strange problem, losing et

[rustbucket]

hey guys, Ive got a weird problem going on. I run 2 different motors in my car with 2 different converters. Every pass I make with either motor, I lose approx. 7/100's. In the last 10 passes Ive gone from a 6.70 on motor to a 7.35.
My 60 ft suffers the most. Started with a 1.45 and now its a 1.7 something.
When I let go of the trans brake, the car feels like im pulling a sled behind it. At around 80 to 100 ft the car starts pulling like it should. I know, It sounds like a too tight of converter, but both motors with 'either or' converter has this problem.
I thought I had stumbled on to something with my batteries but after replacing both batteries, the problem is still there.
I've spoken with Sid Neal (tranny guy), he said its not the tranny, Spoke with kenny @ptc and he said if the converter will still
stall on the brake like it should, its not the converter. Any ideas? The only other change to the car in the past couple of years was a paint job. Im thinking I need to start sanding. thanks again, tony

[John_Heard]

What all have you already looked at?

[rustbucket]

I cleaned and checked fuel filter, checked fuel lines for kinks,battery voltage, fuel pressure, float levels, timing, plugs, brakes.
thanks again, tony

[sc racing]

Just losing et or mph also ?

[John_Heard]

So you're saying regardless which motor is in the car, your passes start slowing down after the first pass? They both start out faster then slow down correct? That is a weird one... I can see why you called Sid, I would be thinking transmission also.

Is it doing it on both Motor and Juice?

What's common between the two engines? Same carb/intake, ignition?

[rustbucket]

yes... sunday's last pass I ran a 7.30. Next time I go back it will probably a 7.20 on the first pass and by the 4th pass i'll probably be running around 7.40 or 50's. So on and so forth. Havent sprayed it with it messing up. Im gonna try a new coil and have the carb looked at. Any other ideas or places to look? thanks, tony

same ignition. 6al, crank trigger, locked dist., same plug wires
same carb. quick fuel 950, same fuel system (pump filter regulator)

[John_Heard]

Can you find a spare ignition box to take with you to test? Sometimes electronics stuff will act up with heat. Anyway of recording voltage during the pass - min max deal? If you can find a fluke voltmeter you could strap it in the car for testing.

[CoMax Racing]

This may sound like a stupid question but nobody has mentioed it yet. Could the weather be affecting your runs? If your first pass is in the morning with cool dry air, the last pass during the hot humid air. This probably isn't the problem but I thought I would throw it out there.

[want-a-be]

What coil are you running and how is it mounted? Have you checked the intake bolts on both engines lately? They can loosen up and cause havoc. Suck in an intake gasket and be hard to find sometimes.

Don

[wikd69]

What coil are you running and how is it mounted? Have you checked the intake bolts on both engines lately? They can loosen up and cause havoc. Suck in an intake gasket and be hard to find sometimes.

Don

Yeah, coil mounting caused me grief - I run a cheap MSD Blaster II coil and had it mounted laying on its side. This uncovered part of the coil windings, caused it to overheat and things would go away until it cooled down. I solved it by mounting it vertically, coil wire up.

[want-a-be]

What coil are you running and how is it mounted? Have you checked the intake bolts on both engines lately? They can loosen up and cause havoc. Suck in an intake gasket and be hard to find sometimes.

Don

Yeah, coil mounting caused me grief - I run a cheap MSD Blaster II coil and had it mounted laying on its side. This uncovered part of the coil windings, caused it to overheat and things would go away until it cooled down. I solved it by mounting it vertically, coil wire up.

wikd69,

You nailed where I was going with this. Seen this problem alot of times.

Where do you have your battery mounted? How are the posts mounted? (left and right or front to back?). What kind of battery is it,...dry cell or wet cell? How do you have your ground wire ran and where to?

Don

[want-a-be]

This may sound like a stupid question but nobody has mentioed it yet. Could the weather be affecting your runs? If your first pass is in the morning with cool dry air, the last pass during the hot humid air. This probably isn't the problem but I thought I would throw it out there.

If a weather change can influence ET that much then he will need to take a serious look at the Jetting in his carb. Actually I'd go as far as saying a combination of jetting and timing. Which would also be common to both engines more then likely.

But I like your way of thinking....

Don

[rustbucket]

my first runs were in the heat of the day and later when things started cooling off problem just getting worse. Even the 1st pass of the day the car was running 5/10ths off what it should. I have a blaster 2 coil mounted vertical. It is about 2 or 3 years old.
I havent tried a different msd box. I run 2 batterys in the rear, both new. Checked intake and around carb for air leaks.
Thanks again, tony

[sunsation540]

a customers car the coil wire was shorting out only on the launch the ign sensed the load and looked for somewhere to go. used a msd ign tester to spinn the ign up with the engine off made strange pops under the dash.. car would run 9.60 and slowed to 10.50s and would load up when on the brake.. we changed carb it got better the leaner we made the fuel, easyer to light.. took 3 races to find he finaly brought it to the shop and left it said i had to take it to the track he was tired of fn with it and was tired of looking like a fool,, these kind of problems are hard to find and when you do you will go i should have known... good luck..

[rustbucket]

wow! ok and thanks guys.I put the carb on the dyno yesterday to compair it another 950 qf.
They ran about the same. I also replaced the powervalve while I had it off.