Anyone had this problem
Thread Starter
Intermediate
Joined: Aug 2005
Posts: 26
Likes: 0
Anyone had this problem
My 71 454 runs great in all but one condition. Wide open it comes on strong until it gets to 4000rpm. At this point it hesitates, once you shift It winds nicely right back up to 4000rpm then hesitates. If you part throttle accellerate it will wind right up to redline with no hesitation. My first thought is wires, then of course the myriad of possible quadra jet problems. So far all I have done is check to make sure the secondary is opening properly. I adjusted the spring windup because it was rather loose. No matter where I set it I still had the same problem. Has anyone seen this?
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
QJet troubleshooting by Lars
QJet tuning by Lars
Could also be a timing issue...
Performance timing paper by Lars
QJet tuning by Lars
Could also be a timing issue...
Performance timing paper by Lars
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
I had the same problem when I still had the LS-5 in my car. It was most noticeable when it was under a load, such as 3rd or 4th gear with petal to the carpet. I traced mine down to the piece of junk Pertronix igintion I had. What type of ignition are you running?
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East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
I am using a small cap HEI so I can retain the igntion shielding. If you are not trying to keep the shielding, then I would just get a large cap HEI from Performance Distributors or MSD.
You can get the small cap HEI's here:
http://www.performancedistributors.com/gmtripower.htm
Or here:
http://www.davessmallbodyheis.com/
Of course you can always get the large cap, (if you don't care to toss your shielding) here:
http://www.performancedistributors.com/gmssdui.htm
I am using the "GM TRI Power Ignition" from Performance Distributors (aka Davis Unified Ignition) they have been in buisness a long time, plus they are only an hour away from me. So far so great, no hesitation under a load. I have heard good things about Dave's as well, but I cannot vouch for them personally. Davis Unified Ignition (aka D.U.I.) will curve your distributor according to your particular application using a distributor machine. I sent them all of the specs on my car, plus a dyno sheet on my motor and they did the rest. Give them a call.
You can get the small cap HEI's here:
http://www.performancedistributors.com/gmtripower.htm
Or here:
http://www.davessmallbodyheis.com/
Of course you can always get the large cap, (if you don't care to toss your shielding) here:
http://www.performancedistributors.com/gmssdui.htm
I am using the "GM TRI Power Ignition" from Performance Distributors (aka Davis Unified Ignition) they have been in buisness a long time, plus they are only an hour away from me. So far so great, no hesitation under a load. I have heard good things about Dave's as well, but I cannot vouch for them personally. Davis Unified Ignition (aka D.U.I.) will curve your distributor according to your particular application using a distributor machine. I sent them all of the specs on my car, plus a dyno sheet on my motor and they did the rest. Give them a call.
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
Originally Posted by Simmo
When I identified my POS Pertronix was a rev limiter, I stuck a Vertex magneto with tach drive in!
Instructor
Joined: Nov 2004
Posts: 194
Likes: 0
From: Appleton Wi.
After 200 miles, the Pertrinix kit I tried fried all my plug wire terminals. The inside of the cap was carbon tracked all over. I replaced everything, except module, back with G.M. stuff, still corroding wires. Swapped the old G.M. module back in, and trouble free for 3000 miles. I guess you can tell I won't buy anymore Pertrinix stuff.
TJ
TJ
Burning Brakes
Joined: Mar 1999
Posts: 1,047
Likes: 3
From: CA
Originally Posted by VETDRMS
You could be running out of fuel. Have you replaced your filter? You may want to check the fuel pressure as well.
Cruising
Joined: May 2005
Posts: 11
Likes: 0
I had the same problem with the Pertronix crap and went to an MSD ignition.
I had the car on the dyno and also discovered the secondary throttle shaft spring wasn't able to open the secondaries...too much vacuum, too weak of a spring. I hard wired them to the shaft, eliminated the vacuum controls and solved that problem...which made it much more fun to drive
I had the car on the dyno and also discovered the secondary throttle shaft spring wasn't able to open the secondaries...too much vacuum, too weak of a spring. I hard wired them to the shaft, eliminated the vacuum controls and solved that problem...which made it much more fun to drive
East bound and down...
Joined: Dec 2004
Posts: 987
Likes: 3
From: Jonesboro Arkansas
Yea the module was the culprit in my case. People can defend these all they want, but there are better soutions out there. For the money, and from the feedback I have heard, the Crane XR-1 looks like a good option.
Anyway I am happy with the DUI setup I have. The dyna mod that you speak of is made by DUI in Memphis. I saw them for sale in Mid-Am. before I realized who made them. Just curious why did you change?
Anyway I am happy with the DUI setup I have. The dyna mod that you speak of is made by DUI in Memphis. I saw them for sale in Mid-Am. before I realized who made them. Just curious why did you change?
Last edited by LS-Five; Sep 1, 2005 at 10:27 PM.
Racer
Joined: Aug 2005
Posts: 308
Likes: 0
From: Salem MA
im having this problem as we speak.
and i KNOW its the ignition module thingy that i replaced my points with.
because if i was running out of fuel WOT at 4500 rpm my engine would probably be a paper weight by now.
thats it. im putting a set of points back in and weighting my ignition options in the spring.
besides. points arent THAT bad.... i just need to find a book of matches.
and i KNOW its the ignition module thingy that i replaced my points with.
because if i was running out of fuel WOT at 4500 rpm my engine would probably be a paper weight by now.
thats it. im putting a set of points back in and weighting my ignition options in the spring.
besides. points arent THAT bad.... i just need to find a book of matches.
Thread Starter
Intermediate
Joined: Aug 2005
Posts: 26
Likes: 0
Man now I am confused yet again. I just wired the secondaries shut on the carb, and went out for a test drive. The thing wound up no problem WOT. I wonder if the load on the primaries is enough for the pertronix to keep up, or if I just have a lean condition. The carb was rebuilt right before I bought the car. Could be improper secondary setup. What do you guys think.
Racer
Joined: Aug 2005
Posts: 308
Likes: 0
From: Salem MA
mission report:
based on the last post i swaped out the accel coil i had in the vette for a blaster 2 i had in stock. and a blaster 2 is better than an accel. end of story.
i am however still having the same problem. just a bit less of it.
i now believe what me and LS5 are experiancing is "spark blow out".
when i had a turbo 4 cylinder running 18 psi of boost i had to gap down to like 0.028 or at high rpms the spark would not ignite the mixture because of the extreme stuff going on in the combustion chamber. it felt alot like a rev limiter because it would and wouldnt ignite randomly.
so im going to get new plugs and gap conservatively. i expect this to solve my problems. because like LS5 i can do high rpms and light throttle no problem.
please o please be spark blow out. i hate chasing intermittant problems.
based on the last post i swaped out the accel coil i had in the vette for a blaster 2 i had in stock. and a blaster 2 is better than an accel. end of story.
i am however still having the same problem. just a bit less of it.
i now believe what me and LS5 are experiancing is "spark blow out".
when i had a turbo 4 cylinder running 18 psi of boost i had to gap down to like 0.028 or at high rpms the spark would not ignite the mixture because of the extreme stuff going on in the combustion chamber. it felt alot like a rev limiter because it would and wouldnt ignite randomly.
so im going to get new plugs and gap conservatively. i expect this to solve my problems. because like LS5 i can do high rpms and light throttle no problem.
please o please be spark blow out. i hate chasing intermittant problems.