71 GY3 GTX update... Comin' together!

[471_Magnum]

After mounting the motor on a new engine stand ($40 from Rural King) I got a couple of the main bearing caps off tonight. Bad news is the mains are scored. Good news is they are STD, as are the rod journals.

I examined the bores. They look really good with the cross hatching still clearly visible.

Right now I'm leaning towards building a good stout short block, using some CAT H-beams and Diamond flat tops. That will give me a nice light bobweight that will rev well with the stick and provide a good basis for any future possible upgrades.

I'll do the port matching myself on the 452s. I'll have a couple of weeks to kill once I get the block and crank to the machine shop.

My friend's motor is completely blue printed. I'll check it out later this week. Frankly, I hate to compromise with cast pistons and stock rods, but we'll see what the price is.

[terrible one]

Been following this thread.

That's a good deal about the motor. At least it's not a total loss, and you have a good block to build from. Nothing beats dependability, especially when YOU do it, because then you know that you've got things right. Goes back to "if you want it done right, do it yourself." As much as it sucks, now you know that it's going to be completely dependable for the future. The car really is beautiful. It's an absolute shame that the money from the mechanical funds was taken for that beautiful body.

[471_Magnum]

Got the call from the machine shop today. Block checked out okay. Just needs honed.

Crank will have to go 10-under, which I expected.

So I called 440Source and ordered my parts: Forged flat-tops, H-beams and all the required rings and bearings. I've already procured pretty much everthing else I'll need. Just need to call Mancini and order a couple of other odds and ends.

With some luck I'll be assembling the motor Labor Day weekend.

I suppose if I get REAL lucky, I might have it together by MMW. That would be pushing it though, and I'm not going to rush things.

Meanwhile I'll start working on those heads.

[471_Magnum]

D'oh! Almost forgot. It will still need balanced. Forget Labor Day weekend.

[Nacho-RT74]

did you by luck took a pic of cilinder walls ? I wan't to know when needs to be honed and not bored looking at cilinders wall conditions.

[471_Magnum]

Nacho,

You can visually inspect for scratches, but the other things you need to look for is bore size, taper and roundness. The latter items can either be out of spec due to wear or poor quality machine work.

In my case, I could still see the cross hatching from the previous honing, and there weren't any scratches, so I knew wear wasn't an issue. I was more concerned with the other potential issues listed above.

If the block was going to need to be bored, I would have had it sonic checked as well. Never a bad idea, especially if you are planning to make some serious horsepower. My horsepower target is pretty modest, so I skipped it.

[72pettyblue]

Man, I can feel your pain.  I took a chance on my 72 charger and the motor looked good from outside, but after driving it for 3 days it was obvious it was junk.  cyl walls scored, had spun bearing but someone tried to polish it and replace bearings, cam lobe was wiped, had cast dished pistons, etc.  From the outside it looked like a hp 440 with nice gear drive, holley super comp headers, weiand team g, holley 850 dp, electric fuel pump, elec fan, subframe connectors welded in.  I bought it off ebay after talking with the guy and seeing pics.  but the motor looked like and old low compression motor that was junk.  Long story short, I rebuilt the motor after considerable machine work and installed forged alum 6 pk pistons and comp xs282s cam.  Of course the trans was junk also with someone trying to rebuild it but put the wrong clutch pack in and ran some metal to metal.  But it is all back together now and I know what I really have now and feel better for it.  Footnote:  It also had the wrong pushrods which I didn't replace and just broke 2 of them.  So, a new set of pushrods will be on their way from 440 source to get her on the road again.  don't trust any parts that were on the motor, sounds like your guy didn't know any better about what he was doing

[Nacho-RT74]

Nacho,

You can visually inspect for scratches, but the other things you need to look for is bore size, taper and roundness. The latter items can either be out of spec due to wear or poor quality machine work.

In my case, I could still see the cross hatching from the previous honing, and there weren't any scratches, so I knew wear wasn't an issue. I was more concerned with the other potential issues listed above.

If the block was going to need to be bored, I would have had it sonic checked as well. Never a bad idea, especially if you are planning to make some serious horsepower. My horsepower target is pretty modest, so I skipped it.

No, just jumping from standart bore stock flat pistons to a Hipereuthic KB240 pistons on standart bore too. Block has 20K unabused miles. ( maybe less ) I wanted to see some visual comparision. By now I'm having some serious doubts of ANY machine shop right now down here.

[471_Magnum]

The "Part Fairy" (otherwise know as the FedEx/UPS man) arrived today with some goodies from 440Source; H-Beam rods, forged pistons and assorted rings and bearings.

I'm not sure who was more excited, me or my 3 year old daughter. "You get car parts daddy?!?!" She thinks the forged pistons are pretty. I have to agree.

Anyway, I spent this evening mic'ing everything. Rods checked out real nice dimensionally. There is about a 4 gram spread on weights. Pistons looked good too. No surprises.

CC'd the heads and they came in at 86 cc. With the 0.040" head gaskets I'll be using, that theoretically puts me at 9.58:1 compression. Tomorrow or Friday we'll mock-up everything at the machine shop and see how far down in the hole the pistons are.  Then it's off to the balancer.

Over the weekend I gasket matched the heads. There was some pretty nasty core shift on one of them, but I got it cleaned-up okay.

With the upcoming holiday, I don't expect to have everything back until the following week.

[Ghoste]

We're pulling for ya!

[firefighter3931]

Right on Jim, hoping the build goes smooth....you deserve some good luck with this project ! 


Ron

[471_Magnum]

Right on Jim, hoping the build goes smooth....you deserve some good luck with this project !
Ron

No such luck. Pistons are going to be too loose.

I'm trying to decide who to be pissed at, 440Source, my machine shop, or both.

My bores measured in at 4.3535, which my machine shop said should be fine with a forged piston.

The pistons from 440Source are actually Keith Black KB822s. The measure in at 4.3455.

That puts me at 8-thou clearance. Too damn much for a street motor.

So now I need to find a different piston. Not sure what I'm going to do at this point. I'm checking around.

I hate to overbore, because going to 60-over will bump the compression another tenth at the current compression height.

[supserdave]

Did they have to bore that much to clean it up, or did they just bore it to that "spec".

Sorry to hear that....Hopefully things straighten up soon.

[firefighter3931]

Right on Jim, hoping the build goes smooth....you deserve some good luck with this project !
Ron

No such luck. Pistons are going to be too loose.

I'm trying to decide who to be pissed at, 440Source, my machine shop, or both.

My bores measured in at 4.3535, which my machine shop said should be fine with a forged piston.

The pistons from 440Source are actually Keith Black KB822s. The measure in at 4.3455.

That puts me at 8-thou clearance. Too damn much for a street motor.

So now I need to find a different piston. Not sure what I'm going to do at this point. I'm checking around.

I hate to overbore, because going to 60-over will bump the compression another tenth at the current compression height.

That Sucks...guess I spoke too soon 

Are those KB's forged or hypers ? Regardless, still too much piston to wall clearance. 

Felpro makes a .051 composite gasket (13cc) if you need to pull some compression out of it.....or you could open up the chambers some. Did Aerohead de-shroud the chambers for the big valves ? 



Ron

[471_Magnum]

Okay. Got a solution.

Take the block 0.055 over and run KB836 pistons.

This will put me at 4.375 bore and 451 cubic inches and 9.3:1 compression.

These pistons aren't super light at 707 grams, but they fit the budget at $439/set.

Unfortunately, I'm faced with a four week leadtime on the pistons. Add a couple weeks to finish up the machine work and balancing. Gonna be a while....

[firefighter3931]

I saw the post on the other board....looks like an interesting slug. 

Are you gonna sonic check the block ? 


Ron

[471_Magnum]

Are you gonna sonic check the block ?

With my luck, what do you think? 

[firefighter3931]

Are you gonna sonic check the block ?

With my luck, what do you think? 

I still had to ask 


Ron

[471_Magnum]

Okay, I resolved my piston dilema by swapping my 30+ over block for a standard bore block. That opened up my piston selection a bit. Unfortunately, the ones that fit my budget (forged KB836) were on back order.

While I was waiting on the pistons, I decided to exchange my cam. I shipped back the Comp XE268H and got a XE274H. That should definitely resolve the previous issue of the weak-ass idle and exhaust note. I'm sure it still won't sound as good as the Charger did, but it no longer will sound like grandma's Newport.

Anyway, the pistons shipped today. They are essentially the last piece of the puzzle.

Machine shop tells me they will be done in "a couple of weeks, maybe a bit quicker". I'm pencilling in the weekend of 10/6 to assemble the motor.

[Charger-Bodie]

AWESOME ! cant wait to hear how it works for ya!

[471_Magnum]

Picked-up the block and balanced rotating assembly this evening.

2281g bob-weight..... ZING! Okay, not as light as the 471 is/was, but pretty darn good for a 440.

Got the block mounted up on a stand. Tonight or tomorrow night I'll file-fit the rings and wash the block. This weekend I'll assemble the motor. I'll take lots of pictures. I'll paint it up real purdy.

Assuming the assembly goes smoothly, I could have it back on the road by next weekend.

There are a couple potential hold-ups:

First one is exhaust manifold studs (3/8" NF/NC x 1 1/2"). Nobody stocks these anymore. Called every autoparts store in town and came up empty. Even called a distributor here in town who normally stocks EVERYTHING. No dice. Finally broke down and ordered them from RT Specialities. It will be mid-week before I get them. Crazy.

Next item is bell housing alignment. Had to line-hone the block, so I expect I'll need to get some offset dowels to correct the alignment. I'm using a different block than before, so it needs to be checked regardless.