Backfire!

[CraigBarnard]

Re: Backfire!

okay my luck just keeps getting better and better. I had a look at the 140 and the side was broken out from having frozen.
Back to looking for a replacement motor.
What engines can I hook up to that outdrive without any modifications?
I have heard of 4.3 vortecs and straight six engine swaps.
Is this correct and if so could I get some specifics on what to look for?

Thanks again, maybe it will be done for next summer

 

[Peaceful Pirate]

Re: Backfire!

Totally understand! Seems like we always have a ?quick and easy? job that ends up our winter project!

Best advice would be to just sit back and keep looking for a decent 140. As for going to a six, either straight or V-6, several things to think about, like well size, weight considerations and mating up to your existing outdrive and all that nasty stuff between the two. If you decide to go with something other than what you have, consider finding a package deal sitting in an old boat. That way you have everything you need to pull all this together. Caution however; just because it says Mercruiser does not mean part A of unit one is the same as part A of unit two.

 

[fishrdan]

Re: Backfire!

What engines can I hook up to that outdrive without any modifications? I have heard of 4.3 vortecs and straight six engine swaps.
Is this correct and if so could I get some specifics on what to look for?

If I were to do the engine swap, I'd replace everything from the waterpump to the prop. Get a rotted glass boat like Pirate suggested.

Change everything if swapping to a bigger engine. The 6 cylinder engines use a different drive ratio and the V6 won't work, too many differences between 65' and 85'.

One question, does the cracked 140 engine run? It's possible to JBweld the crack and seal it up. A marine engine water jacket (RW cooled) doesn't get pressurized like an automotive engine, so the JBweld just needs to seal the water jacket, not hold 15-20# of pressure.

 

[CraigBarnard]

Re: Backfire!

Well summer has pretty much passed us by and I finally got the boat in the water running properly.
I have been working on this boat all summer. Even had it to two marine mechanics who could not solve the backfire problem.
I was an automotive mechanic for 20 years but I know boats even though similar have their own specific issues sometimes.
So after I had exhausted all my knowledge and skill I assumed it was a "boat specific problem".
As it turns out the biggest issue was the timing. It was my first thought and I checked it. Timing was on spec.
Everyone I spoke to suggested the same thing. Many people on this forum suggested the same thing.
The timing was checked and checked again. And again. Still on spec. still backfiring.
So I tossed out the manual, timing light and the "proper & professional" procedures.
I kept turning the distributor and held the throttle open slightly until i could rev the engine up to 3000 rpm.
No more backfire!
Shifter and throttle linkage still seems a little wonkey to me but i can live with it for now.
Had it out on the lake for a few test runs, didnt go far just is case but all is looking good for the next 2 weekends left of the summer.
Now this winter the interior restoration will start.