Timing Chain Life
- Thread starter Shel_B
- Start date
You mean on OHC engines, right? The alternative is gears.
I've wondered the same. I hope he's OK.
Never changed a short chain on a V-6 or V-8, except for my 1973 351W with the nylon/aluminum cam gear. It jumped a tooth, but I was able to drive it by adjusting distributor. Changed it a few days later. Nylon teeth were shredded. Long chains on OHC cars I let go to about 250K. Don't trust the guides anymore. Prone to cracks and wear.
My neighbor has a full sized Blazer with a 454. He replaced the timing chain with gears similar to this. The sound coming from the front of that engine is amazing.
The same can happen to a belt.
Also, many people mess up the belt jobs too, either by poor quality of work, poor replacements parts, or both.
There is no failure proof solution.
That's new to me. Never seen a set up like that. 100% gear to gear. Nice !
The whine they make is glorious.
I could imagine that, with all those gears meshing together.
JHZR2
Staff member
The effort required to do anything besides “roll in” a new chain, or replace a thread-in tensioner is immense.
Swapping a belt is super easy.
Both have intrinsic concerns of screw-ups.
JHZR2
Staff member
I noticed the FB25 subaru engine uses a chain for each bank, but I assume its just easier to do that with a flat engine? Also the timing chains just rotate the cams, as the oil pump is run right off the end of the crank shaft in the timing chain cover. The early FB's had some locating pins for the guides that fell out of the block which caused some clatter, but it seems that was an easy fix in the factory for the next ones.
It is kind of crazy how many big chunks of aluminum have to fit and seal well, for oil and coolant to go and stay where it is supposed too in these engines.... But it seems the headgaskets aren't an issue anymore at least! And the timing chain isn't a problem.
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Many(most?) diesels use a gear drive timing set due to its durability and to eliminate any timing variances that could be caused by chain stretch.
Yes, I had to ask a guy if he had a supercharger in his nice original square body, but he said he had replaced the timing chain with gears. Even at idle it has a nice sound.
OVERKILL
$100 Site Donor 2021
My '88 F-250 had the 300 I6 with the nylon timing gears, which failed on the 401. That was an expensive tow.
Speaking of timing gears:
Somebody developed a gear drive swap for the venerable 427 SOHC back in the day.
Speaking of timing gears:
Somebody developed a gear drive swap for the venerable 427 SOHC back in the day.
Apparently the placement of the coolant thermostat fixed the warping of heads.
My 300 I-6 is all gear from the factory!
As far as I know mine still has the nylon gear in it at 265k/37 years old.. Its weird to feel like I have the most reliable engine in history and a ticking time bomb at the same time..
These have been around forever, Pete Jackson was the preeminent vendor.
The straight cut version is noisy, they made a helical cut version that was nice and quiet.
I also had a ford 4.9 I-6 with nylon gears. I had them changed for steel ones before they broke. Bevelled gears are much quieter than straight cut gears which is why you hear them sing.
Ilmor engines often used in boats have gears instead of chains, I believe.
Ilmor engines often used in boats have gears instead of chains, I believe.
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