350 Motor Questions

[elks]

At what points in time have the changed the 350 block?

I have a buddy with a 98 Tahoo that needs a new motor... We have a mid 70 motor, can we make the 2 mesh? I know the 350 is awesome because it has been relatively unchanged for years, but where can I find a chart or information about what years are all the same and how different years may be able to work.

Thanks a bunch. I am atr work and do not have time to research right now other wise I know I could find it.

[allengator]

The original design of the small block remained remarkably unchanged for its production run, which began in 1955 and ended, in passenger vehicles, in 2003. The engine is still being built today for many aftermarket applications, both to replace worn-out older engines and also by many builders as high-performance applications. There were, however many minor changes made to the engine over the years.

1986 - 1995
The troublesome leaky valve cover surfaces were changed such that cylinder head mounting lip was raised and the bolt location was moved from 4 bolts on the perimeter, to 4 bolts down the centerline of the valve cover (this design debuted on the Corvette in 1984, and Chevrolet 4.3L the year before). The troublesome rear main seal was changed from a 2-piece rope design to a 1-piece design that used a mounting appliance to hold it in place. This necessitated a change in the flywheel/flexplate bolt pattern as well. Also changed were the mounting angles of the center 2 bolts on each side of the intake manifold (from 90 degrees to 73 degrees) and the lifter bosses were increased in height to accept roller lifters. The alloy heads for use in the Corvette still retain the non-angled bolts (center 2 bolts attaching to the intake).
1996 - 2000
This was the last change for the Generation I engine, and continued through the end of the production run in 2003; all 1997-2003 Generation I engines were Vortec truck engines. The cylinder heads were redesigned using improved ports and combustion chambers similar to those in the Generation II LT1. This change resulted in significant power increases.


From the web of course....

[mrein3]

Originally Posted by elks

At what points in time have the changed the 350 block?

I have a buddy with a 98 Tahoo that needs a new motor... We have a mid 70 motor, can we make the 2 mesh? I know the 350 is awesome because it has been relatively unchanged for years, but where can I find a chart or information about what years are all the same and how different years may be able to work.

Thanks a bunch. I am atr work and do not have time to research right now other wise I know I could find it.

You could do it but it would be tough. If you re-used the 98's heads all the top side stuff would work.

I don't have a lot of experience with the new ones but I believe you need a crank position sensor and knock sensor. A fuel pump block off. I sure there is other stuff.

I did once help a guy in that situation. He had a 5.7 liter in a 99 Suburban. He got a used late 90something 5.7 liter out of a van from a reputible used engine supplier. We pulled his bad one and put it on a stand. We put the "new" one on a stand. Then we threw a few gaskets on the "new" one. Resealed the intake that always leaks. And put his accessories on the front of the "new" one. We got that done in three afterwork sessions in my shop.

I'd go that route before trying to make an older one work. It will fit just fine but it will take a lot to make it work.