Okay, here is how it looks things are panning out partswise& could use any suggestions since last engine I just helped put together was in like 1982 (thank you John Chamberlain: ) My buddy is insisting I use his 72 Stage 1 heads, on my standard bore non Stage 1 70 engine. I hope to be able just to get away with bearings and rings & reuse the 10 to 1 pistons. My original goal was all 1970 parts, stock or Stage 1 and then run a Window Rattler cam. Just concerned about the compression drop with the 72 Stage 1 heads and whether that will support my(still need)Window Rattler (OR PM me if you have a nice rumpidity rump used cam and marked Rhoads or other lifters). Also running Mickey Thompson Super Scavenger headers,B4B intake, Thermoquad or 850 cfm Quadrajet. Depending on condition will be using the M20 Muncie already in the car with an M21 as a backup/spare and running a factory 1970 10bolt 8.2 with 3:64's. and I have zero clue on distributors/ignitions. John Kemper (God rest his soul) gave me some of his thin copper head gaskets in our last shipment so that hopefully will help bump the compression back up some from the 72 heads. The goal for the car is mainly when I am feeling blue is to have a turn key,low maintenance big block that hits a MEAN LICK through those Super Scavengers, fair brakes, and the ability to go down the road boiling the hides if the urge hits me even if I kick it around 30mph. Would like to win races but the technology on new cars today kinda spoils that but I will be MORE than happy to go thumping around,barking gears,roasting tires or feel the force of a big block with the secondaries flapped wide open pushing me back into the seat and plastering a HUGE grin on my face for days! Thanks in advance for any guidance,assistance, and if you have any reasonable used parts that will play well in this mix please pm me. Remember this is my "Poor Touring" car so function is the primary goal, & crusty vintage parts are a plus! I also want everyone who has helped on this homely beast in any way to do me the honor of signing the underside of my trunklid when I can get her to a show, and Thank You again for all who have already donated or sold me parts at very fair prices, lot of good buddies here! : )
If you can find the $$ you could have the '72 heads milled to up the squeeze and or the block if in that will be taken all the way down for a re-ring? IIRC the '70 heads are 69cc while the '72 heads are 71cc, that would only require you to have 3cc removed to get the '72 heads down to the '70 head's chamber size of 69 cubic centimeters. GL
Hey, I like the way you are thinking! Taking my buddy with the 72's in for a procedure today will ask him after they dope him up if I can mill his original heads heh heh Seriously though he would probably be all for it which is why he took those off and used 430 heads. Will that than require adjustable pushrods or just 70's? Appreciate it ! Great idea: )
Milling just to gain back 3 CCs is a waste of money! If you want to gain back those 3 CCs and have greater power install long reach plugs one heat range colder then normal which will allow you to run less timing as a side benifit!
How far down the hole are the pistons? First Guess: Milling metal off the block will be far more effective than milling the heads. Second Guess: A tiny offset-grind of the crank will be even more effective than milling the block; although you still want the deck surfaces "square" with the crank saddles. Let's say your pistons are 0.030 down-the-hole. You mill the decks so that they're square--maybe that requires a 0.010 cut. Then you offset-grind the crank by 0.020. You've now got a proper zero-decked short-block with 0.040 extra stroke. Stroke changes 2x the offset-grind. 'Course, your numbers vary with the amount the pistons are really down-the-hole. Maybe they're 0.040, or 0.070 or whatever. You'd have to adjust the crank grinding accordingly, within the limits of available bearings. (If you weld the crank journals, bearing sizes are of no concern--but you're not likely going to weld the crank.) Then you cut the decks to get the pistons level, or close to level. Maybe you find it easier or better to get custom pistons that sit higher on the rods, or you get longer rods. There's lots of ways to fix down-in-the-hole, any of them can be good. Certainly better than leaving the pistons down-in-the-hole. "I" would buy a camshaft that makes power in the RPM-band that's most useful to you. Installing a cam simply because it idles bad is poor practice.
Just to be clear, to "offset-grind the crank by .020", looks like by your definition you're saying to move the centerline by .020" means grinding off .050" from the crank journal; .040" off to move centerline .020" and an extra .010" to make sure crank cleans up on new centerline for .040" extra stroke. To get .040" of more stroke requires the removal of .040" of material + the extra .010" to make sure every journal cleans up. Another way to get the pistons up in the bore is to use Pontiac aftermarket rods to get piston up .020" to .025" in the bore because those rods are .020" to .025" longer than the factory BBB rod length.
