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Anyone have a definitive accounting of which timing covers were used on the 65-74 big block cars? Dowel pin/no dowel pin, harmonic balancer diameter, timing pointer design, etc.
Special Hi Performance will be different from Hi Performance units. Early covers will not have dowel pin holes, not sure which years started dowel pin holes. Special Hi performance balances will be 8 inch along with Hi performance 454, high performance 427 balancers are roughly 7 inches in diameter.
I just did this job on a June of 68 427/390 stock car.
No dowel holes observed in timing cover, balancer is 7", as stated above the timing scale is in 2* increment up to 16* BTDC and 10* ATDC.
This degree scale is mounted on the drivers side of the timing cover as the motor turns counter clockwise (from drivers seat) and is fastened utilizing two timing cover bolts.
Now this 1968 stock.
Hope this helped.
Marshal
Marshall135, any chance you could post a pic of the pointer like 71 Green 454 did?
I have built a period correct clone L88 for my December 1969 production (38318) car and have the AOR pointer but have wondered if this is correct.
That is the correct style timing chain cover for a 2nd design L88, as far as the date code goes I can't say. 8 inch balancer. I have L88s, L72s, and L78s waiting rebuilds in my shop right now, I know that cover well. Now the question is: what letter is on those timing chain cover bolts? Is that a L I see?
Last edited by Vortecpro; Feb 11, 2021 at 09:15 PM.
Thanks VortecPro. Indeed the bolts have the “L” but I honestly have no idea if that is correct.
I have a cover for sale listed in another post that another member inquired about which is what triggered this post. From what 71Green454 posted, it looks like I have the same. Now the question is what applications does mine go with?
Thanks VortecPro. Indeed the bolts have the “L” but I honestly have no idea if that is correct.
I have a cover for sale listed in another post that another member inquired about which is what triggered this post. From what 71Green454 posted, it looks like I have the same. Now the question is what applications does mine go with?
Thats a run of the mill 454 cover. L bolts are correct for a special HI PER 1969 427. I also have a 1971 LS5 454 Corvette engine in my shop from a member on this forum, it has a bolt on pointer.
Last edited by Vortecpro; Feb 12, 2021 at 08:59 AM.
69L88,
I owe you an apology. I went out this morning to take a couple pictures of the timing tab and did not realize it is obscured by the AC idle pulley. I can not get a good view from in front above nor either side. I'm sorry.
My block is a December 1967 321 block. My tab looks similar to yours.
It has the zero and 16* BTDC and it looks like 10-12 * ATDC.
Now the fun is going to be trying to time this thing with the obscured timing tab argh!
Marshal
Last edited by marshal135; Feb 13, 2021 at 08:08 PM.
Marshall, no apologies necessary! Thanks for making the effort. If I were closer, I would lend you my endoscope. Interesting you say it goes into double digits ATDC whereas 71 Green 454’s goes to 4, my “for sale” cover to 8 and my SPL Hi-Perf AOR to 16.
69L88,
I was able to time my car tonight with the aid of my brother in law behind the wheel.
I leaned way over the drivers side fender and had to pull the upper radiator hose back towards the block to see the zero on the tab. I stand corrected it does have the A 0 R on the tab so it is the same as yours in the above picture.
Anyway with the new balancer it was a snap to line up the marks.
I have 12 base and 36 at 2500-2800 and all mechanical was done advancing by 3000 rpms.
My original 360 vac advance adds another 12 on top for a total of 48* total at cruise.
I chugged the car around at 1500 rpms in 3rd gear and accelerated and no detonation.
Same again repeatedly in 4th gear and no ping.
I am pleased with the outcome.
With regard to your timing tab it looks like they used the same one you show in above pic on the 321 cast blocks too.
Marshal
Big Block Timing Cover
