Well I got my 410sbc back in the car and running. Problem Im having is the engine will back fire once it gets a little heat in her. Fresh rings and open headers. What am I missing? Too lean? Timing is locked out at 36deg I believe. I didnt set it. My buddy did. Would mufflers help since there is no back pressure. Its got a 4150 carb on it also.

 

When does it backfire? Under load? When decelerating?

Could be too lean. Could have an exhaust leak around the manifold gaskets. Probably needs some back pressure. Exhaust valve adjustment might be a little tight.

 

It backfires while idleing no load.

 

Check the timing. Check the valve lash.

 

Ok thanks. It doesnt do it cold. Only once it gets warm.

 

Well im still fighting this issue. I have exhaust on the car now. Timing is set at 37deg. New plugs. Carb tuning checked. One thing though was the header temp. 7 of the header tubes all had the same temp except number 4. It was 40 degs hotter than the rest. We loosened the exhaust valve some. Temp came down a little. The cam is hydraulic not solid lifter. Is it possible the lifter is bad?

 

Also it breaks up under hard acceleration. Maybe it is to lean on the top end. The backfire is around idle though.

 

I don't know if it's an option but try a different distributor. What kind of distributor are you using. I know with crank trigger systems, if the gap is too great, you'll have the same kind of problem where the ignition breaks up under load. I was having a problem like that a couple of years ago and I needed a new crank pickup. Maybe the pickup in the distributor is on it's way out.

 

Its an MSD Pro Billet brand new. MSD 6al and a blaster HVC coil.

 

compression check? lash too tight?

 

What lifters are you using? Some are designed for a lot less preload than others. On my comp lifters, they call for 1/8 turn. I usually set them a little less than that. It sounds like you found the problem (lifter preload). I would go back through and do all of the valves.

 

The cam is a comp 305H Hydraulic cam and comp lifters. I forgot to mention. We removed this engine from my buddies car. It ran great in there. It sat for about a year before I got it. We disassembled it and put in new bearings and piston rings. The engine hardly had much run time before it sat for a year. Stuck it in my car and now this. The entire setup is exactly the same that ran great before. We will check the valves again.

 

I will check compression also.

 

well I got between 185 and 190 except number 4 was 175 on the compression test.

 

That could be from valve lash. It's not great but it's also not a dramatic difference. Squirt some oil in the cylinders and do it again.

 

Well after all that messing around it turned out to be a bad MSD box. We got it fixed and running good now. Thanks fellas.