About engine mounts - 3.0 to 4.3

[skijunk]

After I get my alignment worked out and have my measurements, what would be wrong with making an aluminum bar mount, lag bolting it to the current stringer then bolting my stock engine mounts to the aluminum bar? It seems this would be easier than epoxy, fiberglass molding..

Thoughts?

Thanks !

 

[HT32BSX115]

After I get my alignment worked out and have my measurements, what would be wrong with making an aluminum bar mount, lag bolting it to the current stringer then bolting my stock engine mounts to the aluminum bar? It seems this would be easier than epoxy, fiberglass molding..

Thoughts?

Thanks !

Nothing wrong with that as long as the lag-bolt points are still in good shape and tight!

 

[skijunk]

Nothing wrong with that as long as the lag-bolt points are still in good shape and tight!

That's what I was thinking, but it never hurts to ask. I think it will be a lot faster for me .
Thanks !

 

[Bondo]

Ayuh,.... I don't like havin' Any "Junk" hangin' under the motor,....

It's always, "In the way" when ya gotta get down in there, 'n fix something,... like a bilge pump or float switch,....

In my ole tinbarge, I bent up some aluminum plate, .090", 'n pop-riveted 'em in to the stringers, 'n ribs,...
Then trimmed out a big hole to be able to get to the starter, 'n it's bolts,....

In a glass boat, usually some small blocks of plywood, a few strips of cloth, 'n some epoxy resin does the trick for Me,....

Hangin' the motor on the rear motor mounts, 'n a crane, with the alignment bar slid in tells Me where to build the mounts up too,....

 

[HT32BSX115]

That's what I was thinking, but it never hurts to ask. I think it will be a lot faster for me .
Thanks !

Now there are some "things" that you should consider.


If the aluminum plate is bolted rigidly to the engine (block) mount point and the shock-mounted engine mount is still sitting squarely on the (wood/fiberglass) mount pad and is still lag-bolted to the stringer, there's no problem.

If you try to bolt a piece of aluminum plate to the stringer (mount point) to off-set the (rubber shock mounted) engine mounts on the plate,those lag bolts will eventually loosen.

If it were me, (and I had an aluminum boat) I would probably do it like Bondo did on his.....except I have a MIller TIG welder. SO I would've just fabbed and welded in new ones!!

If the engine is out, and the stringers are wood, I would cut some blocks of hardwood, locate, grind and screw/epoxy in a new wood mount point and glass'em in.

When I replaced my old OMC 460 with the 454, I only had to move my engine mounts an inch or so on the existing pad.

 

[achris]

Do it right, do it once.

 

[skijunk]

Now there are some "things" that you should consider.


If the aluminum plate is bolted rigidly to the engine (block) mount point and the shock-mounted engine mount is still sitting squarely on the (wood/fiberglass) mount pad and is still lag-bolted to the stringer, there's no problem.

If you try to bolt a piece of aluminum plate to the stringer (mount point) to off-set the (rubber shock mounted) engine mounts on the plate,those lag bolts will eventually loosen.

If it were me, (and I had an aluminum boat) I would probably do it like Bondo did on his.....except I have a MIller TIG welder. SO I would've just fabbed and welded in new ones!!

If the engine is out, and the stringers are wood, I would cut some blocks of hardwood, locate, grind and screw/epoxy in a new wood mount point and glass'em in.

When I replaced my old OMC 460 with the 454, I only had to move my engine mounts an inch or so on the existing pad.

This is a 1998 Tracker Tahoe Runabout (ski boat) My plan was to do what you suggested in the second paragraph - to lag bolt the aluminum to the existing wooden stringer, drill and tap holes into the aluminum block to bolt my rubber engine mount to that. I had not considered adding a block above the rubber mount affixed to the lug on the engine block.
In my case, since the 3.0 mounts are on the front of the engine, I am creating mounting points for the 4.3's side mounts. The more I read and research, I am coming to the conclusion that fiberglassing in a wooden riser is likely the best choice. Not to mention the dimensional piece of aluminum stock I will need for the riser will be more expensive and probably no more effective than epoxied wood. I may be overthinking this and what I need to do is just do it.

 

[Rick Stephens]

I just made up peanut butter and laminated 3/4 inch plywood to make my mounts. I can't see a need for hardwood. Hardwoods usually rot just as fast as anything else if you let it get wet. Don't let it get wet, do final install of the lag bolts with a liberal application of 5200 to seal them permanently. Make your mounts as small as you can, taper them in and round all the corners so your glass wraps easily. Grind ALL gelcoat off to bare pink fiberglass before putting down any new resin. Run your glass all the way from the transom to as far forward past the old front 3.0L mount as you can. It will last forever.

When checking level for your new mounts, run a string across under the transom plate motor mounts, up through the holes, then cross them and pull tight on to top of new mounts on each side - in an 'X'. If the strings meet in the middle of the X your mounts are level to the transom plate mount points.

I just did the same thing last winter.

 

[skijunk]

I just made up peanut butter and laminated 3/4 inch plywood to make my mounts. I can't see a need for hardwood. Hardwoods usually rot just as fast as anything else if you let it get wet. Don't let it get wet, do final install of the lag bolts with a liberal application of 5200 to seal them permanently. Make your mounts as small as you can, taper them in and round all the corners so your glass wraps easily. Grind ALL gelcoat off to bare pink fiberglass before putting down any new resin. Run your glass all the way from the transom to as far forward past the old front 3.0L mount as you can. It will last forever.

When checking level for your new mounts, run a string across under the transom plate motor mounts, up through the holes, then cross them and pull tight on to top of new mounts on each side - in an 'X'. If the strings meet in the middle of the X your mounts are level to the transom plate mount points.

I just did the same thing last winter.

I am with you. My first thought for using wood was to use a block of hardwood but as you and Bondo suggested using plywood or maybe I could use pine, I can see the advantage of the plywood / porous wood wicking up the resin and probably making a more durable, water resistant block. I'll take that tip for crossing the string for level too!
thanks !

 

[HT32BSX115]

I just did the same thing last winter.

NICE JOB!

 

[achris]

I prefer to use hardwood. Reason is it doesn't compress, and so the engine alignment stays 'in' for far longer. Using pine or plywood will mean you really do need to be checking and adjusting the alignment every year. JMO....

In Australia we use a wood called Jarrah. Hard like nails!! In fact, when you want to drive a nail into it, you need to drill the hole first. It's almost a shame to use it for engine mounts, it is a naturally beautiful wood, and a lot of furniture is made from it too.

Chris.....

 

[HT32BSX115]

I prefer to use hardwood. Reason is it doesn't compress, and so the engine alignment stays 'in' for far longer. Using pine or plywood will mean you really do need to be checking and adjusting the alignment every year. JMO....

In Australia we use a wood called Jarrah. Hard like nails!! In fact, when you want to drive a nail into it, you need to drill the hole first. It's almost a shame to use it for engine mounts, it is a naturally beautiful wood, and a lot of furniture is made from it too.

Chris.....

:thumb: I like hardwood because you're less apt to strip a lag bolt or have one become loose. polyester resin and glass properly applied will stick well to any type wood......