Tech Tips

General

Degreasing

One of the first things I do when I get in a truck or tractor is to degrease it.  It makes it easier to work on, and allows you to see what you have and where problems may be.   Any off-the-shelf degreaser will work although I have recently been using Zep’s Citrus Cleaner/Degreaser (available at most Home Depots) and been very impressed.   Scrape off the worst of the crud, spray on the degreaser (I have a garden sprayer dedicated to this – fast and easy) and let it soak in.  Usually 15 minutes or longer is necessary to have any effect on old, dry grease. I have the luxury of being able to have hot or cold water at my shop outside hose.  Warm, or better yet hot water, will tremendously improve the action of any degreaser as it softens the grease and will even strip it away by itself if the water is hot enough.  You may need to hit it two or even three times if it is really grimy.  Most petroleum based degreasers react with water so the engine will need to be thoroughly dry before you give it a second degreasing.   Citrus Degreaser is already water based so you can give it another application as soon as most of the water has dripped off.

Removing broken studs or frozen bolts
1) Soak the part with penetrating oil. I really like Kroil by Krano Labs – it seems to be the very best out there (see “Resources” for link Krano Labs)
2) Tap the part repeatedly as well as the area around it.
3) Patience. Any penetrating oil takes time to work.  Let it soak over night, spray on some more, and tap again. Let it sit. (If the part looks like it may be hard to take off in the beginning, you are better off starting with this approach BEFORE you break it… soak-tap-let sit-repeat)
4) Any thread is under tension as it goes in and the tightest contact is on the side of the threads toward you. As long as you don’t care about the broken end, place a flat punch, socket, welded on nut or other hard surface against the broken bolt end and give it a good whack INWARD with a hammer. This will reduce the tension on the threads and maybe let in some penetrating oil.
5) Try turning, and if necessary, repeat #4 above. An impact wrench is very effective here if you can get it on it. If it is a rounded nut, you can use an air chisel directed to drive the nut off.
6) If it still doesn’t budge, use heat. When it is hot (but not too hot – you don’t want it soft) give it another whack with the hammer. Try to loosen. Let it cool and contract and try again. Repeat the heat/cooling cycle which through uneven expansion/contraction will often break the rust bond.
7) If it is still stuck, heat it again and while it is fairly warm, melt paraffin wax on the bolt and let it flow into the threads.
8) If it moves at all, put on more wax or paraffin and retighten. This may seem nuts, but if you repeat this a few times it works the lubricant into the threads.
9) Another option is to drill down the center of the stud all the way to the back side. Soak with penetrating oil or paraffin. It is more likely to be effective here as there is more space on the backside of the threads.

Engine

What year is my 235 engine?

Look for these features to determine the year of your Chevy 235:

’41 – ’48 – Very small (10 mm) sparkplugs
– Tall push rod cover that surrounds plugs (pass. side)
– Two screws in center of valve cover
– Small plate with curved oil line on lower center, driver’s side of engine
’49 – ’52 – Same as above but plugs are standard size (14 mm)
‘ 53 – Same as ’49-’52, but no plate and oil line on drivers side of block
’54 – ’62 – Four screws hold on valve cover
– Push rod cover ends below plugs
-Water pump body is below the head gasket surface (’55-’62)

Note: Ignition components will differ between model years outlined in chart above

Want to REALLY nail down the date of manufacture?  Look for a 3 or 4 digit date code cast into the block just above the oil pan and behind the starter on the distributor end (NOT the stamped numbers by the distributor).  The first will be a letter A – L corresponding to January – December.  The middle number(s) are the day of the month it was manufactured, and the last number is the year.   Hence a block with a casting ID of “D 12 4” would have been manufactured April 12, 1954

– To cross-reference your Chevy block/casting number, go to http://www.oldchevytrucks.com/casting_numbers/casting_numbers.htm.   to cross-reference your GMC block numbers go to http://www.inliners.org/casting/numgame.html or http://clubs.hemmings.com/clubsites/chevytalk/GMhistory/cast.html

– 1953 was the transition year for Chevy.  The ’53 Powerglide transmission that year went to insert bearings and full-pressure lubrication, as did all later models.

– If you want to retain your original 194* engine, you can have your rods machined to accommodate insert bearings if necessary or desired.  There is a wider selection of sources for parts for the newer 235’s however if you decide to re-power it instead.

– The rear of all  1941 – 1962 Chevy 235 engines is identical, making swaps fairly easy.  Reuse your original bell-housing, flywheel and starter, and everything will line up just fine.  (Patrick’s Antique Chevy & GMC @ 820-836-1117 has a variety of parts to assist with upgrading your older 235 to a newer higher performance version).

– If you are swapping engines to a newer 235 cid, use the water pump that comes with the engine, but install a smaller diameter fan.  If you don’t,  the larger fan won’t have enough clearance. Kits are also available through Patricks (see above) with short water pumps and pulleys to allow ’55 -’62 engines to be placed in earlier vehicles and still have clearance. (Thanks to Steve Keith)

– The easiest swap is to stick with a Chevy 235, although I have seen other Chevy engines (261, 292) installed in them.  The 261 is one of the easiest and best swaps if you can find one.  The 261 was used in Chevy’s trucks (C-60) and buses from the mid 50’s through the early 60’s.  The engine will bolt right up to your existing 40’s Chevy bellhousing.  Although there was a Canadian version that was not, the 261 was a full pressure oil engine.  It can be identified by the oil filter mounted on the forward part of the intake with two lines that look like hydraulic hoses hooked to it.

It is a difficult project to fit GMC engines (248, 256, 270, 302)  into the Chevy due to the fact it is longer than the Chevy, the power train sits lower, and the starter linkage is on stand-offs. Modifications are necessary, and can be done but it is usually not worth the aggravation and labor.   (Thanks to Steve Keith)

Drive Train

There are two transmissions.  The original with a granny 1st and a military version with close ratios 1st gear.  The military version has two grooves in the cluster gear shaft. (Thanks to Steve Keith)


Painting

  1. I prefer Gillespie Paint.  Color # 33070 was used by the Army up to and including much of 1944.  Color 319 was used late in 1944 and later.  Marine Corps vehicles are typically 23070 (semi-gloss olive drab)

  2. Xylene, Synthol or mineral spirits will all thin Gillespie paint.  Use Xylene if you want to have the spray cans match later for touch up. Addition of hardener will give a more durable finish but one that is glossier and tougher to touch up. Generally, thin 4:1 without hardener or 8:2:1 with hardener (paint:thinner:hardener).

Shop Tips

I have very hard water at my home and shop.  A few years ago I tried a Scaltrol water treatment system which is basically a polyphosphate feeder about the size of an oil filter.  It is easy, safe, and best of all it works great.  If you have a pressure washer in your shop it is well worth the protection.  Lots of info at www.homeandfarmsolutions.com