Rebeldryver's '70 Caprice Granny's Luxo-Muscle-Barge

[68scott385]

Same problem I have had before. Leaky rear main seal, which may not be fixable at this point, but it doesn't much. But, more important is the lifters bleeding off badly once the engine warms up.

Can we assume you're going to freshen up the short block. If memory serves me correctly you had the heads off fairly recently, right?

[Scott Liggett]

did you try an offset seal yet? I put one in my 55, it helped

I don't think it's the rear main seal. Just my crap job at installing the oil pan gasket.

[DanStokes]

Gosh, if you knew where to find a decent engine shop in your area maybe they could DO something! (Hope you track down the issues).

Dan

[Huskinhano]

A number of years ago Pat Gahnal did an article on rear main seals leaking on engines originally equipped with rope seals. He was saying since asbestos has been banned, it's been a problem with rope seals leaking. I forget the gasket company,but the new owner thought that there must be a material that works. What he ended up using was a material used in steam pipe valve packings or something like that. Gahnal was having problems with the 54,235 in his 51.He used this new seal which IIRC, did the trick. I think I'd reccongise the brand if I saw it.

[squirrel]

BBCs all use neoprene seals. Small blocks used rope seals thru about 1958 or 59.

There is a neoprene replacement seal for the 235, but one I worked on still leaked...the seal bore was not concentric with the crank bore, which is not a problem with a rope seal, but it is with a neoprene seal.

[Scott Liggett]

Some pics of the engine disassembly. Check out the factory check marks on the pad next to the bellhousing.



Casting date Sept 25th 1969. I am told all the 1970 454's were hand built and had forged innards. This one definitely has a forged crank.







The serial matches the car is not up on the head surface, but above the oil filter.


The bearings looked good. #1 main and #7 rod had scratches, but nothing fatal.





Cylinders on the thrust side had these marks. Can barely feel them.









Amazing how a little bit of PB Blaster will clean grease off my block.

[squirrel]

Cast pistons. Do they say GM inside? What do the bearings say on the back? they often have a date code, month and year they were made, as well as the size


It looks like a normal old big block, actually.

[Scott Liggett]

The bearings are all dated 2009, shortly before I rebuilt the engine. I installed the new bearings and rings. If you go back near the beginning of this thread when I originally took the engine apart, the orginal bearings were all dated Sept 1969. Those are the original pistons and it has never been bored. I only honed the block as there was no bore ridges, scratches, or weird taper to them when I first took it apart. The engine still sported the original timing chain as well.

[Scott Liggett]

I showed pics and talked with our techs here. These guys tear apart engines all day like CSI agents. My first duty is to take the calipers to the pistons top and down at the skirts to make sure they have not collapsed. I asked about fuel wash. Not sure, could be debris in the cylinders.

Looking into my cost to have the short block bored and line honed. Then have the crank rods balanced with new pistons.

[Scott Liggett]

I ran the honing tool over a couple of cylinders last night. took the glazing off instantly and took down the weird marks somewhat, but there are scratches on the bores as well. Nothing really deep, but can catch the ole fingernail running across them. I didn't spend any time on on honing. Just a few seconds in each cylinder.

Waiting on what it would cost to run my block down our line for boring, honing and line honing. Seeing if have any forged pistons in our line of engines that I can get cheap too. I know I can get hypereutectics dirt cheap here.

[squirrel]

Is the compression ratio "right" now, with the larger chambers and small dome piston? no pinging issues?

[Scott Liggett]

Compression ratio calculated out to 9.21:1 with the original pistons and the 119 cc heads. I physically checked the chamber size when at the machine shop. It runs great on cheapy 87 octane and didn't seem to lose any power.

My lifters all failed the bleed out testing. All came back weak. Replacing cam and lifters. We use this Comp Cam in our 480 hp 496 with the same heads:

http://www.summitracing.com/parts/cca-11-246-3

I can get the cam, lifters, and timing set for about $150. My car will have a nicer idle lope too instead of the dump truck idle. My Isky double springs should work fine as well. I was considering reusing the Cloyes double roller chain I have as it was still nice and tight.

[squirrel]

If it was me spending my money....I'd probably forgo the bore/pistons, and instead spend money on a hydraulic roller cam and lifters and pushrods and possibly springs. The springs you have are not too old, but they may be a bit much for the cam you selected, and it appears to be a kind of agressive ramp, and it's in a big block chevy, and has a hair over 550 lift, so I would expect it to have problems with going flat.

but that's just me

[Scott Liggett]

If it was me spending my money....I'd probably forgo the bore/pistons, and instead spend money on a hydraulic roller cam and lifters and pushrods and possibly springs. The springs you have are not too old, but they may be a bit much for the cam you selected, and it appears to be a kind of agressive ramp, and it's in a big block chevy, and has a hair over 550 lift, so I would expect it to have problems with going flat.

but that's just me

Old cam's specs, .550/.565 lift, 221/229 @.050 114* LSA. Nearly the same.

Not interested in the price of retrofit roller lifters. Our company uses Delphi's because our new block castings have the provisions for factory lifters. Would rather get good heads instead.

Complete machine work of the block is nothing for me.

[squirrel]

I guess you have better luck than I do...