Harmonic Balancer applications
My 1969 L46 has a CE replacement motor in it from 1971. This was a warranty replacement block. During disassembly, the timing chain cover was damaged beyond repair, so I purchased a replacement from ZIP (http://www.zip-corvette.com/catalog/...g-chain-cover/
-
-
Re: Harmonic Balancer applications
Peter------
Based on your description, I would say that your balancer is correct. The timing mark on 1969+ small block balancers is offset by about 9 degrees from the keyway and that's just about what you have found.
However, the timing tab location on 1955-68 timing covers is different than that for 1969+. So, the ZIP catalog listing showing this timing cover as applicable to 1966-69 327 and 350 cannot be correct. The cover could only be correct for 1966-68 OR 1969+, NOT BOTH. I expect the cover is for the pre-1969 applications and you've used it for a 1969. So, I fully expect that's your problem.In Appreciation of John Hinckley -
Re: Harmonic Balancer applications
Joe that is what I feared. I should have done a dry run with the timing cover and the balancer at TDC, which would have saved me the anst I'm feeling pulling the pan off and starting from scratch. But, I also feel that this is an egregious error to list this as a '69 350 SHP timing cover. It also appears that Paragon lists the exact same timing cover with the same years and motors: https://www.paragoncorvette.com/p-35...ing-cover.aspx
Do you have any qualms reusing the 1-piece fel-pro oil pan gasket?
Do you or anyone else have a recommendation on a correct timing cover for the '69 SBC?Comment
-
Re: Harmonic Balancer applications
If originality is not a concern you could stick with the cover you have and remark the balancer. I have remarked one using a hack saw and the mark is pretty much indistinguishable from the original. One concern might be that the relocated tab is obscured from view with all the accessories in place.
SteveComment
-
Re: Harmonic Balancer applications
Steve I like this idea to remark the balancer. I could also put an "x" on the new line or something to distinguish it from the original line. I am in a time crunch to get this done as we are dropping this motor in the car on May 30th for a chapter tech session.
PeterComment
-
Comment
-
Re: Harmonic Balancer applications
Peter,
TDC is always referencing the position of the piston, the sprocket offset is only an indexing of the cam, so you should mark according to the crank/piston.
The most accurate way to determine the new zero point is the piston stop method. You stop the piston near, but not at, the top of it's stroke with some kind of mechanical stop. Make a pencil mark on your balancer at 0 on your tab. Reverse the direction of rotation and when it stops coming up from the other side, make another mark at 0. TDC is the exact midpoint of the two marks.
You do it this way because there are several degrees of crankshaft rotation when the piston has stopped moving at the top of it stroke as the crank moves over the top.
SteveComment
-
Re: Harmonic Balancer applications
Peter--------
It can be re-used, no problem. This is especially true because it's a very recent installation and you haven't even run the engine. But, even if you had, it could be re-used. Another advantage of the one piece gaskets.
I also agree that it is an egregious error on the application. All 1969+ small blocks, 307, 350, etc., used the revised timing marks. There was one 350 that did use the earlier configuration. That was the L-48 350 used in 1967-68 Camaros. However, once again, no 1969 350 did.In Appreciation of John HinckleyComment
-
Re: Harmonic Balancer applications
Peter-------
Justin's wrong.
Also, I have an even easier solution for you. Simply cut of the existing timing tab, leaving just the spot-welded-on portion. Then, install a bolt-on timing tab. The one you need, GM #3991436, is discontinued. However, auto parts stores/speed shops often sell these, usually chromed. Make sure, though, that you get the one for the 8" balancer as there are two different versions available----one for 6" balancers and one for 8" balancers.In Appreciation of John HinckleyComment
-
Re: Harmonic Balancer applications
Joe,
Am I correct to assume then that the timing line on the '66-'68 balancers is closer or even right at the keyway location? If the timing tab location changed the balancer line would also have to move because top dead center didn't change. Top dead center is too dead center.
PeterComment
-
Comment
-
Re: Harmonic Balancer applications
I am a little confused as to when GM converted to the one piece oil pan gasket on SBC's. Does this engine normally use one.....or has someone engineered a one piece replacement for the normal 4-piece gasket set used on the early 283's and 327's that I haven't heard about? I'd sure like to have the details if they have!Comment
Comment