68 NJConv 454

Yanked motor thismorning to identify crank casting #'s in a late 70's 454 block. Discovered crank casting 3904815NF with a MR020 stamp near the front of the crank and a D11 towards the middle. The casting # was at the very rear of the crank.
3904815 is listed for a 396, 402...cast, nodular iron.
I originally thought it is 3804815NF but I can't find that anywhere. And it does say GM on it.
3804816 is listed for a 396, 402, 427...cast.
What do you think it is?

Has a double roller chain and a high vol oil pump. I-beam rods, no idea about cam or pistons. I know its cast b/c crank has a thin parting line at the crank throws. Not happy about that.
Block says 454 PERF at the rear facing the flywheel.
Was only pulling this block to put a cam...lifters and replace motor mounts. DO NOT want to pull this damn thing apart and spend $$.
Need to know if its internally or externally balanced....front balancer is not counter weighted nor was the flywheel which is why I thought 427 crank. Don't see counter weights drilled in the crank. Have to order clutch and flywheel.
WHAT TO DOOOOOOOOOO!?!?!?!?!?!?!?! don't have enought room to get the engine around my vette to load it into a truck and bring it to a shop.
NEED HELP & ADVICE!!


This is my previous thread leading up to this madness...http://forums.corvetteforum.com/show....php?t=1420926

GOSFAST

You've got yourself a 396/427 (same) cast crank. MR020 stamps are probably the size of the journals, mains .020", rods .020". Thanks, Gary in N.Y.

P.S. It may not be the best choice for a performance build but It'll get a decent amount of power if you're not looking for "super" high numbers. If it's in good condition and can be polished, use it, if it needs another cut, 30/30, walk past it. Those shafts are easy to come by. With that stroke
and the 4.250" bore you've got yoursaelf a 427" unit. It's also an internal balance in the ***'y you have.

jeckel

Actually this block casting could be a 1970 454.

http://rowleycorvette.com/stats70.html

The casting for a 1970 454 is show at the link above to be the same as yours. The NF at teh end is a code stating the motor is for a pass car and the motor is rated at x hp.

68 NJConv 454

Jeckel, I don't see what ur looking at on that link. Don't see crank casting #'s. My engine block cast # is 361959 which is located fifth down on this link. http://www.mortec.com/bbc.htm
The block says HIPER PASS at the rear facing flywheel and a stamp at the very front near driver head that reads C9Z209270 which i think at one time someone said its from a late 70's pickup.

Gosfast, thats what i'm thinking....in the end a 427. My pops tends to think that the crank is from a 396, rod and pistons from a 427. The block is a 454 and probably machined to give me a bore/stroke that would equate to all the above ending up as a 427. Hate the idea of mismatched stuff...and unless someone will sell me a good hp, well built ready to go 427 for cheap, i might just have to chug around as is until winter when I hit the lottery.
Until then, no cam, no lifters, no upgrades except fuel pump and gaskets and get the rest of the car done. Don't want to push the envelope if I don't know whats really in the block.
Agree?

p.s. one thing bothers me, if it is internally balanced like any other 427/396 then shouldn't i see slugs on the crank used to balance the rotating assembly? all i see is a large vertical hole drilled out on the crank on both ends, no horizontal weights. This is what bothers me alot. If its a 427 then i don't have to worry about external balancing ie. front balancer & flywheel. If it isn't internally balanced and I don't use those I will kill my main bearings. I HATE NOT KNOWING THE FACTS.

markdtn

427 and 454 use the same bore so you can make a 427 from a 454 (and vise-versa) by changing the crank and pistons.

GDaina

427/454 use the same rods and pistons, so only need to change the crank.

jackson

Disagree ... 427 & 454 have same bore size (4.25") ... and same rod length (6.135") ... but not same pistons ... 427 about 1.767" CD, 454 about 1.640" CD. 427 stroke = 3.766", 454 = 4".

If you change to a 454 crank, you'll need different (454) pistons too.

68 NJConv 454

how can i identify what pistons are in the block without riping the heads off? I see a 242-99 number on the bottom of the pistons.

68 NJConv 454

Alright, got as many casting numbers and measurements as I could without taking the heads off.....
Crank casting #: 3904815NF = 396 or 402 cast.
Block: HIPER PASS casting #: 361959 made on May 31, 1979 454ci
Front stamped # in center: T0626TRT, pass side lip: C9Z209270
Mains stamped: TGM61 and TGM34
Rods: aprox 6.5 inch length, stamped 276,273,272,278
Piston: stamped 242-99 on bottom of piston head, not on skirt.
Cam: stamped GMC, very worn
Bore is 4.25", stroke is aprox 3.76".
All the above leads me to beleive it all adds up to a stroked 427 due to the 402 crank. Is this good or do I rebuild with all 427 internals?
The cylinder walls look like they still have some cross hatching so this may be a recent rebuild with low miles.

Heads are 427 rated b/w 390 & 400hp.
Passenger side: 3964290 GM10T B3 70
Driver side: 3964290 GM7T H2S 9

Intake: aluminum # 3885069 3-hole closed plenum. Used on original 427 rated at 425hp.

Budget 1k, do I rebuild entire engine (want low compression as a good foundation for forced induction in the future) or use as is until more $?
If rebuild any suggestions? what are my options?

markdtn

396/402/427 all use the same crank. I think you have a 427. Maybe somebody bought a complete 427 that was frozen or something and used a 454 block. Maybe he had a 454 and wanted a 427. Nothing magic, just a 427. Happened all the time back in the day.

68 NJConv 454

So if you were in my shoes what would you do?
Leave it? or rebuild it?
1k to spend to get low compression high hp on midgrade octane gas.
Replacing fuel pump, crank, cam, pistons, rods, bearings don't worry me much, rebuilding the heads is what gets expesive and machine shop fees. Hoping since I can still see some cross hatching that I won't have to get it to a machine shop.
What would you do?

GDaina

You are correct.....piston pin location.......me bad..

GDaina

buy a new cam, hone the block, new rings, bearings, lifters, gaskets, 3 angle grind, that should take care of your budget.

Down the road you can plan on a new set of Al or porting your iron heads