Mercruiser 3.7 Build, 1970 Cj5? Big Block Hurricane!

Searching local for bell now, while I get the rest tore down.
I was thinking bout a crank extension pilot bearing. If needed
I'll get the bell bolted up, then a trans mount bell to crank end measurement.
Thanks
And yes if that 300$adapt does it, I'll buy it.

 

How bout a press in pilot holder in the flywheel,
Maybe tack it in between the studs?

 

Why not bolt it in with the flywheel bolts, much easier and no welding to throw crap out of balance.

 

Thinking of future problems.
29in long puts the balancer bout 1.5in under the radiator.
Maybe shorten the grille box couple inches and push rad forward?
Is the v6 grille any shorter than the 134f grille box?
Anyone done this grille box shorten thing to install longer engine?
I'll need 2inches, 4 would be better.
Probably have to run elect fans, I'd rather belt drive one, maybe of an idler pulley?

 

Reading this thread, I've been wondering about that... I don't have any experience with the Mercruiser engine, but I do have a 460 powered pickup, and I was looking at the length of that engine compared to the Jeep engine compartment and wondering how it was ever going to fit.
The radiator on a 72 and up Jeep is real close to the grill you might take a look at one of those.

 

You can remove the shroud and even cut into the headlight buckets if need be. Often done.

 

I'd rather not butcher my original grille housing, it's in near perfect cond.
So a 72 up cj grille will bolt on and look the same, from the outside?
Thanks

 

Is this the one to try?

3840383 Bellhousing Chevrolet GM Corvette Nova Chevelle Camaro bell housing 4 | eBay

 

It will work fine. I put a ‘74 grille on my ‘64. I needed more radiator and the ‘74 allowed a much larger cross flow radiator. I the only bad part was I lost the glass bee-hive turn signal. I didn’t want to butcher up my ‘64 grill either.

 

Oil pan off!
Everything looks good!
Found a bell, should have by next weekend.

 

Your photos show why there are two sump areas, one for the oil pump, and the larger for the pickup. At least the larger sump is at the rear! I love to see a forged crankshaft with 5 mains in there. Your rear crank snout is the same as my 470.
-Donny

 

How do you know it's forged by looking at it? A forged crankshaft is unusual in a modern engine.

 

A cast crankshaft has a narrow line down the middle where the two sides of the mold come together. That line is much wider on a forged crank...easily seen in the last picture above.
I'm curious about the oil pump at one end and the pick up tube at the other end, what's the reason for that?

 

Marine engines seem to prefer a rear sump because boat often operate with the bow higher than the stern, keeping oil toward the rear of the engine.
-Donny

 

I think it's benn into before?
Rods are numbered, and double row timing chain.
Chain has a tensioner, I'm not sure why?
Hamb said it's the same chain as a BBC?
If so, then a line hone chain,shorter than stock,can be used?
Tensioner not available !
Benn researching gasket sets,marine engine stuff,higher than car stuff?
Pistons .028 down in hole.
Going to have .025 took off deck, not for more compression, but to
tighten quench,to help stop detonation.

 

The head gasket really should be OEM Mercruiser only. The rest of the gaskets can be other brand like Sierra. My engine also has a double roller chain and damper. The dampers usually have little to no wear, so this is usually reused. Chains stretch with use, so a fresh chain will usually take care of your slack. There was a lot of minor variation during the production run of these engines as far as what parts were used. The Mercury dealer likes your serial number when ordering parts to get correct parts for your vintage. The numbered rods are typical. These were hand-assembled engines.
I would not recommend decking the block unless it has a damaged surface. I believe decking the block that much will contribute to increased pinging/detonation.
HAMB has a lot of mis-information, so read their stuff for entertainment, not for absolute facts.
-Donny

 

Sounds reasonable, but the vast majority of the 2.5/3.0L Mercruisers were front sump.

Marine parts, gaskets included, are often quite a bit higher in price. The OEM head gaskets in my marine 2.5s were all stainless steel and thinner than conventional head gaskets.

Just a few days ago, happened to look at my 2 easily available 2.5 (153) blocks and looks like neither has been zero-decked and both have the top of piston about .03 down in the hole. One is marine and one is Chevy 2 or postal.

Will the stock 470 oil pan work for a vehicle that sees crazy angles as a 4x4 does?

 

I'll use a merc head gasket, and generac gasket kit!
Rear sump plenty for jeep angles.
Tightning quench helps stop detonation.
I'll remove some material in head around valves, as per 460 head porting instructions, to get back
to std compression.
.025 off block, with a .038 head gasket is still plenty safe?
And maby it's not benn into before, no gasket sealer showing on gaskets so far?
Numbers on rods are really nice and even, better than I could do it?
Might have had the double chain stock?
Gonna deck block and leval head, I want every chance of sealing this thing up!

Reconmondations on where to get a 72 up grill, for more clearence?
With head port matching, tightening quench,and a good tune,roller rockers.
I hope to be bout 200hp, and 250 torque? All in before 4500rpm?

 

I have that grill at a friends house- getting it tomorrow. But it's a long way to ship.

The stainless Mercruiser head gaskets seem thinner than auto ones for the 153. Can't say about the 470 gaskets. Maybe deck it only enough to get it flat- same with head.

All your pics show a pretty clean engine- inside and out. Some boats see very little use of just a few hours a season. You might have gotten one of them. Any ridges on the cylinders?