Previous Thread
Next Thread
Print Thread
Page 1 of 4 1 2 3 4
60 ft frustration is driving me nuts #2785702
06/15/20 01:08 PM
06/15/20 01:08 PM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Offline OP
master
dvw  Offline OP
master

Joined: Mar 2006
Posts: 9,791
MI, usa
Though we won last weekend the car hasn't been good. 60ft varies wildly. 3 different tracks. This weekend rd 1 1.40, rd 2 1.29. Its been as wide a spread as 1.29-1.46. Car leaves flat, deviously 12-16" up for 40-60foot out. What I've done to try and fix it. New M/T 10.5wx31, loosened the shocks and tightened the shocks, the fronts as many as 15 clicks. Varied tires 12-15 psi. Then with video realized there is zero tire spin . Next swapped converters, new plugs, cap, rotor, carbs apart cleaned and adjusted. Varied timing by 6 degrees. Same leave rpm, water, oil temp, intake temp. Incrementals after 60ft are spot on. Same fuel I've always run, Renegade Pro114. R/T are getting slow also. However on the practice tree they're fine. Foot brake only. Leave at 2700-3300. Eddy 750 carbs. The combo has been untouched and pretty decent for 7 years. Thoughts?
Doug

Re: 60 ft frustration is driving me nuts [Re: dvw] #2785708
06/15/20 01:24 PM
06/15/20 01:24 PM
Joined: Jan 2003
Posts: 10,009
MN
J
JERICOGTX Offline
I Live Here
JERICOGTX  Offline
I Live Here
J

Joined: Jan 2003
Posts: 10,009
MN
If the 330', 660' and 1000' are the exact same, I wouldn't worry about it. Could be where your car is tripping the 60' timers.


69 GTX 68 Road Runner
Re: 60 ft frustration is driving me nuts [Re: dvw] #2785709
06/15/20 01:28 PM
06/15/20 01:28 PM
Joined: Jan 2003
Posts: 19,304
Las Vegas
Al_Alguire Offline
I Live Here
Al_Alguire  Offline
I Live Here

Joined: Jan 2003
Posts: 19,304
Las Vegas
Well I would be looking hard to the converter. Reaction times obvious would change with tire slippage, but if it is dead hooking and running slow on the tree and 60' I would be looking for a converter to toss in it for sure. Might look at the trans as well but sure sounds like a converter issue to me. Just went through this on a biddies S/ST car. Pulled converter and found some fins had been knocked loose from brazing, same deal. Reaction times and 60's inconsistent down track was fine.


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: 60 ft frustration is driving me nuts [Re: JERICOGTX] #2785711
06/15/20 01:29 PM
06/15/20 01:29 PM
Joined: Aug 2003
Posts: 4,662
On the parachute mount
N
n20mstr Offline
master
n20mstr  Offline
master
N

Joined: Aug 2003
Posts: 4,662
On the parachute mount
Originally Posted by JERICOGTX
If the 330', 660' and 1000' are the exact same, I wouldn't worry about it. Could be where your car is tripping the 60' timers.


ARE your result different at different tracks? Maybe they have 60" light at different heights ? ALso do you have a transmission blanket? possible sometimes its hanging down??

Also the diff reaction times same thing, maybe the rollout is different form one track to another


....BAD A$$ STREET CAR.....
Re: 60 ft frustration is driving me nuts [Re: dvw] #2785717
06/15/20 01:37 PM
06/15/20 01:37 PM
Joined: Jan 2003
Posts: 20,645
So Near, Yet So Far
topside Offline
Too Many Posts
topside  Offline
Too Many Posts

Joined: Jan 2003
Posts: 20,645
So Near, Yet So Far
If I understand you correctly, sounds like it won't pitch-rotate and dead-hooks ?
Sounds like you've thrown some tweaks at it but it's not hitting the back tires enough or inconsistently ?
I assume it leaves & goes straight ?
Converters are known entities & behaving properly ?
I don't recall if it's a ladder, 4-link or leaf car, but I'd snoop around the rear suspension area...including bushings, heim joints, spring rates still good...

Re: 60 ft frustration is driving me nuts [Re: topside] #2785730
06/15/20 01:49 PM
06/15/20 01:49 PM
Joined: Jan 2003
Posts: 2,289
NE Ohio
DoubleD Online content
top fuel
DoubleD  Online Content
top fuel

Joined: Jan 2003
Posts: 2,289
NE Ohio
Its' one of three things - Converter, Converter or the Converter........................ your car is normally deadly consistent

Re: 60 ft frustration is driving me nuts [Re: dvw] #2785745
06/15/20 02:43 PM
06/15/20 02:43 PM
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
T
TRENDZ Offline
master
TRENDZ  Offline
master
T

Joined: Jan 2005
Posts: 2,540
Milwaukee WI
Does your trans allow converter pressure changes?


"use it 'till it breaks, replace as needed"
Re: 60 ft frustration is driving me nuts [Re: TRENDZ] #2785759
06/15/20 03:33 PM
06/15/20 03:33 PM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Offline OP
master
dvw  Offline OP
master

Joined: Mar 2006
Posts: 9,791
MI, usa
We have about 15 good videos of the rear tire from the last 4 weekends.There is ZERO tire spin. I thought converter as well. So it was swapped about 20 passes ago. The trans was gutted then also. saw nothing. The 1st converter is at the shop . Getting opened up this week. Its had the issue with both converters. It's lame right at the hit. 2 pretty knowledgeable guys say they can hear it sound flat directly after the throttle is floored. The play back tach thinks that there is a peak around 3400 rpm. The tach has always done this since I've been running the car. The other thing is it will idle at 1500 with the carb speed screws backed out all the way (throttle plates closed). I'm assuming vacuum leak. Checked the carbs, carb adapter plates, and manifold lid. I'll pull the lower intake this week. It puzzles me if it is an intake leak, why it doesn't consistently run poorly? it has no adjustment for the converter pressure.
Doug

Last edited by dvw; 06/15/20 03:36 PM.
Re: 60 ft frustration is driving me nuts [Re: dvw] #2785783
06/15/20 05:19 PM
06/15/20 05:19 PM
Joined: Jan 2003
Posts: 2,289
NE Ohio
DoubleD Online content
top fuel
DoubleD  Online Content
top fuel

Joined: Jan 2003
Posts: 2,289
NE Ohio
You might want to check the intake gaskets - that has been an issue I have seen three times now using the red gaskets - also check your carbs where the air adjustment screws seat into the casting - that area is really weak on the edlebrocks and any little backfire can cause cracks in the casting for some reason

Re: 60 ft frustration is driving me nuts [Re: dvw] #2785798
06/15/20 05:56 PM
06/15/20 05:56 PM
Joined: Aug 2009
Posts: 235
Central Mississippi
mopar97 Offline
enthusiast
mopar97  Offline
enthusiast

Joined: Aug 2009
Posts: 235
Central Mississippi
Originally Posted by dvw
Though we won last weekend the car hasn't been good. 60ft varies wildly. 3 different tracks. This weekend rd 1 1.40, rd 2 1.29. Its been as wide a spread as 1.29-1.46. Car leaves flat, deviously 12-16" up for 40-60foot out. What I've done to try and fix it. New M/T 10.5wx31, loosened the shocks and tightened the shocks, the fronts as many as 15 clicks. Varied tires 12-15 psi. Then with video realized there is zero tire spin . Next swapped converters, new plugs, cap, rotor, carbs apart cleaned and adjusted. Varied timing by 6 degrees. Same leave rpm, water, oil temp, intake temp. Incrementals after 60ft are spot on. Same fuel I've always run, Renegade Pro114. R/T are getting slow also. However on the practice tree they're fine. Foot brake only. Leave at 2700-3300. Eddy 750 carbs. The combo has been untouched and pretty decent for 7 years. Thoughts?
Doug


Have you checked to see if the advance in the distributor is functioning correctly? Provided that is not an issue, I too wonder about the AF screws being all the way out making no change. It does appear to be a vacuum related problem, the idea to check the intake gaskets is a good one but also the carb base and those gaskets also.
Good Luck


Mopar born, Mopar breed, when I die, call me Mopar dead!
Re: 60 ft frustration is driving me nuts [Re: mopar97] #2785803
06/15/20 06:24 PM
06/15/20 06:24 PM
Joined: Jan 2003
Posts: 19,304
Las Vegas
Al_Alguire Offline
I Live Here
Al_Alguire  Offline
I Live Here

Joined: Jan 2003
Posts: 19,304
Las Vegas
What ignition is on it, also check for vacuum leaks. Was the converter you swapped in a known piece? I would want to hear whats said from the converter guy myself. Have you noticed a change in shift recovery or flash at all? I cant see a vacuum leak causing this issue with 60's and lights and not downtrack, but who knows. I mean if its got a leak at idle and down low it would get worse up top one would think.


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: 60 ft frustration is driving me nuts [Re: mopar97] #2785812
06/15/20 06:36 PM
06/15/20 06:36 PM
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
T
TRENDZ Offline
master
TRENDZ  Offline
master
T

Joined: Jan 2005
Posts: 2,540
Milwaukee WI
With changing converters, the next thing I would check is the stator shaft. Be sure the splines are ok and that it is not able to spin in its mounting.
Never daw this with a TF, but many times on GM trans.


"use it 'till it breaks, replace as needed"
Re: 60 ft frustration is driving me nuts [Re: TRENDZ] #2785847
06/15/20 08:23 PM
06/15/20 08:23 PM
Joined: Mar 2006
Posts: 9,791
MI, usa
dvw Offline OP
master
dvw  Offline OP
master

Joined: Mar 2006
Posts: 9,791
MI, usa
It does have the pink/red gaskets so that's on the list. They were replaced about 100 passes ago when the heads were off. Its MSD crank trigger, MSD 7AL 2 box, MSD 8201 pro power coil, Taylor 8mm wires NGK 8 plugs. Shift fall back with converter 1 was around 900, with converter 2 800. Converter 2 is a known piece from ATI built for a 936 hp 572, had 40 passes since new when installed. The incrementals 60/330 330/660 are nearly dead on going back to 2018. Both are 9.5 cores which outwardly appear to be the same core style. Stator shaft support was replaced about 40 passes ago. Its tight and splines are nice. Always careful with the idle screws as you say this is a known problem. My friend has a similar engine that has been dynoed at Best. Same intake with a a pair of Pro Systems 950's. Going to just switch the entire upper half with his upper and carbs.
Doug

Last edited by dvw; 06/15/20 08:25 PM.
Re: 60 ft frustration is driving me nuts [Re: dvw] #2786000
06/16/20 12:28 PM
06/16/20 12:28 PM
Joined: Jan 2003
Posts: 19,304
Las Vegas
Al_Alguire Offline
I Live Here
Al_Alguire  Offline
I Live Here

Joined: Jan 2003
Posts: 19,304
Las Vegas
Be interesting to see what you find .I just don't see the intake or carbs causing such an issue with reaction time and 60' but run great at the other end. Those kind of things generally don't clear up down track and get better.


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: 60 ft frustration is driving me nuts [Re: Al_Alguire] #2786283
06/17/20 09:59 AM
06/17/20 09:59 AM
Joined: Jan 2003
Posts: 4,003
Shelby Twp. Mi
HardcoreB Offline
master
HardcoreB  Offline
master

Joined: Jan 2003
Posts: 4,003
Shelby Twp. Mi
In the interest of stimulating feedback to ultimately help point you to an answer, I will reshare my thoughts on the forum. It is a fuel issue IMO. Maybe a signal issue at low-speed (gasket) not allowing a rich 'storm' in the plenum to compensate for the inherent lean condition with edelbrocks at the hit. What running/warm-up sequence preceded the 1.29 60ft? OR...erratic fuel pressure at low demands (assuming nothing got overlooked during recent carb inspection) Again although the edelbrocks are not going to be as fast or quick as a holley IT SURE RAN BETTER and more consistent before so, something changed. This is where having data that looked at trans rpm and fuel pressure coordinated with dual a/f widebands would help.

Re: 60 ft frustration is driving me nuts [Re: HardcoreB] #2786303
06/17/20 11:11 AM
06/17/20 11:11 AM
Joined: Jan 2003
Posts: 19,304
Las Vegas
Al_Alguire Offline
I Live Here
Al_Alguire  Offline
I Live Here

Joined: Jan 2003
Posts: 19,304
Las Vegas
Rich at the hit is typical for anything that spends time on the brake for sure, never seen it cause an issue like he is having though. I have seen 10-1 fat conditions at the hit. A combination of lots of carb and being on the two step dropping cylinders will cause it. If it was a over rich condition a quick review of video could help confirm that, one would think if it is bad enough to cause the car to slow that much there would surely be signs of it on the video. I think it would need to be WAY fat to cause that. But ya never know I suppose. Only other way I have seen that happen is fuel dumping out the vents that will create a bog for sure and a tell tale puff of smoke, but he says it dead hooks and goes so don't see it being anything like that. Kinda like an intake leak, it should be present all the way down the track, cannot imagine that would repeat from knonw good runs with the extra air. Unless we are assuming it is "sealing" itself with more heat?

IMO most people run WAY to much fuel pressure to begin with, usually to mask an inadequate fuel system. My car is at 4.8 lbs throughout the run. Data logging might certainly help to narrow this down for sure. Would love to see a driveshaft and an acceleration graph for sure.


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: 60 ft frustration is driving me nuts [Re: Al_Alguire] #2786354
06/17/20 12:38 PM
06/17/20 12:38 PM
Joined: Jan 2003
Posts: 4,003
Shelby Twp. Mi
HardcoreB Offline
master
HardcoreB  Offline
master

Joined: Jan 2003
Posts: 4,003
Shelby Twp. Mi
Originally Posted by Al_Alguire
Rich at the hit is typical for anything that spends time on the brake for sure, never seen it cause an issue like he is having though. I have seen 10-1 fat conditions at the hit. A combination of lots of carb and being on the two step dropping cylinders will cause it. If it was a over rich condition a quick review of video could help confirm that, one would think if it is bad enough to cause the car to slow that much there would surely be signs of it on the video. I think it would need to be WAY fat to cause that. But ya never know I suppose. Only other way I have seen that happen is fuel dumping out the vents that will create a bog for sure and a tell tale puff of smoke, but he says it dead hooks and goes so don't see it being anything like that. Kinda like an intake leak, it should be present all the way down the track, cannot imagine that would repeat from knonw good runs with the extra air. Unless we are assuming it is "sealing" itself with more heat?

IMO most people run WAY to much fuel pressure to begin with, usually to mask an inadequate fuel system. My car is at 4.8 lbs throughout the run. Data logging might certainly help to narrow this down for sure. Would love to see a driveshaft and an acceleration graph for sure.


His car is always a footbraked. And was thinking it was LEAN until it got a stronger signal to the carbs. I would think down track, a localized signal loss has less affect than it would during that footbrake transition. I have seen a few manifold leaking conditions where it wouldn't be obvious there was a problem based on downtrack performance...other than idle.

Re: 60 ft frustration is driving me nuts [Re: HardcoreB] #2786499
06/17/20 05:51 PM
06/17/20 05:51 PM
Joined: Aug 2016
Posts: 61
The Great State of PA
tabletop390 Offline
member
tabletop390  Offline
member

Joined: Aug 2016
Posts: 61
The Great State of PA
We just ran into something similar on a buddy’s car and the fix believe it or not was a new master switch. The initial hit and vibration off the line and during the burnout was causing the disconnects and reconnects and making his MSD go nuts. Once he got out around 30-40 ft car settled and didn’t vibrate as much and ran like a champ. We did everything, converters, carbs, rebuilt the trans, etc.

Re: 60 ft frustration is driving me nuts [Re: tabletop390] #2786572
06/17/20 08:03 PM
06/17/20 08:03 PM
Joined: Dec 2012
Posts: 1,823
Wind Gap,Pa.
S
Sammy Offline
top fuel
Sammy  Offline
top fuel
S

Joined: Dec 2012
Posts: 1,823
Wind Gap,Pa.
Originally Posted by tabletop390
We just ran into something similar on a buddy’s car and the fix believe it or not was a new master switch. The initial hit and vibration off the line and during the burnout was causing the disconnects and reconnects and making his MSD go nuts. Once he got out around 30-40 ft car settled and didn’t vibrate as much and ran like a champ. We did everything, converters, carbs, rebuilt the trans, etc.



How did you figure out that was the problem?

Re: 60 ft frustration is driving me nuts [Re: Sammy] #2786598
06/17/20 09:03 PM
06/17/20 09:03 PM
Joined: Aug 2016
Posts: 61
The Great State of PA
tabletop390 Offline
member
tabletop390  Offline
member

Joined: Aug 2016
Posts: 61
The Great State of PA
Had a programmable MSD 6 and with the laptop hooked up, you could watch the MSD go. Tried a new MSD, same problem. Damn near threw the laptop against a wall to verify it wasn’t vibration to the laptop. Started double checking connections and found the master was barely making contact. If you just turned it on it was fine. If you put a little pressure on the switch it would turn the car off. Put a new switch on, car’s been fine since. I talked to the guys at Auto Rod and they told me they see it all the time and if you don’t change your switch out every 3-5 years you’re asking for it. Told me as well that you can really see it with a Racepak but I’ve never experienced it myself.

Page 1 of 4 1 2 3 4






Powered by UBB.threads™ PHP Forum Software 7.7.1