Just built a new 393 and I am using a Melling high volume oil pump. As tight as I have the distributor hold down, it appears that the distributor is rotating very slowly and my timing is retarding. I can't go any tighter on the hold down, is there another way to keep the distributor from moving? Will this go away when the motor breaks in? Should I just switch to synthetic soon? I am using 10w30 oil. Maybe 5w20 would work better?
Wow ... I'd be more worried about how much stress you are putting on your cam and distributor gears and the oil pump rod ...
What kind of oil pressure is at idle on start up etc? Have you tried to prime the system with a drill motor? and does it pull it down or stop it completely. Something about the high volume pumps on those 393's that is not right, but can't remember what it is. I think mavman had to use a std pump for some reason. Just for info, did you use an O ring and base gasket on the dizzy? Loosen the clamp and using a feeler gage, check to see if the thing is flush with the block. Also the shaft play in the housing and any other parts that could be binding, check the gear for unusual wear and that the retaining pin is ok. Just a few thoughts on it.
I don't have an OP guage in pounds, I have the factory guage and the pressure is good, but not off the charts. I used the same o-ring that was on it from before I built the motor. Same block and dizzy from before the stroker kit to after, and I didn't have a problem with it before. Retaining pin is ok. It takes about 100 miles of driving at about 3000rpm to get it to move about 15 degrees, so it is just gradually creeping. It's weird.
Make sure the pin is not sheared and the friction of the broken pin is making gear feel tight on the shaft but is slowly rotating on it. Make a mark on both and observe them after the problem comes back.
Try a different rotor and cap, something is causing the housing to rotate. If the shaft is free it should not cause any binding unless the oil pump drive or the pump drive socket is out of alignment. Could always prick punch the collar on the bottom of the dizzy and see if that might hold it from rotating. Or put some small pieces of emory cloth under each side of the hold down clamp, doubled over so there is rough surface on the clamp and the dizzy. Sounds a bit old backyard way, don't it, about like the time I used a piece of leather belt for a rod bearing in model A to get it home. he he he. Sometimes it works, sometimes not.
Yeah thats pretty scary. I would check to see if the oil pump shaft is bottoming out in the dizzy. that would hold the dizzy up and if the hold down clamp was tight enough, I imagine it would cause enough bind to rotate the housing. Especially since the dizzy housing isnt pinched between the block and the hold down. When I built my last roller motor, I used an ARP oil pump shaft and ran into the "too long" problem. I took a little off the bottom of the dizzy and it would then seat in the block like it was supposed to. AC
Did you ever figure this problem out? I just discovered that mine has done the same thing, but I've got at least 1000 miles on the motor now, and it just started acting up bad last week. Last week I drove it to work and it was stumbling badly and backfiring through the carb if I gave it too much gas below 2000 rpm. Once it got past 2000 RPM it pulled good and ran normally. I finally put a timing light on it and the base timing had retarded all the way to 2* ATDC. No wonder it couldn't get out of it's own way!
Yep, I got one of those chrome hold downs from a Mustang house and it had little serrated teeth on it. Tightened down REALLY hard and it is not moving anymore. Of course, I only got about 200 miles on the motor before putting it into storage.
I'll bet if ya dont get the drag from the oil pump down...you'll spin the dist gear on the shaft..why High volume ?.standard pumps use less HP
