VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc '55 235 oil pump mounting problem

This could be the post that puts me forever in debt to the VCCA chat forum. I'm in the home stretch of assembling my 235 for my '55 Bel Air. The block was bored, decked, & line bored, so there's a bit invested there. The long block is assembled, and it's time to button things up.

Today I attempted to install the oil pump. No big deal; slid it in, put the set screw in and snugged it up. Everything seemed fine. Then I tightened the lock nut on the set screw, not crazy tight. Then the oil pump was loose! To make a long story short, the cast oil pump bracket that's permanently bolted to the block is cracked vertically through the set screw hole! It seems to have been that way for a while.

Now what do I do? There are 2 bolts from the outside of the block that hold the pump bracket to the inside of the block. The heads of these bolts are machined after assembly, apparently with the intention that they are not to be disassembled. I imagine that I could get them out somehow, maybe by slotting them & using a screwdriver or something. But then what about a replacement bracket? My guess is that a bracket casting was bolted to the block first, with the bore still rough (not machined). Then the distributor and oil pump bracket bore were cut in one operation. It seems unlikely that a part from another engine would fit right.

One option would be to have a machine shop make a new bracket out of billet, then bolt it in, then bore it concentric with the distributor bore.

Another option would be to get another used part from somewhere. I could make a bar that fits the distributor bore & oil pump bracket bore precisely, fit it through the the block and the pump bracket, then fuss with shims & whatever it takes to get the oil pump bracket to align. I don't know if that's a recipe for success.

Does anybody have any suggestions? Any input is welcome!

Thanks,

Joe

Your seconed idea seems the best to me. I would try to find the retainer from an old block. Be willing to bet a 216 and 235 would be the same. I would bolt it in place and stake the threads.
You are correct that it was designed to not be removed.

Joe,

I suppose Gene's suggestion would be the most economical way to go.

A longer way around would be to get another block. It would be nice to get one that only needs boring to the same size so that the pistons, rings and bearings would simply swap over. Trouble is, if you're going for a show car, you'd need to look for a 55 block. Of course, the latter would broaden the search owing to a need for proper numbers. I think that, in the long run, you may be better satisfied.

Good luck with whatever you decision,
Charlie

Thanks for your input so far. No magic bullets, as one might guess.

My son the machinist thinks that he can take advantage of machines at work, & is sizing up option 1 (make a new bracket, install it, and bore it in place). Making the bracket seems pretty straightforward, since much of it can be sawn. Boring it in place is the tricky part.

However I go, I'll try to take photos along the way & post them to show what was done. Maybe somebody else will benefit from my positive or negative experience.

Thanks again,

Joe

Well, the oil pump mounting bracket was fixed nicely, but it was a lot of work, made possible because I had access to some rather specialized resources. Here's a somewhat abbreviated version of the story:

1) Remove the bracket: I cut slots in the round bolt heads, then used heat and a screwdriver to remove the screws.



2) A friend at work did a 3-D scan of the part geometry. The part was put on a turntable and rotated as a laser scanned up & down to create a computer model (.stl file) of the part. The same guy then created a CAD model from the scan, adding back material that had been machined off. Next, he scaled the model up to account for casting shrinkage. Finally, he used a 3-D printer to "print" a casting pattern made of plastic.

3) A local Amish foundry ("Cattail Foundry" in Lancaster County, PA, see Farm Collector article ) used the pattern to make 3 iron castings for a total of $22.50!!!.

4) My machinist son machined the new casting to fit. Luckily, he can use machinery at work for this kind of personal work. The job was pretty tricky. Here's the starting point: the original cracked part and the new casting from Cattail:



Some details of the process:

The flats on the mounting faces were milled, and one of the holes was drilled & tapped.



The original shoulder bolts that go through the side of the block had 7/16" diameter shoulders. We replaced them with off-the-shelf bolts with 1/2" shoulders; the holes in the bracket AND the block were machined together to the new size. First the bracket was located in the block using one of the original bolts. Then the other side was drilled, tapped, and the shoulder counter-bore was reamed. Next the new bolt was installed in the finished side, the old bolt was removed (& a clamp added), and the second side counter-bore was reamed.




Now that the bracket was fitted to the block, the hole for the oil pump could be bored. This hole must be coaxial with the hole for the distributor. The boring operation was done on a Bridgeport mill with the head tilted to the angle to duplicate the angle of the distributor hole. Don't ask me the details of the measurement process - that's my son's expertise. In general, it involved a lot of checks with indicators and fine adjustments.





The final bore was made to be 0.002" larger than the oil pump O.D. The original was 0.005" larger, but seemed a bit loose, so we tightened it up. In the end we assembled the distributor and the oil pump into the new block & bracket, and they fit perfectly! The distributor turned freely. There was much rejoicing.

One more step that has not been done is machining of the set screw hole in the pump bracket. This may never be done because I've since had problems with a main bearing cap, which may necessitate a new block anyway! If we return to this project to finish it, I'll add the final details. The placement of the set screw hole is important, since it determines the amount of engagement of the distributor tang in the oil pump drive. It must be placed so that the oil pump doesn't apply a thrust loading to the distributor shaft.

The moral of this story is "don't let this happen to you!". Before you spend a lot of money on reconditioning a 235 block, be sure to magnaflux of otherwise inspect the oil pump bracket for cracks.

Joe

Great looking work !

Between the oil pump and the bearing cap, you have had more than your share of unwanted cracks.

Wow! Did you have to get a different block after all?

If I can find a replacement bearing cap, with a little fuss, I should be able to keep the original block, so that's the focus for now. Let me know if you have a source for one!

Speaking of cracks, I didn't mention an interesting observation with the original cracked oil pump bracket. There was a number 7 cast into the original bracket, and the crack went right down the vertical leg of the 7. That's a nice engineering school example of the consequence of a stress riser. Check it out:



Joe

I doubt if that had anything to do with the crack.

Getting back to the main bearing cap. If the "new" cap is bolted up and bearing is too tight shims can be installed between the cap and block. If too loose some material can be removed from the cap....if too much removed shims added.....So a machine shop is not reqired.
Keep us posted.

If you would reveal WHERE in PA you are located, perhaps we could assist you in finding a block.

If you're in the Witness Protection Program, no need to reveal your town.

I'm in Strasburg PA.

I mentioned to my son that somebody had searched Craigslist *for me* and found my ad for an engine block there. His comment was that, aside from what you hear about people online, there are a lot of really nice folks out there. Very true.

Joe

Back when, in the '60's, we traveled from Cleveland, Ohio to King of Prussia, then to Lancaster, then back to Cleveland for family visits. They are all gone now, but know your overall area.

Here's one from Philly, but pricing for engine, trams or rear seems excessive.
http://philadelphia.craigslist.org/pts/4830587022.html

I am trying to get information on an ad in VT. Craig's List. Waiting for a call back. Got the call back. 1955 cyl block and other parts. $100.00 Jeff Price 802-895-5391 q5shg-4811579459@sale.craigslist.org Not sure if the link will work. I think it's worth the phone call though I realize it's a fair distance away-Derby Vt. near the Canadian border.

Some 235 blocks now on ebay. See none close to your area.

http://www.ebay.com/sch/i.html?_nkw...p;keyword=235+engine+for+sale&crdt=0

I am not a machinist, but, being that the posters engine was already align bored, I would be hesitant to install any bearing cap that is not align bored and a perfect match for that engine and the other caps. Just my .02 cents.

I am with Bob on this, the bearing cap needs to be aligned in all directions. If the hole is not a "perfect circle" it will not fit or work properly.
Tony

I disagree. The cap will adjust its self (center its self) as the cap bolts are tightened. The actual clearence will need to be adjusted.(up and down).

"The actual clearence will need to be adjusted.(up and down)".

The crankshaft assembly, within the block, is the heart of the engine assembly.

If it were my engine, I would find the correct cap, not a tang cap converted to a dowel cap, then install the correct dowel cap .... then redo the align boring.

The align boring job must be accurate and precise.

The opening in the block will not be changed so line boring is not necessary is my thoughts.

I understand your point of view, concerning the block, but the "new cap" would be installed, then block would be align bored again. New main cap would be "trued", by align boring, if out of specs.

I offered my thoughts, as if I owned the engine with the broken cap.

I agree 100% I was following this thread for awhile, you must align bore anytime the caps are altered

I think Gene's opinion has merit. The bearing insert will act to align the cap to the block horizontally while adjusting vertically may be necessary to get the proper clearance.

And if the "new" main bearing cap is egg shaped or out of round ? The bearing insert will not true up the cap.

In the align boring process, the "saddle" of the block and the main cap are trued up, as one unit .... a perfect circle, so to speak. If the "new main bearing cap" is out of round or egg shaped, the cap cannot be trued up, without align boring.

After align boring, the block and cap are a perfectly machined and matched unit .... functioning as one uniform, perfect circle.

Perfect circle is a poor phrase to use here, but cannot think of the correct term to use.

Just as in boring a piston cylinder to bring it back into shape, the same process applies to the main bearing journal area.

This exchange has been quite interesting. I still think that with no other options available, fitting a cap from another engine could work. I would't worry too much about the sideways dimension being a little oversize - that's what happened when one followed the Chevrolet endorsed procedures of removing shims. And the parallelism through the bore with the cap in place can be measured (top to bottom at the front vs. back).

All very interesting, BUT - the latest development is that I have a lead on a '55 block!!!

Somebody from VCCA or TriFive has been beating the bushes for me (!!!) and has put a guy in VT in touch with me. He has a '55 block that he advertised on Craigslist. He has already sold some parts off of the engine (dual carb & exhaust setup), since the engine developed a rod knock. He's willing to part with it for a very agreeable price. Also, my most helpful machinist son is willing to make the 2X 9 hr road trip this weekend (weather permitting) to go get it.

This seems to be the best scenario. It would be interesting to "save" the original engine with it's cool new oil pump bracket, but it would be cooler to not wonder how the bearing cap experiment is going a few 1000 miles down the road.

I'd be interested to know who made the connection to the VT guy for me. I'm really impressed and appreciative that somebody would do that. I'll keep you posted on the next big steps, & hopefully, the happy ending.

Thanks again for the support!

Joe