307 Loves timing

[Madctafter52]

I have a Chevy 307 that will not run properly unless i give it tons of timing. If i set it to around 8 degrees btdc it will backfire out of the carb under acceleration but if i crank up the timing to lets say ~22 degrees (I don't have a dial back timing light so that's just a guess) it stops popping and runs fine. I have verified my TDC with a piston stop tool and my marks are correct.

The distributor on it right now is the one that came with the truck and its some no name HEI that looks like it has seen better days. So I'm wondering if that's the source of the issue?

Thanks for any help!

[VileZambonie]

A piston stop doesn't mean you've found TDC, it's for setting your degree wheel. If you want to find TDC, use a coat hanger and rotate the crank by hand until it's all the way up or buy a bore scope you can use with your cell phone and watch the piston reach TDC. Then compare zero on your balancer to your pointer.

[Geezer77GMC]

Timing marks on a damper don't allways match a timing tab. Set your timing where your engine & vehicle/ fuel combination runs & starts best. Keep the timing less than pre-ignition or detonation, (commonly called "valve rattle sound") and you should achieve decent performance and mileage from your combination. If your timing marks have been verified against the internal part rotations they are an excelent reference to begin fine tuning your specific set-up. My 16 degree BTDC current setup may or may not work on another vehicle.

[Madctafter52]

A piston stop doesn't mean you've found TDC, it's for setting your degree wheel. If you want to find TDC, use a coat hanger and rotate the crank by hand until it's all the way up or buy a bore scope you can use with your cell phone and watch the piston reach TDC. Then compare zero on your balancer to your pointer.

I rotated the engine clockwise till it hit the stop and marked the balancer, then I rotated the engine counterclockwise until it hit the stop and marked the balancer, then I split the difference between the two marks and it was right on my balancer mark. that's how I was taught to find TDC. But if that doesn't work properly I will try using the coat hanger method.

[Madctafter52]

Timing marks on a damper don't allways match a timing tab. Set your timing where your engine & vehicle/ fuel combination runs & starts best. Keep the timing less than pre-ignition or detonation, (commonly called "valve rattle sound") and you should achieve decent performance and mileage from your combination. If your timing marks have been verified against the internal part rotations they are an excelent reference to begin fine tuning your specific set-up. My 16 degree BTDC current setup may or may not work on another vehicle.

One thing I have been wondering is how obvious is spark knock? The exhaust is currently cut right below the cab so its pretty loud, would I still be able to hear the pre-detonation? (Hopefully I can get this fixed so I have the motivation to put a proper exhaust on it )

[Madctafter52]

Here is a picture of my distributor cap. I'm guessing a new distributor is in order since I have no idea where the current one is from or where to get parts for it. Could this be causing or at least contributing to my issue?

[ehjorten]

Is this a stock cam? Are you running premium fuel?

[Madctafter52]

Is this a stock cam? Are you running premium fuel?

I dont know the absolute history on the truck but im 99% sure its a stock cam. I run regular gas.

[VileZambonie]

Run high quality ignition components. Get OE or better. When you buy a new cap and rotors, it will come with a new carbon button.

[Madctafter52]

Run high quality ignition components. Get OE or better. When you buy a new cap and rotors, it will come with a new carbon button.

Yeah, I have been looking at DUI distributors since an MSD costs a lot more then I want to spend on this truck at the moment. Anyone have any experience with DUI distributors?