michel88 Posted December 27, 2007 Share Posted December 27, 2007 I recently put a 1947 Buick (320 cu in) rebuilt engine in my '40 Roadmaster coupe. I started to rebuild the original engine but found that the block had a crack. I was lucky that a member of my Buick club had a 1947 Roadmaster engine that he sold me and I had this engine rebuilt. This engine is almost identical to the 1940 engine including motor mounts. I also replaced the entire clutch assembly. All work was done by a professional mechanic who is also in my club. The engine runs excellent but now I have a problem. When I let off the gas in high (3rd) gear it jumps out of gear. It did not do this before the engine was replaced. Does anyone know what might be causing this? Link to comment Share on other sites More sharing options...
The Old Guy Posted December 28, 2007 Share Posted December 28, 2007 The bell housing was originally mounted to the block ,and then the trans hole was machined. This was to make sure that it was in perfect alignment with the crank. The machines of 60+ years ago were not good enough to make sure that this would happen. The best way to check your Buick is to remove the trans ( I know what a pain that it ) and check the runout with an indicator. I it is not concentric, you can pull the bell housing locator pins and move the bell housing until it is concentric. Bolt it down tight, and then put a tapered dowel in the old holes after reaming the holes. There may be another answer, but this is the only positive cure I have found. Link to comment Share on other sites More sharing options...
michel88 Posted December 28, 2007 Author Share Posted December 28, 2007 Thanks Joe, I was hoping you would reply to this post. I wish the fix wasn't so hard though. One of the jobs I did on this project was to take parts home and clean them. The '47 engine was complete with the bell housing and I am not sure which bell housing was cleaned up and used when we put in the engine but I suspect it was the original '40 bell housing. Do you think if we swapped the bell housings this would solve the problem? Link to comment Share on other sites More sharing options...
The Old Guy Posted December 28, 2007 Share Posted December 28, 2007 woody If you have the bell housing that came off the 47 engine, it should work just fine. The problem with changing the bell housing is that you must pull the flywheel in order to do that. This entails removing the pan and rear main cap ,knocking out the flywheel bolts and in general swearing a LOT!There are housing bolts behind the flywheel, and there is not sufficient room to pull the wheel back to clear the bolts. Originally the housing was bolted on before the crank and flywheel assembly was dropped in. I wish I had better news, but that is the way it works. You can always hang a weight on the shifter arm, and that will work most of the time. If I remember right, there is a boss on the drivers side of the housing that has a hole tepped in it on the 40 housing that is not tapped on the later housing. check it out as it is MUCH easier to tap the hole before you mount it. Link to comment Share on other sites More sharing options...
michel88 Posted December 29, 2007 Author Share Posted December 29, 2007 Joe,Thanks for the information. I will probably wait for warmer weather to swap the bell housing. Until then I will try it with the weight on the shifter. Link to comment Share on other sites More sharing options...
The Old Guy Posted December 30, 2007 Share Posted December 30, 2007 Good Luck Woody, and Happy New Year Link to comment Share on other sites More sharing options...
michel88 Posted December 30, 2007 Author Share Posted December 30, 2007 Happy New Year Joe. I hope to meet you in person at Flint. Link to comment Share on other sites More sharing options...
critterpainter Posted December 31, 2007 Share Posted December 31, 2007 Have you done the "little things" like check the shift linkage bushings? Also is the "tapered snap ring" in place that keeps tension on the input shaft bearing and the sleeve the throwout bearing slide on. It is often missiing.Bill Link to comment Share on other sites More sharing options...
michel88 Posted January 1, 2008 Author Share Posted January 1, 2008 Thanks Bill, I will check these items. Link to comment Share on other sites More sharing options...
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