Dreaded rod knock

[Guest Dean_H.]

While driving through the bay area traffic yesterday I pushed my little engine too hard and it started to knock. I recently changed the carburetor, installed a new muffler and few other tweaks, which has increased the power. It's now easy to keep up with traffic, but the engine rpm hits redline (3200) at about 75mph and I was probably a little north of that when the motor began to knock. I pulled off to the side of the road and opened the hood, it ran quiet at idle. I got back on the highway and noticed it would only knock under load. If I cruised easy, it sounded OK. The oil pressure and water temp looked normal so I limped home and took off the oil pan. I can't tell which bearing is loose by feel so I guess I'll have to take them off one at a time to figure out where the problem is. The oil pan didn't seem to have any metal, but any debris might have gone out with the drained oil. I pulled off one of the mains just for curiosity, but I think the problem is a rod.

[JFranklin]

A rod knock usually shows up during deceleration and mains under load. You will learn the expense of pushing the boundaries that your engine was engineered for. Good luck and let us in on what you found and your cure.

[Guest Dean_H.]

The mains eh? I couldn't see looseness on any of the rods when rocking the flywheel. I haven't had time to do much to it yet, but I'll check the mains first.

I normally drive it easy, but the traffic was moving fast and I started going with the flow. The motor was making good power and the car was handling the speed well. It was an absolute thrill to be keeping up with the modern cars. When it started knocking, my heart sank, I knew I had pushed it too hard. :-( Oh well, shouldn't be a big deal to get it going again.

[keiser31]

Ah Dean, Dean, Dean...had you adopted me when my wife wanted you to a while back, I could have saved you from the dreaded rod knock. I NEVER would have let you do 75 mph in that car without installing an overdrive unit. Do you have babbit bearings in that car?

[Guest raywilks]

i,too, followed along with your restoration and was very proud for you.

now i feel your pain. wish i was close enough to do something to help you. good luck, ray wilks.

[Hupp36]

An old time mechanic's good friend, this will help you Dean. You can get it at NAPA

[Guest Dean_H.]

You guys are the best! :-) I haven't had time to work on it yet, but after having a second look at that main cap, it looks a little rough. Also, on one side, the babbitt has worn thinner. When I originally checked the tolerances while assembling this engine it was very loose - 10 to 12 thousands on the journals. I didn't have a book on Hupps, but an old tractor manual on my bookshelf recommended 1 to 3 thousands on the rods and 2 to 4 on the mains. After taking out all the shims, I was able to get the rods to .003 and the mains to .004. It was on the outside of the limits, but I 'assumed' if driven easy, it'd be OK. Doh!

There are no removable inserts on this engine. On this main cap there's a brass shell with a thin layer of babbitt. The brass seems to be soldered into the cap.

I noticed a babbitt hand book on eBay, I think I'll read up on it and at least attempt pouring some new bearings.

[Guest Dean_H.]

A few months back I ran into a guy who had two old Hupp motors sitting in the weeds. I of course bought them, figuring the parts might come in handy some day. The first one is a 1930 model, and it was sitting in the elements with out the head. It looked pretty rough, but in 1930 Hupp started counter-balancing the crankshaft. If the crank is usable and would fit in my '29 block, it might be a nice upgrade.

Here is a picture of the 1930 motor

The second motor is more complete with head still on. I'm not sure of the year, but it looks like a 1929 or earlier, I suspect 1929.

Ding ding ding... looky there! No rust in the bottom end! It must be my lucky day. Check out the counter weights (red arrows). From measuring and appearance this crank looks like it might fit into my original block.

Uh oh, number one connecting rod has leather for bearings. Maybe the other motor is worth having a look at. I'll keep you guys posted.

[Guest Dean_H.]

These old motors are in amazing shape for sitting outside 40-50 years. When I pulled the pan off this other one, it also looks good on the bottom end. It turns free and is also rust free. I put it on my engine stand figuring maybe I could clean it up and install it in the car to get it running again. That way I could take my time on rebuilding the original engine. But after closer inspection, I found the rings are very worn and wrist pins are loose. It just isn't good enough even for temporary use. It also is a 1927 motor with a slightly smaller bore and stroke, so I can't interchange parts. Bummer... the car was my daily driver, hate to have it out of commission for too long.

[Guest Dean_H.]

Well, it turns out the bearings were not the problem. One piston had seized. I've seen this happen on other engines but this Hupp seem to run clean without smoke, so this was a surprise. Fortunately the cylinder looks pretty good. I have an extra piston, so it won't be too hard to fix. For now the engine is at a shop to replace babbitt, it won't be long... the old car will be up and running again. :-)

Here it is minus engine.

And the offending piston..

[keiser31]

Thanks for the update. I (and I am certain others) have been wondering how the progress was going. Hope you can make it all come out on the good side. The car looks a little forlorn with the front end parts removed.

[Guest raywilks]

i am also happy for you! i have visited this thread dailyn since you last posted.

don't forget to add a governor this time!!

[Guest Dean_H.]

Finally got the motor back together. I've been busy with other stuff and it took a little longer than I'd hoped. Mostly worked on it late at night, it was my only free time. The first picture is machining a piston to size.

Here the motor is being lowered into the car. Piece of cake now, just have to bolt a few accessories on.

Doh! One of the flywheel bolts stripped! This turned out to be a bit of a setback. I had to pull off the oil pan and remove the rear main seal holder to get enough room to push the bolt out. This close up picture shows the stripped bolt sitting on the ledge.

Before I put the harmonic balancer back on, I decided to take all those screws out and see what makes it tick.

Interesting, there is a clutch setup in there. It looks in pretty decent condition, I cleaned it up and reassembled.

All that's left is - bolting the headlights on and throwing the hood on. Maybe I should take a spin with out the hood, like the hot-rods do.

I hate the looks of cars without hoods, and what a good looking hood it is. just needs the radiator cap and we go for a test/joy ride. ....where'd I put that #%&*..cap

The motor runs like a top, but the generator doesn't want to charge. I probably need to polarize the thing. I figured my battery will hold up for a short cruise and take off. Man... this is an exciting car to drive, there must be some law against this. It's too much fun to be legal! I went down an old country road a few miles, figured I'd stay away from street lights since the paint is so dusty. When the headlights started to get dim, I spun a U turn and headed back. What a great ride! Just as I pulled into the driveway the generator started charging. :-)

[Guest raywilks]

that is great!!! we are happy you are up and running. very neat car.

also appreciate your keeping us up to date on the 32 ford.

man, i can see where you are burnibg the candle at both ends, working on two cars, building a house, and everyday chores can not leave you much spare time.

hang in there, it will get better!!!