Inliners International Forums General Discussion Engines 181 Mercruiser flywheel

Hi, I'm sort of new here. Just been laying low and getting a feel for the Bulletin Board. Now it's time to ask for some help from the group. I'm building a Mercruiser 181 (3.0L) 4 cylinder for future use in a light hot rod, perhaps a Model A roadster pickup. I'm planning to install a T5 manual trans behind this motor and need an automotive flywheel. This is an earlier engine with the two piece rear main seal. Looking at the marine flywheel I have, which is not machined or drilled/tapped for pressure plate, it appears to be a "neutral balance" flywheel meaning that the motor is internally balanced. Is that correct? The flywheel bolt pattern appears to be the same as any pre-'86 Chevy V8 and I6 flywheel, Correct? Can I use one of those flywheels? Thanks for any help or suggestions for my build.

Bob

Yes the flywheel from an internally balanced small block Chevy V8 or a 194 - 230 - 250 engine will be correct. Depending on the size of the clutch for the T5 you can use either the 12 3/4 inch or 14 inch flywheel with the appropriate starter and bellhousing, also from the same sources. Pilot bushing if you need it is also from those engines.

Mike G , thanks. Looks like your response confirms my observations. I'm inclined to go with the 10.4" clutch and small flywheel. It should be more than enough to cope with the 4 banger's power and the smaller bellhousings are more plentiful than those for the 11" clutch.

Bob

You're welcome. I'm not familiar with the splines on a T5 input shaft as to if you can get a clutch disc in either 10.4 or 11 inch size. That is why I would check into that before buying the rest of what you need. According to what you are going to build I would use the smaller diameter set up as you mentioned; if you have a choice. In fact I am building about the same project. A 181 Merc, Saginaw 4 speed, rectangular tube Model A type frame, and a bare bones 25 T coupe body. I am using a light 12 3/4" flywheel with a 10.4 dia clutch disc. Overall I expect the finished job to come in around 1500 lbs. There will be nothing on this car that is not absolutely needed for driving and safety.

I have just put a post on the driveline section about a great clutch set for the T-5--should suit your needs--check it out.....52er

I,AM building one of these engines also right now.... also going the t-5 route for a trans.
bob in tn.

Going to be a lot of surprised boat owners come Spring. I hope they have sails. LOL

While we've got a 181 thread going here, let me ask what you guys know about head interchangeability on the Mercruiser. Talked to the machine shop that's doing my engine machine work today and they informed me that the head had a crack between the valve seats in one chamber. They also informed me that they have a fresh 153 Mercruiser head that was never picked up. The obvious question is will it work on the 181? Head bolt pattern is the same, I'm told. The 181 head has larger valves, but what about combustion chamber volume? Is it the same? I'm thinking it is, and the compression was brought back down on the 181 by dishing the piston rather than enlarging the chamber. The obvious difference is the port configuration, and the 181 head is probably a better breather, but I'm not concerned over a little power lose if the 153 head will work otherwise. Comments?

Bob