Early 40hp engine, what would you do?

[pastellgreen]

Have to redo the engine of a may 61 beelte. There is a strange knocking only when cold (two different sounds at the same time), I suspect there is a partial plugged oil gallery, where only warm more fluid oil can pass. Or it has to do with the change to newer valve springs alone. But we will see.

What I did before:
This engine is supposed to have 180.000 km on it.
- I opened it, and cleaned the case (there was 1cm layer of oil mud as bitumen on its ground).
- the crankshaft was in specs so I gave it new bearings.
- the old style cam was ok
- piston and liners replaced through AA
- cylinder heads replaced by the next type with a straight cover gasket. Changed to short studs. New valves together with later, progessive style springs. New guides.

Now this engine has this knocking what it not had before the rebuild. After 150 - 200m drive the knock disappears, the engine is smooth. Put 3000 km on it, no trouble. Only that knocking that drives me crazy. It sounds harder the colder it is at starting the engine. A deep knocking is present, a high sound only to hear at load, not at idlde but at same time with the deep knock. After short driving both are away. I had trouble with one rod that did not fall down so easy through its own weight. But I cannot believe that this is the cause.

My question is not about the knocking, you can't help me with it.

Next week I get an industrial engine from the same era with 110 hours on it. I plan to open the matching number case and clean it better, especially the oil galleries. Perhaps it might be visible, what the knock was. But however, I would like to take the internal parts of the industrial engine to complete the matching numbers block, of course only, when they are as good as I suppose them to be.
I also will reuse the piston and liners, because I don't like the kind of modern c-clips of the AA pistons and want to stay stock. I also don't like the 3-part piston oil control rings.

My question is concerning the valve train. Of course in any way I reuse the rebuilt to short studs changed heads with additional bores in the fins for cooling.

1) should I stay era correct with old style cam, valve springs and cam follower? Or are these componentes prone to fail?
2) as above but also using the newer style progressive springs? These are in place but I have this knocking in the valve train. After the manual, the newer springs could be used for all engines, also mixed with the older stye springs in one engine. But I doubt this a little.
3) should I update to the newer style cam together with the newer progressive springs and latest style of cam followers? That was introduced one year after my original engine. For this, it is needed to rework the follower bores (grind them shorter) and change the driving wheel of the cam.

Extra question: When I could reuse the piston and liner of the industrial engine, should I control and reset the position of ring gaps or it is recommend to let them as they are? Not that they fit the liner anymore. I have read in one thread, that the rings would change their positon constantly during the run of an engne but I highly doubt this theory. If this would be the case, we would have the situation of smoke at start from time to time.

[Dusty1]

[AlteWagen]

Here is what I usually see in 40hp engines with a knock that goes away when warmed up

Worn connecting rod bushings
Worn connecting rod bearings
Worn lifter bores

That rod you mentioned is a HUGE problem and should have been addressed with the 'rebuild'

Rebuilt rods should have been put in with new bearings and if that was the case a 'stiff' rod will bite you in the ass

You can get the lifter bores sleeved but for a 40hp its usually cost prohibitive
_________________
Grapes of Wrath $200 Engine Rebuild
Official Dual Carb Thread
Cylinder Head Quick Reference Sheet

[pastellgreen]

Thank you both for the first answers.
I forgot to say, the rods have been of course fitted with new bearings. Nonetheless, the one rod fell down by its own weight, but not as fast as the others. Of course I used the light hammer to correct the alignment of the rod halves, but it stayed what it was. I disassembled it agian, had a close look, nothing to see and after reassembly, it stayed.
After reading "worn lifter bores" I hope it was the rod. This would be easy to fix.
The industrial engine has 110 hours, these are about 5000 to 7000 km driving. It was maintained well, the seller said he turns all engines he has in storage by hand regularly after applying a drop oil to the cylinders. I suppose the bearings, piston and liners to be not far away from new and will have a close look on the crank bearings that could be removed. If these are clean, I reuse the whole crank with these bearings, including still assembled rods for the other case.
Or, as Dusty recommends, I use the industrial engine as is. The only thing I would change are the heads, to some with short studs.
I will keep you posted, but it will take some time. Next week it will be very cold again outside and so in the barn, and I will start working at it about 10 degree.

[Dusty1]

[AlteWagen]

Also forgot to mention worn cam bore as these early cases did not have cam bearings. Good luck finding a machine shop to bore case for bearings these days
_________________
Grapes of Wrath $200 Engine Rebuild
Official Dual Carb Thread
Cylinder Head Quick Reference Sheet

[pastellgreen]

[fl59bug]

Does the engine turn over by hand? Is the knocking present then?

Maybe check for excessive endplay ie front to back movement of the crankshaft. Grab the pulley or flywheel and try to move it back and forth along the crank's axis. Should be just the slightest amount of movement, perhaps .003"-.005" with no heavy clunking/knocking.

What about the oil pump? Can you remove that, check the gears for wear and check the cam where the oil pump gear tang engages?

If all the above checks out then I would say its time to split the case. You'll find the source of the knocking with careful checking, starting with the easiest stuff first.

Let us know what you find please

Ted

[esde]

Here's what I see as a possibility: two opened engines, both with some issue, and a VW that doesn't run.
Put that low hour industrial engine to work in the beetle, and enjoy it.
Open the knocking engine that you care to save, and find the problem. If you can't figure it out, send the rods and crank to dpr for a grind, rebuild, and balancing. He'll send it back perfect. Lifter fit is a real issue, I think that many people chase bearing clearances looking for oil pressure issues when the lifter bores are just whooped. But if this case is original to the car and you find the bores to be worn, yeah, have them sleeved. Valve springs, I would choose whichever spring is newer and not worry about standard or progressive wound. Remember these are low revving tractor engines, and not likely to float valves with normal use. Old springs get fatigued, so I generally swap out the springs on any "original" engines that have been asleep for 40-50 years.
Diagnosing the knock
Impossible over the net. Could be piston slap that lessens when the pistons heat up and fit tighter in the cylinder.
Rods generally knock MORE when the engine oil heats and pressure lowers,
but yours is knocking at start when oil pressure is high.
I would suspect a crank knock, coming from a loose main bearing in the case. When the case heats up and expands it grabs the bearing tighter and the knock goes away. Mine takes about 10-15 minutes to get to temp. Only way to know is to measure everything, but with the other engine in and driving you won't be in a hurry, so you'll get it right.
Good luck. SD
_________________
modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[Dusty1]

[esde]

[pastellgreen]

Thank you esde and dusty.
Perhaps I will run the industrial engine as is and only swap to short studs and add the 6 bores to each head for better cooling. That requires at least disassembling the heads.
I believe, at end it will be something easy to fix with this knocking. The case will be usable. This og engine was never opened before and had no problems with crank bearings loose or similar. Perhaps it is the one rod, or/and it is a partial blocked passage, perhaps in a lifter bore, push rod or rocker. Something like that.

[pastellgreen]

[Seb67]

You said new pistons from AA. Did you get the stock size or go with larger diameter for 1385cc? If so, the pistons skirts might be touching a little bit.
_________________
1964 Type 1

[Dusty1]

[pastellgreen]

Just worked on the engine, reset the axial end play. Pulled out the long studs to replace them by short ones. On the outlet valves from the first and third cylinder, there was to find that only these valves seemed not to rotate during their operation of the whole first life as indurstial engine (with 110 hours). The surface of the valve shaft end is absolutely untoched beside the little mark, where the screw was touching. Should I worry about it?