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Engine Swap

From Dick Larrowe, Ron Cox and Barry Weeks
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Swap that 216 for a 235
or bigger engine

    A lot of truck owners aren't comfortable with the low oil pressure and slower revs of the venerable 216. But neither are they comfortable with sacrificing their truck's original appearance. Here are two articles to help you if you decide to replace your 216 (or older) Stovebolt with a newer six.


By: Dick Larrowe And Ron Cox -- Our friends from the Stovebolt Engine Company

   One of the simplest methods of improving the overall performance of 1937-51 Chevrolet passenger and trucks is with the installation of a 55-63 Chevy 235-261 six. Not only does the increased displacement enhance performance, but the later engines are a far better design! The 235-cubic-inch inliner made its debut in trucks in 1941 and in passenger cars in 1950 (available only in Powerglide automatic-equipped DeLuxe model cars). The 235 offered improved performance over its 216-cubic inch predecessor, but it still had a number of shortcomings; namely the splash oiling system used to lubricate the rod bearings.

   For 1953, Chevrolet introduced an improved version of its venerable six again in Powerglide-equipped cars and featured pressure-lubricated rod bearings. Beginning in 1954, all Chevrolets featured full pressure oiling; this significant change improved the inline engine dramatically. Obviously, swapping one of these engines into an earlier car is a desirable retrofit. But '53 Powerglide and '54 full pressure aren't as easy to come by as they once were, making the more plentiful '55-'63 engines an excellent choice for such swaps. With the same dimensions as the splash system the later engine is a simple and effective up date.

A simple swap for '37-51's

   The '37-51 cars all used the same basic engine mounts, which are the rubber biscuit type. Two are used, one on each side of the motor plate. These mounts are also used on the 1935 Master, '36 Master and Standard, as well as all 1937-51 passenger cars and sedan deliveries.

   The first step toward improving performance and reliability for these early cars is yanking the original 216 or 15 bolt-head 235 out of the engine compartment.

   Once the engine is out ( a process made much easier by removing the sheetmetal from the firewall forward), remove the motor mount plate from the block. To do this, the vibration damper must first be taken off the end of the crankshaft.

   Next, remove the oil pan and the two screws from behind the front main cap that secure the timing cover from the inside. Now remove the four bolts and two studs from the rocker assembly and lift it off as a unit. Older models have the oiling tube attached with a screw-on fitting, so loosen it. Later models fit the tubing into a hole in the head. Set the assembly into an overturned valve cover so the springs don't push the rocker arms off the shaft. Punch 12 holes into a cardboard box and number them 1-12. Remove the pushrods and put them in the cardboard in order. Use an egg carton to hold the lifters in the same manner.

   The crankshaft can now be turned, either by prying against the teeth on the flywheel or turning it with a special socket that fits over the end of the crankshaft, until the two holes in the camshaft timing gear line up with the two screws in the retainer. These screws are best removed by an impact driver. Pull the cam gear forward and remove the shaft. With the camshaft out, three flathead screws will be visible . Remove the screws and the remaining hex-head screws that retain the plate with the impact driver used earlier. (If the engine is a 37-41, the crankshaft gear must also be removed to get the plate off.) Tap the plate lightly to separate it from the block.

   Use the identical procedure to remove the motor plate from the 235/261 to be installed. Install the mounting plate from the old engine on the new one. For high performance application (ease of changing the cam) we suggest you at this time drill the tapped 5/16-inch holes in the timing cover all the way through and tap thread to 3/8 coarse, then install studs. Now you can get the timing cover off without removing the pan!

   Install a new seal in the timing cover and slide into place, using the crankshaft socket to center the seal on the shaft then tighten the attaching screws and nuts on the new studs. If you plan to use the wide V- belt the 216 vibration damper and pulley may be used. Remove the pulley from the 216 water pump and press it on the late pump until the belt groove lines up with those in the vibration damper and generator (this operation requires a 10 ton press), then cut off the excess shaft. To make things easy, the Stovebolt Engine Company has these modified pumps in stock. Install the original generator or the wide groove pulley on an alternator. Cast and polished alternator brackets are also available from the Stovebolt Engine Company.

   If the late narrow belt is desired, use the vibration damper off the later engine with the water pump pulley from the 53-54 Chevy, Stovebolt also has pumps available for this combination. Use an adapter in the late model head's temperature sender so the early temperature gauge capillary tube can be installed. Install the flywheel and bellhousing from the old engine, along with the original starter and clutch. Now the engine is ready to go back in the car. If a 261 is being installed, make sure a oil filter is used. The 261 is a full flow system on the later models, and no oil pressure will be the result if the oil line to the filter is disconnected.

Jimmies for early Chevys

   Interestingly, the procedure outlined can be used to install a GMC 228-248-270-302 in a '36 Master or Standard passenger car by using a '37-51 passenger car motor mount plate. Use the water pump and the vibration damper from a '37-40 Chevrolet, along with the bellhousing, transmission and starter from a '37-39 Chevy car. When using a GMC with a 4 bolt crankshaft flange, use a '37-39 Chjevy truck flywheel for the 9 bolt heavy duty clutch. For the late GMC's with a 6 bolt crank flanges, use the GMC flywheel with a heavy duty passenger car clutch. NOTE: The '37-39 bellhousings will only accommodate a 10-inch clutch.

Late Sixes for '52-54 Chevys

   To install a late 235-261 in a '52-54 Chevrolet passenger car, there are two methods to consider. The first is to locate the holes for the late front motor mount in the IFS crossmember (still called knee action by Chevrolet until 1954 ). The holes have to be drilled in the correct places. On the 1952 models, there are flat stops in the right place, but on the 53-54 models there are no indications of where they should be, so you will have to get the measurements from a 49-51 and copy them. Then install a 37-51 passenger car front plate on the late 235-261 engine.

   The second way to accomplish this swap is to buy custom mounts from Stovebolt Engine Company The kits come with frame and engine mounts and are a bolt on. The stock '52-54 motor mount towers are riveted to the frame and have to be cut off, as they will obstruct our frame brackets. Once engine mounts are attached lower engine into position, bolt down the transmission rear mount. Then locate the frame brackets. Drill frame holes at this time and bolt in place. The Stovebolt Engine Company motor mount kit is also of value when installing a Stovebolt automatic transmission adapter behind a 235-261 because it shortens the spread to the tail shaft of the transmission.

216 to 235 Engine Swap

By Barry Weeks

In this article, The Stovebolt Page good friend Barry Weeks explains how to have the best of both worlds. Reprinted from the Oct/Nov '93 "This Old Truck" with permission.

I have been running a '57 Chevy 235 in one of my '40 Chevy trucks for over four years now and am in the process of putting together another '40 half-ton chassis with a '62 235 in it. The 1955-62 235 sixes make very good replacements for the old 216's. If you are concerned with drivability more than originality (*see note at end), the 235's have a lot to recommend them. They have insert bearings and full pressure oiling, which allow for higher RPM's than a 216, and 1955 to 1962 235's can be found in running condition in my area for $100-$200. Most can be bought very complete from car owners who have replaced their sixes with V-8s.

I thought the tricks involved in installing a 235 in place of a 216 were fairly common information, but I receive a lot of questions about my conversions. Chevy sixes seem to be getting more popular, so I thought I should share some of what I've learned so far, since it applies to '37 and newer Chevy trucks.

The 235 will bolt right up to the older bellhousing. This would be a good time to replace the rear motor mounts on the bell- housing, if necessary. The front mount should bolt right up if your 235 was originally front mounted. If it is the later, sidemounted version, you may have to drill two holes in your front mount plate and maybe even reinforce it like the 216 mount plate. If you have the camshaft out, you can also bolt the 216 plate onto the 235 motor. Use new rubber in the front mount, as it is cheap to buy.

The 235 flywheel is slightly larger and has more teeth than the 216 flywheel. It also uses a larger clutch. The easiest thing to do here is to use the flywheel, clutch, and starter from your 216. There are a few different 216 flywheels, with different size crankshaft bolts and a slightly different center hole diameter. My 1940 flywheels bolted right onto my 235's. If the teeth are worn on your flywheel, evenly heat the ring gear with a torch to expand it, then remove it. Then grind a small chamfer on the inside edge of the diameter that will fit against the step on the flywheel. Replace the gear by heating to expand and letting it air cool to a tight shrink fit.

The 235's have longer water pumps than the 216's. It may be possible to move your radiator ahead, or you can buy a shortened water pump with matching pulley. Being the cheapskate I am, I shortened my own water pumps by pressing the hub down the shaft farther and cutting off the extra length of shaft. You will need a shorter water pump pulley to calculate how much to shorten the pump. I found the correct pulley on junkyard motors which I think were '53 or '54 235's. This shorter pulley is only abut 2 1/4" long and uses the narrow fan belt. It also has a different bolt pattern from your old 216 pulley. Use a straight edge to check for proper pulley alignment when shortening the pump.

Your 216 thermostat housing will bolt onto the 235. This will allow you to use your original upper radiator hose. For a lower radiator hose, you will need to locate one having the correct bends and a different diameter on each end. These hoses, along with the previously mentioned shorter water pump and pulley, can be purchased from suppliers such as Jim Carter Truck Parts or Chevy's of the '40's. I was in a hurry, so I bent a piece of wire into a pattern and found a hose at my local parts store that I could cut down to fit my pattern. The exhaust, fuel line, throttle linkage, wiring, gauges, and choke cable shouldn't give any problems that aren't easily solved.

I've driven my 235-powered 1940 half-ton pick-up from Minnesota, across Wisconsin to the Iola swap meet. In a distance of over 500 miles, I averaged 22 miles/gallon at a steady 55 miles per hour. Not bad, considering I still have the stock 4:11 rear-end, and am running two Rochester carbs on a Fenton intake manifold.    I am also running Fenton headers with dual exhaust. This motor makes more power than I thought it would. I rarely need to downshift, as it will pull most any hill in high gear. In my case at least, a '55- '62 Chev 235 has worked out great!

Do any other members have information and/or experiences to add to this? If so please write to me:

Barry Weeks
Weeks-End Garage
3647 Lake Elmo Ave. N
Lake Elmo, MN 55042

* Note on Originality:

There are parts suppliers who now sell rocker arm covers, shortened water pumps and pushrod covers to make a 235 virtually indistinguishable from a real 216. Most of the parts vendors also have swap kits to allow you to complete this entire procedure without having to fabricate anything yourself.

(Thanks, Dean)

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