VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1932 Engine Rebuild

Hi All,

I am beginning to plan the restoration of my 1932 Coach and have some questions about the engine rebuild. It is the original 1932 straight 6 with no prior work done to it. I know this because my father is the second owner and he knew the original owner before he passed. I would like to get hardened valve seats installed for use with modern fuel as well as getting the bearings updated for durability. I would like to know your thoughts on these two procedures. Do you think it is a good idea. Does the engine builder need to specialize in antique motors. Also, I am in the Phoenix, AZ area and would like to know if anyone had any recommendations on who I could go to to have this done. Any thoughts or help with this would be great. Thanks Guys.

An early 6-banger does not need hardened valve seats.

The remainder of the engine should be rebuilt as it was when new. We could get into an argument about modern shell bearings. Go with the original design and save pains centered in the head and lower extremities.

Yes, the engine builder must be familiar with the antique/old engines. Modern specifications do not always apply to the older fellows.

I strongly agree with the above.

I just talked to a guy on Monday who is installing a 1931 engine in his 1932 sedan. (no comment)

He asked the same kinds of questions. What I told him was similar to the comments above:

HARDENED SEATS:
You don't need them on a 1931/32 engine because the compression is only about 6 to 1. Until you get to approximately 10:1 (1960's) then the modern gas won't have an affect on the valves. And you do NOT need to add any lead additives.

ROD BEARINGS:
I am a big fan of insert bearings. The problem is that matched combinations are not readily available. For some reason, I'm not aware of any list of replacement bearings that have ever been published. So, from everyone that I've talked to, each rebuilder ends up finding their own bearing match. Personally I've used Allis-Chalmer bearings.

The factor that I'd most use as a Go/NoGo decision is the amount that you need to turn the crank down. The greater the oversize, the more likely that you should NOT use babbits. The thicker the babbit, the more likely it will fail. The rule of thumb is that you want your babbit (and insert, for that matter) to be as thin as possible.

And the last point of interest is that insert bearings are much harder than babbit bearings. So, again, I tend to lean towards inserts as the perferred solution.

EXTRA:
One last comment that you didn't ask about. Original cast iron pistons verses aluminum pistons. If you change-out the pistons and go with aluminum, then the overall load (or force) on the rod bearings will be significantly less -- and the bearings will last longer and are less likely to fail.


Okay, that should be enough to solicit some more personal opinions.

Yes, the Allis-Chalmer bearings seem to be the bearing of choice by many.




Actually, when the crank is turned down that is an undersize, not an oversize. Even though the rods have thicker babbit for the undersize crank, the rods are undersize as well.

I also agree that hardened seats are not needed and they are a total waste of money on the early Chevrolets.

Bill,
You asked? Well I fully understand the theory on the cast iron vs. aluminum pistons. I rebuilt on '32 engine using aluminum pistons, matched weight of the set of pistons, rods (both ends) and the rod/piston assemblies (total and both ends) to a gram or two. Felt that static balance should be okay so didn't spend the extra money to have the engine dynamically balanced. It was the one of the least smooth '31-'32 engines I have ever run. My guess is that the counter weights on the crankshaft were sized for the original cast iron pistons so produced vibration when lighter pistons were used. Since then I have rebuilt several '31-2 engines with cast iron pistons. All run well, have reasonable pickup/horsepower and are smooth running.

I have and will continue to recommend rebuilding Chevrolet engines with the original type parts. The engine were designed for those parts and seem to still preform well with them today. That includes babbitt rod bearings. Have been told by the machine shops that I use to rebabbitt rods that the type they use is harder than the original so much less likely to pound out. I run my engines harder than most and have not had problems to date.

Holy Cow....I don't believe this but I agree with Chipper once again.

I always recommend original cast iron pistons for the 1929-32 Chevrolet engines....especially if the engine is totally balanced. I don't know why dudes are afraid of cast iron pistons. My original 1932 engine has never been rebuilt since new and after 81 years it still runs fine with the cast iron pistons and the engine still has the original babbitt as well. Ya, I know, the engine really smokes.....but that is the original 1932 smoke!

There's a guy in Tucson that can build your engine for you. A little private shop. Does them like original. If you're interested, let me know....Joe

Thanks for all the input guys. It really helped me in understanding the pros and cons.

After reading this post,I wonder if I should be using lead additive in my 33 Master.I have used it since I bought the car.Do I need it or not?

NO!

Thank you.You just saved me $5.00 a bottle.