V2Rocket

Raj,
Re: the Balance belt...
I have seen when the BS belt strips teeth and stops working but never seen a broken one, though I don't doubt it happens...

But I would think the BS belt is less likely to break as it's so loose?

joeystanker

Thanks for all of the posts of personal experience.

jhowell371

The Pontiac went on sale in the fall of 1965 with the new 1966 models. I owned the OHC 6 Sprint with 215 HP in a 1967 Firebird. Standard engine was 165 HP. The Sprint version had a 4 barrel Quadajet, hotter cam, compression boost and dual exhaust manifolds. Thing ran like a scalded cat, it embarrassed a few V8s My Grandfather (66 at the time) traded his 63 Mercury Comet for a 67 Tempest with the 165 HP version and 3 speed transmission. The first time he crossed a bad intersection near home he gave the OHC 6 the same throttle he had given to the underpowered Comet and laid rubber thru the intersection with my Grandmother yelling at him all the way It was his favorite car of all time.

mikey_audiogeek

Nice! Didn't know that. I had a Fiat twincam (false advertising I guess) but have never seen that Pontiac engine.

Found another candidate: https://en.wikipedia.org/wiki/Glas_1004

Cheers,
Mike

Jay Wellwood

I have no direct experience to quote, but I would offer that this is a Porsche tool designed to perform the same function. Some have professed to twisting the belt in the same fashion - and have had positive results.

YMMV

BlackOp

Quick question...my TB has only 15k on it but is getting old. What would be the labor charge on just swapping the belts. I've never done the job...obviously and dont have enough free time to get "experimental".

Is changing the rubber bits as labor extensive as replacing the wp/rollers?

Tiger03447

When I took off the badly broken plastic belt covers on my car, I found the BS belt to be in two pieces and partially wrapped around the crank pulley...A complete replacement of all the pulleys, rollers, cogged wheels, water pump and plastic covers has ensued from this point. Culminating of a pulling of the engine, and REALLY going through it all. Hope that S/hacker is wrong about the Uro water pump and other parts they sell...

konakat

The rollers aren't a big deal if you are in there already for the belt. The water pump is a bit more laborious. If the WP only has 15k, just leave and do the belt and rollers. If its older, probably best to replace it while you're in there.

V2Rocket

Timing belt, balance belt and all rollers should take about 2-3 hours for most cars at a shop that knows 944s.

If they quote longer than that, keep looking.

+1

jhowell371

Looks like you have the winner there with production starting in May 1962.

V2Rocket

Wanted to bump this up with a thought...
944 belts probably have a short life because they are subjected to a lot of stress/varying tension, due to the solid (non-adjustable) belt tensioner.

The engine is cold when you put a new belt on and set tension...but in colder weather or hot weather and running engine the temperature varies widely which affects belt tension, but the tensioner does not compensate...the 87+ "spring" tensioner is not automatic, it just "automatically" sets the initial tension but is not dynamic...

Whereas the 968, with a hydraulic piston pushing on its belt tensioner, can allow for belt stretch due to temperature fluctuation, a little looser, a little tighter...I found an old Porsche document saying the 968 was approved for 60k mile belt services, up from 30/45k on the 944.

I think I have something in mind...

RajDatta

Have you seen the difference in width between a 944 and a 968 belt. That alone would equate for much longer intervals. The 968 belt is massive in comparison.

V2Rocket

968 uses same width belt as a 944S/S2 with the "spring" tensioner...and those still have problems, but no doubt they are still tougher than the baby 944 8v belt simply by being wider.

Humboldtgrin

I already explained. It's a big four cylinder engine with a lot of vibration at idle. That vibration is the reason for the TB change interval along with many other smaller details such as heat and time and mis-tension and the width(size) of the belt. The 968 TB has a 60k interval change. I took advanced engine diognisis in collage, as well as all the other auto classes in collage and that's what I was taught on that matter. The automatic tensioner is locked into place once the tension is set on the later blocks so it acts just like an 86 block would if tensioned properly. And an OHC 6 cylinder would see much less vibration at curb idle due to the fact that the power stroke of the pistons on a 6 cylinder engine have no power under lap or overlap. At 120 degrees firing order the next piston will fire not slowing down the crankshaft at idle compaired to a four cylinder that has 180 degrees between fire order. Every standard gas engine that I know of (not a hit n miss or any other) has 120 degrees of piston power stroke from TDC. So from 120 degrees to 180 degrees the crankshaft is slowing down a hundred or so RPM's on a four cylinder. This is due to the fact that the next piston in a four cylinder is going up for compression and aiding in slowing down the crankshaft as well for 60 degrees. That is why there are ballance shafts on these big four cylinder engines. It helps smooth it out but doesn't change that fact that the crankshaft still slows down on every piston fire at idle on a four cylinder. That's why your not suppose to let these 924s/944/968 cars sit and idle. This is not my guess, this is the fact. I'm glad I can teach you all something. Go and research what I'm talking about if you don't believe me please. Also comparing a Subaru with three times the length timing belt and wider on a boxer engine does not compaire to this Porsche 2.5 SOHC models or the 3.0 SOHC turbo TB. If Porsche made a wider belt like the 968 has for the SOHC then it would last a little longer. Have you seen the difference from a cheap 944 TB to a nice Kevlar gates one? The Kevlar belt is just a little wider to match the stock width but the rollers can only handle so wide of a belt, the cheap belts are 75% of the width of a stock belt is looks like. I will change out the Kevlar belt at 45k as well. It's just a good practice to insure your car won't send a valve into the piston. Or you can biuld these into a non interference engine and not worry about it. I have seen that done. Need custom Pistons made in most if not all cases. I am looking into using the 928 S3 DOHC head with 944S Pistons to see if it's a non interference setup to use on my turbo. It looks like it may be a non interference but I'm not there yet.

bonus12

Not to interrupt but can someone explain why the accepted interval is 3 years / 45,000 miles? I assume it's whichever comes first? That would imply some people drive their 944s 15k miles/year for three years?