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12-11-2014, 04:59 AM | #1 |
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Location: Auckland, New Zealand
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Camshaft wear pattern
I pulled the motor apart on a members car for a knock and found the centre main cap had lost most of the babbit, due to poor or no tinning. But I also noticed a circular wear pattern on all the cam flanks. See pic no 1. Is this pattern normal or indicative of too small a follow foot for the cam grind. Grind is said to be 100E (English ford 10) and follower foot diameter is 1.00 inch. I know no more about the cam, neither does the owner, though he delivered the cam to the re-grinder about 15000 miles ago
Many Model A's here use this "100E grind". And many use the 1 inch foot. I saw the same pattern on my wife's Tudor, so I put in a new IB330 Stipe cam and 1.125 inch single lock followers. Was I being too careful?[/B] Crank is coming out tomorrow to see what the babbit in the block looks like. Front and rear caps look OK, except the rear one has an extra groove I would like to fill in to retain pressure in the cap. And there are small shiny patches all over the babbit which I am not sure about. As in a previous thread, before I took the engine out I measured deflection in the bearings with a DTI and hydraulic jack and got 0.004 in the centre and 0.0015 in the rear and .004 end float. I will see if Plastigauge agrees tomorrow on front and rear. There are no shims present anywhere. I apologise for the poor focus on the babbits. I will fix this tomorrow. SAJ in NZ Last edited by SAJ; 12-11-2014 at 05:22 AM. Reason: added info |
12-11-2014, 12:28 PM | #2 |
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Re: Camshaft wear pattern
the wear mark does look like too small of a lifter is being used, otherwise it's a nice looking cam. the wear isn't too bad, you may be able to have the cam polished and save it??? stipe cams are very good, you'll be happy with it.
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12-11-2014, 02:33 PM | #3 |
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Re: Camshaft wear pattern
Thank you Jim. I will polish it and put new larger lifters in. The Tudor goes really nicely. I took 12 lb off the flywheel, welded bob weights on the crank and put in a 5.5 Snyder head.
I have your book. Its a great read and very helpful to me, and I recommend it to anyone who loves Model A's and their racing history SAJ in NZ |
12-11-2014, 04:45 PM | #4 |
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Re: Camshaft wear pattern
SAJ, At what speed does this guy drive? Failure of the centre main bearing is often caused by driving too fast. When I looked at a car to buy recently, I walked away when I asked "At what speed do you cruise?" and the answer was over 45 mph with standard gearing (no O/D).
As for the shiny marks on the rear main. Could it be that the boring bar "chattered" when they were bored? Anybody got timing and lift figures for the Stipe IB330 cam? Wait, its probably 330 thou lift!!
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12-11-2014, 10:12 PM | #5 | |
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Re: Camshaft wear pattern
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12-11-2014, 10:21 PM | #6 |
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Re: Camshaft wear pattern
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12-12-2014, 01:52 AM | #7 | |
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Re: Camshaft wear pattern
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I also agree that lugging is bad news on all of the bearings.
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12-12-2014, 04:57 AM | #8 |
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Re: Camshaft wear pattern
Thanks for the replies folks. Crank came out today and babbit in block on front and middle is toast too. The middle is crazed all over and fell out in pieces. To me it looks like a lead-content babbit, due to the crazing and dullish colour. I will check it for lead if I get time later out of curiosity.
The photos play tricks and you cannot feel or see any wear on the cam lobes- just the staining at present. There are two dark stripes on the heel of two of the cams which is peculiar, since there should be no contact here unless there was no clearance at some time. Pic attached Due to the quality of the centre and front babbiting, I feel we cannot trust the rear main either, although it looks re-usable at present. Unfortunately I don't feel there is a reliable bearing pourer near us in NZ, so we will go for a full line-bore and shell mains, leaving the current standard oiling system and full flow filter as fitted. The owner was using Penrite 30W/70 oil and at room temperature working on the oily engine is like working in maple syrup! The owner drives at 45 mph everywhere, with accidental exciting digressions to 50 down hills when not paying attention! It is a 1930 Cabriolet. I hope he doesn't read this! I agree that lugging is far more harmful than running easy. Diagnosis of the failure was interesting, since no one except the owner thought there was a problem when hearing it run and driving it. So I sped up the idle, pulled the spark right down and messed up the mixture with the air screw until the car had a jerky, staccato idle and then, wow, the knocking really started unmistakably. A listening tube under the sump put the rattle at the rear main, but it was sound travelling from the middle bearing, in fact. A mechanics stethoscope with rigid prong magnified tappets etc but not the knock. Shorting plugs made no difference, and retarding it smoothed the idle so the clanging was reduced anyway. It was a buggered engine still running like a good'un! The shiny marks on the rear babbit may be chatter marks, but don't look typical of chatter to me. Maybe James could identify, but unfortunately, by the time I got to my workshop today, a team of three had the whole engine down (See pic) and parts put away so I only got the two more pics. Crank journals are all 1.6005 to 1.601. I bet there are no shells this size! Thanks for the replies SAJ in NZ Last edited by SAJ; 12-12-2014 at 02:17 PM. Reason: too many zeros |
12-12-2014, 05:24 AM | #9 | |
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Re: Camshaft wear pattern
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As for running over 45 MPH, I wouldn't have a car that wouldn't run over that for at least the day. I don't change out of second till I hit 35 and that is every time I drive my car. This engine was built 5 years ago and is done as Ford built them. The motor has never given a minutes trouble and does not leak except for a quarter size spot overnight when I drive it long distances. I pulled the engine last spring to freshen the paint and while it was out I decided to check the bearings since, I had to pull the pan for paint anyway. There was absolutely no wear or damage to the mains or rods after 12,000 miles. The mains actually looked just like they did when I closed it up after the rebuild. I say "drive 'em like you stole 'em". You'll be much happier in the end. JMHO Another thing I noticed in your last picture, and just my opinion. Ever hear that "too many cooks will spoil the porridge"?
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12-12-2014, 05:54 AM | #10 |
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Re: Camshaft wear pattern
James, as I mentioned I would have removed that extra groove with babbit puddlintg stick if I had reused the rear main. I believe it would also have the effect of leaking out the hydrodynamic oil wedge vital to keep the bearing and journal apart.
I also never work with a crowd when machining and assembling. Jobs done on club night meetings are a disaster, in my opinion. I am not in that photo, but they are 3 really good workmen who saved me a lot of time in the tear down. I am running my manufacturing company during weekdays and just fit this stuff in for favours and fun and as a hobby. Machining and reassembly will be just me and the owner watching to learn. SAJ Last edited by SAJ; 12-12-2014 at 05:55 AM. Reason: spelling |
12-12-2014, 08:47 AM | #11 |
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Re: Camshaft wear pattern
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12-12-2014, 01:58 PM | #12 | |
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Re: Camshaft wear pattern
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You are a good friend of these guys and IMO, they are lucky to have you as their friend and club member ! Good luck with this build and let us know how it comes out ! |
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12-12-2014, 02:35 PM | #13 | |
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Re: Camshaft wear pattern
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12-12-2014, 03:06 PM | #14 | |
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Re: Camshaft wear pattern
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Last rally we took clutch parts from a museum show case down South and put them in broken a club car. It seems there are parts stashed everywhere in NZ I just fixed a lovely '30 phaeton for the rally, this cabriolet is next. The we will put a Mitchell in the Phaeton, Then I suspect a '30 coupe will arrive for bottom end check, more cars for wheel balancing, king pins etc-- and so it goes on. Ain't life grand? I love it, but worry about how I will fettle my own car. I have a Mitchell on the bench to put in my Wife's Tudor - one day! SAJ in NZ |
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