Nola Mike's 3.7/470 --> 4.3L swap thread

[Lou C]

Looks like they made a mistake and later caught it. Are the Vortec manifolds still known for leaking if you use good gaskets and follow proper torque specs? I don’t recall this being an issue with the old style pre Vortec intakes.

 

[achris]

Looks like they made a mistake and later caught it. Are the Vortec manifolds still known for leaking if you use good gaskets and follow proper torque specs? I don’t recall this being an issue with the old style pre Vortec intakes.

Only time I've heard of a manifold leak on a vortec is when the wrong torque has been applied to the bolts.

Follow the spec and you shouldn't have any problems.

And those specs are not Merc, they are from GM. I suspect GM didn't get it right initially, then issued an amendment, which Merc forwarded to their dealer network.

Chris.......

 

[Rick Stephens]

All I got to say is that all these details from dealers are a godsend to owners. Mercruiser never really intended that their product be serviced outside the dealer network. That dealers have made the service manuals a widespread available knowledge base is awesome. Further, that dealers like Chris share their hard earned knowledge is gratefully received.

 

[achris]

... dealers like Chris ....

Ex-dealer....

 

[nola mike]

Ex-dealer....

Yeah, much appreciated. I'm having a hard time navigating all the different sources of information. I would have never known about that SB. Like Lou C said, looks like a typo fixed after the fact. I found the proper specs when I went looking at gm. Trying to keep this thing leak freeI.not used to working on engines where a leak in the intake manifold ends up in the crankcase. Apparently it was a problem at some point, and they came out with a new gasket design.
achris, that's what I'm talking about in the transom shield. My lower studs corroded. Didn't realize that they were screwed into the gimbal housing, haven't looked too closely at it yet. As far as the shift cable, mine was fine. I cut the core when removing my stuck outdrive. Wasn't sure if that was somehow keeping it on (turned out to be a seized gimbal bearing). Only the outdrive is removed at this point.

 

[achris]

..... Like Lou C said, looks like a typo fixed after the fact....

Unlikely a typo. The mistake was in 4 different manuals. V6s and V8s... More likely bad info from GM...

..that's what I'm talking about in the transom shield. My lower studs corroded. Didn't realize that they were screwed into the gimbal housing, haven't looked too closely at it yet. As far as the shift cable, mine was fine. I cut the core when removing my stuck outdrive. Wasn't sure if that was somehow keeping it on (turned out to be a seized gimbal bearing). Only the outdrive is removed at this point.

The very bottom 2? If so, those are bolts. Just unscrew the nuts and drive them out. (#18 in the drawing below)

 

[nola mike]

They're already out. There was some rot around them, dug it out and filled with pb. Going to redrill the holes and put the new ones in. Those in the diagram were what I had in there, so no threads in the gimbal housing. 35 ftlb was the spec on some of the bolts on the old heads...

 

[achris]

IIRC, it's just those 2 at the bottom that are bolts.. And yeah, 35lbs/ft...

 

[nola mike]

Finally got a chance to get back to the motor. Got the rockers/pushrods in, valve covers, a few brackets and accessories, put in a thermostat (that spacer was fun to remove), coupler on. Starting to look like something that might actually run at some point. Only issue was the flywheel cover. I used the bolts from the old motor, but I'm thinking the new motor might be metric. The bolts went in ok, but started to strip out when I tried to torque them down. Neither my 3/8-16 nor m10 taps went in smoothly. This metric/sae crap kills me.
Next up, maybe Monday: distributor install, coil/wiring harness, oil pump wiring.

Also, can someone confirm the crank pulley torque? Merc manual says 74 lb-ft in one place, and 40 in another. Other sources of the web show 74 for the Chevy.

 

[Scott Danforth]

If the bolt is a 7/16-20, the torque is 60lb-ft

 

[achris]

..., but I'm thinking the new motor might be metric.

What is the engine block casting number? You'll find it on the back of the block, on the outside of the flywheel housing behind the starboard cylinder head. If it ends with an 'M', you have a metric block... And no, bolts from the non-metric block will not fit.

Here's a suggestion. Before you go too much further, record all the casting numbers, block, heads and if you still have access, crank, rods, etc....

Chris......

 

[nola mike]

I went looking for casting numbers before, the pic is what I came up with. Didn't think to get numbers off the internals before I put the pan back. I'll get the heads. The bolts when I thread them seemed a bit loose in there. One partially stripped, wasn't able to torque it all the way. I got one, but it didn't feel solid, if that makes sense. I stopped after that since I wanted to be sure. 30 lb-ft on an iron block shouldn't be an issue at all. Might end up as an m10 anyway.
scott Danforth, where do you find 60?

 

[achris]

That's not the casting number... Look here. (you're looking for an 8 digit number, possibly with an 'M' at the end)

 

[achris]

.... 30 lb-ft on an iron block shouldn't be an issue at all. Might end up as an m10 anyway.
scott Danforth, where do you find 60?

The damper bolt will be imperial, it's part of the crank, not the block. Here's the toque spec from the Merc manual for 4.3, up to 2001 (beyond 2001, it became 70lb-ft).

 

[Scott Danforth]

I went looking for casting numbers before, the pic is what I came up with. Didn't think to get numbers off the internals before I put the pan back. I'll get the heads. The bolts when I thread them seemed a bit loose in there. One partially stripped, wasn't able to torque it all the way. I got one, but it didn't feel solid, if that makes sense. I stopped after that since I wanted to be sure. 30 lb-ft on an iron block shouldn't be an issue at all. Might end up as an m10 anyway.
scott Danforth, where do you find 60?

all SBC balancer bolts that are 7/16-20 are 60 lb-ft lubricated with a dab of engine oil.....been that way for decades

 

[nola mike]

Still can't find the casting number. If it's on this block, it's well hidden. That's where it is on the old block, new one is blank. Also removed what I initially thought was a core plug, but turned out to be a seal for the balance shaft. Actually the rest of the plugs appear to be brass already. Removed one but am going to leave the rest.

 

[nola mike]

Got a bit done today. Still can't find the casting number, but got an m10 bolt, and yes, those flywheel cover bolt are indeed M10. This block is some unholy bastardization of SAE and metric. It appears that the flywheel cover, starter bolts, and mount bolts are metric, and everything else is SAE. Absurd. So I'm off to pick up up some metric bolts tomorrow. The holes on the starter were for 3/8" bolts, so the M10s are *just* too big to fit through. Was going to drill it out a bit, but I think I'll just get a new PMGR starter instead. Also inspected my squish mounts, and 1 base was corroded a good bit, so I'm going to get a pair of solid mounts as well (looks like the correct barr part is actually 8-0006, has the 3/4" stud). I got a 2.5" crank pulley bolt, and torqued to 60 lb-ft. All went well. Exhaust manis installed. I replaced that balance shaft cover/seal, reinstalled flywheel. At this point, here's what's remaining on the motor:
1. Distributor: 3 of the cap screws broke off in the base, so I'm going to need to drill them out Need new cap and rotor, and might as well get new plug wires.
2. Carb. Put in the studs, and have my 1409 waiting. Any way to tell what jets I have in there? I saw some of Rick Stephens posts about tuning his, wondering if I should just go ahead and order those jets and rods?
3. Fuel pump. Need to wire that in,and pick up a tee tomorrow to plumb in the switch.
4. Misc hoses and belts
5. Power steering. STILL can't find the right hose. Took it down to the NAPA machine shop near me, they told me maybe they could make me something, but not confidence inducing. I found a place that specializes in hydraulic line, going to swing by there tomorrow.
6. Wiring. It looked obvious when I disconnected it...

I think I'm going to bring it to the boat tomorrow and work on it down there. Only problem is that if I need a part, I'm pretty much SOL.

 

[Scott06]

On the edlebrock if it is new and unmolested -check the 1409 page here https://www.edelbrock.com/pub/media/...ers-manual.pdf

if it’s used potentially molested pop the top the jets have part numbers On them u can match up. They either have the size or part number stamped in them.

on the PS hose yes a hydraulic shop is best but you can also check shops that sell and maintain forklifts they will generally be a keto make hoses

 

[tank1949]

That's what it takes to get a post out of you these days, eh? I've been threatening to do it for years. .. you'll be laughing at me when I realize that this was way more work than I thought it would be. Already starting to miss the 3.7 a bit. Manifolds and risers are expensive and you need 2. Plugs and oil filter are a pita to get to.

If your refurb is salt water boat, add closed cooling. More expensive up front but it will save big bucks in the future. Make sure transom is not rotten. If so, now is time to rebuild it too. Trust me! These rebuilds keep your mind sharper.

 

[Rick Stephens]

Yes, the new 1409 is calibrated too mongo for a 4.3L. Start where I ended.

Rick