212 hemi questions / boat motor build

[fowl_language]

I've tried looking around for awhile now and can't seem to find basic information on the 212 Hemi. I bought a motor off the shelf at HF and it turned out to be a hemi model. I am doing a boat motor build and I just want the thing not to blow up ungoverned. Not really looking to burn the thing up. This is my first build and I really don't know what I'm doing so I'm sure this thread will have all sorts of dumb questions in it.

First things first to ungovern I figured out so far...I think... I need; billet fly wheel, mod 2 cam, billet connecting rod, SS valves, 26 ish lb springs with locking retainers. I will also get the idle adjust carb and jet appropriately later.

Is that the idea anyways? I can't seem to find any places that have SS valves for the hemi model, or are they just 25mm and 27mm shaft at 5.5 mm?

Another question I have is, is it possible to run the stock gravity tank on an ungoverned 212? It would help when the boat lists to plane out, otherwise i've heard the pulse pumps don't have enough suction to get the fuel up to the motor.

Is it possible to run a low pressure electric fuel pump on these things?

Thanks all for the information, like I said I'm kind've lost to the point of not even starting this build, the forum has been great and getting me more confident everyday, i'm just trying to see potential problems before they come up. All the best, FL

 

[trinik7597]

ok so one thing about the hemi is it comes stock with 27/25 valves no real need to replace those . heavier springs yes 26lb . rod you should be good with a plus .10 as the piston tends to be in the hole .billet flywheel yes make sure it is for a hemi as the have a kohler taper . carb now there is your issue !!!! everybody i have seen using them on boats and using a stock or stock appearing carb runs out of fuel when they are tipped for extended periods . also make sure you pull the low oil shut off and plug the hole that can also be an issue with your application. that being said i would use a mikuni carb , intake and uni filter with a square mikuni pump pulsed off the intake and you should be fine :thumbsup: cam is your prefference depending on what rpm range you are looking for and where you want to make power

 

[trinik7597]

welcome to OldMiniBikes by the way :thumbsup: i am sure some of the more knowledgeable members will chime in to help maybe someone who has done this already !!

 

[fowl_language]

welcome to OldMiniBikes by the way :thumbsup: i am sure some of the more knowledgeable members will chime in to help maybe someone who has done this already !!

Thanks for the information and the welcome! I appreciate it a lot, you've inadvertently answered a couple more of my questions with your reply. I have been watching some of the head removal videos for the hemi online and I was wondering about running the stock valves. That should give me a little less of a headache to find parts.

I will definitely look into your carb suggestion as I was going to replace that anyway during the build.

I've been reading lately about the trouble with the pull start being too tough with some cams without something special...can't remember...something to do with exhaust relief or something. I think I might look into that more because I would still like to keep the pull start to make the motor as light as possible. The whole reason for this build is to basically get where other guys can't, one advantage to having a light motor is being able to portage the boat over land to launch and then take off from a head start. If I can pack a bunch of power into a small package it would be great.

I'll have to look around at cams tonight to see which offers the easiest pull with the most torque, I'm sure it's like anything else I want to do though. I'm sure if I have one...I won't have the other lol.

Thanks again for the information! Glad I found this forum.

 

[fowl_language]

Just found that topic again. Compression release on the cam, that's apparently what I need for sure.

I'm just updating this thread as I go, I figure it will be good for me to look back on and keep going. I will be updating with things as they happen hopefully someone else might find it informative.

 

[trinik7597]

yes you deff. want comp release on your cam if you plan on pull starting . also you do not want to exceed a 275 lift with the hemi head !! past that you will have problems . i think the mamba jr would be a good cam for your build but there are many good cams on the market and i have no exp. with the mod2