Dual Idler Gear Timing Set

[britannic]

Tore the front of the engine down today and discovered why my timing chain actually rattles: it had over an inch of play!!!!!

Based on this chain wear, I'm revising my the mileage on my engine, which I now be believe must be in excess of 150,000 miles.

Considering how much power my engine already makes, I'm expecting some improvement in the lower rpms :D !!

[patrick m.]

mine had 170k on it when i replaced the t-chain and gears.
i measured 7/8 of an inch on the old set, and very little on the new set.
good luck with the new gears
BTW, my truck runs SO MUCH BETTER! im ready to call JK for a fuel adding chip :D
Patrick

[britannic]

Finally got it buttoned up again yesterday (had to wait for a new balancer). The difference is incredible; the engine has real torque down low and I don't need to shift out of OD below 1500rpm on hills (used to lug badly). Engine is smoother, idles very consistently and there's absolutely no rattle anymore!

The power band that used to feel like I had hit an imaginary nitrous button is gone, it's just smooth pull all the way through the rpm range now.

[britannic]

Initially I had set the timing a 1/32" advanced past the mark and I had plenty of power, but a good fog of brown black smoke under heavy throttle.

Checked the timing and found I had 4.78 BTDC @ 1400-2000rpm. Set the timing at TDC @ 2000rpm and found that the lines are 1/16" retarded if I still had the conventional timing chain.

Warning, "Gush" mode redface.gif :

The engine is unbelievably smooth and crisp, idles like a gas V8, power delivery is like a steam locomotive and I only get some black smoke under full load up my favorite hill in OD (don't worry, I just wanted to see if it would pull OD for a few seconds :D ). The Dodge Ram 1500 magnum in front of me was having a hard time believing I was still on his tail :D !!!

Those gears are the best $260.00 including shipping I've spent on this engine yet, it really feels like I have a brand new motor.

[ 10-13-2003, 10:01 PM: Message edited by: britannic ]

[CleviteKid]

Well Britannic,

Are you ready to sell that Duramax now that your CUCV is running so well ;) ?

I spent last Friday at Crane Cams in Daytona Beach on one of my consulting projects (I know, its tough work, but someone has to do it) and the tech guys there acknowledge the benefits of gear drives for the cam and injection pump on a diesel, but have had a few annecdotes of problems in high RPM gas engines (above 8000 rpm, I think). They are speculating that the torsional vibrations at the end of the crankshaft are transmitted via the gear drive to the valve train and setting up harmful resonant conditions in the inner valve spring, causing valve spring fatigue failures. The slack in a chain isolates the valve springs from this resonance, they think.

I have not heard of any valve spring failures among those of us using the gear drive on our diesels, so I still recommend gears as the way to go. Sounds like The Brit is a big believer now, too ! ! !

Dr. Lee :cool:

[britannic]

Originally posted by CleviteKid:
Well Britannic,

Are you ready to sell that Duramax now that your CUCV is running so well ;) ?

I spent last Friday at Crane Cams in Daytona Beach on one of my consulting projects (I know, its tough work, but someone has to do it) and the tech guys there acknowledge the benefits of gear drives for the cam and injection pump on a diesel, but have had a few annecdotes of problems in high RPM gas engines (above 8000 rpm, I think). They are speculating that the torsional vibrations at the end of the crankshaft are transmitted via the gear drive to the valve train and setting up harmful resonant conditions in the inner valve spring, causing valve spring fatigue failures. The slack in a chain isolates the valve springs from this resonance, they think.

I have not heard of any valve spring failures among those of us using the gear drive on our diesels, so I still recommend gears as the way to go. Sounds like The Brit is a big believer now, too ! ! !

Dr. Lee :cool: My wife won't let go of the Duramax :D and it does have A/C, power everything, grade braking and 300HP etc - so it's staying for now, although she's now yearning for a VW Touareg V10 diesel next year!

Interesting point on the rpms, but it shouldn't be a concern if we drive our diesels properly - I'm sure other stuff would start breaking above 5500rpm :D before the valve springs failed.

I am a believer on gear drives and have been ever since I found the Ford Powersmoke engine had one - they always idled well and old ones still had reasonable "get up and go".

[britannic]

It just gets better and better:

Before the gears were installed and after the 700R4 conversion, the best mileage was 16mpg for a 150 mile run. The last 400 mile run yielded 19mpg average and 90% of the driving was between 1800-8500' elevation. Awesome :D !