Thread: For Don Shilady

Tweet

Correct me if I'm wrong fella's, but I don't think a 1st gen sbc has a cam button and if so where is it located?

Correct Ken and Rodger the first gen SB didn't use a cam button and my comment above won't apply to Dons motor (sorry Don). I thought Don might be running one of the later generation engines (it was probably a second Gen my friend was working on based on how long ago we talked about it).

I also thought about the possibility that the roll pin holding the distributor gear to the shaft might have sheared but the gear still being tight enough on the shaft to only gradually creep back causing the timing to gradually change (I've run into that a couple of times). The only problem with that is the timing change that occurs is for it to retard the timing not advance it.

So basically guys, I got nothin but will be interested in seeing what Don does find.



.

Then it's very possible that Don has one the chinesium msd dizzy's and good possibility the same is true for the bad flexplates.

Baring something wrong inside the distributor (as posted earlier), there is only one other thing I can think of that may be causing your distributor to creep; occasionally the distributor's shaft bottoms out in the oil pump not allowing the distributor's base to fully seat requiring shims to slightly raise the distributor.

NTFDAY I need to chat with a builder of Gen1 SBC. Maybe they did not have a cam button but maybe that is why the later 350s did have one. Maybe there is a retrofit? The engine came from a 1976 Corvette as proved by the engine number.

Don Shillady
Retired Scientist/teen rodder

36Sedan, Thanks for that suggestion. It is a lot easier to shim the distributor than to pull off the electric water pump. I will check this first.

Don Shillady
RetiredScientist/teen rodder

Originally Posted by Don Shillady

NTFDAY I need to chat with a builder of Gen1 SBC. Maybe they did not have a cam button but maybe that is why the later 350s did have one. Maybe there is a retrofit? The engine came from a 1976 Corvette as proved by the engine number.

Don Shillady
Retired Scientist/teen rodder

Don, your engine and mine are twins, so to speak, and neither require cam buttons. If you pull the distributor check both side to side and up and down movement. Too much up and down movement can be lessened by installing a shim or two. If you find, IMHO, over 1/8" side to side movement I'd be looking at a new distributor.
Hopefully Jerry Clayton or anyone else with considerable time building engines will chime in and offer other suggestions as I'm not an engine builder per se.
I believe that in the past you've been given some bad advice which has negatively effected your wallet.

Originally Posted by NTFDAY

Too much up and down movement can be lessened by installing a shim or two.

I'm sorry, I'm talking about a base shim, not internal. Base shims raise the distributor at it's base to add clearance at the oil pump.
https://www.speedwaymotors.com/Moros...yABEgKf1_D_BwE

Originally Posted by 36 sedan

I'm sorry, I'm talking about a base shim, not internal. Base shims raise the distributor at it's base to add clearance at the oil pump.
https://www.speedwaymotors.com/Moros...yABEgKf1_D_BwE

I know what you're talking about, not the same as what I was referring to. What I was referring to requires pulling the gear off, driving out the roll pin, and installing a shim or two. That will lessen the amount of movement of the rotor in reference to the cap.

Please don't miss understand, I'm not trying to challenge or argue with any one, simply trying to clarify so as to not confuse OP.
IMHO, while to much play in the distributor may cause irratic time (jumping up & down), only a few things can cause the timing to creep (advance). One would be something inside sticking and not returning completely as I mentioned earlier (advance plate sticking), or possibly something external influencing the distributor base. And why I mentioned base shims, if the distributors shaft does not engage the oil pump correctly (slightly too long, it happens, why they make shims), as the motor heats up it could move the distributor slightly. Of course eventually if not corrected it will damage the gears. Just saying it's worth a check.

Originally Posted by 36 sedan

Please don't miss understand, I'm not trying to challenge or argue with any one, simply trying to clarify so as to not confuse OP.
IMHO, while to much play in the distributor may cause irratic time (jumping up & down), only a few things can cause the timing to creep (advance). One would be something inside sticking and not returning completely as I mentioned earlier (advance plate sticking), or possibly something external influencing the distributor base. And why I mentioned base shims, if the distributors shaft does not engage the oil pump correctly (slightly too long, it happens, why they make shims), as the motor heats up it could move the distributor slightly. Of course eventually if not corrected it will damage the gears. Just saying it's worth a check.

I totally agree with you .
I believe these are the shims I'm talking about
https://www.ebay.com/itm/Moroso-2614...5Zz633&vxp=mtr
and these are the the shims you are talking about
https://www.ebay.com/itm/Moroso-2615...!US!-1&vxp=mtr

Hello All,

My main computer really freaked out but I am back on the Internet with an old spare laptop using Windows7. Meanwhile I went a short distance up the street to see Chester Houghtaling at Progressive Auto (engine builder with his own dyno) and he confirmed the Gen 1 did not have a cam button and flat tappet cams have tapered faces to rotate the lifters and this only retards timing if the cam walks a bit. Roller cams need a cam button because the faces are flat on a roller cam. Overall the car starts easily now but for how long? Soooo I also tracked down the Big End to China and even though the electronics of alternate Pertronix dizzies are made in the USA the mechanical part of those is also made in China. Now I think the advance mechanism sticks on a high angle while running but when I start the engine the advance is way too high. Maybe a slightly stronger spring might pull the advance back to 10 degrees but I have not been able to find the right set of springs for this distributor. I guess I am looking for a Pertronix D100700? but that will take a week or two. Maybe I could "debur" the distributor I have now?

Don Shillady
Retired Scientist/teen rodder

Don. Why not do a "test"? Back out some number of degrees initial timing.. 4,5,6? Whatever.
Then do a few test starts / running cycles. See if it has ANY impact. You may be chasing a unrelated gremlin.

If you own a timing light and the appropriate wrench, it won't cost you a dime!

You could run something like this
https://www.ebay.com/itm/SBC-Small-C...RZh1HE&vxp=mtr

If it were mine I'd probably find a good used early points dizzy and put a Petronix module in matched with one of their coils.

34-40 and others,

I have other things going on but my first option is to gently add a drop or two of Marvel Mystery oil on the edge of the centrifigul weights. I went through TWO sets of Pertronix kits in a 327 distributor and I would like an inexpensive fix of what I have. As NFTDAY implied I have pretty well used up my budget for a "spring tune up" until I start my summer job in June so I will try a few drops of Marvel's oil in some strategic places to reach the undersides of the weights. My main computer is now working again.

Don Shillady
Retired Scientist/teen rodder