The Stovebolt Site Forums The Shop Area Engine Shop 235 main journal clearance

My machinist says he may have found two 235 blocks. If at least one of them is good, then I'll have a buildable core. Yeah, this is the same 235 project I've been trying to get going since December.

My 1st series 235 uses shims between cap and block to set the main journal clearance. You want a perfectly round hole for the bearing halfs to sit in, right? So can I shim the bare bearings saddles to achieve a perfectly round hole? Then install the shells, snap the I.D., mic the journal for the O.D., subtract to verify clearance. Then the crank should drop in, and the clearances be correct?? Is this right?

Chip

Most people don't bother to shim the 54-55 1st series 235. And those that do fall into two different camps. One camp uses plastigage to check the bearing clearance, the other camp (which includes Proffit) believes in miking both the crank and the bearing. It all depends on what you expect from your engine. The real perfectionist will insist on line boring the mains, which requires a special tool due to the different sizes of bearings. Do the bearings have to be exactly round? Not really, but it's your engine and you know what you expect out of it.

Chip, this engine if it is a 55, should have insert bearings. If I remember correctly they started using inserts in 48 or 49. If indeed you do need to use shims then you shim the caps to match the crank journals, not usually the other way. Unless of course if you are building a Proffit racing engine then the rules are different. But I don't know how many have the money to go there-Or the "beer-LOL.

OK, so you're saying I should mic the journal, then shim the clearance of the main bearings to get about .0015" to .002" If I then snap the bearing 90 degrees from that measurement, what is the permissible out-of-round?

Should I take these measurements with the bearings dry? Or with some light oil applied to prevent the snap gauge from marring the bearing shell?

If I set the crank on the bench, then lay the #3 thrust shell on the journal and measure the end clearance with a feeler, will that give me a rough measurement of end-play? I plan on checking it in the engine with a dial indicator. But I don't want to put a lot of labor into the clearances if the end-play is off from the start.

Once I'm sure that the clearances are right, should I torque the crank down w/out the oil seal and see if she'll spin freely? Then remove crank and install oil seal, cut the ends flush, and seal the rear mating surfaces with Halomar in a spray can? Do I leave all the caps loose, or just the thrust cap when I "tonk" the crank snout to line up the thrust bearing?

As if you couldn't tell, I plan on being obscenely anal about this build. I want this engine to last a long time. Not being able to drive my car has been agony for me. I will use as much money, time and beer as it takes to do this perfectly.

Thanks

Chip

Chip, you cann't have your cake and eat it too. What you are wanting to do is very "labor intensive" and you need to be a machinist or have one in your hip pocket. To balance and blueprint an engine takes lots of time, labor and money. Forget about the beer- you won't be able to afford any for a looooooong time to come. Dang I hope you have someone (a darn good machinist) on the ground there helping you. To check the thrust you should really have the crank in the block. If you go to all this, make sure you balance the crank, fly wheel, cluch disc and pressure plate. Also, balance all moving parts. If you wish to be "anal" then do it "all" correctly. Get in touch with Profit, he can probably give you a fair idea of what you are taking on. My experience in this is what most would call "ancient"-LOL.

Why is this supposed to be very expensive or difficult? Seems like any careful person with knowledge, tools, and a calculator could do this. I just need the knowledge of the procedures for some of this stuff.

I already got a set of decent chinese snap gauges, outside mics, calipers, dial indicator, magnetic base, thread taps, torque wrench, Comp Cams degree wheel, etc. The machine shop says they can balance the crank/rods/pistons/flywheel/front pulley.

I plan on getting the machined parts back from the shop, then doing the final assembly myself. I know two toolmakers at work in case I get in trouble with measurements & stuff. I got a swayback garage to work in and enough stubborness to go around. What else will I need?

How does anybody else build and engine? Just throw it together and hope it runs?

Chip

Chiphead,
OK here we go. 1st thing is to find machinist that will work the way you say!!!! Then take your mics and standards and compare them to his. Another thing is to keep the temp pretty constant when you measure anything. Your machinist should be able to advise you as to what size bore you can use, order up your pistons before he bores it. Then discuss what kind of piston to wall clearance you want to run. He can then clean the bores to that dimension. Unless you are going to run something exotic I would forego line boring the mains. Discuss how much the crank will need to be ground. Then order up the appropriate bearings and torque them into your block and measure them. Give your measurements to the machinist. As far as thrust measurements, I would kinda wing it by measuring it with the old stuff in it and then comparing the new thrust bearing against the old. Number all the rods and caps so they can go back in the same. Have the rods rebuilt. Have the machinist install the cam bearings as the tools are not worth having unless you're gonna make a carreer of this. Be sure to check that the oil holes are lined up on the cam bearings. Static balance the piston/rod assembly. Dynamically balance the crank, damper, flywheel/pressure plate seperately. I'm tired of typing now. If you need the top end stuff It'll have to wait for another day.
Regards
Dennis

Chip....Please get a late 235 and put it in!
Then play with that SIMED CRAP forever and some day
put it in!!

I take issue with those that say I'm a prefectionist.....I'm not I am LAZY and only want to do this stuff once!

Chipper, take a close look at this and then buy it. They are among the best and are very rare. It will also take two Rochesters if that is your preference, but the Carter work very good. One if these is what I have had for about thity years and I am putting it on the wifes 235. Tattersfield

Chip et al.....

235 SPEED Equipment just means you'll get worse gas mileage and your butt wacked by the first kid on a fast bicycle....
Please don't waste your money!

Back to the original question:

How do I put the *#@$ crank in?

chip

Back to my original answer....Get a newer motor and
keep the Shim one to look at!

Chip I don't think you need to have another 'BUMMER MOTOR'

Just my thought

Fine JH.

How do I swap in a 235 that doesn't have side mounts? The '53-54 sedan is the only Chevy that used a 235 with side mounts. I would have used my '60 235 if anybody could have given me a straight answer on how to do it.

Chip

Chip, I didn't see that you were thinking of a newer 235, but if you go look in the Tech tips Engine Swap by Barry Weeks you will probably find you answers.

I checked it out, and that page does help. Too late now anyway. Ive got the '54 engine parts and the machinist might have found a '54 block. If not, I may do the '60 235 swap.

I would get the shop to install the crank for me, but I want to bottle brush the oil galleys myself. I also want to run a tap through all the bolt holes and clean all the shavings from the block. Kinda hard to do that when the crank is in the way.

Has nobody here built a shimmed 235?

Since when did a relaxing hobby become stressful?

Seriously, if I had known it would be this bad, I would have continued to run my car till the 235 blew. Then I would have swapped in the Pontiac 400.

Chip

Yes Chip.....people have built shimmed motors....over and over and over and over and over
How many time do I have to say this before you realize that we are on the same side??

Make a coffee table outta it.....Rebuild it over the next ten years.....and PUT A LATER MOTOR IN!!

Have that machinist send the parts you don't need BACK!!!! and get the parts for the more modern(presumably better) engine. When you are wanting perfect circle for that older engine, you are talking a lot of money and time to get it. Yes, if you actually decide to rebuild the older engine there are many on here that will assist you, and if no one else will "I will". But you must realize that you aren't building an old time racing engine. Now-a-days it just isn't worth the money. You can do a good rebuild, that will last along time, with out balancing and blueprinting it. The "prudent man" would build on the 60-235 since he has one. Let us know what you decide to do.

When Oily and I agree.....You should listen!
or call a plumber