FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
|||
|
|||
This isn't really a "racing question" but I think it applies.
I've got just under a thousand miles on my new 468 and I've had the car WOT a few times but never over about 4,500 RPM. This afternoon I took it out to one of our local highways and let'er rip. Above 4,500 RPM the car starts to miss, pop, and lose power. Don't want this happening when I *do* take it to the track. Until just a few miles ago the carb was way too rich but I've changed the jets. I've got a new set of plugs to install in case the old ones are fouled. While I'm at it I'll make sure none of the plug wires aren't touching anything--though they don't arc at low RPMs. What else should I look for? I'm running the following: - HEI with new cap, module, plug wires - Autolite 3924s with 0.045 gap - Holley 950 with 76s in front & 78s in back - 1/2" fuel line from tank to carb - Holley fuel press. reg set at 6 lbs - Holley electric fuel pump (sorry don't remember which one--not my install--just know it's LOUD)
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#2
|
|||
|
|||
This isn't really a "racing question" but I think it applies.
I've got just under a thousand miles on my new 468 and I've had the car WOT a few times but never over about 4,500 RPM. This afternoon I took it out to one of our local highways and let'er rip. Above 4,500 RPM the car starts to miss, pop, and lose power. Don't want this happening when I *do* take it to the track. Until just a few miles ago the carb was way too rich but I've changed the jets. I've got a new set of plugs to install in case the old ones are fouled. While I'm at it I'll make sure none of the plug wires aren't touching anything--though they don't arc at low RPMs. What else should I look for? I'm running the following: - HEI with new cap, module, plug wires - Autolite 3924s with 0.045 gap - Holley 950 with 76s in front & 78s in back - 1/2" fuel line from tank to carb - Holley fuel press. reg set at 6 lbs - Holley electric fuel pump (sorry don't remember which one--not my install--just know it's LOUD)
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#3
|
||||
|
||||
Kerry,
Check out my thread below on this very same subject. I have been trying to trace this same problem on my car and think I may have it solved. Hopefully my experiences will save you some time and aggravation. I don't know how to post a direct link - but look just a few topics down from yours in this forum. Tim High rpm misfire - help? |
#4
|
|||
|
|||
You're right. Lots of good suggestions there. I'll give some a try and see if they make a difference.
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#5
|
||||
|
||||
...try a Q-Jet and see if the problem goes away.
HIS
__________________
12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
#6
|
|||
|
|||
Hmmm... Don't have one laying around--only another Holley.
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#7
|
||||
|
||||
fuel delivery??? Are you running power valves? If you have good vacuum and too low of power valves you will lean out realy badly at wot once the vacuum rises. I recently did this, put in the proper power valve and it fixed the problem. Float level set correctly? Clean fuel filter?
__________________
72firebird 3800# 496 316cfm eheads, 11.1:1 compression, custom solid roller, victor 4500 intake port matched, 1050 dominator, continental converter flash 4400 stall. 3.73. 2 inch headers with 3.5 with x to mufflers reduced to 3 inch full exhaust. mallory 250 fuel pump, cal tracs with split monos ..Pump gas 91 octane. |
#8
|
|||
|
|||
It's possible it's fuel delivery. Not too long ago I got some crap stuck between the needle and seat, which made the carb puke fuel into the manifold--so much so it wouldn't run.
I'll check the fuel filters. Regarding the power valves, yes, the carb has them--30 cc versions (I'm assuming power valves are the same thing as accelerator pumps). The carb is a Holley 950 HP. I'm a carb know-nothing but mine has mechanical secondaries. Do the power valves still operate on vacuum. I'd assumed not.
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#9
|
||||
|
||||
Make sure you have 12 volts to the HEI distrib. If you use the coil wire (from the car's harness) from a points coil (on a pre 74 car - you have a 69 GP?) then you do not enough spark
Early Pontiacs with points run a resistance wire to the coil that knocks the votage down from 12 volts to approx 9 volts It does sound more fuel related though
__________________
~~~~~~~~~~~~~~~~~~~~~~~~~ www.spottsperformance.com East Coast Pontiac engine builder - still going strong 4 month waiting list email spotfam@verizon.net 1981 Trans Am 455 w/6X heads 4 speed 4 wheel disc (for sale) 1969 Trans Am clone 9.79 at 139 so far 1964 Banshee clone project - Opel GT platform |
#10
|
||||
|
||||
Great suggestion Paul, without that $6.00 replacement wire, the car acts just like fuel cut-out at higher RPM's.
MRDAN7 |
#11
|
|||
|
|||
The fellow who had the car before me did the HEI conversion, had the car for 20 years, has been a mechanic for more than 20 years, and the wire you've pictured looks just like the connection to the HEI unit.
Moreover, the original 428, which had the same HEI unit ont it, revved like a trooper as far as you'd push it.
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#12
|
||||
|
||||
Anyone have any idea what was the reason for the resistance wire? Why did they not want 12V going to the coil in the older model ignitions?
|
#13
|
||||
|
||||
Guys, My 65 was misfiring last year too and I may still have the original resistance wire in my 65. I'll have to look but how far back does this wire travel? To the ignition switch?
Phil
__________________
_________________________ _________________________________ http://www.youtube.com/watch?v=_qZgOpn-w-o <<< Burnout Video ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Treat Me Good, I'll Treat You Better; Treat Me Bad, I'll Treat You Worse" Sonny Barger ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
#14
|
||||
|
||||
6567GTO-Phil, The Resistance Replacement wire, starts at the HEI, & goes all the way into the fuse-block at the firewall.
Remove the fuse block at the firewall under the hood, and make certain you have the correct wire before removing. I would suggest getting the wire from PY, as theirs has the correct connector that plugs right into the Fuse-Block. The one I posted is from Summit, notice it does-NOT** have the correct metal pinch type connector for the fuse Block end, also it is not long enough and you do not want to splice THIS WIRE AT ALL. I can post a pic of an old one if you need it. MRDAN7 |
#15
|
||||
|
||||
MO-CRAPP-OUT... Here is an actual pic of the resistance wire I removed from my 70. Notice the Metal-connector present, this plugs into the firewall Fuse-Block, under the hood-side. You new wire should have this connector on one end, as well as the HEI Plastic coupler that fits into your Newer-HEI-Distributor.For my application the new wire needed to be 3 feet long, PY sells these I believe. BIG-TIME-DIFFERENCE. I have seen 30 year mechanics miss this trick! Then replace entire fuel systems, and upgrade to Ignition systems that were beyond what they could actually use!!
|
#16
|
||||
|
||||
The resistor wire was used to drop the voltage while running so you would not burn your points. On start up, I believe you bypassed this resistor wire and put full 12V on your system. This would help give you more spark for starting. ... Eric.
__________________
Runner Up Q16 Norwalk 2013! |
#17
|
|||
|
|||
Well, I'll have a look at that too. Don't want to miss something because I *think* someone else has taken care of it.
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#18
|
||||
|
||||
Thanks MrDan7! I'll check mine out. I did replace my original under hood wiring harness a few years ago with one that I purchased from PY.
Kerry, didn't mean to hijack your thread. Phil
__________________
_________________________ _________________________________ http://www.youtube.com/watch?v=_qZgOpn-w-o <<< Burnout Video ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "Treat Me Good, I'll Treat You Better; Treat Me Bad, I'll Treat You Worse" Sonny Barger ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
#19
|
|||
|
|||
No problem Phil.
Between this thread and the earlier one, there's got to be a solution.
__________________
69GPModJ Moderation in everything--including moderation. WC Fields. |
#20
|
||||
|
||||
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by MRDAN7:
MO-CRAPP-OUT... Here is an actual pic of the resistance wire I removed from my 70. <HR></BLOCKQUOTE> News flash. That isn't your resistance wire. The resistance wire on a '70 is under the dash. It it black with pink print. It runs from the ignition switch the the bulkhead connector in the passenger compartment.
__________________
Less said,,,,,,,, Less mended. |
Reply |
|
|