The Stovebolt Site Forums The Shop Area Engine Shop Which head to use? How difficult to repair?

In my first post to the site I originally posted this to the wrong forum. Newbie mistake!

I have some mechanical questions for my 39 Chevy. I am "in the knows enough to be dangerous" category when it comes to precision work on the engine. Therefore, I could use any and all help!

For reasons yet unknown, I decided to drive my truck for a few miles on the local freeway. Long story short, I managed to bend two push rods and knock a third completely out of position. I was able to do a temp repair to the rods to get the engine running. I suspect I've bent some valves as well since it is missing on several cylinders.

Thanks to research on this site I have learned that the engine in the truck is a 1948 235 with a 1953 216 head. It has run very well since the mid 90's in that configuration. Long ago I disposed of the block the truck came with, but kept the head, which is a 41-48 216 / 235 head. Being in the Arizona desert, it has little rust and is mostly filled with dust. After inspection, it looks to be in great condition with some cleanup.

Here are my questions. Would it be better to take the '53 head, replace the valves and put it back on the truck, or clean up and use what appears to be the correct 1948 head for the block? I like the idea of a matching head and block, but also understand that if has been working well why mess with it.

In either scenario, how difficult is it to disassemble the head and replace parts? If I use the '48 head, what would be the best recommendation for cleaning it?

Sorry for the wordy post. I have been doing lots of research on line and I have found little information on this topic. I know that this is probably a very basic question to most of you, but I have been lucky in not having to do much mechanical work to this truck. Any and all posts to my personal email, or to the forum would be most welcome. Thanks!

39 AZ 3/4 Ton,

There is a similar 'head' related thread on the forum. If you checked it out maybe it might answer some questions for you.

I will share some of my thoughts...I would doubt you bent any valves..they might be stuck, but not bent. Getting a bent pushrod 100% straight again is a toughie, so replacing them would be the ticket.

It isn't advisable to switch and swap valves between cylinders not less between heads. They wear to a pattern and don't like being relocated unless the valve and seat are ground.

The head is simple, but precise. It takes semi-special tools to dissasebly it, and very specific knowledge and tools to grind/check/assembly it properly.

Any head work is better left to a automotive machine shop..they will rebuild it and return it ready to go.

The catch 22 is slapping a healthy head on a worn bottom end. This subject is slippery...some folks say it's fine and some will tell you it will strain a worn bottom end resulting in oil consumption which might not have occurred if all the components were left in a equal state of wear!

I would find and fix whatever problems your current engine has short of swapping heads. If you find the head is part of the problem, have it repaired with thoughts of rebuilding the rest of the engine soon.

And you thought your post was a mini-novel?

Stuart

Here are a few words from someone who really shouldn't be giving advice, but I'll tell you what I have done on my own truck. When I first got started working on it, I had to deal with both bent pushrods and stuck valves. The guides and seals were none too healthy, and in any event those old valves always wore fast. The head needed to be rebuilt, so I lifted the head off and left it to a machine shop. It cost a few hundred bucks plus the parts, but they did all the work and it was well done. I replaced all the valves and seats with modern harder valves in the hope that I can burn unleaded without worrying about what I might damage, on the recommendation of the garage that did the work.
One thing I did not do which I am sorry about is repaint the head before putting it back in. But with the newly rebuilt head the motor runs like a charm. I did not do anything to the rest of the block, but that will have to happen in a few years too. The truck runs great. I had to set the valves roughly to get it running and to warm the engine up, then reset them with the engine warm, but you can read about that from any number of books or earlier posts from people who know a whole lot more than I do.
As far as what head to use, you are going to have to mess with either of the heads, so its just to choose one. I would take the older head, but that is just because I would rather keep the engine as original as possible. But unless you've done this kind of work before, leave it to a machine shop I say.

Thanks for all the information! All the responses have been pretty consistent so far. The main thing I took away from this is that I really should look into the block side of things as well. I put the engine in myself in 1993 after purchasing from a yard in the vacation mecca of Gila Bend, AZ. I have done nothing to it since then and based on what it looked like at the time (it ran great on blocks!), it does not appear to have been worked on for quite a while.

A rebuild would be good a thing except for the $$$. It would give a chance to see where that rattle is coming from near the flywheel!

Thanks again.