[DeTomaso] Belt Drive vrs Timing Chain?

Donny Williams Donnylee at ccwebster.net
Sat May 5 12:04:06 EDT 2007


Truth is their our advantages and disadvantages to each type, be it Roller 
Chain,  Belt, or Gear Drive.   The problem with a chain is they stretch  and 
wear over miles and thats why checking timing  is almost always a part of a 
tune up as they stretch and drift.   The belt system offers ease of Cam 
timing position changes or "tuning" that the other two do not.  The Valve 
train has zero frequency harmonics introduced with a belt, though I am not 
sure this is as big deal as some lay claim to.   I have never seen a 
valvetrain suffer anything from these so called harmonics.

The most accurate non drifting timing system is a gear drive.  But your 
un-able to easily re-position the cam on a gear drive like you are open belt 
setups with their adjustable pulley and that is there main drawback.  The 
best setup for solid timing accuracy,  fully adjustable, and highly 
reliable, is a belt.

At the end of the day all 3 types in my opinion are valid setups setups for 
the wicked street engine.  But if your running just a mild 351, I would 
agree the need for anything other then a true roller chain is probably not 
money well spent.....At the end of the day solid rollers are usually thought 
of just for race engines.  But that is what I run in my street driven 
Pantera.  And have run 9K wicked strong miles without hiccup. An Exotic 
valve train for some, perhaps, with its quiet gear drive in front of it that 
requires a little preventative maintenance on valve adjustment and 
occassional lifter replacement.  But is nothing next to maintenance required 
on the other exotic machines that we all know and respect so well.... My 
ability to rev this top end out to 7500, is immaculate, flaweless, brute rip 
your bag off impressive for a street engine!

At the end of the day, the guy building a lap dog, or building a beast, has 
to decide what he wants out of it, what they our willing to put up with for 
maintenance, and give up for performance................As we know build 
types, preferences, engine manners, are truly vast out there........ I would 
disagree though that Timing belts require anymore maintenance then a chain. 
If that were the case you would see Honda's and about every 4 banger made 
these days dead on the side of the roads...  Replacing a stretched chain on 
a Pantera is not a fun job!

Just another opinion....

Donny



----- Original Message ----- 
From: <forestg at att.net>
To: <detomaso at realbig.com>
Sent: Friday, May 04, 2007 4:15 PM
Subject: Re: [DeTomaso] Belt Drive vrs Timing Chain?


>I think belt drives are great on race engines that get torn down and 
>inspected regularly. For a street engine I think it is hard to beat a good 
>double roller chain and steel gears.
> Forest
>
> -------------- Original message from "Dan Courtney" 
> <dfcex at pacbell.net>: -------------- 
>
>
>> I'm wondering if anyone has an opinion / preference regarding the choice 
>> between
>> a belt drive or a timing chain for a high rpm (8,000 +) race engine?
>> The Beast had a belt drive, this engine shop (which does not specialize 
>> in race
>> engines) converted it to a timing gear/chain set-up, telling me steel is 
>> better
>> than rubber.
>> Since I didn't get the engine in time for Pahrumph I'm planning to take 
>> it to
>> the top race engine shop in town to have the cam timing, clearances and 
>> balance
>> verified / adjusted and I could have them re-install the belt drive.
>> This timing chain set-up is adjustable to only three positions, through 
>> key-ways
>> on the crank gear.
>>
>> Dan
>>
>>
>> Dan F. Courtney < BR>>
>>
>> Excalibur Commercial Real Estate Services
>> La Jolla, CA
>>
>> Phone (858) 551-5455
>> Fax (858) 551-5456
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