where to find 351 harmonic balancer

[LoganP]

Searched Google, searched this forum, can't seem to find a source. The rubber is shot in mine and I messed it up worse when I was removing it. I read that they are narrower than an automotive balancer and trying to use an automotive balancer would throw off the pulley alignment for the belts.

[michael hunter]

Where did you read that? I have the 351 out of my comp now . I have inspected it completely and it looks to me to be a stock Ford engine with a few bolt on marine components.

[haugy]

Where did you read that? I have the 351 out of my comp now . I have inspected it completely and it looks to me to be a stock Ford engine with a few bolt on marine components.

Well it worked fine when I converted my 351w into an engine in my Jeep. I do have a custom belt pulley set up though. But as the for belt itself, other than length (added power steering pump) it's the same width.

[LoganP]

It came up in the Mastercraft forums when I was searching Google. Says "3/4 inch thickness instead of 1 inch, and 28 oz not 50 oz"

[michael hunter]

I checked the 84 351 i have on the stand its 3/4''. I don't believe PCM changes the crank , flywheel or damper when they marinize an engine. The damper is there to help balance the crank you cant change the weight without effecting the balance of the crank. Summit has a stock small block ford damper for 60.00
Stop listening to that other forum they are evil.

[LoganP]

Noted, thanks for the information haha

[cadunkle]

Yeah, just order appropriate imbalance from Summit and call it a day. I doubt you'll have alignment issues, and even if you were out by 1/4" that's not a huge misalignment and you may be able to get a minor misalignment like that dialed in with a few washers if need be.

[SupraLaunch21V]

X2 on the above, I was looking in my garage for a spare balancer. I'm in the process of building a 331 stroker from a Ford small block 302 base. I thought I have some extras around.

Would the 351 / 302 balancer be the same? Cranks might be different, but I thought these were interchangable.

Do you want me to search and send one to you if I find it?

[LoganP]

Got one ordered from Summit. They have one balancer for all the Ford small blocks.

[cadunkle]

No, there are two imbalances for SBF. Your 351w is 28 oz imblanace as are all early SBF engines (260, 289, 302). I forget the exact year but at some point around 1980 they changed the 302 to a 50 oz imbalance. Cheaper to hang weight on each end than to get closer to internal balance. 351w remained 28 oz imbalance through the end of production ('97 I believe). Just make sure you've got a 28 oz imbalance as Summit does sell 50 oz balancers and flywheels. Also be sur you've got the correct mounting for your crank pulley, either 3 or 4 holes.

[chris young]

I've been poking around on this topic since the fall when I pulled mine and brought it home. As said above I'm pretty sure the aftermarket balancer will work fine, but the timing marks may not line up. There are also a couple of places that will rebuild them, I'd consider it but they're in the US and the shipping etc. would kill me. If I knew what rubber compound was needed I'd just rebuild it myself, I still might.

[CJD]

I had to do this. You need Dow Corning Sylguard #170. The bad news, the 2 part rubber is pricey, since you have to buy enough to do at least 10 dampers. The job itself is not that difficult, though. If you find the rubber and want to give it a shot, I'll post the details...

[chris young]

By all means, please do. How did you find out that the Sylguard 170 was the right stuff? I figured once it was all cleaned up I'd lay it on a flat surface and use 5 or 6 drill bits of the right size to keep it perfectly centred while the rubber was poured in. Is that the basic method you used? And of course, mine has moved, which is why I pulled it, so I have no sure way of aligning the ring for the timing marks, any suggestions on that front?

[cadunkle]

Use a piston stop to find TDC of #1 and mark it on the inner hub of balancer. Given the cost of a new balancer, ballpark $100-$200 depending on what you get, I'd just get a new one.

[chris young]

Use a piston stop to find TDC of #1 and mark it on the inner hub of balancer. Given the cost of a new balancer, ballpark $100-$200 depending on what you get, I'd just get a new one.

Well, that's what I should have done, but I was rushing to get everything done and I didn't think to do that until after I'd pulled the balancer. My intent was to buy a new one at the time, so I was just pulling it to have in my hand when I sourced a new one. Now I'm afraid I'm stuck with just marking it when it goes back on and living with the fact that the etched marks will be in the wrong place. BTW, according to my notes, the exact balancer appears to be C9OZ6316E. But I can't confirm it 100%, and there's only one hit on the net when you search it. I've been meaning to call my local Ford dealer to see if it may be possible to get.

[chris young]

Turns out you get a lot more hits when you search the number as C9OZ-6316. The problem is I came to that number by what was on my casting. I can't be 100% sure it's original, although it likely is. Maybe I'll see what kind of info I can get out of PCM.

[chris young]

I contacted PCM and they sent me their parts manual, so I have the exact P/N from PCM, and the 351W LH rotation damper is R064003(list price 297.00) but that's a PCM # and I can't find a cross ref to a ford # so I guess we're back to either a brand new aftermarket or a rebuild. I think I'm going to rebuild mine, I can get a similar rubber kit to the one CDJ mentioned for 44 bucks, so I'll just sandblast polish and paint the one I have.

[CJD]

Chris...not ignoring you, I'm on the road and don't have time to one finger type the description till I get home. I rebuilt the balancer on my V12 Jag. It is a sorry set up on the car, where a pulley actually goes around the balancer ring, so it puts a ferocious load on the rubber spinning a 120 amp alternator. The factory couldn't keep them intact, but so far my rebuild is 1 year and still going. I contacted Dow and 3M, and studied spec sheets for months before I went with the Sylguard. It was pricey for a pint, but nowhere near $300!

I'll post details in a few days on the procedure...

[chris young]

No worries I hate posting from a phone as well. I'm not in any hurry, I still need to pull it apart and sandblast it.

[LoganP]

Got my new balancer from Summit, definitely doesn't look the same. Will post comparison pics later.

[CJD]

Finally back home...

After I removed the bad balancer, I used a press to shove the center free from the outer ring. The one I was working on had a convex shape on the inner hub, and the ring was cup shapped. This kept the ring centered even after the rubber had failed. I have worked on Chevy balancers that were just flat, so the ring could work its way forward or backward.

Next, I taped the machined surfaces where the crank seal seated, and sand blasted the ring and hub. I was glad to hear you have a blaster! The rough finish you get after blasting helps the rubber bond much better than at the factory on smooth cast iron. Do not paint till after you have re-bonded the ring.

I now took a smooth sheet of plywood and drilled a 2" hole near the middle. This allowed me to rest the center hub on the board with the front upward, and the back downward, with the seal snout poking down through the hole. I levelled the board and placed a sheet of wax paper down, also with a hole cut out. Then place the center hub on the wax paper with the front up. Now place the ring down around the hub.

At this point you have to position the ring. First align the timing mark in relation to the keyway. To do it right, you need a timing dial (available from many parts houses or performance shops) or, in a bind, just a decent proctactor. Turn your engine so the number one cylinder is TDC on the compression stroke, and measure the degrees from the keyway to the timing mark on the timing shain cover. Transfer this measurement to the balancer outer ring.

You now need to center the ring around the hub. You mentioned using drill bits...they will work perfectly. Start with a size that looks about average for the slot between the ring and the hub, and adjust up or down. I used the bits to shove into the slot, and worked around the ring and hub, moving the hub towards center. When you have it perfect, the bit will feel the same anywhere around the hub that you slide the bit. Once you are satisfied, it's time to mix the rubber.

The Dow Corning Sylguard #170 comes in 2 cans. The rubber and the hardener. Mix it exactly according to the directions. I paint, so used the cheapo paint measuring cups you can get at any paint supply. I mixed 8 ounces total, but it only took about 3 ounces. Mix thouroughly for about 3-5 minutes. The resultant rubber is about the consistency of maple syrup. Now slowly pour the rubber into the slot between the ring and hub. I pour in only one spot, and allowed the rubber to flow around, so the air did not get trapped. Fill till the rubber is level with the top rim. Come back about every 5 minutes to top off, as you will get a very small amount of leakage around the wax paper at the bottom. After about 30 minutes, the rubber is thick enough that it will not leak, and will actually expand just a bit. That is a sign to leave it and go do something else for 24 hours.

At this point, the specs on the Sylguard recommend letting the rubber set for 2-3 days. I didn't have time, and proceded after 20 hours. Remove the newly bonded balancer. The front will be perfect. The rear may have a small amount of leakage. Trim the back if it is ugly. I started to, but was so impressed with the bond that I just left the extra rubber in place. It is as good as paint, and does not show on the engine.

Now tape the snout and paint the "new" damper. I had mine installed and in use within 24 hours, which was too soon, but I have had no problems with it.

Just a note...the balancer should be nearly perfectly in balance with the way we have re-assembled it. At most, the outer ring can only be about .001" off center. If you have the time and want to do a perfect job, a speed shop can re-balance it for you. I did not worry about it.

I'll let you know if the balancer ever de-bonds. With the sand blasting prior to the bonding, I think it will last much better than the original bonding ever did. The Jag V12 has a real problem, since it drives the alternator from the balancer ring...so if it is going to be weak, it'll de-bond on my car first. So far so good, though!

To finish, the time involved is not bad at all. About 30 minutes to sandblast, including set up and clean up. About 1 hour to set up the jig with wax paper and pour the rubber. At least a day to sit and cure. And, finally, about 10 minutes to paint the assembly. All told, it problably would have cost me more time to box the damper and drive to the post office and back.

[chris young]

Thanks for the write up, I'm definitely going to do the rebuild. based on your experience, it seems that any reservations I had about the rubber bonding to the metal are not a worry. I'll post up pics when it's complete. I'm doing the carb this winter as well and I need to get these projects going.

What did you pay for your rubber kit?

[CJD]

I have been trying to remember. It seems like it was in the $60 to $90 range. I know it was not over $100. It's one of those items that individual consumers rarely buy, so it's a rip off when you go through the specialty suppliers who carry it. It sounds like you've been googling...as I remember they call it a "kit", LOL!

I'll keep looking for the receipt and let you know if I find it...

[chris young]

no worries, I was just curious. I used to work in maintenance on jets and we had all different kinds of these 2 part rubber kits depending on what it was needed for. There are a few places around I can buy this kind of stuff. There is another product that seems to have similar specs that I can buy locally.

[CJD]

The main spec you are interested in is the temperature. A lot of the rubber compounds break down at relatively low temps. That eliminates the real rubber and neoprenes. You are left with the silicone type. The Sylguard was good to over 300 degrees, so that was my main concern. Some of the silicones are rather low in shear strength. So the goal is relatively high temp with decent shear strength. I would be willing to bet these properties are common in the aircraft circles...and you just need a few ounces.