Here's how to fix a not so visible power pirate

In this, episode 69 of PowerTec 10, DV looks into a source of power loss that can easiy be over looked. Often money can actually be saved by fixing the timing chain issue that is dealt with here as well as make 10-12 HP more on any Detroit V8.

[RobertEHunt-dvsq]

David, you’re not old, you are a Classic. Your tips and engineering expertise are phenomenal. I find your information extremely useful for my small 4 cylinder race engine builds. Thank you Professor David.

[JimSampson-yv]

Good tips david. I'm 73 years old.... still driving my 64 mini cooper s... thanks to your 'tips' on those ! Anyway... Did lots of drag racing in the past. All 354 and 392 chrysler supercharged stuff. Even tho we used only gears for timing we still spent hours getting the 'slack' just right. To tight, even on gears, cost hp. To loose and it was even worse ...causing 'spark scatter' and costing hp and possibly blower explosion !

[i-am-that-what-i-am]

Here's an interesting anecdote for you all, based on my build and repair experience of Caterpillar C15's...
The specificaton for harmonic damper/balancer replacement is 500, 000 to 600, 000 miles, depending on the application, and also specified by CAT to be done at leaking front seal replacement.
If not changed out at seal replacement, the seal will begin to leak again within a very short time, and it has nothing to do with the condition of the running surface of the damper where it contacts the seal as it's a two piece seal, where the inner part of the seal is a sleeve that rotates with balancer.
Furthermore, when the damper is changed, it improves the fuel consumption by approximately 8 to 10%, which is noticeable immediately after seal and balancer changeout, even when no other repairs to the engine are being performed.
The conclusion drawn to by myself and peer colleagues is, the damper is an accumulator of energy at the firing of each cylinder, and that, the elasticity performance of the rubber between the two damper parts deteriorates, and although it may not appear to be damaged or broken, on a micro level the bonding of rubber particle does become compromised.

[donbenson]

Hi,
I figured out / learned the lesson when I was 10 years old in the early 1960's. I really tightened the chain up tight on my bike and found I could hardly peddle it, then playing around after a while the chain broke. When I started building engines and racing I made sure the timing chain was a little loose. I believe today you can get under size sprockets for non nylon type sprockets. By the way the Chevy nylon sprocket is 1/2 inch wide the 1958 Corvette was 5/8 wide.

Don

[dodgeboy]

Thank you David! Your wealth of knowledge that you freely share is priceless!

[daledavies]

The linkbelt timing chains wore like the devil. A guy I worked with used to say when doing a tuneup, if the timing chain had any more than 30k miles you needed to replace it. Without doing so he said, you could never get the engine to run 100%. To a point he was correct but a little anal about it. My experience was 50k to 60k was kind of the wear limit. Now we need to realise oils and metalurgy were not what we have today. For long life a truroller timing set is the answer as they will generally go 100k miles or more.
You can rotate the crankshaft forward and backward to just take up the timing chain slack to get an idea of the state of wear without removal of the timing cover.

[randylankford]

I'm getting addicted to these tips. Thx DV

[richardscott]

Every little bit adds up. Thank you David!

[corvettejohn]

My experience from running too tight of a timing chain is that the front cam bearing wears in (i.e. excessive wear) before the chain and gears break-in. This makes sense since the cam bearing is much softer than the steel chain and gears.

[jerryadams]

Interesting .. I would have never thought the power loss would be 11hp and the fact that the gear would be worn, that interesting as well. A loose timing chain was said to be caused by stretch and a worn gear contributed to the loose chain was never considered in my experience. I can't wait to see what other knowledge nuggets you have to share in the future.

[ktr]

I would love your knowledge on fluid dampers vs fix weight dampers. Thanks for all you do DV!

[strattuner]

WHAT i've found is that tight timing chains will rub the bottoms of the cam bearings and reduce the effectiveness of the hydrodynamic lubricating wedge and literally eat the bearings causing a lot of unnecessary bearing scrub, timing chain components have to be matched to the load put up on the vehicle, in racing, constantly changed, everyday driving, every 85 to 125k or the retarded timing with eat the exhaust valves and seats right out of the head, DAVID IS THE ONLY ONE WHO HAS EXPLAINED THIS PROBLEM perfectly, this is the man who has been there, learning BY DOING, thanks DAVE

[andyjones]

As always David thank you so much for sharing your vast knowledge!! Wish I’d known you when I was a young man. I absorb this like a sponge. My mind spins constantly pondering how to make things better!! Faster stronger!!

[andreasfiska]

Thank you for this knowledge sharing, I would not have thought of this remarkable loss. If timing gears are used instead, have you Dyno tested timing chain vs a timing gear setup? Again, I really appreciate how you use your time to share your extensive experience with us.

[kpgsx]

I always use a Mopar Timing Chain Tensioner, and my timing is always Spot On.

[MichaelWilson-snyo]

The farm boy in me says you can probably stretch a tight chain? I totally follow your logic on how this could affect horsepower. Thanks for the tip

[jollybejarano]

Thank you David, for sharing your knowledge.

[gregquinn]

It’s not just friction with an initially tight timing chain. As the chain spins faster it flings out from the cogs a little bit and gets even tighter. Thanks brother!

[georgedreisch]

A frequently overlooked factor I’ve seen, is distributor gear backlash and the resulting chatter not only resulting in ignition scatter, but, crazy vibes being fed back into the camshaft.
I’ve also wondered if it may have contributed to oil pump issues.

[donbrutcher]

If I recall, Grumpy Jenkins used stock nylon chain sets rather than double rollers. He said he put on a new set for every rebuild.