Engine Missing/Popping Under Load

Okay so here's the background... a buddy of mine let his car sit without backing the valves off over the winter two years ago. He tried racing a couple times in 2009 but as soon as he would take off under green the engine would pop and wouldnt run worth a squat. So after going to the track like 3 times and never running a feature he gave up for the year. Well last year he wanted to race so he had his carburetor rebuilt, changed the plug wires, distributor, plugs, battery, changed battery cables, swapped carbs, and probably more that I cant think of right now but the engine still ran like crap on the race track. It would run like a champ in the garage and rev with no issue but once on the track it went to hell. My question is could it be the valve springs are to whipped once the load is put on the engine? Or maybe something else? Any suggestions would be appreciated. I hate to see him get discouraged or waste anymore money going to the track to not make it through a heat race.

This is one of the worst problems ever to have to any engine as it is not easily replacated. First things first, replace fuel filter and make sure that the pickup tube in the cell is not partially plugged, etc. Next I would run a new battery wire to your ignition switch, check all grounds and connections, and if running a MSD I would run a ground straight from the battery to the MSD ground wire(large black). If this still does not fix the problem I would get a new battery. This sounds like an ignition problem and 9/10 times I have resolved the same problem with one of those few things.

Next I would look at fuel delivery more and carburetion. It is very important to run a fuel pressure gauge and BE ABLE TO READ IT WHILE RACING. This will tell you alot.

If this does still not fix it I would start looking into engine mechanical starting with vacumm leaks and moving my way to the bottom end. I dont believe that this is where you will find anything

Our car did this same thing .........took a grinder to the chassis where the motor mount sit on it ........ground off the thick powdercoat and set motor back on it .........fixed it . My buddy said his car did the same thing and it was because the powdercoat was so thick and not letting the motor ground good . Good Luck

What MSD Box & coil is he running? Reason I ask. if the coil is a Blaster2. Then the next question I have is the coil laying on its side? The tower needs to be facing towards the sky. They will cause popping and barking if the coils are laying on their sides. Has the MSD box been welded around? if so this will cause the MSD box main amplifer transistors to lay down. This also can cause the popping issue. A battery that is getting down to 11.5 to 10 volts the MSD box will loose its mind..... I hope this helps your Buddy out.

Pat Collins

TechWest Racing Services
techwest@techwestracing.com
www.techwestracing.com

we had same problem a few years ago spent alot of money and found out it was the ignition switch

Thanks guys. Hes running an HEI but I'll try all the other ideas.

He needs to replace his ignition. Mine did the exact same thing last year would run fine until a load was put on it.

We had the same problem last year running HEI. Long story short it was the coil. We put a new coil in it and it fixed the problem