Timing on a supercharged small block
 

I have a smallblock Chevrolet running a B&M 250 supercharger at 3 pounds of boost and twim 850 Holleys. My question is what should the timing be set at? I know that it has to be retarded, but to what extent. This motor is in my 20 Cig and it wont run past 3000 rpm's. Any help would be much appreciated as I am stuck on the dock so to speak. Thank You

3000 RPM ????????? are you runnin out of fuel pressure ( 6 or 7 lbs ) timing should be at 34 degrees .
good luck:drink:

Yeah 3000 rpms. A month ago it ran 76 mph at 4600 rpms, but that was before I replaced the cap/rotor and the coil. Im running a msd 6al. I think that the distributor was rotated as it would not wind up past 3000 rpms after I replaced everything (at least thats what I think happened). I have not checked the fuel pressure but I will check it as soon as I set the timing. Thanks alot for the reply, I wanna get out on it this weekend as its beautiful out.

might want to check those plug wire again on the cap and make sure # 1 on the Distr is on # 1 CYLINDER

Wouldn't that cause the motor to backfire/misfire? It runs great otherwise. I know only the basics about motors, as a friend of mine in Virginia built it for me, however Im eager to learn, and am a huge fan of oso and pouring over the forums.

The timing should be advanced, not retarded. with the engine running at 3000 rpm your timing should be set to 32-34 total advance.If it went bad after doing repairs, go back to what you did, the problem is more than likely there somewhere.

it wouldnt necessarily backfire. deffinatly double check everything and make sure the wires are pushed on all the way. also take a close look at the wires, sometimes the wire and terminal will slide inside the boat preventing a positive connection.

make sure you didn't cross #5 and #7. Happens all the time.

PS, twin 850's on that combo are WAY too much carb.
Your former max RPM is 4 to 600 low at least as well.

Twin 600's and 3 prop sizes down is what you need to think about.

Whatd you ever find? If I recall the previous owner had the same problem when he cooked the head

fixx
 

That was the first thing that came to my mind,go like hell then poof now what !

check fireing order,,18436572 clock wise rotation.1357 port side 2468 starboard side, if all is good do a compression test or a cylinder leak down test.. one will tell you for sure...if the distributor moved whyle moving then you may have some burnt valves..like mentioned 850's is way to big for a sbc,try and find a single carb upper manifold and use one of the carbs or switch them to 600's like mentioned..