[SRR]

If you end up needing a STD block and crank, I have several. I'll give you a great deal. 1969 blocks didn't have those dimples in the lifter valley.

[darbikrash]

Yes, the block is a 1975 casting (not a -557). Not numbers matching after all, and by the looks of it quite a few rebuilds under its belt. I got word this morning that the hone cleaned up at 4.1850, so at least my block is a usuable at +.065 over. PM sent.

[Formulas]

The crown / tip of the lobe isn't exactly square it has a taper to match the face of the lifter for rotation
OP could of measured the short side and he could of lost a thou. or so
And SR if i remember correctly is Summit Racing ive got a 2801 on the shelf will have to look at it again

[77 TRASHCAN]

And the sides of the lobes look to be cast

[steve25]

With the ware that those Bearings are showing I from what looks like grit would check / Mic the lifter Bores to see if there still usable before you sink money into a rebuild!

Wobbling lifters will not spin as needed and you will wipe out some Cam lobes before you know it.

[HWYSTR455]

Might be a Schneider Racing cam, like the LSP-35H:

http://schneidercams.com/hydraulicli...shafts-23.aspx

.

[54nomore]

What ever came of this? Curiosity has got the best of me.

[1968GTO421]

Originally Posted by 54nomore

What ever came of this? Curiosity has got the best of me.

^ X2

[darbikrash]

Not much resolution on the cam ID, but plenty of progress on the short block.

The bore cleaned up at 4.1850, so this gives me a good start on a 467 using a 4.25 stroke crank. Here are some shots of the block machining which was completed today:



Main bearing bore with ARP studs and align honing:


Cylinder bore close up:


Deck set to 10.210 for zero height:


A new set of Molnar 6.800 rods with 2.200 rod journals:


And a matching Molnar crank with 4.250 stroke:



This sure is a nice crank:




Balance sheet:

[darbikrash]

For pistons, I used Mahle. I am a huge Mahle piston fan, in my opinion they are the best. The choices for Pontiac are limited though, so they don't get used much. They have only 4 pontiac P/N's- all for strokes of 4.25" or 4.5".

In my opinion, if you have a stroker Pontiac this is the best piston you can get.

Most of the old school guys wont use them because they use very thin rings.

Mahle makes the piston and their own rings, so you get a fully engineered package rather than using somebody else's rings. These are 1.0 mm top ring, 1.0 mm second ring, and 2.0 mm oil ring. Thin. When you put the rings on the piston, you don't need a ring expander, they pretty much just install with finger pressure, which is actually kind of scary. Installing in a bore using a proper tapered installation sleeve they slide in with thumb pressure, no banging the piston in the bore with a mallet.

511 grams for the piston at 4.185 bore.

The coatings are state of the art, and the pistons are off the shelf with no waiting from Summit. About the same money as any top line piston.








There is a good thread on Speed Talk which discusses using these modern Mahle pistons with thin rings on '60's muscle cars.

https://speedtalk.com/forum/viewtopi...=55166#p775612


Here is a snip:

Love Mahle Motorsports' 1/1/2mm ring package. My first experience was daunting to say the least so I understand where the OP is coming from.

I had a chassis dyno shop (that I do work for) call me up 4-5 years ago I guess, they had a problem with an LS7 Corvette and oil consumption. They suspected the heads since the short block had been machined (by another shop) and assembled with new forged pistons (not mentioning the MFG) . Long story short I found nothing with the heads but did correct them and install good valves etc... Engine still burned copious amounts of oil. Dyno/tune shop sends the long block back to original builder and he claims the rings didn't seat so re-hones and re-assembles. Engine still burns oil. Understanding that the dyno/tune shop is located 4.5-5 hrs from me is why they shipped the heads only the first time as it is easier and much cheaper than shipping a long block. Also this shop has very high end clientele (bankers,lawyers, doctors, criminals-its all interchangeable isn't it?) so Vette owner tells them to ship it wherever in order to make it right.

Now I get the 7.0L in and can see the bores/pistons are thrashed-big skirt clearance on the pistons like .007"-.008" so I go to my favourite piston catalog (MM) and see what the latest offerings are. MM makes a nice PowerPak kit for the 7.0L but I notice the ring pack is 1/1/2 and the skirt clearance is something like .0025-.0033" all of which makes me nervous. So I call the techline and we discuss. I ordered the piston kit even though I wasn't convinced. Pistons come in and honing commences. I set the cylinders @ .003" skirt clearance, filed the rings , assembled and out the door it went.

Long story longer--I get a phone call from the dyno shop and they report the engine doesn't use any oil at all and it picked up something crazy like 25-30 rwhp. From time to time I still get updates that the engine is still in the same state.

I think the smaller ring sections conform better and when used with a stable piston that doesn't rock around its nothing but win. My .02c . J.Rob

[54nomore]

Very nice!