4.3 omc knocking/casn I get a chevy v6?

[abqrb2000]

My 91 Four Winns I/O motor seems to be knocking. I am sure it is bad. It looks like a chevy v6 and has an Edlebrock intake and carb.
I was told that that boat motors rotate in reverse?

I wanted to get a decent 4.3 v6 from a junkyard truck. Is this an option?

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

Can I get a good bottom end from a car and swap the heads and cam over if they are in food working order.

 

[Don S]

Re: 4.3 omc knocking/casn I get a chevy v6?

The ARE a Chevy engine. With a marine cam. You will also need to replace all the core plugs in the automotive version if you don't have a closed cooling system. The marine version also uses a hi-volume oil pump, and you may have to change oil pans and use all the marine carbs, fuel pumps, starters, alternators, distributor and electrical.

 

[JCF350]

Re: 4.3 omc knocking/casn I get a chevy v6?

It's the same rotation as automotive. You can use the "preloved" motor but you'll be down in power. You'll have to swap everything over, plus even if it is cammed for a truck it will still come up short I believe.

Dang! I must type slower than I thought. :-D

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

Awesome! I will see what low mileage options are out there. I will swap cams and heads if necessary. Or even build a 4.3 at home. I have been playing with cars for a while and now boats too.

Do you guys have any after market cam suggestions. It's a 19 foot cuddy cabin? I like to ski and wake board.

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

I guess I have a summer project. Probably won't be going to the lake with a baby coming in March anyway. I hope my neighbors bobcat can lift the motor out of the boat.

 

[Bondo]

Re: 4.3 omc knocking/casn I get a chevy v6?

Ayuh,.......

I'll Add,...... Be wary of the Vintage of motor you buy,....

The 4.3ls have gone thru Many Changes,.......
All are Over-comeable,... But some are Much more expensive to Fix......

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

Thanks. I will stay with the same year block and most like rebuild the heads that are on it now so the manifolds are guaranteed to bolt up.

 

[bjcsc]

Re: 4.3 omc knocking/casn I get a chevy v6?

What makes you think it needs to be replaced? When my 4.3L was knocking (actually it's what brought me to this site) it turned out to be an intermittent connection in the distributor cap button. Before I found it, I pulled the engine and was checking for bearing problems, etc.. as directed by other members here. Anyway, make sure it is scrap before it is scrap...

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

Thanks for the advise.
I will look everything over again.
It all started when my wife started it while I was parking. She said it made a popping noise. I opened it up and notice the oil pressure was a little low. Then it starts smelling bad and smoking from the engine compartment. I immediately shut it off. It turned but would not start after that. After about 1 hour it started and ran horribly ruff back to the dock. Once at home I started it and heard a knocking and have not messed with it since.

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

Oh ya, the knocking increases with rpm?

 

[Silvertip]

Re: 4.3 omc knocking/casn I get a chevy v6?

There are some service bulletins on these engines (automotive) but that may apply to the marine version as well. Two in particular come to mind. Balance shaft motors have always had an issue with the balance shaft creating a noise that sounds like light pre-ignition. It takes a good ear to hear it and it happens only and very light throttle. It is not an issue if you can't hear well and even if you do hear well and can detect it, service is not required as it is not damaging. The other is a leaky oil pump "O"-ring. That allows the pump to suck a bit of air and that air can get trapped in a lifter which can make a knocking sound. Before you go through the trouble of pulling the motor, do some diagnostic work to verify what you are dealing with.

If you start junk-yarding for a V6 the first balance shaft motors were the "W" series engines that appeared in the 1992 model year. Most of the Chevy/GMC Astro/Safari all wheel drive vans had that motor. They had the "spider" type fuel injection system so plan on using your existing manifold and carb. Those injectors were $500 years ago and are probably much more expensive now. And that may be why the vehicle is in the yard in the first place.

 

[Windykid]

Re: 4.3 omc knocking/casn I get a chevy v6?

Definately check the dist. and where the knocking is coming from. Upper(cam) or lower(crank). Carbon build up on pistons can also make a knocking sound.

 

[abqrb2000]

Re: 4.3 omc knocking/casn I get a chevy v6?

Thanks for the advise guys.

 

[blueoval1]

Re: 4.3 omc knocking/casn I get a chevy v6?

I would think that the Edelbrock Performer Plus cam would be a good choice. It runs well from idle to 5500rpm. More than adequate for your 4200-4400 WOT range. Plus you are already using Performer parts anyway. The Performer cam was designed to be used with your intake and carb.
Good luck and keep us posted!

 

[flabum]

Re: 4.3 omc knocking/casn I get a chevy v6?

Do a compression check. Those motors are famous for dropping a valve. You may just need a valve job