Just installed my 250 in a 72 mav, and the timing seems to be off. It was hard to start and the vacume guage says "late valve timing" I know the timing marks lined up when it was installed. It is a new claysmith cam. Tha only way I can get it to run is to move the dist. counter clock wise till it hits the dip stick and it still needs more. Could the cam be off? Like I said i triple checked cam timing befor closing it up. Any suggestions? Thanks!
Late valve timing?
- Thread starter mleega1
- Start date
What is the timing at? If you cant get it where you want/need it you need to pull out the dizzy and drop it in a tooth or to the other way. You may have to move the oil pump drive shaft slightly to get it to drop in all the way. Or you could cheat and move all the plug wires over one and then rotate the whole dizzy back so the rotor is still pointing at the same wire it started at. This should buy you the room you need to clear the dipstick but may make some of the wires a bit short but it beats fighting with the oil pump.
Valve timing and ignition timing are pretty different issues, though. Carefully dialling the cam might tell what's going on there.
I'd suggest hopping all the spark leads around one position to remove any need for further distributor rotation. Move them in the opposite direction to where you were twisting the distributor.
Cheers, Adam.
I'd suggest hopping all the spark leads around one position to remove any need for further distributor rotation. Move them in the opposite direction to where you were twisting the distributor.
Cheers, Adam.
Most vacuum gauges are marked for stock engines. If you have an aftermarket cam, you may have lower-than-stock manifold vacuum at idle, so the gauge will read lower and into the "late timing" area.
I have the same issues with mine. Can't tell you how I'm on edge waiting for a key'd double roller timing set. I purchased degree wheel kit from Clay Smith w/ the video, dialed it in the cam, double checked to make sure I used an early '69 timing set, TDC is right and it's still 4 degrees retarded.
I pulled the head to do some work on it; it's now back together. I'll hook up the carbs and see if I'm still having the same problem that you're having. I used an older cylinder head and got it running fairly well just sitting in the driveway, but it was overheating real bad and never got it on the road. Radiator fans are now in place, new head installed, so I'll see if I can't get this road worthy hopefully this weekend.
I pulled the head to do some work on it; it's now back together. I'll hook up the carbs and see if I'm still having the same problem that you're having. I used an older cylinder head and got it running fairly well just sitting in the driveway, but it was overheating real bad and never got it on the road. Radiator fans are now in place, new head installed, so I'll see if I can't get this road worthy hopefully this weekend.
at least I know im not crazy! Had the same problems with over heating as well. i havent evev atempted to drive it like it is. I also had this same problem several years ago with a 200 and a clifford cam. Had to walk the plug wires around the cap to be able to get it to run, any one else have this retarted timing problem?
OK I walked the plug wires around and set the timing. The vacume guage reads late ingnition timing, The timing is set at about 8 deg. I drove it and it is very weak. It also stumbles on acceleration. I think the cam timing is off. Maybee the key way was improperly machined? Any thoughts?
Set the timing with the vac gauge and see if it pings. 8 should be safe but maybe your timing mark is off? Mine would run without pinging up to around 40* total, that made the base around 14. Is all your advance stuff working properly? Whats your total advance?
Yes the advance is working. all seems to be as it should, but the dist is what seems to be a tooth off although it was set in in proper orientation with the rotor pointed at #1 and the timing pointed at 8 deg. This should have been perfect. If the cam was retated them that would also throw off the dist settings right?? I think the cam was machined wrong. But we will see this week end when I tear it back down.
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