Day goes from good to bad in one shift

[SSsssteamer]

Originally Posted by Dave in Denver

The pulley rotates freely with the belt removed. It also moves up and down and side to side. I need to try and push it in and then try to remove the 15/15" bolt. The pulley is a billet steel variety.

Also pushing the car in gear without the rotor in the distributor turning at the same time..... Sounds like a broken crankshaft to me. I would also venture to guess that the front main bearing is wiped out too. It is now time to pull the engine.

[Jim Brierley]

It's not Riley's that are hard on timing gears, it is the added spring pressure which is required for any modified cam, overhead valves add even more strain. An aluminum gear will last almost indefinitely in any street engine, OHV or not. I've even seen many of them running in Bonneville engines although I recommend bronze or steel.

[Purdy Swoft]

Unless the crankshaft was broken before it reached the timing gears, you wouldn't be able to turn the pulley by hand. I did see one break that way on a chevy 235 but the model A crankshaft is forged and breakage is probably rare. I may be wrong but my guess is the pulley has failed.

[Dave in Denver]

MOre info to the drama I am going through. Took off the side cover of the timing gears, placed the car in gear and pushed it forward. The cam gears did ot turn, the rotor did not turn. In looking more at the pulley, it rotates but will not push back in and only moved in and out maybe 1/8". Next thing is to pull the oil pan to look deeper ito what happened.

The engine has inserted main and rod bearings, so if the front bearing was sacraficed, I am hoping that the mounting suface can be resued for a new bearing. Once I pull the pan and look inside I will post some pics of the carnage.

I am out of town tomorrow so the oil pan looks like a weekend effort.

Thanks to all so far.

Based on what I keep finding it is beginning to sound like the engine will be coming out of the car.

Dave

[Dave in Denver]

I concur with Jim's opinion on the Riley's. This is my third Riley Two port and even had a 4 port in a roadster a few years ago. All of the engine performed well and were very streetable.

[Dave in Denver]

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Ed, thank you for the suggestion. This additional experiementation is much easier than pulling the engine. Dave

[modelAtony]

dave. I have 31 tudor and same set-up except no riley and trans, but do have 3.27 rear and all other stuff. 40,000 miles in 4 years. I have friend thats great race car in last race all ok . 2 prev races like you broke cranks each race. broke at rear both times. reported to be bad cranks.

[Dave in Denver]

I pulled the oil pan yesterday to see what happened. My original hypothesis was confirmed. The crankshaft sheared between the 3rd and 4th cylinder. Looks like the engien will be coming out this next weekend for some major surgery. I have attached some pics showing what I first found and what is is supposed to look like after I rotated the crank. I have heard about some counterbalanced forged cranks for Model A's. Has anyone had good experience with them?

Thanks, Dave

[Jason in TX]

Holy cow! That's a discovery to make your heart sink!

And it's sooooo pretty in there with the painted crank, glyptal crank case and aluminum pistons.

Being that it's so clean, DID YOU HAVE OIL IN IT??? (haha.. joking!)

Good luck on the rebuild.

[Milton]

At least it is a clean break and the engine didn't disintigrate.

[Dave in Denver]

I agree. Now I just need to decide what type of crankshaft to go back in with. And also, my teenage sone who is taking auto shop at school gets to work on a different project thanthe modern iron he has been studying.

[darrylkmc]

If this were my engine I would want to diagnose how this crankshaft failed. Insert bearings, welded-on counterweights and who knows what else.
Makes me wonder if the radius is ground correctly on the failed journal. I would take a close look at all the machine work on this engine.

Darryl in Fairbanks

[RcT]

I'm no expert on broken crankshafts, but I would think that after the big bang, the crank continued to spin a bit, causing possible damage to the camshaft, possibly valves, timing gear... yes or no?

[mkmskm]

I've got a photo that looks just like that from a fellow club member here. The engine had 500 miles on the rebuild and what he suspects is that the crank was built back up and the heat was wrong doing it. On his break you can see about 1/2 the metal in the diameter just plain failed. Any ideas on the history of your crank? Yours obviously had weights hung on it. What else was done to it? Makes me wonder if it had the same issue.

[JohnW]

That crank is broken.

[Jason in TX]

^^ Ha! ^^

[columbiA]

Back in 1960,I bought an early 2-port Riley-with plugs on RH side & put it on a stock A engine with fiber timing gear & put over 75,000 miles on it.In the mid 80,s I put the same head on an A block with a drilled 33 B crank with mains cut down to 1-13/16" & heavy steel main caps made up for front & center mains.Also used a special oil pump & alum timing gear,light F-wheel,large updraft carb etc.It would really perform & I put many more miles on it. As for broken crank shafts,a fellow gave me an A block with a brokenC-S.It had the full circle C weights shrunk & pinned on & brgs brought back to std,but I could see that the radius on the journals was to sharp & that was where it failed Even eyeballing it,you could see several other crank pins starting to crack.Crank must have been ground by someone used to grinding heavy modern cranks & not useing the proper radius.

[James Rogers]

Never seen one break between #1 and #2 cylinder.

[2935ford]

WoW! What a mess...but thankfully repairable.

Does anyone know of stock cranks doing this? I have not known of anyone having a broken stock crank.

[bogdonj]

This is the first for me seeing that! wow