304 to 345 Engine Conversion Questions

[AZScout]

I purchased a 1980 Scout II (4x4 w/ manual trans) in great condition for a low price with just one problem...the 304 motor is bad and needs to be rebuilt.

I've finally saved up the money for a new engine and I was looking to upgrade the 304 engine to a 345 however before I do that I need to understand the costs involved. While I am not a mechanic, my friend owns the best mechanic/fabrication shop in northern Arizona so I'm good on the labor costs.

1) will the engine mounts for the 304 to 345 match up ?

2) what other parts will I need to buy for the 345 engine that will not transfer over from the 304 ? (oil pan ?? Other parts ??)

3) are there any other mechanical issues I May run into doing this engine swap ?

Thanks in advance for your time and knowledge in replying to this post.
~Robert

 

[MarkO]

The externals of the sv blocks were basically identical regardless of displacement and application.

In other words, the motor mounts and bellhousing were basically the same whether or not the engine was a sv266 or sv392 or in a Scout or a loadstar.

The biggest differences were in the heads. The sv266 and sv304 were narrower in the valley than the sv345 and sv392. There is also the difference between the ic (improved cooling) versions and the non-ic versions.

You will need to save your tin because non-Scout applications had different oil sump pans.

Flywheels were also different in the different applications--you really don't need a loadstar sized clutch in a Scout.

 

[Robert Kenney]

Assume you will be sourcing a complete 345 from some known reliable place.

For the most part the 304 and 345 are the same except for the longer stroke in the 345.

The 345 block is taller by about 5/8". Because of this height increase the intake manifold is wider and the 345 has a different intake port size and shape.
Also due to the taller block the exhaust manifolds will be higher. Plan on having to add the the cross over pipe or collectors.


You will need the intake and heads along with the block.....
Other than these you're good to go for the swap. All of the ancillary equipment will bolt up.

 

[AZScout]

thanks that's good info...as this will help me build my parts list.

For the rebuilt engine I was considering two sources:

s & j engines (spokane wa) (7 year/100k mile warranty)

or

jasper engines (3 year/100k mile warranty)


the engine parts not included in the rebuilt engine block are...

Air cleaner/ignition/valve covers/timing cover/intake manifold and oil pan.

I'd guess that means finding compatible valve covers/intake manifold/exhaust manifold/fly wheel and oil sump pan. Assuming the air cleaner and ignition components from the 304 match up with the 345.

Are there other parts not included on the above list that will not transfer over ?

ps: any engine upgrades to the engine components (headers/ect) that you folks would consider doing since I'm swapping out all the components ??

 

[Scoutboy74]

The valve covers are all the same and fit all engines from the 152/196 4-poppers up thru the 266-392 sv8 engine family. Just retain and transfer over from the pukey 304. Make note of which side each is on now for crankcase ventilation plumbing purposes so that you orient them in a likewise manner on the new block. Same goes for your Scout II specific oil pump/pickup/dual sump pan arrangement, as well as your exhaust manifolds, ignition components, and fuel mixer/rock-insect strainer. That's what was meant by all ancillary in rk's post above.