The Stovebolt Site Forums The Shop Area Engine Shop 235 smoking, blow by, low oil pressure low power

Hi all,
Likely my first post here.

I have a 1962 c10 that was my granddads, I rebuilt the body (amateur backyard style) and got it on the road. Only took 4+ years of welding on the body etc.

So the truck was in another state at my dad’s house the entire time. He got the brakes working and got it running and driving, and stored it.

When I went to load it up to bring it home… apparently we both forgot that one of us had drained the oil at some point….

Basically idled it for roughly a mile without oil in it. I thought it was the noisy clutch, as it had been 6+ months since I had seen or driven it.

So when I got it home I drove it a bit (with oil in it of course), low power, cylinder 4,5,6 (or some combo) not making power, and burning oil. (Split exhaust so I know at least two of those cylinders were not firing. And a good bit of oil burning from 4,5,6.
After about a dozen test drives I pulled the original engine and popped in a used 235 I found for free. (This used one also burns oil and had low power, and cylinder 4,5,6 not firing (that turned out to be some combo of ignition: plugs, wires, distributor etc as I now have it firing on all cylinders, but still burning oil))

Anyhoo…. Ran without oil for a bit…That explains the worn bearings. And low oil pressure once hot at idle.

The low power was some combo of throttle/carb/etc as it now has decent power with a new universal carb from mikesCarbParts.

But…. Today I got the engine on a stand and pulled the pistons… to my surprise the rings look quite good, cylinders look pretty good (other than the hatch marks gone).
(Certainly will re-bearing and re-ring it).

Can just the lack of hatch marks on cylinder wall explain the burning oil?

(The valves guides are also quite sloppy) and most of the o-rings in valve stems were broken… )but this thing smoked all the time, especially under load.

Also, can I somehow measure the cam… maybe measure highest point? To see if cam is any good?

Also, is it likely the crank survived? With bearings showing copper (or whatever other metal) ?

The old Sun Electric Co. slogan that they put on all their diagnostic equipment definitely applies here- - - - - -"We test- - - -not guess!" Before you start throwing parts at the problem, some precision measurements need to be involved. The cylinders wear tapered, with the majority of the wear happening in the first 1 to 1 1/2 inches of the piston travel. If you can hang a fingernail on the ridge at the top of the cylinders where the rings don't travel, chances are a re-ring job won't last long. The ring ridge can be machined away with a tool made specifically for that job, but if the taper wear is much over .005", the rings will flex constantly trying to maintain contact with the cylinder walls and they will lose their tension quickly. You'll be back to burning oil when that happens. A ring running in a taper-worn cylinder is flexing 66 times a second at 2000 RPM. A quick and fairly accurate measurement of cylinder taper can be made with nothing but a used piston ring, a feeler gauge, and a calculator. Position the ring up against the top of the cylinder where the ridge begins, stack up feeler gauge blades to measure the ring gap, and write the measurement down. Use a piston to push the ring to near the bottom of the cylinder and measure the gap again. Subtract the bottom measurement from the top, and divide by 3. (Actually Pi- - - -3.14) The result will be the cylinder taper in thousandths of an inch.

Example:
Top measurement: .045"
Bottom measurement: .020"
Difference: .025"
Divide by 3.14 = .008"- - - - -time to rebore and install oversize pistons.

Also measure the crankshaft rod journals with a micrometer (not a dial caliper!) They should be round within about .001", and the taper wear from front to back should be .0005" or less. Egg shaped or taper worn crankshaft journals will wear out bearings in a hurry, and will also drop oil pressure.

Good luck with your rebuild!
Jerry

I did cylinder 1 ring gap check…

Top ridge: .103
Top: .129
Middle: .066
Bottom: .063

.129 - .063 =0.066

.067 divided by 3.14 = .021

So…. Guessing .030 over might be what I can expect (or more).

(I will be bringing it to a machine shop clearly).

(I wonder why the top ridge is bugger than bottom of cylinder… previous backyard re-ring?)

How far down the cylinder did you take your first measurement? If you measured up high (top 1/4 - 3/8" of the cylinder), it could be that a previous "rebuilder" may have gotten over zealous when removing a cylinder ridge to remove pistons. I would remeasure your cylinder bore at least 1/2" below the deck top, then re-compare your measurements.

Though I did not measure from deck to ring, I would estimate 7/16” down when I measured the ‘top’. I will get a few more measurements toward top of #1.

Am I wrong In Thinking that my ring gap should be .017 max, and have .063 at best… .129 worst … so might be a junk block? .112 is more than .060 over (which I assume is the max overBore). Or since I don’t know original ring gap… that ring might be the problem in my math…. ?
Edit: ^nevermind .129/3.14 is .040 over so I think I jumped the gun there.

I will probably do the other 5 pistons measurements tomorrow assuming I have some time after work.

I was not planning on needing all new bearings and pistons, but what’s another 7/800 dollars for an old truck…

I am guessing 1200 in parts and 1500 at machine shop. That’s likely a low Guess.
Now to find a machine shop.

Here's the most accurate way to measure cylinder taper, but unless you're building more than one engine, it might not be worth the cost. I've been using a shop full of precision tools for the past 50-something years, so sometimes I don't even think about the idea that not everybody is equipped that way!

www.ebay.com/itm/286564765887?

Jerry

So… I have been trying to remove the camshaft… and like a dummy I did not ask or buy a book etc.

So what book should I buy?

Turns out the valve lifters are all stuck in their hole.
I don’t want to use channel locks on them to get them out…. Surely that damages them?

Could I use feeler gauges (or some other quite smooth steel) to shove between lifter and cam, then rotate assembly to help push the lifter(s) out a bit more?

(I have them soaking in some combo of wd-40, roil, and pbBlaster for now).

Thanks.

PS: I am sure the machine shop would pull the lifters and cam… but I have never removed a camshaft… so I want to pull it,,, even if I just put it right back in.

Wally - On your question "what book should I buy?", for your 1962 C10 you will want to start with a 1960 Chevrolet Truck Shop Manual like this reprint form Classic Parts. Then you should get a 1961 Shop Manual Supplement, or you can get a CD with the full set of 1960-62 Shop Manuals.

These are available from a number of other sources too and you can also find used originals for sale if you do some web searching.

On trying to pry your existing lifters out by inserting something between the cam and lifter I would highly suggest NOT to do that unless you are planning to replace them or have them reconditioned. You are likely to damage the surfaces removing them in this way. And definitely do not use vise grips to try and grab/remove the lifters. Not only will this destroy the lifter surface, but it could also damage the lifter bore when trying to further remove the damaged/scored lifter.

Patience, Grasshopper- - - - -turn the cam until the base circle of the lobe is under the lifter, tap it down against the cam with a brass drift, and soak the whole works liberally with PB Blaster or KROIL. Repeat as required for all 12 lifters. That gets the lifters moving in their bores without having to pry or risk other damage. Once all the lifters are at their maximum upward travel the cam will slip out from under them. They don't necessarily have to be removed until later in the disassembly. Don't forget to remove the fuel pump and unbolt the thrust plate. it's accessible through the holes in the timing gear. The best "service manual" to have is a healthy dose of patience and common sense, no matter what engine you're working on. Stovebolt engines can handle an 80 overbore without any problem, but that would be the max most engine builders would attempt. Anything bigger requires "semi-finished" pistons that are ground to the diameter needed, and they are virtually impossible to find these days.
Jerry

It's possible to build a stovebolt engine with non-original parts- - - - -connecting rods and rod bearings for a big block Chevy V8, pistons for certain Ford, MOPAR, AMC/Jeep, or Japanese diesel engines- - - -roller valve lifters for a big block MOPAR, and non-standard main bearings. Unfortunately, that requires something that's even more scarce that OEM stovebilt parts- - - - -a competent machinist!
Jerry

Ordered those books. Thank you.

I got the lifters out today. Took about 15 minutes each of wiggling them up and down while rotating. Pretty sure the soaking in Kroil/seafoam mixture for about 24 hours assisted. A plastic stick assisted sometimes.

Cam slid out no problem.

That plastic cam gear is pretty wild stuff for the 50’s-60’s I would think.
I assume a new aluminum cam gear is recommended?

I remember rebuilding a mid 60’s mopar 383 that had a timing gear with nylon(if i remember correct) teeth.
I found the idea of plastic teeth nuts at the time which was back in 80. Funny thing is all the teeth were intact.

Pontiac used nylon (or some kind of plastic) chain teeth on late 60s-early 70s camshaft sprockets. Lots of them failed.

Stovebolts in cars ran a fiber gear (Bakelite) back as far as the early 1950s, at least. Trucks ran an aluminum gear. The plastic coated timing chain sprockets (not gears) were used in other engines during the 1960s. Those were notorious for the plastic getting brittle and breaking up- - - -and the debris would clog up oil pump pickup screens and cause low or no oil pressure.
Jerry