: 48 Sedanette install 472-TH400

Don East
09-29-10, 10:10 AM
I have a 48 Sedanette that I'm restoring and will be installing a 71-73 472 engine and a TH 400 transmission. I'm currently working on the 472 rebuild. This is the first time to restore this engine. If there is anyone in this forum that has made a similar engine swap, I'd like to discuss your experience. I'm also new to this forum so would like suggestions to items in this forum I should review. My first specific question to this engine follows: The timing gear had what I would call ex-stream wear. The top of the gear teeth on the cam gear were reduced to points. Any suggestions at why or what would have caused this ex-stream wear?

09-29-10, 06:46 PM
Those timing chain sets are famous for that failure mode. The original cam sprocket had plastic teeth, which may fall off any time at this age. Just put on an all steel roller timing set and forget those problems.

A TH400 trans this age also has failure possibilities. The seals (on the pistons that drive the clutches that connect the motor to the wheels) age and may let clutches slip, with disastrous results. Bruce Roe

Don East
09-29-10, 11:47 PM
Brice, thanks for the reply. I didn't mention that I forund all kinds of plastic pieces in the oil pickup. Now I now where they came from. I plan on having the trans rebuilt.

10-01-10, 12:54 AM
Can you send any pics. of your car?.

Don East
10-05-10, 10:46 AM
This engine was loaded with carbon. My guess is the timing gear was largely responsible for this. I've miked the rods and main bearings. the rods were 1.5 clearance. That seems good. The mains were 2 to 3 clearance. That seems to be high. What do you all think? There is a very small ridge in the top of the cylinders. I'm considering putting in a new timing gear set and putting the engine back to gather. The person I bought the engine from thought maybe the engine had about 80,000 on it when it was removed. I'd like all the input and comments I can get. So fire away!! I also have a source for a fuel injection system for this car. Its the type that showed up on Cadillacs after 1975. I'm also open for motor mount suggestions.
Thanks Don
I'll include some pictures in the next post.
If there is interest I'll create a photo and comment section of the build progress.

Don East
10-12-10, 10:25 AM
Can you send any pics. of your car?.
Here is a photo of the 48 Caddy project. The shot also shows the 33 Chevy project.:bonkers:

Don East
10-12-10, 10:29 AM
Photo of 48 Caddy and 33 Chevy projects.http://picasaweb.google.com/ydeast/CarProjects#5527165347184682290
Not sure how to include pictures. I'll give this a try.

10-13-10, 01:43 AM
Those 70s open loop Electronic Fuel Injection have reliability problems, and little advantage over a Qjet. Not recommended for new installations. An approach some people use, is to adapt a modern closed loop EFI to work with the 70s intake manifold/injectors/throttle body. The 70s GMC motorhome people have done a lot with EFI 403/455/500 engines. You can see some info on 70s EFI on my PHOTOBUCKET.


(that is a lower case "L"71, not an upper case "i"71)

click on an Album at left
click on a picture to enlarge + description

Bruce Roe

Don East
10-14-10, 08:52 AM
Bruce, thanks for the information. Do you know of anyplace where I can find more information on this work?

10-17-10, 01:01 AM
I don't have websites handy, but try some searches on GMC MOTORHOMES, look for EFI. Russ Harms has a huge amount of info on his Old & Cad fuel injection conversions to modern closed loop, programable systems. There are also some MAF based systems that work with hardly any programing. good luck, Bruce Roe

Don East
10-18-10, 08:44 AM
Trying a picture link again. If this doesn't work can someone guide me to the instructions for doing this.

Don East
11-01-10, 12:22 AM
Today engine torn down and ready for the machine shop.

Don East
11-07-10, 09:05 AM
Looking for suggestions: I want this car to be a driver. I'm going to replace the timing chain, cam, lifters, rocker arms and new bearings. I don't know about the pistons yet. This engine is the 71-72 type with soap dish pistons. It came with a quadrajet carb. My goal is to keep the cost down and as I said earlier create a good driver.

What suggestions would you make for the parts I need. All suggestions will be considered.
Thanks Don

Don East
11-17-10, 10:19 AM
Going to pickup the block and engine parts today from the machine shop. The work begins.:

11-20-10, 09:38 AM
Be sure to open the oil pump and check the clearances. If you had the gear teeth in the pick-up screen, the pump may have starved.

Don East
11-30-10, 01:03 AM
Motor mounts designed and patterns sent to the machine shop to be cut out. Working on painting engine parts.

Don East
12-18-10, 09:41 AM
Currently working on the motor mounts. I'll included some pictures in the next post.

12-18-10, 09:08 PM
I would suggest you don't use one of those cheap timing sets that they sell for $30 ... get youself a good coyles chain and sproket set-up.. they have a few grades from $80 to just over $100... these have 3 key slots so you can adjust your cam timing.. If you bought one of the cheap ones .. don't use it. Using 68-69 high comp pistons will make you happy you did.. I seen some on ebay , for what I'd say cheap...