Engine question

[Vova]

I have the original engine in my 70 c10. It runs ok but it smokes.
I have a 84' 350 with 30-40k on it that I am planning to swap.
My question is will all my accessories bolt up to the 84?

I also have a th400 with low miles. Is it worth replacing my original leaky th350?

[swamp rat]

Is the original engine a 6 cyl or an 8? A origional 350 will have a short water pump, the 84 will be a long water pump so all the pully's and brackets will need to be transferred with the engine.

[Vova]

Originally Posted by swamp rat

Is the original engine a 6 cyl or an 8? A origional 350 will have a short water pump, the 84 will be a long water pump so all the pully's and brackets will need to be transferred with the engine.

The original is an 8. The newer motor has a new water pump and carb on it.
So all the brackets are the same?

[sean1969c10]

You'll need to replace the water pump on the 84 350 with a "short pump" for a 70 350, then all of the brackets and pulleys will fit the newer engine. The TH400 is a great trans but it won't just drop in place of the th350. Driveshaft slip yolks are different, th400 is longer so the driveshaft may have to be shortened, depending on the length of the th350.

[Vova]

Originally Posted by sean1969c10

You'll need to replace the water pump on the 84 350 with a "short pump" for a 70 350, then all of the brackets and pulleys will fit the newer engine. The TH400 is a great trans but it won't just drop in place of the th350. Driveshaft slip yolks are different, th400 is longer so the driveshaft may have to be shortened, depending on the length of the th350.

Sound like I'm in good shape for the engine.
I'm shortening my frame son I'll have to do the driveline anyway so it might be a good time to swap out the tranny.
Is the linkage the same?

[GASoline71]

The TH400 will rob a bit of power from that 350. They are made to handle the TQ of a BBC. Even though some were put behind 350's in these trucks from the factory in HD applications. The TH400 is prolly the best old school slush box The General ever made.

Gary

[killerpanel]

depending on what your doing for exaust, the dipstick might be an issue. the moved the dipstick to the other side of the block in the 80's. The 70 manifolds will not work on the 80 up engines. if the 84 has manifolds, they might not fit back to your exaust. if your using headers.......nevermind.

[Vova]

Originally Posted by GASoline71

The TH400 will rob a bit of power from that 350. They are made to handle the TQ of a BBC. Even though some were put behind 350's in these trucks from the factory in HD applications. The TH400 is prolly the best old school slush box The General ever made.

Gary

Interesting point. The TH350 is working well just a little leaky. maybe I'll just reseal the Th350 and sell the 400.

[Vova]

Originally Posted by killerpanel

depending on what your doing for exaust, the dipstick might be an issue. the moved the dipstick to the other side of the block in the 80's. The 70 manifolds will not work on the 80 up engines. if the 84 has manifolds, they might not fit back to your exaust. if your using headers.......nevermind.

I have the manifolds for the newer engine and have to get the exhaust redone anyway since I will be rerouting to go through cross member.

[bbcmudtruck]

I think its 80-85 the dipstick was relocated to the passenger side of the motor. I know my motor is an 84 and its on the passenger side. I run headers and have no fitment problems.

[MARKDTN]

Originally Posted by killerpanel

depending on what your doing for exaust, the dipstick might be an issue. the moved the dipstick to the other side of the block in the 80's. The 70 manifolds will not work on the 80 up engines. if the 84 has manifolds, they might not fit back to your exaust. if your using headers.......nevermind.

Why won't the old manifolds work on later engines? I know late 305 manifolds can be an issue, but 350 all have the same exhaust pattern and some of the later ones have the dual pattern. Is there a hard interference with the dipstick? Some blocks are drilled for both. Can't you just bend the tube a little to clear?