Alpha One 4.3LX Won't Start & Backfires

[rl65028]

If the compression doesnt increase with oil added to cylinder problem probably in heads. New ones aren,t too pricey. Try clearwater cylinder head or alabama cylinder head.

 

[bondo]

The only issue of concern that I can think of is the flywheel and coupler. it may need to be changed due to a different crankshft bolt pattern but I am not sure on this.

Ayuh,... In this case, that's irrelevant, as the change was in '87....

 

[RicardoMarine]

Jkm3093.... your thread of October 2011 has been resurrected. I just did a quick read of it!
Although it looks like you're past the diagnosis portion, and on to a new engine........, here's a tid bit of information for you for future use.

Adding oil to cylinders of a V engine is not always going to offer you the results of what you are looking for.
First.... the cylinders are not perpendicular to gravity, so the oil will pool at the lowest section of the cylinder....... and this works against us.

Secondly.... oil has a volume to it. Any volume added to a cylinder consumes space. Consumed space by a non-compressible substance intrinsically increases cylinder pressure as the piston reaches the top of its travel.
Ultimately we want just enough of this oil to seal around the compression rings.
This is very tough to do on a V engine.

As for the valve lash idea, valve lash rarely decreases due to component wear... unless the valves themselves are becoming worn into the seats.
Any wear to the rocker arms, ball swivels, push rods or cam follows or even cam lobes, increases valve lash if anything.
I'm not suggesting that this NOT be checked, but I think this is somewhat doubtful that this is holding a valve partially open.

As for camshaft wear, this too increases valve lash when the follower "plungers" can no longer take up the lash.

I was curious as to anyone mentioning the SA system as per what Kghost posted! This was a good suggestion, IMO.
IOW, don't just look at it and assume that it is OK, completely disconnect it, and give it a try!

Fast forward to your most recent post:

The 1994 crankshaft flange will be the same as the Vortec. The flywheel should work for you if both engines use the 1 pc rear main seal.... of which they should.

The 4.3L engine has some of the same characteristics of it's cousin, the SBC V-8.
The cylinders heads also incorporate a wedge area.
The 4.3L typically used the dog gone full dished pistons!
Here's a thread that may interest you when selecting your new components. ... and in particular, pistons......, and in particular with the Vortec cylinder heads if you want to take full advantage of them!

Have fun, and Merry Christmas to all of you guys!

 

[jkm3093]

Hi guys,

Thanks for the additional comments. In the end I bought a new GM vortec head long block & 4 BBL intake manifold. Progress is pretty slow since I've been tied up with other things & goal is to have this thing running by Memorial Day. Current status is I pulled the old motor and they are both sitting on a bench to swap over parts. Attached are a few pics.

I think I'll start a new thread as kghost suggested since I have a few questions about motor differences.

Thanks, Jim

 

[guyjg]

Nice shop. Take a close look at the coupler splines. If the spline edges are rounded you might consider changing it now since the engine is out.

 

[jkm3093]

Thanks, Guy. My shop is a work in progress at our Cave Run Lake weekend house - too bad it is a 2 hour drive to get there.

I take it you mean the edges along the length of the splines? Both male and female splines? The male ones looked good but I'll look closer. I'll also change out the water pump / impeller while the outdrive is off. I made a cradle on a Harbor Freight dolly to remove / store the outdrive.

 

[guyjg]

Cool dolly.

I take it you mean the edges along the length of the...female splines?

They are made of aluminum. A slight misalignment of the engine/OD ruined mine. Do you need an engine alingment tool? I have one you can have if you pay the shipping.

 

[jkm3093]

Thanks for the offer, but I bought an OEM alignment tool since I thought it is good to have on hand. From your experience, I better make double sure alignment is right on! Since I removed the front engine mounts by the lag screws into the stringers and didn't loosen the adjustment nuts, I hope it will be pretty close when I put it back together.

 

[kghost]

One piece of advive........

Remove the dole fin for now ( I actually would not use it at all but that is your choice).
When handling the outdrive. especially when re installing it will save many cuts to your arms and legs with it off!!!!

 

[jkm3093]

That's a Stingray Hydrofoil I put on shortly after getting the boat on the advise of a friend to help get on a plane sooner pulling a skier up and to be able to plane at lower cruising speeds. The outdrive is lined up to the transom studs with the dolly I made, so it doesn't get in my way installing the outdrive but I'll be taking it off anyway when I break the lower unit apart to change the impeller.

Your comment prompted me to look into if I want to keep it l all, but I guess this should be another thread. I haven't quantified the foil's benefits which is something I'll do during the summer after this project is done. I think smart tabs would work better for me to eliminate low speed steering wander, easier low speed planing, reduce porposing, increase top end speed, etc.

I can't say the foil has helped much but it does make a nice step to climb back into the boat!

 

[kghost]

The use of a hydrafoil is NOT reccomended by merc that is the first thing!

Second, If you are going to pull skiers then drop the prop pitch 1 or 2 (from a 19 to a 17 or 15 pitch) this is the correct way to do it. You gain hole shot but loose high speed (over rev) but you will yank the skier out!!

There are also torque thrust props that start at a low pitch and at a certain rpm "shift" to a higher pitch and are adjustable ($$$$)

When using a hydrafoil it does bring a heavy under powered boat on plane quicker YES

BUT the downside is it forces the bow down, it puts a real strain on the steering system and with some boat configurations it will actually cause the boat to over steer at high (er) speeds........Very dangerous!!


Also with the new power plant you are installing it may work as designed when new so I would at least start WITHOUT it.

Just my opinion.......

 

[jkm3093]

OK, good points - I'll start with stock conditions. The extra 30-40 HP with the new motor might be enough.

Smart Tabs still look interesting - thoughts for a recreational lake boat?

Thanks, Jim