The Stovebolt Site Forums The Shop Area Engine Shop 1937 216 rebuild

In the planning stage on 216 rebuild and need some advise from the experts.
I have a 37 216 that is beyond economical repair due to wear and cracks block casting # 838710, machine be shop says head has a lot of cracks.
Picked up a 39 nos short block but no head casting # 838941
Found a 42 block with good head block casting # 839770.
Here's the problem
38 has flat pistons
42 has domed pistons
Plan on using all engine components from the 37
Machine shop guy says if I put domed pistons in 38 block I can use 42 head.
Is that true? Any problems?

Next question: if I can use domed pistons should I buy standard pistons or should I bore block and use .040 pistons from 42.

Other option is to build a 235 full pressure

Truck is completely disassembled right now for frame off restoration.
Thank, Johm

If you are not building a concourse de elegance quality build, you would be money ahead by building full pressure 235.
A '53 235 With Powerglide Engine (that is what they call the engine, you don't want the Powerglide transmission). or, a '54 235 from a truck or a car would be a direct bolt-in.
Any 235 '55 or newer will require some modifications to make it work. Nothing too difficult though.
It is hard to find anyone capable of rebuilding a 216. If you find one who can, it will be considerably more expensive to have rebuilt.
I hate saying this, because 216s in old trucks is too cool.
Carl

Just a little correction,
1937-40 had dome pistons, everything after that had flat top pistons.

Just a friendly heads up, check your title before you scrap the original block as the engine serial may be on the title. If that's correct, than that's the only place its marked on the truck...

Mike B

If so, need to see DVM to get SN assigned VIN.

Ed

Your correct Dave I have it backwards. Thanks for setting me straight.
So if I tried to put flat pistons in the 39 block with a 42 head would I be asking for trouble?

Thanks for the information Carl. I have a line on 3 235 cores. One is a 56 that is a good engine block # 3837004. Sitting at engine shop half built.

The other two block #'s 3769716 & 3738307 (1960 & 62) are unknown condition cores under cover.
What modifications would be required on these engines?


Thanks for your help, John

Have you looked in the Stovebolt Tech Tips (the link is on the menu at the top of this page)?

Engine Section

high pressure engine swap?

waterpump relocation, by Pre '68 Dave

Thanks for info. Read it.

Using flat top pistons in a 1937-40 engine is not a problem, as long as you use a 1941-53 head.
Using a 1937-40 head would give you very low compression and power.

Boring the block .060" oversize and using Std. size 235 flat top pistons would probably compensate for the compression loss with the domed head. That makes the "216" a 224 cubic inch engine. It also replaces the cast iron pistons with aluminum- - - -less reciprocating weight, faster acceleration, and less stress on the Babbit rod bearings. Doing the same thing with the head for the flattop pistons will give even better performance.
Jerry

Thanks Dave that's what I wanted to hear.
Thanks for info Jerry.
Since the 39 short block is new old stock standard bore I'm thinking flat top aluminum standard pistons with a 42 head. This way I don't have to pay for a bore.
I like to do things right but I'm kinda cheap
What do you guys think, John

Sounds like a good plan.

Aluminum 216 pistons are pretty expensive. People give me good condition std. bore 235 pistons just to get them out of their way when they rebuild their engines, and I recycle them into 216 engine buildups. That usually makes the cost of a rebore job a moot point- - - -especially since I've got a couple of Van Norman boring bars and a "retired old man" work schedule!
Jerry

i will run that by my engine guy but if I don't have a source for good used pistons from 235 isn't the cost for 216 and 235 pistons about the same?
John

About the only source I'm aware of for aluminum 216 pistons is Egge Machine, and they think they're made of gold, not aluminum alloy! Original equipment 216 pistons were cast iron. Try an ad in the "parts wanted" forum- - - -somebody's probably got some good used 235 pistons left over from an engine job gathering dust on a shelf somewhere.
Jerry

Just so you know, a standard bore 216 would need to be bored .062” over for a standard bore 235 pistons.

Most machinists bore any cylinder to the diameter of the piston that's going into the hole, and put the skirt clearance in with a hone to eliminate the machining marks. The finish bore would end up 3 9/16" for a 235 Std. piston, with about .0025-.003" skirt clearance- - - -3.0625" final diameter, with the clearance built into the piston skirt. To do it accurately most good machinists insist on having the pistons on hand before they start whittling on the block, and fit each piston individually.
Jerry

Actually 3.5625 to be accurate Jerry.

Also, before using any used aluminum pistons, look very close at the ring lands/grooves for wear.

Maybe I missed something but I thought OP said he had an NOS shortblock. If that's true what's the need for boring and pistons at all. There's a lot to be said for a stock bore and pistons not to mention the stock size rotating assembly. Basically all he'd have to do is come up with a properly aligned oil pan, pump and have the head rebuilt. What am I missing? I've been on pain meds from a kidney stone removal so that's certainly possible. Drink more water!

What's a half an inch between friends?

The issue is the nos short block doesn't have a good head. Anybody know where I can find a good head for a 216 With domed pistons?
I still have one more local source looking in his collection.
Started getting parts around today and plan on going to engine shop on Wednesday.
Thanks for all the imput. Will keep you informed on progress
John

A photo is attached for an odd Ross pop-up “domed” piston is attached (from an ) Internet search.

Did the head have to be special/adapted to use those pistons?

You may want to check if the 39 rocker arms are usable on the newer head. Also the 39 doesn't have a rear main seal.

Started getting parts around yesterday.
Noticed push rods are different lengths for 37and 40
I do have rocker arms for both heads
I think lifters are different also
Will look closer today

The olds Parts manual does not show the lengths for push rods, but it shows if different years had different: Push Rods (0.426) (as you posted)

Rocker Arms: 0.386
Lifters/Tappets: 0.469

'37-'39 had the long pushrods to go with the "cup" style lifers. In '40 Chevy started using the milk can style lifters with shorter pushrods. When I bent pushrods on my '38 I had to put the newer milk can lifters and shorter pushrods in it because I couldn't find a supplier for the longer pushrods.

So head casting #. 3835517 turns ou to be a 50- 52 head. I do have the rocker arms and push rods for it

It does have the milk can lifters. Will probably buy new ones since 39 block is new

While discussing options today with engine builder he wonders if using aluminum pistons instead of cast and possibly a different flywheel might cause a balance issue that should be addressed.was this ever an issue on your builds Jerry?
I know we're not building a race car but would hate to find issues after the fact
Going back to engine shop on Friday and hopefully make some final decisions then
Thanks, John

I fat-fingered a key and erased a long post- - - -let's try again. I haven't encountered any vibration problems when swapping to aluminum pistons. An inline six crankshaft is inherently well-balanced due to the exact 120 degree spacing of the counterweights, and stovebolts don't spin fast enough for any real reciprocating weight concerns to develop. The cylinder head design pretty much restricts RPM to slightly over 4000, even on engines with dual carbs and Fenton headers. It's like joining two pieces of heavy chain together with a paper clip.

I'm working up a stroker 235 engine, using Carrillo NASCAR tool steel connecting rods and a big stroke increase, from 3 15/16" to 4 3/8", for a total displacement of 266 cubic inches. Since the connecting rods are much lighter weight than original, I'm planning to set up the crankshaft in my lathe and turn about 1/2" off all the counterweights, and then have my buddy with a crankshaft balancer spin it up to check for vibration. I'm doing a bunch of other modifications to that engine, all hidden inside. It's going to look bone stock from the outside. I'm also working on a version of the same rotating assembly that will fit into a 216 block if everything goes right. That will require changing the width of the thrust bearing area of the 216 block and main bearing cap to accept the 235 main bearings. That one's still on the drawing board, but a 266 with full pressure lubrication that looks like a 216 might be a real sleeper!

Lots of 216's have been modified with 235 pistons, with no problems with vibration. Stock-bore aluminum pistons instead of 60 over should give no trouble at all. Have fun!
Jerry

Interesting readings. What is the plan on flywheels, trans , and rear diffs on this project?

I have 1940 milk can lifters and the shorter push rods in my 1939 216 engine. Everything else is stock 1939 including the head. The engine runs very well and quiet.

Rick

The prototype(s) will probably end up on a run stand on a trailer, with my water brake dyno hooked up to a stock bell housing and clutch. After a few demonstration runs, my grandson might end up with more orders than both of us working together can fill! I wonder how many guys would like to have an engine compartment that says "I'm a 216" and enough torque to pull a 3.55 rear end at 70 MPH?
Jerry

I used aluminum pistons in my '38 with no issues. In fact it's smoother.

Thanks for the input Jerry and Tiny

Here's the plan
37 1 1/2 ton
37 tooth ring gear don't believe original.stamped 746i on housing
10" stepped clutch and flywheel from 37 motor
Original driveshaft and 4 speed non sync transmission
38 nos block w standard flat aluminum pistons
1950 head with its pushrods, rocker arms, and adjustable lifters ( I think)
Pertronics electronic ignition
Carter w1 carb
Original manifolds is usable
Using clutch and flywheel on left in picture

Good stuff- - - -EXCEPT- - - - -run, do not walk away from that Pertronix ignition! If you do a search on this site you'll find that there's about a 50/50 split of opinion about Pertronix. Would you choose to go to a doctor if half of his patients died suddenly? The Langdon's "Mini-HEI" uses GM original HEI parts which are available at any corner parts store, not proprietary electronics from who knows where, in a distributor housing modified to fit the stovebolt engine. I build the same type of system in my own shop, but most stovebolters don't have the machine tools necessary to make the housing fit. The large-diameter HEI from the electronic ignition 250 and 292 egines is a much closer fit, and it might be a little less spendy than the mini distributor.
Jerry

X2 🛠

Good advice thanks

Cleaned up cylinders yesterday. Will finish hone when have pistons.
Mains checked out .002- .0025 no taper with plastigauge.
I'm puzzled on rods. Torqued assembled and checked with bore gauge.
All were to tight ranging from negative .002 to .003.
Some had 3 shims some had 1. One rod had 3 on one side and none on other.
This was a assembled nos shortblock when I bought in 2011. Still had cosmoline on it. I disassembled in 2011 and put on shelf till now.
Seems to me rods should have been adjusted at factory. ?
I suppose I could have lost some during disassembly back then but on every rod?
Plan is to go back through and start with 3 shims on each side on Monday.
Thanks to all for suggestions and recommendations, John