LOST 10mph AND ABOUT 6 TENTHS
 

So, I have gremlins in my car... the motor is fine on the dyno, the MSD and coil from the car are fine on the dyno... the trans is fine - the converter has been sent out and is fine... has anyone had any issues with a Racepak causing an issue like this?? It’s really the only change we made over the winter... car made a few good passes and then lost the time and speed... it’s quite a discouraging problem - if anyone has any ideas, please help!! Thanks!

Joey Cole - GT/DA - 454 BBC - Turbo 350

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Check fuel system, , the 30 second jug test is a good start, replace the battery/batteries....Have you done any welding close to the car ? .....Some racers have reported that their car became MAGNETIZED and they lost plenty of ET and MPH ......3 ideas to PONDER ......

Re: LOST 10mph AND ABOUT 6 TENTHS
 

In my experience I lost .3 and 3 mph and chased it to find out fuel pump. I had gauge mounted on windshield and always showed the 6 psi range. But it did not have volume. No symptoms of miss or stutter just a full range of loss of ET.

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Check compression and leakdown , for engine health .

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Did the fuel system test - all good - the welding is an interesting thought... batteries are pretty new - Racepak shows all good with fuel pressure... but something to think about with the volume - thanks everyone! Keep the ideas coming!!

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Just curious, how much did it pump in 30 seconds,.....carry on....

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Gallon in 18 seconds so volume is good

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Not to bash, but it was a Barry Grant pump. It was aerating the fuel. So the gauge was actually air/ liquid pressure. No O2 sensor at the time. Also at the time I was not to smart and threw about 1500.00 and 7al, wires, new tach, plugs. Checked valve springs twice. Cam timing, compression test. Three different outings at track. It was a real learning experience.

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Put the 3 speed back in it...LOL
Do you run foam in the fuel cell?
Pull the cap off the fuel cell vent, check the vent for obstructions.

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I do still have the foam in the cell - thanks for the reminder - someone else mentioned that...

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I don’t have an O2 sensor yet either... we did the new plugs and wires too! Brand new MSD too lol - what’s interesting is that we originally thought that it was the MSD box because when we changed the box and made a pass, it went back to what it should’ve been running - then, after that, it went back to being slow again... ugh

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What else do you know about the magnetized thing? Very interesting...

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I know a local racer that determined the spun bearings came from arcing on crank to bearing clearance and made pit mark's on journal. He had connected ground to block and welded on frame.

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MSD's pull ,and need, about 8 amps at WOT . They also get a lot of vibration in our cars.. Put a new high current kill switch in it. Their relatively cheap.

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Ck your grounds.

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Joey this may sound strange
Years ago Micheal Iacono built the yellow SS camaro car was brand new front to back .
Then it developed a gremlin changed everything msd fuel pump retire
Lee Zane was driving the car. Finally made few runs shutting accessories
Bad electric water pump.
Wouldn’t do it unless under a load Worth a look

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Funny u say that - the fuse blows on the water pump intermittently...

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Did that too... :(

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[QUOTE=Jeff Stout;629310]Not to bash, but it was a Barry Grant pump. It was aerating the fuel. So the gauge was actually air/ liquid pressure. No O2 sensor at the time. Also at the time I was not to smart and threw about 1500.00 and 7al, wires, new tach, plugs. Checked valve springs twice. Cam timing, compression test. Three different outings at track. It was a real learning experience.[/QUOTE
Jeff This car use to be fuel injected and it still has the high pressure pump in it with regulator to knock down the pressure. regulator is set at 7.5 lbs also we dyno'd the engine and it still has the same power from when it was built

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grounds. disconnect, add serated washers and no lock nuts. nylon in locknut can melt from cranking engine when wire gets hot.
fuel lines. any rubber can actually close down and limit flow when hot

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I agree, grounds are most likely weak.
Run a redundant ground wire from the side of the engine block back to the battery ground. Or, if your ignition box is inside, as most are, to the ground that is common with the ignition box and battery.
Use a good size wire and a star washer under the connector at the block.
Also, if you don't have a good size ground wire from the box to the battery negative post put one in.
Grounding to the chassis is always a crap shoot in a race car and the root cause for the majority of electrical problems.
Good Luck
Chuck Gallagher

I should have said this about engine block grounding. The most important task your battery does in your race car is provide a steady, high level of amps (current) to your ignition system. Racers in all forms of motor sports have been able to make more power over the decades by putting more fuel and oxygen inside the combustion chambers and completely igniting that mixture with higher power spark across the plug gap from the coil. The power (amps) of those sparks will never be greater than the resistance of the current path from the threads (ground side of the plugs) of the spark plug back to the negative post of the battery.
A weak engine to battery ground path does not always produce engine miss, usually just incomplete combustion resulting in less power.

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When I weld on my car I ALWAYS disconnect my MSD and all grounds to the engine block. Jerry Doughty from Louisiana was the racer that had to DE MAGNETIZE his stocker. Perhaps him or his brothers could jump in here on this thread. I remember it involved a compass and a cell phone ...his stocker had the same symptoms as your car....

Re: LOST 10mph AND ABOUT 6 TENTHS
 

[[/QUOTE
Jeff This car use to be fuel injected and it still has the high pressure pump in it with regulator to knock down the pressure. regulator is set at 7.5 lbs also we dyno'd the engine and it still has the same power from when it was built[/QUOTE]

If the engine ran good on the dyno , then what parts are different between the car and the dyno ? Usually the dyno has it's own ignition box and it's own fuel system . Maybe check these two systems out to start with .

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Does the car have a timing retard box. I hade one go bad. I had the box checked, MSD said it was good. Hooked up box and car was slow, removed box and the car was fixed.

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If the engine ran good on the dyno , then what parts are different between the car and the dyno ? Usually the dyno has it's own ignition box and it's own fuel system . Maybe check these two systems out to start with .[/QUOTE]

We took the coil and ignition box out of the car and ran it on the Dyno made good power

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Thanks so much! Think we will be taking this car apart almost completely to check it all out!!

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I don’t think anything was in the car when we welded but still a good thought - thank you! Nothing is a bad idea at this point!

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Is this a Quadrajet motor or Holley? If it’s a q-jet I would bet money it’s in the fuel system.
It’s critical to have enough fuel volume and a q-jet on a 454 SS motor would really stress your fuel system. A good pump like a Magnafuel, a #10 line from the cell to the regulator, appropriate return line, and a # 8 line from the regulator to the carb would ne required. Even if it’s a Holley I would do the same thing.

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Is the chassis still lose? Are all the wheels free, brakes bearings? What about the rear end? Could it be getting tight and slowing the car? Just something else to think about.

Lee.

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To slow down that much, and not have a miss, or a bog and not blow up quickly, has me thinking the timing is backing up on it. Somehow.....We had a bad transmission last year after the filter gasket became unseated and lost .13, but our MPH never budged, and your loosing both. That's a hundred horsepower your dropping. Do your headers look like they are getting hotter than normal? Like its baking the coatings ect?

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It might be time to check the Rubber brake lines or Stainless Steel hoses they might look good on the outside but swollen on the inside. I've had to change them on my pick-up truck so i know they go bad. Kenney Kelley

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Hey Jeff how you doing. I am one of the guys working on this car. The car sounds good in the pits and going down the track. Headers look fine so i don't think it's going lean. To be honest it's driving us crazy and thanks for the suggestion keep them coming BTW how's your brother and Amy doing

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have You done a leak down test ?

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The grounding subject has been brought up before.

Due to many possible issues, when wiring a race car, especially with EFI and electronics, you should avoid grounding to the chassis and/or engine. The best approach is a single grounding location for all the electrical and components, directly to the battery ground.

Since several ground points will creates a ground loop it is probably the reason why the car that was mentioned earlier magnetized.

You are asking the chassis and engine block to carry electrical loads and DC power requires to travel both ways, positive and negative. When you have a single point for all the grounds to the battery you are minimizing the chances to have a grounding issue.

When you have a ground loop, most electronics do not behave properly because the reference to ground is different and can make a sensor output measure incorrectly.

A friend of mine that builds chassis cars such as Top Sportsman and Comp Eliminator cars, had issues with some of the electronics on the new cars and he kept adding grounds. After he called me to ask about the issue, I suggested he used a single point ground. After doing so, all the issues went away.

Just remember, in the early days, we had carburetors and points distributors, and later on, electronic distributors. Nowadays, the cars are loaded with all kinds of ignition boxes, EFI and electronics, therefore, the electrical power demands have increased exponentially and just adding additional or higher voltage batteries does not solve the issue. Many chassis cannot ground properly because of corrosion, paint, rubber isolators, etc...

Although I do not support the product they sell, the link below has some great information and guidance about race car electrical systems.

"https://moretraction.com/2018/12/31/2416/"

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Yes Don we checked every thing including bearings valve springs. etc thanks

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Hi Bill ! Amy is driving John nuts with all the virus stuff. She's absolutely ate up with it and John...is John. It is what it its LOL . But all is well up here.
On this guys car, I had a car last summer (Rich South) that had me look at his Holley system. I found a severe grounding problem. Its a long story but it also had a mismatch of "type verses set up" in the programming of the crank trigger. His car went from a 7 under car to a more than a second under car. Like yours, it didn't miss, didn't run bad, just did not run like the dyno said it was going to. I'm betting your going to find something like I did. Keep lookin

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Thanks for getting back Jeff. This car has is not fuel injected. We did check the crank trigger and have changed every piece of the ignition 3 time. Tell you brother and Amy i said hi

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We took the coil and ignition box out of the car and ran it on the Dyno made good
power[/QUOTE]


So the only part that remained in the car and was not tested on the dyno was the fuel system . Not sure what type of pump or regulator you have , but the entire fuel system is in question including the fuel cell and any filters . Also check that the fuel cell has an open vent so the cell doesn't get a vacuum in it while the pump is running .

Re: LOST 10mph AND ABOUT 6 TENTHS
 

Had a similar situation as this when I first started in Super Stock in 2007 or 2008. Ended up being the fuel pump. We had a Barry Grant fuel pump and regulator on the car and switched over to the Magnafuel units and all the problems went away. Mine would pop/bang on the big end like an electrical miss when in reality it was lean because of the fuel system. I was running a QJ at the time also.

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Is the car down everywhere in the run or is the early part of the run still about the same?


Stan