Force 70hp Rebuild

[atengnr]

So more questions for you all. Do I need to replace all the bearings? I see that the main bearings are showing as nla oem. Are these after bearings ok (i see them being sold as part of kits).

thanks

 

[Nordin]

If bearings looks good and the surfaces of the crank are good, then reuse the bearings.

I have done this a lot of times when I have rebuilt with bore and new pistons and rings and it has worked every time.
Well you can check the value of the bearing surface both of the crank bearings and the connecting rods by measuring with a micrometer to look if they are in spec.
But most of the time i have rebuilt the value s has been in spec when the surfaces has look good.

 

[jerryjerry05]

Just reuse the old.
The old adage,"when in doubt" "toss it out"

 

[atengnr]

Thanks. What sealant is recommended for crankcase to block surface? Also, there was a bunch of rtv under the top bearing cage. Rtv under there?

thanks

 

[Nordin]

I am not so familiar with the 70Hp one carb engine and do not know if it has a spagetti seal as crank seal as the other Chrysler/Force 3-4 cylinder engine has.
I use Permatex Form a gasket no 3 together with a new spagetti seal and also use it as glue for other gaskets except for the head gasket.
It works perfect.

 

[atengnr]

Hey see some decent looking 75hp powerheads. Will this work easily with my force 70?

 

[jerryjerry05]

I use the black Permatex sealant.

What year powerheads on the 70 to 75 hp.
The big changes will be the adaptor plate seal/gasket.

 

[flyingscott]

The base gasket will be the least of your worries. Your motor more than likely has the Mercury lower unit. So the driveshaft splines might be different on an older powerhead.

 

[jerryjerry05]

The 70 91-94
The 75 95-99
Both used Mercury lower units, different Mercury units.
So the chance the 75/70 will change out is slim to none.

 

[atengnr]

Hey silly question, what sealer do you all use on the threaded fittings to vacuum such as the fuel pump vacuum line fitting and the recirc line fitting at the intake manifold? Thanks alot

 

[jerryjerry05]

If it needs sealer?
I use the white sealer tape or plumbers putty.
The white tape seems to be the easiest.

 

[atengnr]

Should i put on the fuel pump elbow? Recirc hose elbow at intake/reed block cover?

thanks

 

[jerryjerry05]

Maybe a pic? Better description of what's missing?
If something like a hose or fitting was missing? then that could be the reason
the motor failed.

If the factory designed a hose or special fitting then it should be replaced.
That kinda like removing the thermostat and expecting the motor to perform like it should.

 

[atengnr]

No nothing is missing. I was just curious about these threaded elbows and whether the threads ought to have sealer on them to prevent small vacuum leaks. For example, fitting number 4 in this diagram??

 

[jerryjerry05]

If the elbow had threads put a sealer on it.
The hose doesn't need a clamp as it fits on fairly tight.