Engine: inconsistent deck height ??

[SuperHawk]

Re: 1964 289 V8 for use in '64 Lark-type

Machine work is done on this block, bored 30 over, new pistons, rings, bearings, block surfaced, etc. I am doing assembly myself. Now that I have cam, crank, and pistons installed, I took a few measurements. With pistons at their highest point in the block, left side piston top to block surface is .015 inches. On the right side, top of pistons are only .006 inches from surface of the block. The pistons are dished, and have about a .280" dish depth. The pistons have no manufacturers identification that I can find. On the last few rebuilds I've done I usually find an Ertl or an Egge name, but not on these. I got them from John Erb some time back, and he does not know where he got them. Maybe they came from the stuff he bought from Lionel after his accident. We just don't know .....

This engine is going into an everyday driver car, not a hot rod. I do want it to perform adequately for its intended purpose, however. I am a bit bothered by the difference in heights between the left and right side of the block. I would like your opinions on whether or not those differences should concern me. Further, I wonder if I should use thick or thin head gaskets.

Thanks,
Larry

[PackardV8]

Re: 1964 289 V8 for use in '64 Lark-type

Machine work is done on this block, bored 30 over, new pistons, rings, bearings, block surfaced, etc. I am doing assembly myself. Now that I have cam, crank, and pistons installed, I took a few measurements. With pistons at their highest point in the block, left side piston top to block surface is .015 inches. On the right side, top of pistons are only .006 inches from surface of the block. The pistons are dished, and have about a .280" dish depth. The pistons have no manufacturers identification that I can find. On the last few rebuilds I've done I usually find an Ertl or an Egge name, but not on these. I got them from John Erb some time back, and he does not know where he got them. Maybe they came from the stuff he bought from Lionel after his accident. We just don't know .....

This engine is going into an everyday driver car, not a hot rod. I do want it to perform adequately for its intended purpose, however. I am a bit bothered by the difference in heights between the left and right side of the block. I would like your opinions on whether or not those differences should concern me. Further, I wonder if I should use thick or thin head gaskets.

Thanks,
Larry

Yes, Larry, Studebaker blocks are not consistent side-to-side. We use a BHJ fixture on our surfacer to make both sides parallel to the main bores, perpendicular to each other and the same height from the crankshaft center line. Expect to pay $150-$250 to have this done. You'll probably never notice the ..009" difference side-to-side, but we think it's worth doing right. Is it worth that to you to optimize a daily driver?

John Erb was Chief Engineer at Silvolite, so it would be most likely that's where any pistons he sold came, but he did get some odd-and-ends from LS.

With dished pistons, you can use the thin head gasket, but with .006" deck height on the one side, it will put compression close to the premium fuel requirement.

jack vines

[Bob Beckert]

Larry, try switching the right side piston to the left side and also check front to back of block That will tell if it is the piston or the deck that is off. A suggestion.... when you gap the Top and also the Second ring keep the end gap around .015 and not higher Some say .022 to .025.. That is too much and believe it or not a lot of power is lost past the rings. It provides great sealing. I would think that they are cast pistons and a tight gap is A OK. First do check the deck front to back and then switch sides.

[64studeavanti]

I thought the shim gaskets are about .017". With .006" deck height, or even .015" for that matter, do we have enough piston to head clearance? I have been under the impression that the piston to head clearance should be around .040".

[PackardV8]

A suggestion.... when you gap the Top and also the Second ring keep the end gap around .015 and not higher Some say .022 to .025.. That is too much and believe it or not a lot of power is lost past the rings. It provides great sealing. I would think that they are cast pistons and a tight gap is A OK.

Maybe. At some point, Silvolite began making hypereutectic pistons for Studebaker 289"s. Their directions state: " IMPORTANT: When using hypereutectic pistons we recommend a 40% increase over cast piston listed end gap."

SuperHawk absolutely must determine which pistons he has before closing up the end gap; .015" would die a terrible death on a hypereutectic piston.

I thought the shim gaskets are about .017". With .006" deck height, or even .015" for that matter, do we have enough piston to head clearance? I have been under the impression that the piston to head clearance should be around .040".

Last shim head gaskets I used were more like .023".

Yes, the .040" minimum is for certain circumstances; 7,000 RPM 4.00" and up bores using forged pistons with .005" and greater piston to wall clearance. Right now, I'm running my Packard V8 with .028" deck clearance. It also has .0025" piston to wall and never sees above 4,500 RPM.

jack vines