I have a pretty strong sbc in a drag car. When I bought it a week ago it was extremely strong. I don't know a lot about the motor. I know it has a big cam since it idles around 1800 rpm. It has a set of 350/350 hp heads I believe. I am not sure on the compression ratio but I would guess about 11:1. When I got it it was supposed to be a high 7 second in the 1/8. When we ran it it ran strong in low but once it went to high it falls on its face and pops real bad. It ran a 10.16 so I was pissed. I put 93 octane gas in it and think it is either that or timing. If anyone else has any ideas I would appreciate them. Thanks in advance for any help
What is your "total advance / all in " in your ignition timing? Also, is there a fuel pressure gauge? What is it as you go through the traps? Try changing your fuel filter in case it is clogged to start. points or electronic ignition? valve adjustment coming loose? spark plug gap? wil www.sakowskimotors.com
It has an accell hei distributor in it. I will check the plugs tomorrow. I am not sure on the timing, I have never had a timing light. It is one of the things I know I need but never bought
Popping in the intake is usually too lean a mixture or exhaust lobe wear on the cam....Too much over-all timing as well.
I agree with most of the comments regarding the exhaust, i'd also check for an exhaust rocker backed off, broken/worn valve spring. You also have a problem when idling, 1800 rpm isn't an idle. That is your first clue, you probably have a huge vacuum leak and that extends to leanout when the engine is under a heavy load (high gear). Any good race engine breathes well and can idle very low, we have ferocious engines idle at nothing. Toss that accell hei and get a decent ignition, that stuff is so erratic that you can't even troubleshoot it - rule of thumb, whomever advertises the most does so for a good reason, they make junk and spend a fortune to tell everybody how good it is.
How long had the motor sat before you used it? Not unusual for the valve springs to lose alot of tension from sitting compressed. Hydraulic or solid cam? If Hydraulic whats your oil pressure when going through the traps and what rpm through the traps? Same carb from previous owner or did you install it? 1800rpm idle is pretty damn high. I have some ferocious motors that idle no more than a grand. Idle speed could be cranked to cover up a noise(sadly common) or a hellacious vacuum leak, trying to gain fuel by running on accelerator pump, and also the previous owner might not have had as much motor as he thought/claimed and thought this made it sound like a race car.
Buy a timing light and install a fuel pressure gauge that you can watch inside the car. Laying down in high gear is pretty common if fuel systems have any shortcuts. Also if it actually is 11:1 then 93 octane is not sufficient. That's a race gas engine. I really don't know why anyone builds 11:1 since 13:1 also requires race gas The timing light comment is a huge red flag, it's such a basic tool. To successfully run race engines you really gotta be willing to step up with tools and instrumentation or it's gonna cost tons of money in hard parts. Like now, you really gotta figure this out before it costs a piston or hammers the bearings out of shape, because leaning or pinging a high horse motor eats parts. It ain't like leaning or pinging an old farm truck. Good luck with the car
I agree, check the plugs, read them and look for lean as in vacuum leak somewhere, check fuel system, filter etc fuel pressure, get it to idle like its supposed to first. If its a flat cam lobe, it will pop when you bring the rpms up in nuetral, doesnt have to be under a load. it also might be worn springs from sitting and the valves are floating under load and high rpm. Most importantly, if its a race gas motor, it wont like 93 premium fuel, use the gas it needs.
The Jalopy Journal
