I still remember from the olden days someone taking in a 330 that would not run properly and was nearly starting a fire every time they attempted to start her. Turns out someone had timed one bank of cylinders 180 degrees out. Ran better after that was fixed. Seems like that was at FAF, but it was a long time ago, so who knows? Cam timing is not a new issue.
I would like to see someone do a proper lock and swap. Check, but don't change, the timing. Then remove the belt and do another lock and swap with a second new belt. Check the timing again. Do it a 3rd, 4th 5th, ... time and build a data base for how much timing changes with a belt swap. I would like to see how this compared to the theoretical limits on max timing change due to belt length tolerance. Of course, we would still have to accept that there will be some variation in the accuracy of the measurements, though if done correctly they should be small. I would also like to see what the timing is for an engine that has gone several thousand miles on a set of belts and how much it changed from when the belts were installed. No one has taken me up on that one yet. On another issue I would like to know if there is any angular variation in where the assembly, or index marks on the cam are. I have been told (reliable source) that they are machined into the cam and if that is the case I would think that the position of the marks, relative to the cam lobes, would be pretty consistent. But I have read here that in some cases the marks are dead on yet in others they may be off several degrees. Is it the marks that are off or is it because of different people timing the cams slightly differently?
I am going to dive in. I probably shouldn't but here goes. First, I am NOT suggesting to anyone how it is done, just gonna pass on some of what I have experienced. Way back, I did a major on a 512TR and the marks were pretty far off. So, being the nice tech that I am and on the direction of a higher up, the marks were lined up. After starting, the idle was really cool sounding but not what it should be. It would rev up really quick and the four gas number were bad off. I pulled it out and aligned the marks and it was all good. I check everyone that I have never done before. I find that if I was in there and degreed the cams before, the numbers are the same if I check it again. So, I believe that if you did it once, it will be the same the next time. Last year I had a good customer buy a 355 that had good compression numbers and a fresh major service. He drove it to me from a state away and said it just does not run well. I test drove the car and it was difficult to get going but it screamed on top end. Everything else checked out and I told him it was most likely cam timing way off. Sure enough, after I pulled it down, marks were pretty far off, cam timing was 15+ degrees off on one intake and a bunch on the other and the exhaust, I didn't check all of them, no need at that point. I re-timed it and then decided to check the compression, guess what? It was bad now. I had checked compression as part of the poor running diagnostics. It was surprisingly high, like 230. One of the reasons I suspected cam timing was off. So valve guides and valve job and good cam timing, car runs great. So that is some of my stories.
I came across this old thread again, as a polluter of some pages with my 355 timing issues. With the 1-4 cil bank timing way off. I bought it cheap without a real test drive or ppi, otherwise I would have noticed it. Belt later turned out to have jumped 3 teeth in the past. Just wanted to say that I learned a lot from this thread, despite (I just read) some info not uniformily agreed upon. Thanks to the info I read here I was able to correct the engine timing. And up to this day my 355 still passes all smog tests, runs very good all they way up to the red line, screams her lungs out on the Capristo3 and even pulls well from very low rpm's. Without SDL or CEL. And with 4 years gone by by now, it is time for a belt change again.
There AT LEAST ONE Tech here who has 'Done That' for Y E A R S. BUT, as one can imagine that is treated as PROPRIETARY Data. He/They ain't giving that to ANYBODY. He Times his Customer's cars to RUN INTO TUNE, NOT 'OUT' of Tune. He gets cars sent to him from around the would. There are often a few shipping conexes 'out back.' He must be doing SOMETHING Right.
I don't understand. for lock and swap, as long as 1. the 4 bolts at the cam gear won't loosen . 2. identical replacement of belts with same-potion belt-cog attached to same-position gear-cog the timing WILL NOT change in the long run. You might have a slight change for each belt change because the belt itself is elastic to a small degree. if you change the timing belt for 20 times, you'll see the average timing WILL NOT change.
One point that seems to be missed is if you are changing the belts it means that the car has been driven with the timing present at the previous belt change for at least however long it's been since the last belt change. The only exception is if a belt jumped a tooth which is unlikely if the belts were correctly tentioned. So now after xx years you suddenly worried that the timing might be a degree off? Proper belt tension should be apparent prior to removing the old belts. If you are so paranoid about what the timing is at the time of a belt change, the implication is that anyone who buys a car with belt driven cams should immediately upon purchase have the cam timing checked. I don't see any of the proponents of timing cam at each belt change making that statement. I can understand why a professional shop may time the cams due to the liability involved, but if you are DIYing it, it's a different story.
Yes. That means you only have to degree the cams with dial gauges etc ONCE. For all later changes, you only need to do lock and swap.
I don't know Id go say 10 or 15 years before I did the next valve timing event. With my Automatic Valve Timing Calculator (Spreadsheet), Valve Timing with the OEM Parts (Cogs and Pins) inplace is an absolute 'Snap.'
I have done a write up with pics on my recent experience changing the belts on my 78 308 in a WORD document. I tried to paste it in the reply box, but the photos did not Ioad. How do I do this ?
don't think this site takes word docs so go to google and type in word to pdf and make a .pdf then upload it
Not sure that you can do that. You can upload a WORD file that others can open, but getting text and photos mixed together in the reply box is a much more "manual" process IME (where you have to be in the "more options" tab, have the cursor located in the text where you want the photo, then upload the photo).
https://www.ferrarichat.com/forum/attachments/210310ferrari-chat-report-pdf.3104033/?temp_hash=29ac85f8904904ae3ed3471f106f2298
Well I've been able to upload it as a downloadable link. How can I get it to open as a standard post ?
You can't -- see post #339. You'd need to write/paste the text and then manually put the photos in the right places within the text in the reply box.
Tale of a timing belt swap gone wrong I bought my 1978 Ferrari 308 GTS in 2011 with 36,000 miles on the clock. In 2018 with 50,000 miles up, I decided to do a belt change. I did a bit of on-line research and on Ferrari chat came across the method of locking up the cams with timber clamps to avoid unnecessary dismantling. As I learned later on Ferrari chat “Lock & Swap”. It seemed a good way to do it, so I ordered the belts, and as advised, a set of new tensioners. I made up the timber clamps, set the crank at TDC, and checked the rear bank cam marks lined up through the oil filler cap. I marked the crankshaft and cam pulleys, and locked everything up. When I had the new belts and tensioners fitted, I released everything, and turned over the engine by hand, to check all was free. It turned freely. With everything back together, I started it up. It seemed to be running ok, so I took it out on my local country road. I hadn't gone more than a few miles when all sorts of noises started coming out from the engine. I pulled over into a gateway to a field, and a farmer who was working there towed me home. On investigating I discovered the there was a problem with both inlet and exhaust valves on No. 8 cylinder. I could see a battered valve head through the plug hole when I removed the flattened spark plug. ”Lock & Swap” works fine if everything is 100% beforehand. In my case it seems not to have been. It was an incorrect assumption. I hadn’t checked. I had gotten a complete service history with the car and the belts had been changed 5 times over 34 years. there was possibly some "mission creep" Back on to the Internet and Birdman's guide to removing the engine looked good. I noted it was advised that a minimum 10 foot ceiling is required to lift out the engine. My garage ceiling is 8 foot. I had built a double A-frame gantry to fit that a long time ago. I cut the centre section out of the main box girder and welded in a cage to take a new electric hoist. Image Unavailable, Please Login To get the lift hook as low as possible and and eliminate the need for slings, I removed the front inlet manifold, and made up a bracket from a length of 3” x 3” angle, drilled to fit the manifold studs, and lugs for a bolt to take the hoist hook. Image Unavailable, Please Login Having removed all the ancillaries, the engine tilted over and came out without any problem. Even with the 8 foot ceiling there was plenty of room. Next job was to remove the cam covers, with the crankshaft on TDC. Rear cams were all on the marks, but the front inlet was 3mm or cam 0.7 degs late of the mark, and the exhaust cam was over 6mm, or cam 21.4 degrees late. Image Unavailable, Please Login There were marks on the remaining pistons 5 – 7 on the exhaust valve cut-outs where it could be seen the valves were contacting the pistons. I made up a set of pullers from some 3” x 10mm bar, like the one in the pic. I tried it with just the two cross bars and the heads came off easy. Image Unavailable, Please Login As can be seen in the pic, there was some serious damage to the combustion chamber. Both valve heads were broken off, and the valve seats and spark plug aperture seriously damaged. Image Unavailable, Please Login The piston was also completely holed. Image Unavailable, Please Login I made extensive inquiries with my motor racing buddies and a machine shop only 40 miles away was recommended. They did an unbelievable job on re-welding and re-machining the head and replacing the seats and the spark plug threads. As a matter of abundance of caution I replaced all the exhaust valves, all the remaining valves on both heads were checked, and were well within wear limits. They lapped all the valve seats. They checked the No 8 cylinder for damage, there was nothing beyond a few marks. The bores were all well within limits, and the gave them a light parallel hone on their special machine. Image Unavailable, Please Login As the engine was dismantled, I decided to fit a set of high compression pistons and higher lift cams and springs, supplied by Superperformance. Catcams inlet 22/52 10.75mm, exhaust 48/18 10mm. Took a while to source the distributor drive plug. It came 0.25mm oversized, so it's in my local machine shop at the moment to be fitted. The flanges on 3 of the 4 cam pulleys had almost cracked off, so they were renewed. The block, gearbox and clutch are now assembled. There are no markings on the cams so fitting them will be my next job. I see that unlike the original cams, they have flats machined behind the pulleys. I’ve also got a set of tapped dowels. I am now closely studying the timing belt discussions on Ferrari Chat before proceeding !
Sean, Normally a 2 valve engine is not very sensitive to accurate-to-the-degree cam timing. The fact that the exhaust cam on bank 2 is off so far means "you" did something wrong when you changed the timing belt. Out of the four cam shafts, that one is most susceptible to snapping off its mark and landing 20+ degrees away. Which seems like that happened on your car during timing belts change. Be more careful this time going back in. While you are no doubt a capable wrench, it is Ferrari experience you need to get under your belt. Good luck with the new cams.
It is easier and safer to just wrap a rope around the rear head and put the motor out so you can tip it easy and not break the window. Many mechanics have broken windows on the V-8s shooting for the hole and not looking at the rim.
