Inliners International Forums General Discussion Engines 250 timing

I read a good a post about timing from someone here I think. I can't find it now, any help. I think I have a little too much. Its slightly modified 250. Clifford intake, headers, 264 cam, Holley 390 cfm, HEI distributor from Tom Langdon. Nothing radical.

Just checked mine. 5 degress BTDC. With vacuum connected all in at 35 BTDC.

If the idle quality and low speed response are good, leave the initial where it is. If not, advancing to 10° may feel better but the extra 5° must be deducted from the mechanical advance curve.
35° with vacuum is less than your best mileage setting depending on how much is from the vacuum can. Vacuum advance alone can be between 10 and 20°.

ADVANCE IT TOO MUCH AND IT WILL SPARK NOCK BECAUSE OF THE LOUSEY GAS NOW. ALSO CHECK YOUR DAMPNER AND MAKE SURE THE RUBBER ISNT BAD BEFOR YOU FULL WITH THE TIMMING IMO
BOB

I've continued on tuning isues. At 3000rpm she wants to act up a little. Put the hammer down a she does a little better. Vacuum readings at idle are at most 14 inches of Hg while setting the idle jets. 390 cfm holley carb on a heated manifold. 195 degree thermostat. Float levels are good. At the moment I'm running straight exhaust with about a 2 foot pipe, dual cast iron headers. Its so loud that I'm not sure I can really hear the valve lash when I try to set them. Hydraulic. Maybe I need some mufflers for back pressure before I get too far into diagnosis. The head was milled 60 thousanths, block zero decked, pistons, rods and crank all balanced. I think the original intake valves were 174's , I went to 194's kept the 150 exhaust valves. Valve throats were opened up on the intakes, unshrouded I guess. Still using the dished pistons.

Gimme any knowledge I'm missing. I'm not a carb man. Its a 1970 C-10 long stepper. Cranks, idles and revs great.

Thanks Gentleman.

Got another big problem now. The engine ran well, I put the hammer down and she ran like H***, then died. It will fire but won't run . Pops back through the carb and will catch on fire. I'm at a loss right now.
Herb

Pulled the front of the engine off. Cam has walked back into the block about a quarter inch. I think I'll drill and tap it and bolt it into place.

what happened to the timing gear-did the cam move 1/4" deeper in the timing gear and block or is the shaft flush with the gear and the cam/gear both moved 1/4" closer to the block. At the back end of the block is a "freeze plug" looking device that is supposed to keep the cam from moving deeper(rearward) I hope it has'nt "popped out!

If cam is 1/4" rearward, then the distributor gear may not even be engaged with the cam (this means no oil pump being driven either). Good reason for not starting.

Double check the distributor gear, if the cam has been walking that much it is likely starting to wear badly.

Drilled and tapped the cam. They should be made that way anyway. Everything looks good so far. Engine runs good. Scared to put hammmer though. Yet.

I had a '69 truck with a 6 banger, hopped up a little, the cam walked back far enough that the fuel pump lobe was running a lifter.

preacher, the cam movement was the timing issue. i got the distributor from Tom Langdon. Said he would send me a new one if that was the problem. Good fellow to talk to. I'll call him today and tell the results.

The hardest thing about the fix was the timing cover to the oil pan gasket. Not easy to do with the oil pan in place. But I did it with no leaks so far.