Chevelle Engine Update

"MM54" (mm54mk2)
02/02/2019 at 11:15 • Filed to: '71Chevelle

I have no pictures of the actual parts yet. Sorry.

Drove out to the machine shop this morning to check out the bottom end parts (had them shipped there; see below) for the 383 build and talk machine work.

Scat forged stroker crank (internal balance), Scat 6" I-beam rods with 7/16 ARP bolts (bushed for floating wrist pin), Clevite tri-metal bearings, moly/cast/cast Total Seal rings, Icon forged pistons (coated skirts), full floating wrist pins. Many shiny parts.

Also finalized the plan for the machine work on the block, which is getting a full going-over as well as the fine-tuning of the rotating bits (which is why they went to the shop despite me doing the final assembly).

Line hone, set main bearing clearances, bore .030 over, hone to match pistons, set clearance on the rod bearings, set oil clearance on the wrist pins (both rod and piston), clearance the block as required for stroker-ness, check the deck height and deck enough to square it all up, light hone on the lifter bores, embiggen main oil galley, final cleaning, install cam bearings and oil galley plugs. The block has already been cleaned and pressure tested. Rotating assembly will also be balanced.

We also spit-balled ideas for heads and cam type (probably a solid flat tappet on the latter, exact spec TBD; exact heads TBD, but aluminum and probably 200cc runner, 64-67cc chamber)

Whew.

DISCUSSION (14)

Manwich - now Keto-Friendly > MM54
02/02/2019 at 11:29

This all sounds great except for that Scat name brand

I recommend you never do a Google image search on ‘scat’

MM54 > Manwich - now Keto-Friendly
02/02/2019 at 11:35

Shhh

ITA97, now with more Jag @ opposite-lock.com > MM54
02/02/2019 at 11:59

Awesome! This is engine building done right.

I like cars: Jim Spanfeller is one ugly motherfucker > MM54
02/02/2019 at 12:51

Should just say screw it and toss a KA24DET boosted to hell in there

MUSASHI66 > MM54
02/02/2019 at 13:01

I like cars, but 95% of this post reads like Chinese to me :)

sdwarf36 > Manwich - now Keto-Friendly
02/02/2019 at 14:04

You better figure your cam pick now-you need it to check rod to cam clearance.

MM54 > I like cars: Jim Spanfeller is one ugly motherfucker
02/02/2019 at 18:15

Hmmmmmmmmmmmmmnah

MM54 > ITA97, now with more Jag @ opposite-lock.com
02/02/2019 at 18:16

I’m working with a shop that really knows their stuff; it’s good to know it’ll all be done right. I’m doing all the assembly but we’ve walked through all the machine work and I know it’s in good hands.

MM54 > MUSASHI66
02/02/2019 at 18:17

Short form: The good engine is underway.

shop-teacher > MM54
02/02/2019 at 23:51

Good stuff! Image is very appropriate :)

MM54 > shop-teacher
02/03/2019 at 00:01

Every time I think about it, it gets more expensive!

shop-teacher > MM54
02/03/2019 at 00:05

I bet!

Future Heap Owner > MM54
02/06/2019 at 01:52

For fun, I’m gonna try to guess what all your jargon means, without looking anything up . I consider myself to have a good high-level understanding of how engines work. Let’s see what that gets me.

Parts paragraph:

• stroker crank: never heard of this. Is it only a balancer? Where does it live?

• I-beam rods: the part that connects the thing that holds the bearing around the crankshaft to the piston head, aka the “ connecting rod”. Yours have an I-beam shape

• ARP bolts: American Retrograde Precision bolts?

• tri-metal bearings: these are the bearings for the rods, and for where the crankshaft is held by the block. I don’t know what the three metals are or why that’s good.

• moly/cast/cast rings: Piston rings. One is chrome moly(?), two are cast iron.

• Forged pistons: pistons that were made from one piece of metal that’s been shaped, instead of cast in a mold.

• Coated skirt: the part of the piston below the rings is coated with something. Dunno what nor why

• full floating wrist pins: I think the ‘wrist pins’ are the part that connects the rods to both the heads and the crankshaft bearings. Full floating must mean that they maintain an oil layer between the parts to reduce wear

Ok, that was the harder one (I think).

Machine work paragraph:

• Line bore: ok I have no idea on this one. “Line” makes me think it goes down the length of the engine . I’m gonna guess this involves the holes in the block for the crankshaft bearings ?

• set main bearing clearances: fine work on the holes for the crankshaft bearings in the block.

• bore 0.0 30 over: widen the combustion cylinders ever so slightly

• hone to match pistons: make sure the piston heads fit nicely in the just-bored cylinders

• set clearance on the rod bearings: pretty much self-explanatory

• set oil clearance on wrist pins: make sure there is the right amount of room for the oil layer that makes your wrist pins “full floating”

• clearance for stroker: make sure your balancer thingy can fit (again, not sure where).

• check deck height & square deck: hmm, I’ve not encountered the term “deck” yet. The first thing that jumps to mind is the flat part of the block you can see if you take the cylinder heads off. If that’s not as level as can be, your head gasket is not gonna seal properly. So I’m guessing this is making sure that’s as flat as possible.

• hone the lifter bores: embarrassingly, I’m not 100% on what a “lifter” is. I know it’s something between the cams and the valves. Is it another word for “tappet”? Or are they pushrods like you’d see on an older V6/8 engine? Regardless, this work makes sure the holes that hold those rods as they move back and forth as some part of opening and closing the valves are good and smooth.

• embiggen main oil galley: make the part of the block where the most oil flows through even larger (dunnno why)

• install cam bearings: these are like the main bearings on the crankshaft, only for the camshafts instead.

• install galley plugs: don’t let the oil just run out when you put it in.

• balance rotating assembly: not sure what “rotating assembly” encompasses; is it the crankshaft, bearings, rods, pistons, and balancer, or those and the camshafts & cams? Or something else?

Whew! Well, I had fun, and I think I figured a few things out. I wo uld appreciate any mistakes you wanna point out.

MM54 > Future Heap Owner
02/06/2019 at 09:48

Pretty close!

Parts paragraph:

• stroker crank: never heard of this. Is it only a balancer? Where does it live?

This is a new crankshaft itself, with a longer throw than stock - that is the pistons move further down in the bore, creating higher displacement (in this case, 383 ci instead of 350). “Internal balance” means that I don’t need an external balancer and can use a neutral-balance flywheel.

• I-beam rods: the part that connects the thing that holds the bearing around the crankshaft to the piston head, aka the “connecting rod”. Yours have an I-beam shape

Correct, these are the connecting rods and have an I-shaped cross-section. This is different from an H-beam rod in that for an I-beam, the two flats are parallel with the crankshaft, whereas an H-beam they are perpe ndicular. It’s a strength thing (H-beams are stronger and a lot more expensive) .

• ARP bolts: American Retrograde Precision bolts?

American Racing Products. Basically very high-grade bolts to keep it from coming apart (or flexing) at 7000RPM.

• tri-metal bearings: these are the bearings for the rods, and for where the crankshaft is held by the block. I don’t know what the three metals are or why that’s good.

The trimetal is basically a secret sauce layering of different coatings over the steel base for the bearings. This are both the rod bearings and the main bearings (crank to block) as you correctly surmised.

• moly/cast/cast rings: Piston rings. One is chrome moly(?), two are cast iron.

Correct on the cast iron, the moly is a molybdenum coating though, not chrome-moly like you’d have in tubing as such.

• Forged pistons: pistons that were made from one piece of metal that’s been shaped, instead of cast in a mold.

Yes

• Coated skirt: the part of the piston below the rings is coated with something. Dunno what nor why

Correct. In operation, the piston skirt sort of ‘wobbles’ back and forth as the piston goes up and down (since the rod doesn’t go exactly up and down, there is sideloading) and hits the cylinder wall , these have a low-friction coating on them to reduce, well, friction (and thus wear) .

The wrist pins are what hold the piston onto the connecting rod. The ARP bolts mentioned earlier clamp the rod/bearing onto the crankshaft. As you said above, a floating wrist pin means it is suspended in an oil film, rather than press-fit into the rod. This means there is a bronze bushing in the little end of the rod for the pin to float in.

Ok, that was the harder one (I think).

Machine work paragraph:

• Line bore: ok I have no idea on this one. “Line” makes me think it goes down the length of the engine. I’m gonna guess this involves the holes in the block for the crankshaft bearings?

Correct! This essentially machines the main bearing surfaces (where the crank meets the block) so that they are correctly lined up and the same size. The factory gets them ‘close enough’ but for a high-performance application you want to get much better tolerances. My block had one almost .002 tighter than the one next to it, and another with a .001 taper front-to-back!

• set main bearing clearances: fine work on the holes for the crankshaft bearings in the block.

Yes.

• bore 0.030 over: widen the combustion cylinders ever so slightly

Correct, this will take the bore from 4" to 4.030" which will remove pitting and scoring, leaving a fresh like-new cylinder.

• hone to match pistons: make sure the piston heads fit nicely in the just-bored cylinders

Basically, yes. Boring doesn’t leave a great finish (which needs to have a cross-hatch for oil retention/sealing/the rings to work right) so the hone will both take it the last couple thousandths to leave an exact piston/bore clearance as well as leave the correct finish.

• set clearance on the rod bearings: pretty much self-explanatory

It is.

• set oil clearance on wrist pins: make sure there is the right amount of room for the oil layer that makes your wrist pins “full floating”

Correct. This applies to the small end of the rod as well as the pin bore in the piston themselves.

• clearance for stroker: make sure your balancer thingy can fit (again, not sure where).

Since the new crankshaft has a longer throw, there is potential for very slight interference between its throws and the block. This procedure removes a little bit of metal from the block as required so it can actually turn.

Right, the deck is the surface to which the head attaches . This operation will both smooth this surface for sealing as well as making sure that the distance from the crankshaft to the deck is the same for all cylinders. This is another thing that factory is “close enough” but you may find it’s higher on one end than the other, one bank is different than the other, it’s twisted, etc. This affects compression and overall performance.

‘Lifter’ and ‘tappet’ are the same, yes. The lifters interface the cam lobes with the pushrod, and ride in little holes in the block. This also serves as a major oil passageway, so it’s important the lifter fits properly in the bore (too tight and it will stick, too loose and oil pressure will suffer).

• embiggen main oil galley: make the part of the block where the most oil flows through even larger (dunnno why)

Correct. With a high-volume oil pump this simply allows more oil to flow through the engine for more lubrication/cooling.

• install cam bearings: these are like the main bearings on the crankshaft, only for the camshafts instead.

Correct. For this engine it takes a special tool and is generally a pain, so the shop is doing it for less than I’d spend on the tool.

• install galley plugs: don’t let the oil just run out when you put it in.

Correct, moreso to keep it from shooting out when you start it :)

• balance rotating assembly: not sure what “rotating assembly” encompasses; is it the crankshaft, bearings, rods, pistons, and balancer, or those and the camshafts & cams? Or something else?

Rotating assembly is the crank, rods, and pistons (and bearings). This gets the balance right so that it spins smoothly and evenly.

Well done!