Chevrolet 235 Engine Swap

 This article comes from Patricks and I am including it because of the
number of requests on how to do this procedure.
Contact Patricks for 1937 to 1962 Chevrolet 6 cylinder rebuild and hop up parts. They have an amazing inventory of early speed equipment
and engine parts.

Click here for a printable text version of this article.

If you own a '37-'53 early Chevy car or truck with a "splash oiling"  216 or 235 engine, and want a smooth, powerful daily driver, installing the later full pressure 235 is the answer.

This new design was first installed in 1953 passenger cars with PowerGlide, thereafter in all models and sizes (passengers and commercial).  Not only does the swap happen easily, without butchering or modification, it brings improved performance and reliability from full pressure oiling, insert rod bearing, and lighter weight aluminum pistons, not to mention improved breathing, thanks to larger intake valves and ports.

Read on for the (9) simple installation tips and identification clues to help you score the right engine. This is one swap "made in Heaven"...

1. The rear of every Chevy '6' block (216, 235, or 261) is the same from 1937 through 1962, and the flywheel/crank-flange pattern is the same from '41-'62! We obviously have wonderful interchangeability. Therefore, using pure Chevy parts, any engine from '37-'62 can be installed into any chassis (car, truck, etc.) from '37-'62! You will however, need to pick the right parts. Here's how...

Whatever you're putting the donor engine into ('41-'53), re-use your original bell housing flywheel and starter. This means your rear motor mounts remain unchanged. '37-'40 installations will need to get a '41-'54 wide tooth (#139)  6 bolt flywheel off any 216, 235 or 261, then use the original bell housing and starter. The 6 volt starter is just fine, even if you're converting to 12 volts... it'll love it!  (Final Note of Caution: the fine tooth (#162)  '55 and later flywheel will not mesh with your original starter! Do not use it.)

2. Pre-'49 cars and trucks will have to slightly alter the exhaust pipe to fit the 235 manifold. By the way, 216/235 exhaust/intakes won't mix and match, and though the entire 216 manifold set can be bolted to the 235 involved, it's a bit Mickey Mouse since the port rings will have to be eliminated due to the 216's smaller port size.

3. If your "new" 235 has the big water temp. hole, ask NAPA for Balkamp part #701-1542 (Weatherhead calls it p/n 202x5x4). Now, your original temp. sender fits.

4. Let's solve the "hydraulic or solid lifter question" now... Solids were the rule on every Chevy '6' through 1949 (either 216 or 235 "Loadmaster"). Between 1950 and '57, solids came with every commercial or "stick" (pass.) transmission, whether 216 or 235 or 261 engine. Hydraulics went only with PowerGlide equipped cars. From '58 to '62, every block was drilled for hydraulic lifters, though some had solids installed. Hydraulic lifters will only function in a block that has the oiling passage drilled through the lifter bores (which hole will be plugged and visible on the rear of the block, just above the cam plug).

'58-'62 engines must use a lifter with chamfered sides to prevent shutting off rocker arm oil! NO oil line from rear cam bearing to block center will be found in the pushrod chamber of these engines and, in addition to the I.D. criteria (above), will have a triangular side mount pattern.

5. Mention MUST be made of the Federal reduction of gasoline lead content to .1 gm/gal. beginning January 1, 1985. This amount of lead additive is 1/10 of the amount your engine was designed for and continued operation will effect exhaust valve/seat life.

Take the time, while you're building your engine, to have the no-lead exhaust valves and seats installed in the cylinder head! (You'll get to do it sooner or later). Call Patrick's for the parts.


1. SPECIAL NOTE for all 1952 and '53 Passenger. Your cars have a side mount arrangement which will require locating a full pressure block from either a '53 P.G. or (any '54) cars or truck.

2. Identifying the full pressure you want to install. (Remember, you're looking for a '53 P.G., or anything later.)

A. Simply checking the style of the water pump will take care of about 90% of the prospects. If it has a pump whose entire body is below the head casket surface, rather than half on the block and the upper half in front of the head, it's gotta be '55 (2nd) through '62. You've found it. The search is over. Disregard any of the next criteria.

B. Check the rocker cover ("valve cover"). If it's held on with four (4) screws (2 on each side), it's a '54 through '62 and the right one. Look no further; you just scored .

C. Walk on by any engine with the tall pushrod cover that surrounds the spark plugs. It is a "babbit pounder".

D. Also eliminate any engine with the little tell-tale triangular plate and curved oil line in the middle of the driver's side. This tells you it has the dreaded dipper rods and splash oiling. The driver's side of the engine you want is "clean" (no plate or line).

E. Disregard any engine with the studs through the rocker cover, except one: the '53 P.G. (first year); but, it will be without the above plate and line, too.

F. Want to pinpoint engine I.D.? On the block above the end of the starter will be an initial (A-L), followed by either (2) or (3) numbers. The initial represents the month: the numbers are the day and year the block was cast. Now then, no more guessing!

3. A note on front of mount plates. They will interchange on every Chevy '6' (216, 235, or 261) built from 1937 thru '62! This matches the bell housing story. It's another story, but the fronts and rears of every Chevy '6' are also the same as every GMC "small" '6' (228, 236, 248, 256, 270, and 302)!
Obvious why these were popular swaps!

4. Throttle linkage may need modifying if your block's bellcrank mount hole is further back (toward firewall). Easy...some of the curve will need to be taken out of the accelerator rod. Squeeze it in a vise until it makes its travel without rubbing the floor pan (as installed in the bellcrank, without return spring). When that's done, measure how much it needs shortening by bringing the whole linkage assemble to "full throttle". Simply cut that amount out of the slender part of the rod and re-weld. Done!

5. Front engine mount pad(s) should be installed on the engine before putting it between the fenders, since the passenger side bolt may only go into the mount with the timing cover and crank pulley (OK, "harmonic balancer") removed. (See front mount hole in addendum item #3.)

6. Water pump/generator alignments depend on each other. Install the water pump first. If your 235 wore the long water pump pulley, DO NOT BEGIN HACKING ON THE RADIATOR CORE SUPPORT and/or LATCH PANEL! Patrick's has the short pump and special pulley for only $109.95. This allows for the use of the larger, late model fan, which provides better cooling. (Note: it is not correct to press the early 216 pulley onto the late water pump, since this spins the impeller approximately 190% of design speed, and may even cavitate the water, causing overheating. In addition, the old back-woods method can literally be dangerous, since it requires using the 216 "low speed" fan which is turned far beyond its design safety.)

7. Now, align the generator with the water pump pulley. If you wish to switch to an alternator at this point, Patrick's has the bracket set for only $49.95. (specify year.)

8. Radiator Hoses and sizes. Upper hose may require re-use of your 216 thermostat housing. No sweat, bolt it onto the 235 cylinder head. Lower hose may need to be dual size. Your neighborhood parts house has them available.

9. Crankshaft Pilot Bushing. Check for the presence of this vital item if you're putting a "stick" tranny behind the later 235! (if the engine came with automatic, it may not have one). Chevy part #3752487. Install with chamfered hole toward you. Drive bushing flush.

10. Enjoy!

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