you need to get it running as good as stock first before attempting to improve. Someone with experience in centrifugal advance distributors needs to be looking at your car. It's hard to believe that most cars have not had distributors PERIOD since the 90's. You may need to look for a guy with some gray in his beard. Chip.

Yeah, we've ruled out the transmission...runs fine at normal speed...just when you get on it, it dies at around 4K

I hear ya, but he's a master judge and well known Corvette expert. I sold my '62 and '63 Split Window about 7 years ago. Thought that was "it" on my Corvette Fever...had six all together..but, recently..well...You know


Went back to his shop after all these years....Pretty tough to deal with these days. You ask for something, and he'll either say, "Yeah..I'll do that, or..."NO! I'm NOT doing that!!!" Not like I'm asking him to lower the car, and paint it orange, or anything...Very tough to deal with.


I know it sounds like he doesn't know what he's talking about, but his reputation precedes. The car was there for two weeks, and over 4K spent...I left the place, and when I accelerated on the On Ramp of the Freeway, she died...I came back, he went out with me, and the car stalled out and died in traffic. He removed the metal distributor housing and she started. Back to the shop, he and his employee worked on it for a while....Was not happy with the strength of the spark, but then said, "It's OK"


I had to pick up my daughter, so I left..and again, she drove fine.....WOT? Died!


Back to the shop a few days later, and he took it out..."Fuel Starved" Changed the line coming from the Tank because it was old and crimpped...Nothing! So, he was off to Corvettes At Carlisle, and is just now back.


According to him, it could be the Fuel Pump, screen in the tank, (He looked in and said it looked OK) Possibly the Fuel Filter, and, lastly....Maybe the Cam...(Don't know the name of the actual part) but, the part that operates the Fuel Filter
I get the feeling he doesn't want to do any work for nothing..I HOPE that isn't it, because he's always been honest, this is now a problem.


Sorry this is such a long post, but I'm baffeled

[Patrick H.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

I'm not saying you NEED to recurve your distributor. You can realize some real performance gains over stock with some adjustments, but you need to get it running as good as stock first before attempting to improve. Someone with experience in centrifugal advance distributors needs to be looking at your car.

Seems to me that this was mentioned about 4-6 weeks ago....

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

With all due respect, it tells me that he is not qualified to work on your car. Start with has he verified the timing mark with TDC on the engine? Has he run out the distributor to check the curve? has he checked fuel pressure @ rpm? Carb float level? Fuel filter? As I said, a 390 hp '67 should tear your head off up to about 6000 RPM, no hesitation, just a strong pull to the redline...! Anything else in unacceptable and must be addressed before you can evaluate the transmission performance.

I hear ya, Bill. I called today since he just got back from Carlisle...I'm being put off another two weeks....He's busy as hell...Rather than get in to it with him on the phone, I came home and email'd him. I'm trying to make him understand that the car is worse off then when I brought it in..and he's been paid in full...And, I don't appreciate being put off like this.

No, he hasn't done any of the things you've mentioned. I picked the car up ..(Two weeks of work) didn't get a mile away and she would NOT accelerate. Brought her back...died in traffic when the mechanic and I went out....Distributor...THAT was straightened out..(I think...I'm still driving around with no Cover on it..he wants if off until he "Gets back to it")
I had to go...Everything is fine, but for the lack of acceleration..I went back again...He changed the hose coming from the tank...Nothing...And, that's where it was left. Said he'd get back on it when he returned..Well, he's back and "Busy"

I just may go elsewhere and have it diagnosed if he doesn't agree that this thing should be taken care or now! To tell you the truth....I think it's the old story...Doesn't want to have to fix something he may have done...No money in that. Don't forget..new carb, messing with distributor...Sounds like something done at the shop

Thanks for listening,

Bob

9944

[Bob S.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

Seems to me that this was mentioned about 4-6 weeks ago....

It certainly was..and I'm STILL waiting. I've been back and forth to the shop...Put off, and now that the mechanic is back from Carlisle, he wants me to wait another two weeks 'cause he's "Busy"

I've know this man for a long time..about 8 years passed since my last Corvettes....Not the same guy I used to know. Back then, he he did something and if it wasn't right..he MADE it right....I'd bet he'd make this right as well...but, you can see how long we've been going around with this. I want to be able to ENJOY my Vette. Not keep driving back and forth while they play games and my very large check has been cashed!


Guess I'll thank YOU, TOO for listening

Frustrated,

Bob
(9944)

[Patrick H.]

Re: 427/390 th 400 shifts fine at low speed, under load...will not!!!

It certainly was..and I'm STILL waiting. I've been back and forth to the shop...Put off, and now that the mechanic is back from Carlisle, he wants me to wait another two weeks 'cause he's "Busy"

I've know this man for a long time..about 8 years passed since my last Corvettes....Not the same guy I used to know. Back then, he he did something and if it wasn't right..he MADE it right....I'd bet he'd make this right as well...but, you can see how long we've been going around with this. I want to be able to ENJOY my Vette. Not keep driving back and forth while they play games and my very large check has been cashed!


Guess I'll thank YOU, TOO for listening

Frustrated,

Bob
(9944)

No problem. We want you to get your car running right!

Patrick