Plastigage and my old 750 sohc

[timtune]

I have a few old 750-4 honda motors and I want to check the main bearings using plastigage. Does anyone know if I need to torque down every bolt that holds the cases together ( 10mm and 12mm bolts both on top and bottom) or would it be enough to just torque down the 12mm bolts that are obviously holding the crank in place?

Thanks

 

[TK4]

If you're checking main bearings everything has to be tight.
Look on the side of the existing bearing and see if there's any of the original paint code left, it will make things easier to fit replacements.

 

[J_F]

^ I agree

if you're taking a rebuild to the level of plastigaging bearing clearances
I'd follow the OEM torque sequence for the all the case fasteners

 

[GreyGhost]

^ I agree

if you're taking a rebuild to the level of plastigaging bearing clearances
I'd follow the OEM torque sequence for the all the case fasteners

Agree, it cant add that much time to the whole process to do them all up. I doubt they are torque to yield bolts, but if they were, I would probably use the old bolts for all trial fits and switch to new ones for the final assembly. Not perfectly accurate, but it would cost a fortune otherwise.

 

[TK4]

Agree, it cant add that much time to the whole process to do them all up. I doubt they are torque to yield bolts, but if they were, I would probably use the old bolts for all trial fits and switch to new ones for the final assembly. Not perfectly accurate, but it would cost a fortune otherwise.

They're just bolts, nothing fancy.

 

[timtune]

Thanks guys. FWIW I asked the same question on a dedicated SOHC/4 site and the response was to torque down just the 10 larger bolts directly over the crank.

 

[TK4]

Thanks guys. FWIW I asked the same question on a dedicated SOHC/4 site and the response was to torque down just the 10 larger bolts directly over the crank.

Because everything you read on the internet is true !

 

[timtune]

Like any job I guess. Get three quotes.

 

[Brian P]

The reality is probably that as long as the mating surfaces are securely in contact (and clamped in the vicinity of the bearings where you are measuring the clearance) you will get a reading that is within the tolerance of Plastigage to be able to discern it. Still ... given that this is not a job that you want to do wrong or twice ... I'd take the extra few minutes and tighten all of the bolts in the specified sequence. You will not go wrong by doing so.

 

[timtune]

I timed it. It took about an extra 15 minutes to snug up and then release the additional hardware. That said I might just recheck a couple bearings with only the crank bolts torqued. This won't be the last SOHC I check.

 

[TK4]

I timed it. It took about an extra 15 minutes to snug up and then release the additional hardware. That said I might just recheck a couple bearings with only the crank bolts torqued. This won't be the last SOHC I check.

Time well spent.

 

[timtune]

For the Record. I rechecked two journals that had a smaller clearance and only torqued down the 10 bolts over the crank. There was no difference. In this case the big forwards on the SOHC4 site were correct.