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Old 07-28-2003, 09:51 AM
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Timing Marks ???

Hi All,
I have just rebuilt my 350, 0.020 flat top hypertectic pistons, moly rings, new cam, double roller timing chain, hv oil pump, performer carb and manifold, 3 angle valve job(rebuilt heads), all the tin was hot tanked with the block. The question I have is this: When I got all my stuff back from the shop, my timing chain cover had the timing indicator spotwelded on in a different area on the cover. If you are facing the front of the engine its mounter about 20 degrees clockwise from the original spot. It was brought to my attention that the balancer that was on the engine I bought (used) had a 305 balancer on it. My engine guy gave me a used 350 balancer to correct this. I assumed thge new location was because of this! When I dropped the distributer in I had the engine sittind at 10 deg by the indicator/balancer. On first startup, (man what a nervous and exciting time) I got my wife to crank the engine. It didnt fire not even a pop! So I started moving the distributer around. Once it fired I did the 20 min cam thing then tried to set the timing with my timing light. I could not see the timing line on the balancer anywhere with the engine running. I took a look at a 305 cover that I happen to have in the shop and the timing marks are aroung the "12 o'clock" area. As mentioned above the "New and Improved" timing chain cover has the indicator at about the 1-1:30 o'clock area. What gives??? Are there different covers for different 350's? With the timing set so that it starts great and does not ping under acceleration the light tells me that the line on the balancer is about at the 11:45 o'clock position. Do I have to make a new line on my balancer to use this "New" location of the timing marks?
Thanks in advance!

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Old 07-28-2003, 07:09 PM
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most 60`s and 70`s 350`s and other small blocks had the timing mark at the 2 o clock position, the 305`s had them in the 12 o clock position, since all small block balencers interchange except the 400 small block`s, it`s pretty easy to get them mixed up, the balencers outer ring can "walk" and the marks won`t line up, the thing to do is find top dead center on the number 1 cylinder, then look at the balencer to see where the marks are, if they don`t line up, then make your own mark on the balencer with a little white paint, red finger nail polish or just make your mark with a screw driver or the like. i do believe in the 80`s they all came with the timing marks at the 12 o clock position.
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Old 07-28-2003, 07:38 PM
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Zeder,
Chevy did make 7 different Harmonic Balancers for the "old" small blocks. The 350 used four of these.
The 305 did have the timing pointer at the 12 o'clock position. The 350 had the pointer at the 1-1:30 position as you mentioned. The base unit measures 6 3/4x 1 3/16 and has a 4 3/8 inch hub. This balancer is also used on the 305 and 327. Part number 6272221. This may be the balancer you had originally.
The second measures 8x1 1/2 and has a 6 1/4 hub. Part number 6272222.Intermediate performance.
The third measures 8x 1 3/4 and has a 6 1/2 hub. Special High Performance. This one is also used on the 302 and is hard to find. Part number 3947708.
The last is 364709. It measures 8x1 3/4 and has a 6 1/4 hub. (Off Road Racing).
For the price you pay for a new one, it is best to buy an aftermarket one. You get a better ballancer.

Vern Bradford
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Old 07-29-2003, 02:09 PM
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Thanks Guys!
I forgot to mention that the block is from a 79 3/4 ton. The shop gave me the 8 1x1/2 balancer. The timing line looks like it should have had the indicator at the 12 o'clock position. Oh well! I think I will do the piston stop thing and find out where tdc is then just remark the balancer to corelate to the "New and Improved" timing indicator. Is there any danger of the balancer being out of phase with the crank because it might be a different one than original?
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Old 07-29-2003, 03:18 PM
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here is a useful tip i like to use. put a white paint mark on your crank pulley to help locate your timing marks. its a lot easier to see at night or when you are under your car.
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Old 07-29-2003, 03:19 PM
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It's a damper not a balancer. It doesn't balance an engine, only dampens the vibration(harmonics) of the rotational mass. It will be fine. I love firing up new engines too!!. Congrats on getting her to run.
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Old 10-08-2003, 07:10 AM
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Bad harmonig balancer

I just traced a lingering timing problem on my 350 to a harmonic balancer with a slipped ring. The timing mark was about 10* advanced on this one.
The part number on it was 3896966. Does anyone know what this originally came off of? Not really important, but I was curious if it was even for a 350.

Thanks,
-B.
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Old 06-17-2013, 10:38 PM
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Sbc vibration damper #3896966

I was hoping some one knew if this was actually a 350 part. I am wrkn on a 1975 industrial 350 and it appears all parts are original. I looked in my parts interchange manual but did not find this number. The motor came out of a 1975 one ton motor home. Figuered it would do to push my suburban around lol.
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Old 06-17-2013, 10:53 PM
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There have been 3 different timing locations through the years.....12:00, 2:00 and 2:30 O'Clock. Look down through this list to see some of the applications......
Damper Doctor Online: Chevrolet & GMC
Do yourself a favor and send the damper to these guys to be rebuilt or exchanged for one on their shelves. The elastomeric material that separates the inertia ring from the hub can break down over time and in the presence of ozone, oil, hot water, etc. These guys separate the ring and hub, install new elastomeric material and clock the hub exactly to the ring so that you can use a timing light to time the motor.
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Old 06-18-2013, 02:33 AM
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Here is a tip for the next engine you build to get a true tdc mark, get the #3 and #5 piston equal distance down from deck surface using a dial caliper that is true top dead then with your front cover on slide you balacer on end of crank dont pull it on just yet . and scribe a mark even with the zero on timing tab and vwala!
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Old 06-18-2013, 04:19 AM
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Quote:
Originally Posted by reevislong View Post
Here is a tip for the next engine you build to get a true tdc mark, get the #3 and #5 piston equal distance down from deck surface using a dial caliper that is true top dead then with your front cover on slide you balacer on end of crank dont pull it on just yet . and scribe a mark even with the zero on timing tab and vwala!
Most builders use a piston stop on #1 (or #6) set to TDC to determine "true" TDC. More at Determining TDC.

There are several different combinations of damper lines and timing tabs that correctly go together. This page describes them.

Info on removing/installing dampers here.
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