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blown VP 170- time to swap?

D

dock_holiday

Contributing Member
I was active here for a while when I first got the boat, then I just lurked and learned for years. Great stuff! Now I am active again because I Just blew something in the bottom end of my 40 year old VP 170. Not sure what, but it sounded expensive! probably a con. rod bearing or wrist pin. Any way, now Looking at the possibility of swapping in a 4.3 V6.. or some other 6 that makes sense (suggestions?) My outdrive is good and I like the boat. Just needs a new power plant. Don't want to mess with rebuild/repair of the "Iron Pig" 170. I believe that I would be best off with a 6 of some sort because the gearing in the leg is specific to 6's. What parts would I need to physically hook up the 4.3 to the outdrive? I know it can be done. I just need to know which BW connector shafts and bell housing ( I know it's not a bell housing in a boat but cannot recall proper term tonight!) I etc. I should start looking for/pricing. Also does the year of the 4.3 matter in terms of the connecting parts needed ? Could I do it w/o switching the transom collar that the exhaust goes out through to the leg by running the exhaust from the 6 out through the transom through new dual ports above water line with or with out flappers? I have lots of questions as you can see, but this forum is awesome and I know you guys will reply with the right info. so thanks in advance. I know that this or similar swap has been discussed here over the years but I am not skilled at searching for old threads... any help?

Thanks!

Dock...
 
Dock, it can be done.... been there/done that, and more than once.

Here's what you'll need if you stay with the 170 transom shield.

You'll need the GM V-8 flywheel cover w/ the course spline PDS.
images


The 153 tooth flywheel and Borg Warner drive coupler (the 168 tooth f/w will not work).

Side engine mounts for the GM V-8 or V-6.

You'll need an AQ200"B" 3" exhaust Y-pipe, or an early Ford engine Y-pipe.
Either will be single exhaust relief. The 170 transom shield is single relief.
images


You'll need the Barr or ??? universal exhaust maniolds w/ the 3" outlets.
You may need to modify the top section of the Y-pipe to accomodate the riser down angle.

The 170 drive ratio (1.89:1) may work for the 4.3L engine. If not, you'll need to find a 1.61:1 lower unit. Either have been known to work OK w/ the 4.3L.

If you change to the AQ225 D or E, or the AQ260 double relief transom shield, you can now use the larger 95mm double relief Y-pipe.........
$(KGrHqYOKjgE5WuvdTeMBOeRLMPz-w~~60_1.JPG

............. and the OEM exhaust manifolds and 95mm riser outlets.

The double relief transom shield is bringing some good money these days..... so don't be surprise to see $800 or so for a good used one.


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Another option would be buying the works from someone who is repowering (Engine, flywheel housing, transom shield, outdrive, etc), then sell whatever is left from yours.

The problem with projects like the one you are looking at is that they usually end costing way more than you initially estimated. Been there and done that. Oh, and some of them never get completed (this wasn't my case, but I have seen a few over the years).
 
Or purchase a donor boat with all of the correct components.

I do understand what Eduardo is saying. However, if you do piece this together, your chances of finding all of the parts are just about the same whether you retro-fit the 170 drive, or go complete with with an AQ260 style components.

The important part will be in learning just what's required in order to make it all work.
IMO, either will work!
One will be all OEM, whereas the other will involve the Barr style 3" exhaust.


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Thanks for the info guys. Got VP part numbers for the flywheel, FW cover, and PDS shaft I will be looking for? Been looking at motors etc. on e-bay. Could I save some cash by not using the exhaust routing in my 270 leg thus not having to buy the y pipe stuff and just dumping the exh from the 4.3 out 2 ports in the transom? Any problems/ issues with this? looks like I can get some used ports for about $50 or so, and I have tools to cut holes with.... Any issues with coming straight out of the risers and right out the back through the transom just above waterline ? If I did this would I be able to just plug up the exh. port in the 270 transom shield or at the top of the down pipe that the 170 manifold connects to? I am thinking I would want to seal off the old exh. system above waterline, inside the boat... right?

Thanks again!
 
Any AQ series GM V-8 flywheel cover will work, but in order to use your course spline female yoke, you'll need the course spline PDS.
This F/C can be one of the RED 1pc units, or it can be the B/W F/C using the Volvo Penta B/W -slash- PDS adapter housing.
Either will work.
The profile is indentical between the two.

Now.... the Holman Moody, Donzi, Eaton B/W -slash- PDS adapter housing.... that's a different story.
These set the engine FWD by 3-1/8".


You can go thru the transom with your exhaust if you don't mind the noise, or if you're 17 to 20 years old. :D
Pick up a set of Salsburry rubber mufflers with flapper tips.



NOTES of importance:
The inner large rubber cushion ring provides the water seal between the F/C and transom shield. Don't skimp out on this to save money...... this rubber cushion MUST be new.
The PDS bearings in the F/C will likely need to be replaced. Again, don't skimp out on this to save money.

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