The Stovebolt Site Forums The Shop Area Engine Shop Flywheel Guide pins (dowels)Chevy 235

I am swapping engines in my 53 chevy PU 3100 and the replacement used engine has all the guide pins that the flywheel fits over broken off. I was able to get one drilled tapped and pulled so far and am getting ready to tackle the next two. Question is are these pins available for purchase anywhere online or will I need to go to my local machine shop and have them made? thanks to all for the help!

Broken off of the crankshaft end? That's sort of surprising. I'm operating from memory, but as I recall there were (3) 3/8" pins used. If I'm correct on that, I'd think you could get a common stainless steel 3/8" rod of 12 inch length for $5 or less and just use it.

Okay, help me remember: are the pins for alignment – to keep the FW true/ concentric with the crank, or for something else?

You may be able to buy suitable pins at a hardware store... or from someplace like McMaster-Carr.

Yes, they're for alignment. There are 6 flywheel bolts which sit between each stud and each group of 2 is locked in place with a typical sheet metal piece which you lift up with a screwdriver and kick a lip up onto the bolt head with a hammer. I measured one on a crank I have out there. It is 3/8 inch diameter, so I think any sort of 3/8" diameter rod would be able to be cut, end beveled a bit and driven or pressed in. Bigtime overkill on the length, but here's one at Home Depot: https://www.homedepot.com/p/3-8-in-x-36-in-Plain-Steel-Round-Rod-802447/204273959 A hacksaw, a vice and a common file to dress the edges a bit ought to put him in business again.

Good grief. Typing too fast. A vise...not a vice. Although a vice would be more fun, wouldn't it?

The pins are also offset to prevent the flywheel from being installed with the timing mark out of position. Otherwise, the timing might have to be set on the #2 or #3 cylinder instead of #1. The bolts are evenly spaced- - - -the dowels aren't. Don't use hollow roll pins- - - -if the dowel holes are drilled all the way through the crankshaft flange like the threaded bolt holes, a hollow pin will cause an oil leak into the bellhousing.
Jerry

As Jerry reiterated, they're for alignment. As long as you haven't done something nutty like drill new holes in your flywheel, the pattern will prevent you from installing the flywheel in the 235 incorrectly. The holes are indeed drilled all the way through the flange and the dowel pins are an interference fit. The length of each pin is 1 1/8" with 3/8" diameter. Good luck.

Thanks everyone! As it turned out getting those pins out was indeed a challenge. I ended up carefully marking the centers of the broken pins( or as close as I could) and methodically drilling progressively larger holes and finally tapping with a 5/16 tap. After a good soaking with PB Blaster and inserting a grade 8 bolt with large washer I used a pulley extractor threaded onto a slide hammer and banged them out. I watched quite a few youtube videos on extracting broken studs but was afraid of applying heat with the torch as I was unsure about heating up the crank end flange and warping something. A quick trip to the machine shop produced a short piece of 3/8 stainless rod for free which I cut, beveled and hammered in. Lets just say the new pins suffered slight distortion re-seating but a slight filing and even pulling with the flywheel bolts seated the flywheel and now I`m back on track to getting that new, used engine in the truck.

Good! Thanks for letting us know. Good luck with the rest of it.