motor question

[hipower17]

just got my motor back put timing light on mark is jumping around so much can't get a true timing i have a 2 piece cloyes timing cover on it and a msd dist 8551 never had this problem before any ideals what i might be doing wrong? thanks

[billetbirdcage]

just got my motor back put timing light on mark is jumping around so much can't get a true timing i have a 2 piece cloyes timing cover on it and a msd dist 8551 never had this problem before any ideals what i might be doing wrong? thanks

Assume it's a roller cam, do you have a positive stop on the timing cover to keep it from flexing and letting the cam move forward/back some? Like a stop on water pump that adjusts to the cover or a billet stiff timing cover (that may be what the 2 piece cover is - stiff).

Also check end play on dizzy and polarity on MSD box

Few things off top of my head, besides another timing light (even a cheap non adjustable one to check it still moves a bunch)

I also assume someone set the end play on camshaft

[doyle hargraves]

Might check inside distributor. Make sure no problems with advance mechanism unless you have it locked out. Possibly slip collar not set right causing excess distributor gear lash?

[fastford]

what type of timing light are you using? i had a dial type do this exact same thing you describe , went back to a old school strobe light and never had another problem......

[Kromulous]

Polarity on the MSD box would be my bet.

[CCHIEF]

You want the light inductive pickup near the plug...not at the cap.

[hipower17]

it is near the plug. i use the old stroblight type, explain the polarity answer please.
the dist is locked out. i thank you all for your suggestions

[Jking24]

If your using a pickup in the distributor and not a crank trigger the pickup wires should be purple and black to green, and orange and black to purple. If it's backwards the box acts very erratic and inconsistent

[96racing]

I've had issues with the heavy racing plug wires before. I always swap out #1 plug wire with an old stock one I have laying around.