New to forum Bunch O Questions

[svilla]

Hey guys I have a 18 foot Sunbird bow rider with a 4.3L OMC and Cobra out drive. I have been lurking in the forum for the past week and have found lots of info. I took my out drive apart to fix a shifting problem she works great now! But now I have some othere questions I hope you guys can answer. what is the diffrence in my motor and the 4.3L H.O? can my motor be converted? I would like to get 65 Mph out of this setup. also I get water draining out of my out drive where it comes thru the transom I suspect that it is a bad piece of tubing that my Father installed he said the tube/hose he got from the parts store was perforated and that does not sound right to me. so any how the water will not drain out of the prop like it is supose to. Any thoughts? Also has any one done a thru hull exhaust on one of these boats I would like the exhaust to exit under the swim platform. thanks and sorry for such a long post.

 

[svilla]

Re: New to forum Bunch O Questions

anyone?

 

[Ralph 123]

Re: New to forum Bunch O Questions

Well let me take a stab at a few things<br /><br />I am not famailiar with the 4.3 but you can take a look at a book like "small-block checvy marine performnace" to get an idea of what mods are possible.<br /><br />Second, you won't see any performnace improvements from thru-hull (I have twin thru hull) the reasons are explained in that book. If you are after HP you will have to change from manifolds to headers to get performance improvement.<br /><br />I'd also recommend you pick up a manual like those published by SELOC for your engine and outdrive. That should help a great deal no matter what issues you have. You can find the manual here in iBoats - just serach the mega mall.<br /><br />Good luck!

 

[Boatin Bob]

Re: New to forum Bunch O Questions

I had a pair of 1989 4.3's (King Cobra) back then the regular 4.3 was 175hp and the King's or HO were 205hp, the biggest difference was going from a 2 bbl carb to 4 bbl.

 

[notinbig]

Re: New to forum Bunch O Questions

Why not sell that sunbird and get an Advantage Off-shore boat, cause thats what your looking for. Your talking about 5-7G's and about 10-20 hp, your not going to get it by building. If you really want to keep the boat, pull the 4.3 and put in a 350,454,0r a 502, then you'll get what your looking for. A 4bbl. will help but only by 4-6 hp.

 

[svilla]

Re: New to forum Bunch O Questions

Thanks for the replys fella's. I thought the diff between motors would only be the carbs and I think the ignition. cool well looks like that is the upgrad I will make this winter. And I guess I will not do the thru hull. And first thing I bought for this boat was a manual .This is a project boat that I got for free, so repower to a 5.7 might be an option. but only after I see where I am at with the 4.3. I think this will be a great little boat with some TLC. Any one know if the exhaust boot from the engine to the out drive is supose to be perforated?

 

[Lou C]

Re: New to forum Bunch O Questions

That is OK I asked about it and the OE ones were not, but aftermarket ones are to let the exhaust out faster and cut down on carbon build up in the engine. Mine is that way too.

 

[svilla]

Re: New to forum Bunch O Questions

Thanks Lou C

 

[tylerin]

Re: New to forum Bunch O Questions

I have a 87 4.3 omc cobra it came factory w/ perforated exhaust bellows. When I bought the boat new in 87 I was told that I had 205 hp and I have a 2 barrel carb. It might be bs but my boat is pretty peppy for a 6 banger. 65 mph is difficult to achieve on water

 

[tylerin]

Re: New to forum Bunch O Questions

I just read the part about water leaking out the tube and this should be fixed. The end towards the transom has a hose clamp but needs to be sitting in a groove first. the other end attaches to the gimbal housing w/ a retainer clip. When I bought my new exhaust bellow the guy handed me a tube of bellow sealant and said to apply it when installing. Worked for me. There is also some specs on how to put the hose clamp. the worm screw should be placed at 3o'clock or your steering radius will be restricted. U-joint bellows is 2o'clock