Camshaft wear pattern

[SAJ]

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

 

[Jim Brierley]

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.

 

[SAJ]

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

 

[Synchro909]

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!!

 

[James Rogers]

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!!

bs! That is just a very crappy babbitt job. If babbitt is done correctly 60 MPH all day is possible without any damage. I believe lugging and slow driving is more damaging to an A engine than speed.

 

[Purdy Swoft]

I've got to agree with you on that one. If it can't be driven over 45 mph why would anybody even bother with a performance cam .

 

[Synchro909]

bs! That is just a very crappy babbitt job. If babbitt is done correctly 60 MPH all day is possible without any damage. I believe lugging and slow driving is more damaging to an A engine than speed.

I agree about that being a poor Babbitt job but even a good one won't take 60mph all day for many days with a crank shaft that is not counter balanced. It will for a while but the centre main WILL fail eventually if the crankshaft is not counter balanced. That's why a lot of people pressure feed it in an effort to squeeze a little more out of it. (or a lot). Once the shaft is counter balanced it is a whole different world.
I also agree that lugging is bad news on all of the bearings.

 

[SAJ]

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

 

[James Rogers]

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 1.60005 to 1.6001. I bet there are no shells this size!
Thanks for the replies
SAJ in NZ

The crank will have to be turned to use insert bearings, there are no .025 under shells. I don't like the way the oil groove is done on the rear. It should NEVER run to the front of the bearing and out the thrust. This is an attempt to keep the rear main from leaking. It will sometimes keep it from leaking when stopped but, it will leak BAD when running. This is because, crankcase pressures will find this path and use it to force the oil out the rear tube and possibly cause starvation and excess wear. I have had 2 engines in the last 2 months with the same problem as this that were bad jobs with inferior babbitt composition, both were repaired by pouring and boring with new Ford composition babbitt the way ford did it. One had the slinger cut off and a crappy modern seal that leaked, BAD. I replaced the slinger and got rid of this seal AND the leak.

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"?

 

[SAJ]

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

 

[George Miller]

I've got to agree with you on that one. If it can't be driven over 45 mph why would anybody even bother with a performance cam .

I got plus 2 on that one

 

[hardtimes]

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

Hey SAJ,
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 !

 

[Marco Tahtaras]

I agree about that being a poor Babbitt job but even a good one won't take 60mph all day for many days with a crank shaft that is not counter balanced. It will for a while but the centre main WILL fail eventually if the crankshaft is not counter balanced. That's why a lot of people pressure feed it in an effort to squeeze a little more out of it. (or a lot). Once the shaft is counter balanced it is a whole different world.
I also agree that lugging is bad news on all of the bearings.

In the mid 1970's my only car was a '29 Roadster. I averaged just under 10,000 miles a year. When I first acquired the car I did a ring job and took up on the bearings. Living in the San Francisco 'east bay area' I drove the freeways to get almost anywhere. The only time I didn't drive 55-60 was on club tours. There is no question I drove at least 10k miles at 60 mph and MANY more at 55+. I have never had damaged babbitt.

 

[SAJ]

Hey SAJ,
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 !

Thanks for the kind words. There is a bit more to this though. We are travelling in a group for a rally of thousands of miles to the South Island next Easter. So I either get to fix the cars in the comfort of my workshop, before we go, or underneath them by the side of the road when they break down later!
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