I am looking for suggestions to my dilema.  I have a mid-sixties 327 that has been bored .040, cam bearings installed and alot of other machine work done.  This was all done a  few years ago and it sits on my engine stand.  One day I thought I should measure how far down in the hole the pistons are.  I was surprised that it measured .060 down in the hole at the top of piston travel, measured from the center of the flat-top, 4 valve relief piston.  I double checked various cylinders to see if that was right because I thought it sounded a little hard to believe. 

So my point is I want to build a budget friendly, street engine for an  elcamino.  I'm looking at heads that have acc. bolt holes on the front for my brackets and of course, performance.  Vortecs seem to be a good option for the money but even with a steel shim head gasket my comp. ratio will be 9.0 to 1.  I was hoping for a little more.  Do I mill the heads a little when I get them?  Or do I need to pull the short block apart and have the deck milled and then put everthing back in?  Should the block deck be milled anyway for head gasket sealing to be the best it can be?

How about the 58cc chambers in the sr 305 torquer's that world offers.  They would raise my ratio to 9.75 to 1 with the same steel shim head gasket, .015 compressed thickness.  What do you all think?  I just don't know what the right path is. Thanks.

with a piston to head clearance (quench clearance) of .075+ the engine's combustion will be poor and you will see a measurable loss of power, also the engine will be more prone to detonation, and probably will require higher octane fuel

are you sure that their isnt something else wrong somewhere in the system, i have heard of the decks being off by some from the factory but never that much, most pistons are set to be in the hole .020-.025, so somehow another .040 was added in, just something to ponder

i believe since it isnt together that you should have it decked, but it somewhat of a lost cause, but something you can learn from for next time, the main point in "decking" a engine is true up the piston to head clearance values and true up compression from cylinder to cylinder (even though this is very little) but another reason is that with a conventional boring bar if the deck is off, your bores will be "crooked", the more straight the bore is the better, this is why nascar uses a technique called hot honing and why even the backyard hot rodders are now using torque plates bolted on the block to distort the block in the way that it will be when the heads are torqued on to make sure that the bores are as straight possible, the bores being crooked can cause a significant decrease in ring sealing ability

but this isnt something to worry too much about, especially if your machinist using high end computerized equipment that bore off the mains instead of the deck

I think some carefull measuring and checking should be done first. Assuming this was a working, assembled, original engine before the machine work was done and new pistons installed, I'd double check the pistons to be sure the proper ones were installed. I'm not as familiar as I'd like to be with all the piston combinations that can go into a 4.040 bore, but I bet it's possible that the compression height (pin location in the piston) is wrong. If there is a part number visable on your pistons, jot it down and make sure it is the right one for your application. If the piston part number is correct for your application... I'd double check the stroke of the crank and the rod length, in case some other parts ended up in the 327 block.

If you cut .040" off each side of your block, I believe it will cause substantial "fit" problems for your intake,  it would have to be modified to fit properly, and your pushrods would now be (essentially) .040" longer.... not to mention how thin your block's deck would be getting...  I don't like it.

What its sounds like to me is those slugs are 350 slugs instead of 327 pistons. The compression height for the 350 is 1.54 to 1.56 and the 327 is 1.675

the shorter 327 stroke will bring the 350 piston further down into the bore....but thenagain...you said it was only .060 from the top. Has the block been decked?

The S/R torquers are cool heads...Id like to have a set of my own..but Im a poor college student. Theyre cheap and have a good reputation.

Make sure pistons are 327 pistons. If not, than buy new slugs...(its hard to find .040 327 pistons...Ive tried).
The only ones I could find anywhere where either custom made forged or cast factory replacments.

Dunno how accurate I am this time but it was worth a shot.
-Shred

I'll bet $20 bucks you're right.  I've seen this happen all too often whereas someone will accidently install 350 slugs with a 327 crank and end up with compression less than a lawnmower.  Unfortunate, but true. 

At the end of the day, you'll need to know how much the block (if any) has been milled off.  The only way you'll build to the desired compression is to understand all the other components of the build.

I checked the underside of the pistons and there is a number 396.  Also I found the invoice and it lists the pistons as BAD P396-040.  I tried to call the machine shop to ask further about the pistons and who manufactures them but the shop no longer is in business.  Great.  Any ideas on finding who might have made these pistons?  I appreciate your input.  

I believe that's Badger Pistons. ... and with my limited ability to google stuff, I think that P396 is a 327 piston part number.... but feel free to google, or call an auto parts store (who probably has a Badger catalogue), since I can't seem to pull one up online.  If it is the "correct" piston for a 327, then back to my first response... double check the stroke of the crank and rod length... I'm not sure how you could get a good deck height measurement at home... but if anyone can help you with that measurement, those three measurements should tell you all you need to know as to why you have such a large piston to deck deficiency.  

I called Badger Pistons today and gave them the part number, p396 and asked them what that number refers to.  They said 1962-1969 327 and they said the compression height of those pistons is 1.667 inches.  So, I'm not sure what I can do or why my pistons are that far in the hole.  Is it not possible that it shipped that way from the factory?  I remember reading a magazine where they were rebuilding a smog-era mopar 360 that had pistons way down in the hole.  But my 327 is not a smog-era motor so I don't know what the deal is.  Thanks for your help and I'm still open to ideas to figure this out.  

that compression height piston figures out to a 8.992 TDC height, so at 9.025 (blueprint SBC deck height) the piston would be .033 down the bore, which is a lot but not .060, are you checking just one cylinder, this extra .030 could be from the stroke being slightly off or the rod length being slightly off, but it is a big problem, if your block hasnt been decked at all this could be were the extra material is that is increasing your piston to head clearance

unless the crank has been offset ground, or the rods aren't 5.7", I'm at a loss....  do you have a way to measure the stroke?  You have measured the piston(s) at .060 in the hole at TDC, can you measure the depth at BDC (giving you the actuall stroke)?

 Since you said they are all at a uniform .060" in the hole, we'd have to assume the rods are all at least all the same length.... but at this point, determining what length may prove helpfull. Can you measure one (center to center)? Once the rod length has been determined, and the stroke has been determined, add in the compression height of the pistons... you should be able to figure out your deck height. 

It's a stretch at this point... but perhaps the pistons were cast in the 327 mold (hence the P396 castings... or was it stamped?), but may have been machined improperly......  with this info, you should be able to determine where your problem lies.... other than that... I'm at a loss.

it is kind of puzzling but im sure the factory deck height is a little tall, possibly combined with a stroke and rod length all slightly off, this is why its next to impossible to get a very true static compression ratio on your computer, the only real way is cc'ing a cylinder, but most wont worry about that extreme degree of accuracy anyway, but it is interesting on a few hot rod articles a while back i remember hearing about a company spec on a cc of a dish in a piston being 3-4 cc off, this is well known company also (Coast High Peformance to be exact) and also of them actually checking the compression ratio with cc'ing the cylinder and it revealing a static compression .400 of a point less than what they had thought

just some food for thought...

Gibs, I'd have to assume one of us is right. (or a combination of all the possibilities)  At this point, I'm hoping that the originator of the thread (78 El Camino) is able to make the measurements to satisfy our curiosity... not to mention, he may be able to optimize his quench if only he knows why/how....

I'm back with a little more info.  I borrowed a micrometer that measures depth using a rod that threads through the center.  I put the rod that measures 3 to 4 inches in and familiarized myself a bit with it.  Then went to work on checking the depth from the block deck to the top of the piston at the bottom of the stroke.  I measured the front cylinder on one side and the back cylinder on the other bank and a couple of cylinders in the middle.  They were all coming in at 3.310, give or take a couple of ten-thousandths.  Subtracting the .060 negative deck height gives me a stroke of 3.25.  That's where it should be right?

Also, someone asked if the block had ever been decked and I'm leaning towards no.  I've only owned it for five years or so, so I can't be 100 percent sure and this engine has been around for about forty years.  But I noticed some code on the front of the right-side deck and they look like they were stamped in.  They are VIII6KM.  I don't know what it means but it is there plain as day.  Thanks to all.

This is way too much deck to crown clearance. Not only does this make getting decent compression difficult but it's too much clearance, especially when adding a gasket thickness to acheive decent squish/quench function, which makes the engine detonation prone no matter what the compression ratio.

Your looking at incorrect deck heigth pistons, universally short rods, a long side of tolerance block casting, or some equally off to one side of manufacturing tolerance problem.

Before recommending a solution, I recommend this engine be dissassembled and the components measured against factory dimensions.

An SBC can tolerate the pistons at zero deck and work the head clearance with gasket thickness, .040 with the gasket is plenty. If this is a piston problem they should be replaced before milling the deck as the deck's thickness relates to rigidity that's needed to clamp the head and gasket stack down. So don't just go milling the deck as .060 cut is probably too much to maintain strength at this point.

This problem must be solved before doing anything with the heads or you'll just throw money down the drain without optimizing the solution.

Bogie