I have a 1970 Buick Electra with less than 50K original miles. The shop manual mentions it has a nylon coated timing cam gear. I have rebuilt many Buick engines in the past including 455s. So I am not afraid of doing the work. But I'd hate to tear the front end of the engine down if not needed. I suspect MOST people would encourage me to do the work as it seems that doing ANY improvement on a Buick engine is what this forum is all about. But here goes: I am NOT a street racer, I have no need to ever rev the car over even 4000 RPM, and with its 2:56 rear gear, probably seldom over 3500. I drive mostly on highways and in town on boulevards. It cruises effortlessly at 80mph. So, does this nylon coated cam gear pose a threat of crumbling due to age? Or can I feel safe with not replacing it with a all metal gear (Cloyes C3083) for some time yet because of the low mileage factor? In short, is age or mileage the biggest factor on these nylon gears failing? If I were to do this, I would also go ahead and install new thrust plate and oil pump kit while I am down there. NO! I am not going to put in a high pressure or high volume oil pump and I am not going to go with a double roller timing set. I have done those things in the past for several more higher performance applications. Not needed for a weekend cruiser. I am aware the 1970 455 has a smaller oil pickup tube and oil passages than a 1971-1976 455. Not a concern of mine.
I would say given the age (50+ years old), it would be a good thing to do. It may run fine now but the plastic teeth were not meant to last forever. Though the worst case scenario is the chain jumps and you are out of time. Which should be pretty obvious when it happens. But are the teeth shards starting to block the oil pickup? Don't know, but I would do it if it were my car.
Yeah. I think I should. I may want to take the car on a cross country trip one day. I have rebuilt nailheads, 215, 300, 350, 430 and 455 Buicks. I have NEVER needed a puller to remove the harmonic balancer on a Buick, like I have with Fords and Chevys. Here's hoping I will not need to with this one. (I have a puller in case I do).
If you're interested, I have an NOS nylon gear, crank gear, and chain I've been meaning to list. Price would be right. If I understand correctly, the nylon was for noise reduction.
I cannot see the reason to replace a nylon gear with another. They should have never been invented. But thank you for the offer.
The nylon breaks down as a result of heat, oil, (contaminants that end up in the oil) time and mileage. 50 years is way longer than the gears were expected to last. At the time, American cars were typically driven less than 10 years and 100,000 miles. Some saw longer life as garaged and not driven many miles. Others were in the junk yards in three years. I saw quite a few cars about 8 years and 50K-70K die while driving when (nylon) timing set failed. And interference engines doing so with lots of noise.
I took apart a documented 50k mile car that already had the nylon gear replaced. The failure rate was near 100% so I wouldn't assume it hasn't been done already. I would suggest pulling the distributor and looking at the chain and gears with a boroscope. If it has been done, go racing! Otherwise inspect the condition of the nylon and make a decision from there. Worst case scenario you'll need a tow home if it fails, which might limit how far you and often you drive it.
That’s good to hear because even though you have low mileage there are blowby combustion gases that get into the crankcase and dry rot that nylon just as if it where a tire exposed to the Sun.
I took pictures but apparently, I have to host the pictures to display here so I am not going to bother. 1. The Cloyes C3083 I got from Amazon did not fit. One of the two holes to mount the cam gear was off by at least 1/4". In fact the part was a solid machined piece and did not look like the webbed unit pictured in their listing. I am not sure what the part they sent me would fit, but it ain't a Buick 455! I assume it was mis-packaged or maybe the newer Chinese Cloyes part is simply screwed ups. Not uncommon these days. 2. I bought an EXCELLENT, Engine Pro brand. Made in Mexico. It is so tight, it has virtually no slop. 3. My original had very little slop, well within acceptable range. The nylon gears still LOOKED good. But leaving the original in would cause me sleepless nights for as long as I left it in. I guess this is all evidence of a low mileage engine, as is the following: 4. My timing cover and oil pump surfaces also look very good. Very minimal scoring. Even though I removed it with no trouble, taking the oil pump cover off resulted in two broken bolts. Pffft. This was AFTER I cleaned all surfaces to reinstall. Frankly that was the most time-consuming operation of all. The original gaskets are as hard as lacquer. You cannot get under them to scape off, you merely shave them off thin layer, by thin layer. Time wasted. I do not have the tools to drill them out and retap them. So I ordered a TA Performance timing cover. I also ordered a shim kit to get the best possible clearances for the new Mellings oil pump and thrust plate. So my project is in suspense as I await the TA performance timing cover. To be honest, had I known from the beginning I was going to end up with a TA timing cover, I would have gone ahead with a double roller, because the TA has an offset mount for the fuel pump to allow clearance for one. I tried a double roller once one a OEM timing over and the arm of the fuel pump rubbed against the double roller timing chain. No big deal though.
The double rollets are nice, but with lower spring pressures the chains don't take the beating........I've had 4 or 5 sets of rollmaster double rollers and I feel they all stretch alot and quickly.....I've used about 6 sets of jp performance here this year on boat motors bbc......so far they seem well.......had a motor apart that had 500 hrs for a cam upgrade and it was still very tight
If this were me, I'd warm the bolt area with a propane torch (not too hot, so as to not melt the aluminum--which doesn't turn yellow/orange/red with heat) and then see if the bolt shanks will unscrew.
I have seen a lot of roller chains get lose very fast . In discussions with the owner of 2 car owners at a car show 3 years ago who had to replace there very very low mileage roller chain I found out that they never did a overnight soak of the chain submerged in light oil, and then spun each roller around to confirm full oil saturation. All they did was squirt can oil on the chain before they slapped the timing cover on.. The chain was then destined to fail from the get go! As most times happens with a engine, you get out what you put in time wise.
Got the parts around 3PM today. Buttoned up at 6. I used a feeler gauge, and the oil pump gears were between .0020 and .0025 above the gasket surface (no gasket installed). So I simply went with the thinner gasket that came in the Mellings thrust plate. I did not see a need to use a mylar shim from TA. That would have given me too much clearance if I understand all I have read here and elsewhere. To be honest, will all the Buick engines I have ever rebuilt, this is the first time I ever bothered to measure! I have always simply used the thinner of the two gaskets supplied. Once installed the oil pump gears were easy to move with a screw driver. Once put back together the car fired right up and the timing was close! I set it at 8BTDC like I had it set before. Even with 91 pump gas, no pre detonation has ever been detected even on Tucson 105F days and A/C on. Tomorrow I will take it on a test drive for 30-40 miles.
