The Stovebolt Site Forums The Shop Area Engine Shop 235 Smoke

yeah, I have seen too much I guess, but heads of this era are very problematic due to their age. Even magnafluxing isn't enough. Nowadays, they do a gas leakdown test to detect issues magnafluxing can't see. There is NO WAY I would have a head rebuilt without new valves, new hardened guides, gas leakdown, a complete surfacing, new springs, etc done. I know expense is a very serious issue, but so is all of the misery involved in not getting what you expect. Hopefully everything turns out okay for you. What made sense for 30 years after the head was made (changing out just the parts that were showing wear) is over and has been over for 20 years. The metal goes thru enough heat cycles and eventually just starts to deteriorate. We are at the point now where we just need to know. Especially at these prices.

Why not have the valve guides replaced and use new, standard valves?
If there is a significant ridge at the top of your cylinders, new .060 rings may not work for you. You need to measure your bores from top to bottom to check for excessive taper.
Carl

I completely agree with you guys that the right thing is to completely rebuild everything. However, that is just not an option right now. I'm just trying to make a runner out of this without emptying the bank account. If the cylinders measure in apec (which is part of the info I need) then I don't see why not just re-ring it and get it to stop smoking. Since I have the time to pop off the pistons, I'm trying to find a place that will sell just the rings (not rings+bearings+etc.).

Look here.

Brad

Are these the correct specs for the ring end gap? (keep in mind it is .060 over) Compression: .007; Oil: .015

Those are MINIMUM end gaps. It's possible to get by with somewhat more gap, but it's important that the ring ends don't butt together as they expand from temperature. If you're planning on doing a shade tree job with badly-tapered cylinders, the ring job will be very short-lived. Unless the cylinder wall taper from top to bottom of the piston travel is less than .005", the rings will flex constantly trying to maintain contact with the cylinder walls. At 2,000 RPM, the rings will be changing diameter 66 times PER SECOND! Good luck with that!
Jerry

Sorry to disappoint you, but this job is being done on my driveway with limited funds. No shop, no extensive knowledge, no experience.
I took the pistons off today after using a ridge reamer to ensure that the rings didn't get caught and break. It seems re-ringing will not do. The end gap on the new rings is enormous (~.031 vs recommended .007). At this point, it seems my only options are to do an engine swap, take this block to see if it can go .080 over, or sell as-is. I'd appreciate any input on the first two options.

There is a quick way to check cylinder taper. Take a ring (new or used, doesn't matter) and square it up against the ring ridge or the top of the ring travel where the ridge used to start. Measure the gap with stacked-up feeler gauge blades if necessary. Use a piston to push the ring to the bottom of the ring travel and measure again. The gap will be narrower in most cases. Subtract the bottom gap from the top and divide by 3. The result is your cylinder taper.

I keep saying, and you keep ignoring me- - - -ring gap specifications are MINIMUM measurements. A gap of .031" is very acceptable. Concern yourself with cylinder taper, not gap. If the taper is .005" or maybe just a bit more, hone the cylinders and re-ring. Just be absolutely sure to scrub all the hone grit out with a stiff-bristle brush, detergent, and HOT water, followed by a boiling water rinse.
Jerry

My apologies and thank you for your continued help. I am used to working on dirt bikes where the specs are very strict. I would have thought 4 times the gap would be way too large. I checked the bore, as you described, and the taper does close in as one goes down the bore. However, I did not note the numbers. I will take pen and paper to it and get some readings. What is an acceptable cylinder taper? What is the maximum allowable end gap?

I have done a short term re-ring job with up to .008" of cylinder taper. I try to keep taper under .005" if I want a fairly long-life job. On a daily driver, that ring job in a badly tapered cylinder might last a year before the rings lost their tension from excessive flexing. On a freshly bored and honed cylinder, there's virtually no ring flex because there's no change in cylinder diameter as the piston travels from top to bottom.

A good dial bore gauge will show you that almost all cylinder wear happens in the top 1 1/2" of the cylinder, where the compression and combustion pressure is pushing the rings tight against the cylinder walls. Near the bottom of the piston travel even an engine with worn out rings will have little if any cylinder wear.

I assume you've been dealing with 2-stroke motorcycle engines, right? Mosquito foggers don't have much tolerance on ring gap because they compress the crankcase on the downstroke of the piston. The rings are also pinned into place to avoid the ends of the rings hanging up in the transfer ports.
Jerry

Indeed! It's pretty amazing to see a 250cc engine deliver 50hp.
I found this info from Hastings: http://www.hastingsmfg.com/ServiceTips/ring_gaps.htm
Thoughts?

Hastings has been at it long before I began wrenching on things, and I've been doing it since the mid-1950's. That's a pretty good chart, but even if the gap is slightly larger, you'll get at least a fair amount of service from a lightly-stressed engine. Since the rings in a 4-stroke engine rotate around the piston during normal running, the only real concern about ring gap is if the gaps on the 1st. and 2nd. rings align momentarily. They won't stay that way long, however. On one of our training engines back when I was teaching high school auto mechanics (with a tempered glass cylinder), we could watch the rings spin around the piston with a delay-flash timing light. Interesting!
Jerry

This is all good news for me I will get to measuring those ring end gaps/cylinder taper and hope that a re-ring will get my through the next 8-10k miles... which for this truck should be about 4 years.

I measured the rod journals today and they seem to be in spec (2.291, which is the is the stock 2.311-.020). The crank is labeled to have been machined .020 on the rod journals and .030 on the main journals.
I also assembled the head. I was having a hard time a hard time getting the keepers in because they would push the seals down off the bottom groove. So, I decided to insert the seal from on top (after putting down the spring and before the keepers) and that seemed to work much better. Please don't tell me I have to reassemble the head...
With this done I can finally make since measurements on the cylinder and decide between boring .080 over or just re-ringing.

That's the way I've been assembling Chevy valves for over 50 years. No problem from my point of view! Just be sure the O ring doesn't get dislodged as you release the pressure from the valve spring tool.
Jerry

Update: I finished assembling the motor last night/this morning (1:15am). To summarize up to this point: The engine was smoking, particularly as it warmed up. The head got new exhaust valves and seats were machined. Intake seats/valves were lapped. Ridges reamed on the cylinders, new set of rings installed.
I took some measurements using the diameter of the ring as a fixed variable and using the ring end gap to check the change in diameter (it is the ring end gap divided by pi, incase anyone else comes across this thread and needs to find cylinder taper and does not have a bore gauge). Based on the recommendations from Hastings, taper should not exceed .004 in. per inch of bore. Therefore, I calculated my maximum taper at .014 in. (3.6225 x .004). The most tapered cylinder came in just under that at .011. I deglazed the cylinders, cleaned them out, installed rings on the pistons, and installed them with a coating of Rotella 30wt on them and the cylinder wall. The bearings also got some assembly lube.
I immediately noticed a difference in trying to turn the motor over by hand using the fan. The belt would frequently slip without being able to turn the crank as soon as I got past installing the 4th cylinder. Once the head was installed, it was impossible to get the engine to turn over without the belt slipping. I hope to test fire today with positive results.
Lingering concerns: 1. The pistons had 7 piece rings installed. I'm not very experienced at all, but I have never seen this set up. It has a top ring, the second grove had 3 rings (one thicker ring, a thinner ring, and a heptagonal ring under those whose job seemed to be to keep outward pressure on the other two), and three oil rings (the center ring was more like a bearing cage than the typical wavy oil ring). Anyone know about these rings? 2. The con rod bearings have a bit of horizontal play. I didn't replace the bearings knowing I'm going to have to do a full rebuild soon, and I hope it is the wear in the bearings that is allowing this, but I would appreciate any input. The caps seemed to have been torqued pretty tight when I took them off and I am seeing some conflicting info on the proper torque. I have not filled the crankcase and would appreciate a torque spec for these before I do. (Currently set to 30ft-lb.)

If you can't turn the engine with the plugs out, you have a serious problem. Given your progressive increase in effort as you installed each piston, I would suspect that your weird rings are the culprit.
Carl

Thank Tim:

http://www.canadianmilitarypattern.com/1960%20235-261%20Engine%20Manual.htm

This is about as good as I have seen. I have never seen more than 3 ring grooves and 5 total pieces. I admire your persistence. Its a great way to learn if you have that sort of patience!

BTW, Pi is 3.14159. It really matters to get down to at least 4 decimal places.

It was not uncommon to have an expander under the second ring, which serves a dual purpose. It seals compression on the upstroke, and twists to provide a "scraper" action on the downstroke to catch any oil the oil ring missed. You're describing a normal 3-section oil ring on the bottom groove, two thin chrome-faced scraper rails and a corrugated-looking separator between them. It's normal for a new ring set to make an engine hard to turn, especially if the cylinders have been honed to the correct kind of crosshatch, about a 60 degree angle between intersecting scratch lines. I hope you cleaned the cylinders after honing with hot soapy water and a stiff-bristle scrub brush, followed by several rinses with almost-boiling water. Leaving even a little hone grit in the cylinders will destroy new rings in a very short time.

You're WAY over the recommended taper so don't expect the ring job to last long.

Torque specs from the Federal-Mogul master specification catalog:

Rods: 35-45 ft/lbs
Main bearings: 100-110 ft/lbs
Cylinder head: 75-80 ft/lbs

Good luck!
Jerry

Thanks for the info and support along the way! I cleaned the cylinders like my 2 strokes- ATF with a clean paper towel until it comes out clean. I'm not expecting to go long before a full rebuild.
I cranked the engine over last night and everything looked alright, so I tried to fire it up. I had no luck. It sputtered a few times, but I couldn't get it to fire up and since I was late I called it quits. I'll try again today. I have noticed that fuel will usually pool up in the intake manifold. Is this normal? Is the engine flooding?

I wore a set of rings to less than half their original thickness in 2500 miles doing a similar type of cylinder cleanup, except I was scrubbing the cylinders with clean paper towels and lacquer thinner. By the time I reached Tennessee from California immediately after a ring job, the engine was using three quarts of oil to a tank of gas. The oil ring expanders were rubbing the cylinder walls and the compression rings had practically no tension left.

Try rechecking the ignition timing. With the pointer and the ball on the flywheel lined up, adjust the distributor housing so the points just break as the housing is turned CCW.

No, the fuel should not puddle in the manifold unless you're choking the carb heavily.
Jerry

I tried again yesterday and it ran for a few seconds and died. I tried messing with the timing and it started to backfire. I wasn't able to find the famous bb to try to get things lined up. I will try again this weekend.

To get in the ballpark on the "BB" position, watch the #6 cylinder valves. Rotate the engine slowly in the normal running direction (CW facing the front pulley) and watch the last rocker arm in line (#6 exhaust). It will open, then start closing. Just as the intake (second in line from the back) begins to open, the #1 cylinder will be at TDC on the compression stroke. Rotate the distributor housing CW until the points close, then turn it CCW until they just barely open. Lock the adjustment down. The timing will be set close enough to run, and the BB should be very close to the pointer at this time. Find the distributor cap tower that aligns with the rotor as the points just break and use it for the #1 spark plug wire. Install the other plug wires clockwise as 5-3-6-2-4. The engine should start and run enough to do a warm-up with the above settings.
Jerry

No luck... I don't think I have spark. This is so frustrating! Nothing in the ignition system was touched but now it won't run. I checked the valve clearances and tried to get the timing close. I suppose I will have to try again later.

I still think this "BB" is some sort of inside joke... No bb, but I got it close and firing up. That's the good news.
The bad news is that the block is cracked on the driver's side. Nearly the entire length of it.

It's becoming clear to me that truck wants a 270 or 302 in it...

There's a local 58-62 235, but it is seized. At $200 I may consider it. Would it be a direct replacement? Thoughts?

What year is your 235 - I think it was mid-50s?

The 58-62 might be a direct replacement, as long as the front motor mount matches (if it does not, there are usually ways to adapt it).

You would be buying another set of unknown problems, if the local 58-62 engine is seized. Are you ready for that?

Mine seems to be a 55. The guy selling it is willing to part it, so I may be able to have a look inside before buying.
What other options do I have? There are a few 305s, 350s, and ls series engine/tranny combos. But I'm more afraid of the increase in electronics and fab work required.

gusco-

After exactly four months of you doing everything you were advised, digging in, and fighting to get this engine up & running...
you've earned a pass on saying "this is so frustrating." Hang in there.

What's the anniversary date? Maybe we can help with sourcing.

Brad

I appreciate the support, Uncle Brad. It means a lot. I certainly wouldn't turn down the help, but I'm probably pretty isolated down here in deep South Texas. I found a few blocks on eBay, but my wife and I are weary because there's no way of really knowing what shape one of these 50+ year old engines are in. A 235 rebuild kit would run from $600-$800, plus the machine work (I estimate another $600). So that would make for at least a $1200 endeavor. I'd say an LS swap would probably run in the $2000 ballpark... making it about a $800 difference. Since my wife left work, I am seriously contemplating parting and selling to try to make some of my money back (I'm about $2400 in it).

BTW- the guy selling the local 235 is willing to sell just the block for, what I would hope, $100.

Went to check out the block today. Owner knows very little of its history (bought it to put in a '46 car) aside from that it is seized. He's willing to do $125 for the complete assembly. 848 head, foot pedal starter, rochestrr carb, manifolds, generator. My thoughts are that at that price, this motor can be disassembled, checked, and sold for parts of it is not rebuildable. However, I'm still worried about the potential cost to rebuild this motor.

If you go to my article here:

http://devestechnet.com/Home/Project1959235

and then I realize you have no intention of taking it as far as I did, but there is an invoice on what a Central Kansas Machine Shop charges for each task. This is a pretty economically depressed area so I am sure the price in South Texas and Central Kansas are pretty much the same. That will give you an idea of what you will have to pay.

My thought is you will be in sticker shock just like the rest of us trying to rebuild these old motors. But paying a little more when it's completely apart is a whole lot smarter than messing with the longevity of the rebuild job.

That is quite the article. I had come across it before. Unfortunately, from my phone I cannot see that machine shop receipt nor list of the work done. What was the total?

another thought is to have the old block stitched, the right guy can do a very good job

I thought of that, but thought the crack must be going into the cylinders for it to cause the engine to smoke... right? The way I'm thinking, if the crack was just on the exterior wall of the block then coolant would leak out and put the engine at risk of overheating, but not leak into the cylinder.

$2600

But everything is itemized so you can pick and choose. Get to a computer and look it over, it will help you decide what to do.

While you check out the prices of everything you may potentially/possibly/might have to pay for- go ahead & order you some Kroil. You'll need it on that $125 motor...
And that could be all you need to un-"seize" it. Did this $125 motor look seized? Meaning, did it look like it had been indoors, or outdoors?

How did you determine your current engine had a crack in it (& exactly where)? What I'm getting at here is if you can't see the BB on the flywheel, through the hole in the bell housing, how cleaned-up is everything else on the engine? A huge crack would explain some things, for sure, so don't think I'm not believing your observation.

Brad

The crack seeps/beads water along the driver side as the block warms and the water pressure builds. Once I saw the beads, it became pretty clear that it was a solid (and long) crack.
The motor has been sitting outside. I pulled the cover and the rockers/valves seem normal, albeit a bit dirty. My estimate of $600 in machine work was for a deck and bore job. Trying to keep it as cheap as possible due to our current economic situation. What I keep bouncing back and forth on is spending approximately $1300 for a 235 (again, assuming around $600 from the machine shop and a basic rebuild kit of around another $600, plus odds and ends, and transfer as many of my internals as possible) or getting that LS ($400) and run a carbureted set-up ($600 intake + MSD 6LS, + $100 for weld in mounts + $??? bellhousing, if necessary) and run a modern 20mpg, nearly 300 hp motor for a few hundred more.
Another option that came up was a shop in Kerrville, TX (about a 5-6 hr. drive for me) that may provide 3 options: 1. build up 235s; 2. 235s taken out of driving vehicles; 3. Ready to machine blocks. I'm really interested in option 2 because it would yield a driver for the lowest cost and allow for a future rebuild or LS swap when my wife goes back to work.