550 Engine Removal

Ron, just a thought but have you had the fences tack welded on the pulley? that's been a problem in the past with the fences coming loose and causing severe damage.

 

Dave, does that change the balance of the pulley? I remember my 308 had the stock plastic pulleys that were go dubious quality and someone was making up alloy ones that were nice pieces.
Philip

 

Darn. I hoped that would do it as I've always had luck. My only other thought is to double check that the tensioner is completely bottomed out. They're so darn tight even with it fully recessed. Every fraction of a millimeter helps.

Best of luck with it. I'm pullin' for ya over here.

 

See this post
http://www.ferrarichat.com/forum/140832766-post180.html

 

Belt slides on nice and easy when: put over bottom first, tensioner in place and fully compressed, both cam cogs off, camshafts pinned, pull up belt in position with belt indexed on cogs and then slide cam cogs on the cam lands. Easy-peasy. Pin cogs and then start your timing by the book. By the way I have pinned cams with matchbooks under caps for 30+ years and tensioned every belt by feel. I have never bothered to buy or make the right tool to hold the camcog so i could torque it. It is on my list! I do this so infrequently that by the time I think I should make the right tool I have found my matches. Light placement of matchbook covers on 4 or so caps will hold the shaft so you can torque it and not rip your belt. If you cut your steak and the meat is jumping all over your plate because you are better with an axe than a knife, and you are wearing the juices then the matchbook method is not for you. Pete uses the correct Hz-meter but it is "not" common knowledge of what is the "correct" Hz for this. The WSM is proported to be wrong. There are some pretty good rumoured guesses out there but I have not personally heard it from the horse's mouth and I'm not sure how much data exists.

 

Billybob: Is the "matchbook" a figure of speech or do you actually use them to determine the tension?

Pictures would be extremely helpful...

Thanks

 

Thanks Dave. Good post. Hard to imagine that with what 30 or 40 years of experience with belts this is still an issue today...
Philip

 

Ron,

What you report is known. Those are not timing mark but assembly marks. That is the point where your pistons will not hit valves by design. Then you need to time. 3/8" is more off than I have ever seen. Hitting piston while on assembly marks I have never heard of or seen. Could it be that someone was in your motor before and not say? With 355s people pay extra if valves have been done. In a car that is not supposed to have head problems doing a head lowers the value in the minds of many. You have a suspicious scenario there with the liner hole ,uncooperative assembly marks etc... It is curious anyway but looks like you got the cure. Keep going.

 

I would love to hear everyones theories on this but in my opinion you set the belt tension right the first time, make sure you torque the tensioner bearing bolts to PROPER spec (from memory I believe it's 59 N-m but double check) and then LEAVE IT ALONE. If you take the covers off at 100 miles or 1000 miles and recheck the belt tension it will almost CERTAINLY be less than you think it should be and then you will be all worked up and want to do another belt service out of fear. Ask me how I know.

I have been told that the engine block and cylinder heads expand a hair when the engine warms up and that probably brings belt tension up to where it needs to be. If you keep checking and retensioning and checking and retensioning you will eventually overstretch the belt and it will break! A little too loose is probably better than a little too tight.

I have put 2000 miles on since the second major that I did and I can say that my car sees 7000 RPM several times EVERY time I drive it and there have been no issues, not even a check engine light. If I ever lose or snap a belt I will be sure to tell everyone and eat crow forever.

Regards,
Pete

 

Pete, I personally think the "set it once and never touch it again" philosophy is flawed.

I think we ought to start a discussion on what the minimum and maximum tensions ought to be for a set of seasoned belts. We've all heard the stories (and some have had first hand experience) of too loose belts jumping teeth, or too tight belts causing premature tensioner bearing failures.

So, shoot fire & little fishes, let's come up with a safe operating range of tensions and just check these belts periodically to make sure they're in range. Sorta like what a semi-automatic tensioner would do

And while we're on this controversial subject let's think about another one. Will an old, worn out, stretched timing belt cause the cam timing to change? Well of course it will! So then what do you think happens to the cam timing between the time you so painstakingly set it when the belt is brand new, and a week from then, once the belts have bedded in and stretched a bit? I think the cam timing will be retarded, and so will the peak power - it'll come later in the RPM band (that's the way I remember what retarded cam timing does, it also "retards" the power.)

So shouldn't we be rechecking belt tension periodically, and also our cam timing? Or do you think Ferrari built these allowances into their procedures for the initial setting? The mind boggles.........

I'm in the middle of doing a "major" on my 550 and I've already checked the tension on my old belts, and they're so loose that the MotoReva can't even get a reading on the long sides. So I really think that before I pop the old belts off, I'll set up the dial indicators and have a check of my existing cam timing to see how far off it is.

 

John,

I'm more with Pete on this one. I think people over think the whole timing issue. For as much timing and power loss there could be from my belt slacking I could regain the performance by taking all the junk out of my trunk. Streetcar!

I have some curious comments. One rumour is that belts are better than chains because they stretch less thus holding timing. I have read that belts only stretch 3% over their life. I have never measured them but I swear my 550 belts have stretched more than that. I have never thought to measure.

Read about all the agony Ron has trying to get the pullys and belts on. how much stretch is needed before a tooth can be jumped? I think it is a lot.

Of my 4 ferraris the 550 belts seem to stretch the most. I think the newer kevlar belt that is the 5 year belt for the 575 stretches less. While the 550 seems to stretch the most, and I don't know why, I have never heard of a 550 throwing a belt or breaking one while on the 8 cylinder end of the world breaking a belt is a common occurence. I don't know why. Maybe there are just more V8's or less maintenance.

My 348 racecar was a single long belt and it did not seem to be as loose as a 550 belt will get.

If the 550 is a belt stretcher maybe that is enough reason to change this belt on the 3 year cycle even though it has been suggested that this be done on the 5yr like the 575.

Dave Helms has worked for a long time on his proprietary HZ setting for the belts. There is a range that works and a point that seems best. There must be a range because Dave tried it and the car survived only to be modified to his desired points. this testing repeated over many cars to arrive at his set point. Because there is no agreed upon set point and I have no access to Dave's data and there is no Ferrari WSM spec for the 550 and because I don't own the HZ meter I still and have for 30 years adjusted belts by feel. It is wrong but it works for me and I have never broken a belt and in my 348 racecar which had belts changed annually that car lived at redline. I'm confident in my belt setting but unsure of how wide my range of HZ setting might be.

For a long time Ferrari used propietary calibrated steager tensiometers. I don't know why they gave that up. It seems that with those unobtainum tensiometers they could let the data out but we still could not use it. Now with HZ meters anyone can set like a pro if they can find the numbers.

 

Carl, retensioning of timing belts (or any cogged belt) is fairly common practice, and in fact was REQUIRED on Porsche models 944 & 928 before Porsche (wisely) went to automatic tensioners. Porsche's service recommendation on these earlier cars was to bring them back in 1000km after a timing belt change for retensioning of the belt, then you were good for the lifetime of the belt. Why did Porsche require this extra step, and Ferrari specifically recommended against it? Different timing belt manufacturers? Nope - Dayco for both. In fact, both Gates and Dayco belts are available for the Porsche but the procedure is the same. Different tooth profiles? Probably not - the early 928's used a trapezoidal profile similar to our 550's, then Porsche wisely went to the much improved curvilinear tooth design for the later 928's (while Ferrari stayed with the older trapezoidal). The big difference is the length - the Porsche 928 belt has over 200 teeth vs our 550 belt at 91, so Porsche needed to make sure that belt was at the right tension after bedding in. However, the 944 had the same retensioning procedure and its belt was roughly the same as ours with 117 teeth.

When you read all belt manufacturers recommendations and their analysis of failed belts, pulleys and bearings, at the top of every list is "over-tensioning". So, I have always wondered why Ferrari's procedure is written so that the belt is overtightened initially, to compensate for this initial bedding in, rather than setting it at a reasonable tension initially, then driving the car and letting it go through a few heat cycles, then retensioning it down the road as Porsche did.

The need for retensioning is the main reason automatic tensioners were developed by the Japanese in the 80's and 90's and are now used by nearly all engine manufacturers, although Ferrari chose not to use them on the F133 V12 engine (and it took the Germans awhile to come onboard too). It would be very interesting to hear from Brian or the other pros why this was, because the 355's V8 of the same era as the F133 did have automatic tensioners, as did the 360's V8. Perhaps Ferrari were having difficulties with this new technology on the V8's and decided not to risk it on the V12's? Or perhaps the power required to drive the V12's cams was in excess of what Ferrari felt could be trusted to an automatic tensioning device? (Although Toyota had been using them for years on their turbocharged DOHC inline six engines with no issues.)

Fascinating stuff IMO (from a geeky engineer's point of view)

 

I have always wondered why there is not an automatic tensioning system on these cars like others with belt timing systems. I just wrapped up the second major on my car and I measured the four old belts against a new one by cutting them and laying them out. There was no change in length. Now, tolerances being a factor here you could argue that this isn't a fair comparison, but to the best of my measuring ability, the new belts I put on 15K ago are no longer now when they were changed. Didn't seem loose when I changed them and they were installed using the method in the manual of loosening the tensioner bolt to allow the spring force to set the tension while slowly rolling over the engine. I looked for a mid point in the range of travel and locked it down.


The WSM is pretty clear on this for the 456 - page B54 states not to retension the belt.

 

Dean that's interesting - no change in length at all? Then the loss of tension must be due to "bedding in" of the teeth (which would affect the ID of the belt, not the OD or OAL).

If the system did not lose tension, obviously there wouldn't be a need for automatic tensioners.

 

Agreed! I hear loud and clear everything you write. But engineering is engineering to the best set of compromises for the time and conditions. I don't think you can apply one technology to another technology without full understanding of the engineering of the rest of the parts. As an example we all have experienced the Japanese make with belts going 90k miles. No Ferrari is anywhere that close but they are all just otto cycle motors at the end of the day. Volvo on the 960 started belts out at 60K replacement, reduced it to 30K, then reduced it to 15K and did not inform owners while my belt broke at under 20Kmiles and smashed valves! What was up with that and how could they have the engineering so far off. It was a cluster F*&^K for there and clustered its way all the way to the consumer. Simple tech completely screwed up. It is all in the engineering or lack there of. It is hard to think we are going to out engineer Ferrari although Skunkworks is doing a pretty darn good job of it.

 

I may be mistaken, (it would be a First for me) , but I don't think the lower cog wheel came from the factory with welded fences,

Ron, when you say "right hand" bank do you mean passenger side?

 

Interestingly page A3.03 of the 575 WSM carries a procedure for testing and adjusting the timing belts between replacement cycles...

 

Philip- If you then look at the maintenance schedule referenced on that page, that refers only to the 50,000 km belt change. Checking and adjusting timing belt tension is not part of normal maintenance actions until they are replaced.

Replace the timing belts (A3.03)

 

Automatic belt timing belt tensioning systems have been a universal failure. Ferrari was wise in not using them.

Ferrari belts are not overtensioned at original installation.

I have yet to see a belt on a Ferrari, or a well designed timing belt system on any motor where if properly installed got loose enough to be a problem during its life. And I am not talking about its recommended life, I'm talking about before the teeth are worn off.

Stupid belt designs like the 928 with a belt too long to begin with may be a different matter but then they were badly designed from the start so we really don't car about those. And since when has Porsche ever designed a sucessful cam drive system? Belt or chain? After the eighth or ninth redesign maybe.

If it is well designed set it and forget it.

 

Workshop manuals are not a product of the engineering or the SAT department.


They are full of mis and disinformation.

 

Ron, here's a blow up of Pete's lower cog from the "Sorting Thread" which shows no welding. How does it compare to your's?

This leads one to believe someone has been in there before you.
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