Brought back the heads that Dan Marvin at Jon Norman's, performed magical surgery on, as there were numerous botches. The time has come to start engine rebuild after the rebore, and thorough cleaning, painting. Setting up the valves and their clearances, was delightfully easy on the bench. A long time ago, on dis-assembly of the engine, the crankshaft was in great condition and the bearings were standard (amazing), as everything else was in pretty sad shape. This week, have been fitting the crank components into the block, with bearings replaced by new ones, even though the old ones looked fine. It just felt a natural thing to do as everything else is new... Using plastigage to check tolerances, number four journal was off by a lot and it would barely squeeze it. Going back to origins, reinstalled the original bearings, and bingo! number four journal, would be smack on the dot. Measuring the crankshaft, number four journal was off the other three journals by almost -7 thou. I assumed that the new bearings were defective, that one was loose, yet that could not be as we found the original half shell, number four bearing, was 3 thousands oversize. The math may not be right as I do not have the exact numbers under my eyes, but the problem and the solution, was definitely there. The branding on the rear of the bearing shells, is the same for all, except for that number four, that instead of having a seven digit number ending with an 80 it ends with an 81. Has anyone run into this before? It would appear that when these engines were being built, they had an assortment of "plus a few thousand" bearings around in order to correct the slight machining mistakes? If that's the case, and hopefully not the rule, it is quite a complication for the eventual rebuilder, to have had the crank turned down and then re-nitride it. Not to mention the $$$. I am simply curious to know if anybody has ever run into this situation before, or if at Ferrari, standard practice, as only they could have the assortment needed. Regards, Alberto
Alberto, I do recall this being the situation with Honda engines back in the 'early" days. I ran into this several times whereby the main journals where slightly different in size. Although if I recall correctly the bearings where supplied in .005" increments. I have never run into this on any other manufacturer. I will be checking the bearings on our Dino in the next couple of months and will report the findings. Take care Jamie
Have a machine shop grind the crank to next oversize and provide the shells, block and mains so they can bring it in to tolerance.. Worth the hassle.
Never seen this before on a Ferrari...Perhaps someone was in there "before you?" You can grind the crankshaft to the first under-size, without going through the re-nitriding process. Ditto Absolutely the best advice and approach!
Yes, the usual turkeys did go in the engine, and it was an orange silicone orgy, with the only caveat that they certainly would not have had access to a bearing that is 3thou larger than the rest. That, unless they worked at the factory. The bearings are there from day one...and the crank, standard, never cut. The original bearings are in great shape, so I have two choices: one, I stick with the originals, two, change the three normal ones and use new ones, and leave # 4 as is. The problem I am faced with, if the undersize road is taken, is that nitriding cannot be done in El Salvador. It is quite a pain to travel with a crank, and mailing it is another huge bureaucratic issue, both in and out and back. I am unsure if the next oversize, 10thou, will warrant the procedure as I ignore how deep the nitriding process goes. plus, the #4 journal is already 7thou under, so only cutting 3thou off is slightly riskier, as being so little, thus 20thou is a very realistic possibility so the nitriding would probably say bye bye... I have no qualms in re-using the old bearings, have done that in the past with street and racing motors, as long as wear and or damage were not an issue. Just like pistons, if all they need is new rings and the fit is within tolerances, why toss them? I assume, that this is a standard procedure from Alfa to Yugo. This is an engine like any other, just the same as any Italian DOHC engine, and actually, not very high in the quality control aspect of things, if the crank issue is taken into account, so I am not terribly concerned. It is moreover an issue of puzzlement, as I would have thought Ferrari built things in a more responsible way. The head studs too, are an issue, but that one has been solved with replacement. Is it feasible that Ferrari would not pre test their head studs to failure? or run such a sloppy crank grinding operation to warrant the trouble of having oddball bearings to solve issues that should have been addressed with a different approach. If here, a crank can be ground to whatever specs you require, then... Dino and Alfa motors have the exhaust sodium valve in common, yet Alfa never drops valve heads. Possibly the 1mm difference in stem diameter might be the difference. I have never run into any problems as these, in more than 20 Alfa Romeo motors. Not even one broken head stud, and they are set in aluminum and twice the length. I did have a starter motor killed by a rod once... wild overrevving being the guilty party. Building a motor properly is not only judgment calls, but also taking the time in measuring everything pre and post assembly, as if you disassemble down the road you need to have base measurements to compare to. While on the topic, as being a total stranger to Dino rod bolts, is this also an issue? Magnaflux? Please do volunteer your opinions as they are always very appreciated and valuable. Thank you. Merry Christmas to all. Regards, Alberto
A. That motor did not come from the factory with that hodge podge of bearings. Sorry B. Never seen an Alfa with broken head studs? Wow. They break so often, at the dealer we used to retorque them before disassembly as a test so it wouldn't happen to us going back together. And talk about a nightmare to fix.
No one makes a 7 under bearing or a 3 under, no one. They came from a different application. Grind the crank and get a set of bearings. And if the guy cannot grind a crank .003 take his Storm Vulcan away from him because he is no machinest.
Brian, you are right absolutely right. No bearings 3 or 7 under, but they did make a mm 0,127 which is 5thou. of which, half, is 2.5thou. What I did mention, was that the crank, not the bearing, at #4, was 7 under. From the "L" series catalog, Tav. 3, it states that: the part numbers are: 4206580 for std and..........................: 4206581 for -.005, which is exactly what I have on the #4 journal. I apologize for my bad measuring as it should be .0025 instead of .003. On the latter catalog, from chassis #2132 the same parts are shown, yet listed as "not available anymore" in the 5 thou. version. It would at this point, appear that Ferrari fired the machinist that did my crank and sent him to El Salvador along with his Storm Vulcan...;-) The part numbers are EXACTLY what is engraved on my bearing shells. It would seem that the application is correct and no "oggi poggi" from Ferrari or the other turkeys that had this motor apart previously, and that the bearings are proper. Now, a possible scenario, is that the turkeys themselves did buy # 420581 and cut the crank only on that journal as on a budget, and then............................... Merry Christmas! Regards, Alberto PS You never commented on the need to nitride or not, if cut 10thou, or about the rod bolts. I would really appreciate your opinion on this. Thank you. Image Unavailable, Please Login
Do not grind crank have your machinist measure it. You trusted him w/your cyl head so he must know how to measure a crank. You looked at your old bearings and they looked good, this tells any good machinist that the crank is good and 'the bearing housing is good. By the way, plastigauge is not a good way to measure the rotating parts of an engine. its for rebuliding an old model t in the middle of nowhere like the sahara desert. Do not think you know more then the factory about bearing clearances. Read the specs and if you are anywhere within their tolerances you are good to go. Yes anywhere. Mis marked bearing shells ar common, especially these cars, just believe me. If you want peace of mind, buy some mikes and learn how to use them. Important, check for bearing crush. Look it up. Install beearing shells, torque down one, yes one cap bolt. You should be able to put a 0.003" to 0.005 feeler gauge between the ends of the bearing cap. ALSO, now that you own some micrrometers. Torque rod bolts by measuring bolt stretch, torque does not hold rod bolts together, stretch does. VERY IMPORTANT, DRILL OUT AL. PLUGS IN CRANKSHAFT, THESE ARE SLUDGE TRAPS WHICH IS NASTY STUFF. They arer drill passages to allow oil galleys to be in crankshaft. Use 0.25 al. material and taper one end and drive into oil galley hole with a little, A LITTLE ,loctite. good luck clay
Clay, thank you for the tips. Don't worry, the crank has been measured through & through, with all the mikes, ins and outs possible. The plastigage was a visual manner of trying to discover other possibilities, not the bottom line. We have always had all the tools to take very accurate measurements, yet, mistakes will be made. The world is full of them. I think what is getting lost in the translation, is that everything is correct, and that Ferrari built this engine with properly marked bearings, that correspond to the catalogs, and are the right ones for the right position and everyone is happy. The question was, and still is: Does anyone know of, or has found a similar situation, or why would Ferrari list in their parts catalog, bearings that are 5thousands off and that are in perfect company in an engine, with others, that are standard in size with all clearances and tolerances in perfect order, when "normally", if a crank is cut, it is at 10 thou or 20thou? List the 5thou bearings, only for the first batch of Dino engines and then NLA? Improved quality control? I wonder at, how many engine rebuilts have missed this potential problem? I was going by what was there and complacently was making a mistake of judgement as taking someone else's word that everything was OK. I mean, when you open an engine, the crank looks great, the bearings are standard in size, except for one. You simply did not notice the difference between all the bearings and the last one. Until you measure.... Here is really the root of the problem. Complacency, taking things for granted. I have my solution, and I will reuse the old bearings as they are in perfect shape and of the proper fitment. The are not mismatched or otherwise of strange provenance as they have the proper factory numbers stamped on them and are of the right dimension. This was strictly an archaelogical excercise, which evidently no one else has run into or has had a similar experience. The rest is conjecture, educated opinions and more knowledge that has been shared for the benefit of all. I have replaced the crank plugs with new ones from Superformance that are perfect for it. Just a touch of manicuring them, as slightly too long. You are also quite right about the deposits of tar and nicotine in the passages... The 3 to 5thou., are those Ferrari crunch standards? in the book, as there are no specs as to rod bolt stretch, would you have them? I have a Carillo rod spec sheet that has the various specs for rod bolt torque and stretch, but I would be concerned about applying them on Dino bolts and nuts as the vastly reusable ARP's. Also nitriding is not on the manual either. Why? On Alfa Romeo manuals, it does specify nitriding on the 2.0 cranks, so why wouldn't Ferrari? Have a great and safe Holidays! Regards, Alberto Image Unavailable, Please Login
I have often found odd bearings which you have described Attribute same to a mistake at factory, non availability of bearings, or damage from heat treating. Thecrank is set asidefor repair by the factory. Even in bearing sets, I have found one shell marked ten under but actually was 0.020 or? As to nitride depth. Nitriding is a term carelessly thrown around by every one. Research what the factory has done ie: how the crank was hardened. This includes: temperature, lenghth of heat soak, cooling down method, what kind of media the crrank was placed in during cool down and for how long. All are necessary before you turn to just the labeling "nitride". As to rod bolts, mag them, performed by any crank grinder. I had bad luck with nitriding dino cranks, Cracked by heat treater. Bad luck. So, I am very cautious about having cranks done but there are very good men out their who can handle the job. Closing, the best method for torqueing rod bolts is measure the stretch: 0.003 to o.005". Also, check bearing crush: torque one rod bolt only w/bearing shells installed. You should be able to get a .003 to .005" feeler gauge into the other side of the cap between the faces. Look up definition of bearing crush. merry xmas clay
Bringing up an old thread, my crank is in good shape as were the old bearings. New std mains bearing set from sf are coming in at 0.003" clearance which is on the upper limit according to the manual. Same for the rod bearings, don't really want to grind it if not necessary... Should I do anything? Thanks, Andrew
