I got back from garage and I am not sure what to do.
I am trying to get my car ready for racing and keep having problems.
Last year I installed ZF6 into my 88 and I was hoping that all the problems (many) with carburetor and auto transmission would be gone. ZF6 will be fun, but first I need to ask for help on setting my carburetor/distributor.
Or at least that's what I think the problem is. All the parts are new and in good condition.
MSD distributor with 6AL box and fire coil.
I set the initial timing to 14 deg. and it tops at 33deg. (mechanical advanced, with light springs)
Carburetor is Holley DP 750 with out choke.
Ever since I converted to carburetor, my car did not run right.
After setting the timing and play with the idle RPM speed I drove it to see how the timing affected the car. I did not put filter on my carburetor and I have hood scoop so from the driver seat I can see the carburetor.
When I drove it about 15 mph, I put it in 4th and give it a little gas to see if it's going to pull or ping. What I did see was nice flame from carburetor, not even a bam from backfire, just nice torch like flame. I immediately back out of it and it went away (no damage done).
Is it possible that the timing is 180 deg off ??
What could cause this?
I had some problems with backfiring before and the power is not there. I should have my 460 HP (according to my dyno sheet, but I might be getting 150) but it’s a dog.
I already set the car on fire once and don't want to do it again, please help me solve this one.
TIA
Ziggy

 

First, put an air cleaner on it. Fiberglass burns. If the timing were 180* off, the engine wouldn't even pop, when you cranked it. If you allow the rpms to build and then nail it, what happens? At first, from your description of a back fire from ultra low rpms, had me thinking a lean transition mixture problem, but the comment, "I should have my 460 HP (according to my dyno sheet, but I might be getting 150) but it’s a dog." makes me think you have bigger problems. What have you changed since the dyno run?

RACE ON!!!

 

You could be one plug off, go through all the plug wires and make sure they are where they belong. I had a similar problem with a 91 pickup. Check the little things first.

 

If I allow the RPM to build up (above 3k), than it's still a dog. Although it pulls hard (not like it should) but it does not sound like it should. It has that humming like sound to it.
When I had it dynoed 2 years ago, it was on the engine dyno when it received new AFR heads and new bearings with new hydraulic cam XR288HR-10. Than it went to the car and all the problems started. I was trying to keep the distributor in, but I had to pull it out because I did not want to break it. I try to run with stock (high pressure) pump with special regulator, but eventually changed it to Holley black pump with their carburetor minded regulator (now I am running 7psi gas to that carb). BTW that's how it cut on fire, when alignment shop flooded the engine and during attempt to clear all the gas out, got a spark from the disconnected coil. Empty 2 large bottles and fried some wires. I changed it all since. I had it on the drag track at some point and it run best of 13.1 with 2 sec 60' times and trap speeds of 114. On one run I got bad start but than in the middle of the run I felt like the engine come to life and just pulled like SOB. I end up with 119mph at 13.3 sec.
I never felt that engine come to life again, but I know it's there.

I will go to the garage now and check all the spark plug wires; I should pull some spark plugs too. Although it fells fine when idle but when revving, I can feel it sluggish when in low rpm too and. When in high rpm it feels fine but getting there from low rpm somewhere in the middle there is hesitation for half second or so.
Please keep it coming, I am getting married in July and my bachelor party will be at the track.
No car, no party.

 

Just came back from the garage.
I checked all the spark plugs - non of them were bad, actually I was surprised because the car runs rich, and the plugs were somewhat clean (couple of them were little dark but not too bad). My spark plugs are FR3LS with 0.047 gap.

Wires are acually less than 100 miles old and look like brand new (8.5 MSD super conductor). All of them go were they should too.

Would one thouth off on distributor make that much of a diffrence?

Any ideas!

 

If you were one tooth off on the distributor it would show up when you check the timing. Is the timing stable at low RPM, does it become erratic at higher RPM?

Have you tried another carb? Also, a vacuum leak will cause some of your simptoms. Have you tried disconnecting all the vacuum lines and plugging them?

Also, try running 6lbs. As far as the Holley Black pump goes, if your running a dead-head type regulator it may be overpowering it. I ran a black pump with Holley's smaller regulator and it would usually run fine, but sometimes it would overpower the regulator and it would flood out.

How are your float levels, and is the fuel pressure constant?

 

[I] Timing is stable, but there is that 2 or 3 deg veriation (jumping back and forward).
I am going to try to set it up from scratch. Get the plug 1 out, stick long screwdriver in and rotate slowly untile I get it to the top, and make sure that timing marks are match and the rotor is pointing cylinder 1. If it's good, than I will be dropping my car at some shop and paying some $ for the work, research and findings [/I].






I had many problems with the fuel pressure, and what I did noticed is that when I start my pump and I watch the gauge, it goes to like 11 psi and then goes down to 9 psi and than it settle at 7 psi. All this within 3 seconds and than is fine.
I don't know what you call dead-head type regulator, but if it's w/out the return line than, yes !.
I did try another carburetor and same results.
My carburetors have the side glass to set up the float levels and I can see the fuel on the bottom of the glass if I shake the car.
I don't think I have vacum leak because only thing I have hooked up to the carburetor or intake is the brake buster. On idle I have about 12 psi of vacum. If I plug the brake buster line I see no changes.
My friend at work says that I have flatten cam, but I think it's highly unlikely.

 

It would make NO difference. It can be 1 tooth off, 3 teeth off, or 180* out of rotation. If the wires are in the proper tower of the cap for the rotor position, it doesn't matter. Your timing readings of 14* initial and 33* total are proof that the distributor doesn't have to be moved.


That isn't a bad idea, just to verify that the ring on the damper hasn't spun, but assuming the marks are properly aligned, timing isn't the problem. As suggested by others, look for vacuum leaks and carb calibrations.

RACE ON!!!

 

I checked the timing today and it all lined up like it should.
My next thing will be to remove my 1" spacer and inspect for any vacum leaks. The other day, I checked the vacum at idle and it was around 12 psi.
I was thinking that I might have trouble with my coil, the way is wired. Since I have MSD box 6AL I wired coil directly to it. There are 2 wires black and orange out of the box, and that's what I put on the + and - on coil.

How can I wire the coil w/out the box??? I would like to confirm that I am not getting some odd spark. Do I need to get power from the positive block and ground??
TIA

 

I can't help you with the 6AL. I've never installed one. Go by the instructions.

To me, it still sounds like a fuel problem. The intake to head gasket is another point of a possible vacuum leak.

RACE ON!!!

 

Today I had some help from my best friend and it looks like my car might just work.
After short discussion we went to work.
We set the fuel pressure to 5 psi, initial timing to 19 and total timing to 36 with 90% coming in at 2800 rpm (the other 2~3 deg came at 3000 rpm). I need to order some more springs so I can make it come in all at 2500 ~ 2700.
Also reset the idle screws and found that the 2 - 1/8" holes that I drilled in the carburetors blades makes the car idle at 1100 rpm with the idle stopper screw all the way out. I will be putting pop-rivet thru those holes and adjust idle with the idle stopper screw.
Took the car for short drive around the block and it felt strong. It still needs some small adjustments, but no more popping and backfiring.
Yea, we did put the filter back on.
Thanks to all of you for the help.

Ziggy
Thanks Mark

 

You want to be sure that when the idle speed is set where you want, that the transition slots in the throttle bores are visible below the throttle plates, the more, the better. I don't think 1/8th" holes would have THAT much of an effect on the idle speed. Have you looked at or set the secondary throttle plate idle speed opening?

RACE ON!!!

 

The secindary are all the way closed.
While the car was running I took long 1/8"piece of wire and put it inside of one of the holes and the rpm dropped about 150 rpm. If I plug them both, I should be able to regain control of my idle with the stopper screw. With the initial timing at 19 deg. motor wants to idle higher. When I was trying to sort things out 2 years ago, I drilled those holes thinking it will help me. WRONG.
I forgot to add that when we finished with the car the vaccum at 900rpm was only 7 ~ 8 ". The other day I measured and it was 12, but the car must of idle higher than I thought.
Ziggy

 

If you have an older Holley, you may have a blown power valve diaphragm if you back-fired the engine.

 

I may have missed it, but are you running an HEI? If so, it requires a 12 volt source. Without it, you will get backfiring/popping every time you stab the throttle no matter where the timing is. Good luck

 

If you'll open up those secondaries, you will be able to close up the primaries, with or without the 1/8" holes. That will expose the transition slots below the throttle plates, which goes back to helping solve the original complaint in the opening post.

RACE ON!!!

 

My carburetor is only 3 years old and has the protection for the power valve.
I put pop rivets in place of those 2 1/8" holes.
Before I was not able to open primery or the secondary plates because as is the car was idleing at 950 ~1050. Since I plug the holes I adjusted the idle with primery and secondary plates.
I can now idle at 600 if I want it.
The car is vry responsive and I need to take it on the road and bring it up to the speed in order to do final tune.
I am in process of getting plates for the car and insurance.
I will let you guys know when I drive it. Going around the block (Chicago) does not give me enough feed back.
Thanks,
Ziggy

 

Hey Ziggy -- if you're really brave, we can trailer it up to Union Grove and make a few runs while you're waiting for the plates. The only problem there is when a car catches on fire, they just let it burn

 

I was tempted to take my PT's plates on Saturday and drive over to your Dad's and do some testing.
After some clouds and couple drops of rain, I changed my mind.
On Monday I should know if State Farm will change the car status to show car. Anyone did this in order to avoid pollution test?
Ziggy