Engine Re-Build on a GS400

[Shakadula]

I'm thinking that my GS400 motor is going to need a top and bottom end re-build late this year or early next year. The problem is I've never done it before (not even a lawn mower engine). Anyone have any ideas to help me out such as a rebuild video. I'm am also looking for a local vocational school with night classes but that isn't looking good so far.

My car is original so buying a new motor isn't an option.

Thanks,

[Turbo Loyd]

[color:"blue"]There are plenty of references on how to a rebuild and engine. Just take your time and select a good machine shop to do the work on the block and crank. They should have the torque plates for your engine to do the work right, plus know the Buick clearance and not apply their Chevy experience. With new piston make sure you get the rotating assembly balanced.

One caution getting pistons for a 400 CI Buick in not an inexpensive proposition, and may take quite awhile. I've heard members in Chicagoland who have paid neary $800 for a set of 0.20 or 0.30 over sized pistons since they have to be be custom made. That is why a lot of guys go over to the 455.

[Guest]

If your block needs to be bored, have it bored to the stock 430 piston size and use standard 430 pistons. It will save you the expense of custom made pistons and you get 30 extra cubic inches.

Regards,

Mark

[Steve B]

[color:"orange"]I would also invest in a 67,68 or 69 Buick Chassis Service Manual. Almost everything you will need to know for a basic rebuild is in there. You can find them on ebay or on the Buick websites.

[Shakadula]

Thanks for the reply everyone. I do have the 67 service manual and have the guts to take this on myself. I was even thinking about buying some used motor and rebuilding it first just to gain the experience before I tackle the orig 400.

Another question. Do I purchase a complete rebuild kit or would a machine shop be willing to use the parts I purchased and any suggestions on where to buy the kit?

Thanks again,

[Sgt Art]

The practice engine is a fine idea. Years ago when I was restoring a Corvette, I signed up for several automotive courses at the local technical college. It was worth every cent of it. Not only did I leard a great deal, I had a lot fun doing it and made some new friends. The only downside was it took longer, but we did every function except turn the crankshaft. That I took to an outside machinist who miked it and decided it was ok. He polished it for me.

I would say this, have a competent machinist check your rod and main journal bearing fit. There are products such as Plastigauge, but for a novice, I recommend having a guy who's done this at least supervise. If you botch the lower end of the engine, all your work and money is wasted. It's a tough lesson to learn. The heads should also be gone over and here again, you need tools to measure the spring tension. It's fun to build your own engine, however, much of the work needs to performed by a skilled machinist/engine builder. You can pull the engine, and tear it down. If you totally disassemble it, you must number the connecting rods to their cylinder and keeping both pieces together. If you mix these up, it's a problem. The same goes for the main bearing caps, if they are not factory numbered, number them. You can scribe them or make light marks with a punch, if you have number stamps so much the better. Your going to love removing the bolt that holds the balancer on the crankshaft snout. If it's like an Olds engine, it's been torqued to over 200Lbs Ft. I used a 1/2 drive breaker bar and socket with a three foor length of pipe to give more leverage. I had a very large friend holding the block stable while I did this. Lastly, cleanliness is next to Penske-ness, a good engine shop will have a hot tank with caustic cleaner that will take the block down to bear metal (iron only, no aluminum parts!) it will remove all the carbon and crude and then the oil galleys can be properly cleaned out, etc. This is something you can't really do at home in you garage or driveway. Again, your going to need a shop to do it right.

[Turbo Loyd]

[color:"blue"] Do not know if a standard 400 block would be able to be bored to accept the 430 piston. The difference in size from a 400 piston to a 430 piston is significant. Earler blocks seldom could be bored over 0.040 due to slight core misalignment while being cast. <img src="http://www.aaca.org/ubbthreads/images/graemlins/ooo.gif" alt="" /> Occasionaly Blocks 72 or later may be bored to 0.060 over.

Maker Size Bore. . Stroke

-Buick 400 4.0400 3.90

-Buick 430 4.1875 3.90

-Buick 455 4.3120 3.90

[Steve B]

[color:"purple"]Well, from an old Kenne Bell catalogue there is this: "The 400 and 430 are identical blocks except for bore diameter, so bore the 400 to 430 specs. These bore sizes maintain adequate cylinder wall rigidity so there is no problem with overheating or ring sealing." I would still have the block sonic tested to make sure you can do it. I hope that helps.

[Guest]

When I had my motor rebuilt they did not have a torque plate for a buick motor. They claimed that torque plate boring is only necessary on high rpm engines. I would have prefered it but I had to take their word for it.