decking my block

[JoeM29]

i have a 77 block which has low compression, i have no head work done, i will be doing a cam, springs, roller rockers, ect in the near future, would i benifit a lot from taking my block to get decked to raise the compression a little, if so how much could my block be done safely
thanks, joe

[rumblefish360]

Before you deck the block, see what pistons are out there to give you the compression ratio your after. Cheap pistons like a set of KB hyperutectics for example.
The piston can be changed ever so slightly to increase or decrease the ratio. Head cc volume has a play in this along with the head gasket.

[amxauto-x]

assemble the piston on the rods,,,,install the ass. in the bores and on the crank,,,measure the deck height of all pistons,,, take that measurement to the machine shop,,,tell them what you want to do with the motor,,,have them check the combustion chamber size of the heads,,,ask them to figure what the true compression ratio is,,,come back here and tell us what you are doing with the engine and car,,,racing,street,or both. ;;;;we need to know every little thing about all componets, leave nothing out,,,guess at nothing,,,all specs on everything...how much experiance do you have?


is this the same engine in your other topic?

[Mopardad]

It depends on what the deck height of the block is. It needs to be measured with a block micrometer. Alot of factory blocks have higher decks then the specs call for, some by .050 or more over spec. Seldom, if ever will you find one below specs. Also deck height side to side/ front to back, usually a block needs to be square & parallel decked. All piston manufacturers base there compression specs off of the block deck height spec. This & align honing the mains is also one of the first machining steps that should be done before boring to achive a true block

[dave571]

I don't know if there is a safe limit guidline as such.

I took .085 off of mine.

The problems that arise start to become evident in things like pushrod length, intake fit, ect.. more than structural integrity.

[JoeM29]

ok, so i think i am gonna leave this to the engine i actually build, cause i have never done one and i have a lot to learn, thanks for all the good comments,
thanks, joe

[FARGO318]

There's easier ways to get compression, like Rumblefish said, grab some KB's, #107's should work OK, and if not, milling the heads shoiuld be a little easier.

[creative1]

and cheaper

[6 packin]

Originally posted by FARGO318
There's easier ways to get compression, like Rumblefish said, grab some KB's, #107's should work OK, and if not, milling the heads shoiuld be a little easier.

LOL I dont think 360 flat tops will work good in that 440
237's is a good piston and the TRW 6 pack replacments are close to the same compresion height. The TRW's are forged and much heavier, and much strong in uses like NOS, the KB'S are much lighter but wont take much detnation or abuse like the TRW's. For a heavy run engine and take much more abuse, the TRW's have been proven over the years, and are the most popular piston and most used piston sold, thta and they been around for years. i think the strength over wieghs the lighter KB's, but depending on use as i said. There about the same price 2!

[crankshaftkid]

And quench is something that you want.....a 0 deck pistion with a closed chambered head and .040 gaskets will give you.....040 quench. You want no more than that.

[rumblefish360]

Now heres a guy (crankshaftkid) thats thinking on my level.
Attaboy!

"LOL I dont think 360 flat tops will work good in that 440" , "#107's ?" LOL, something like them.

Nuff said. lol

[71SATELITE]

Did anybody see that article in a recent Hot Rod mag. about the 400 HP 318? It mentioned in there about uneven deck to piston measurment from cylinder to cylinder of the 318's that caused unven compression ratio. First off say it isnt so...How could you fix this besides milling the tops of pistons so they all match?

[Mopardad]

Originally posted by 71SATELITE
Did anybody see that article in a recent Hot Rod mag. about the 400 HP 318? It mentioned in there about uneven deck to piston measurment from cylinder to cylinder of the 318's that caused unven compression ratio. First off say it isnt so...How could you fix this besides milling the tops of pistons so they all match?

This is the kind of thing I was talking about in my earlier post. You need to machine the block to correct the problem.

[amxauto-x]

Originally posted by Mopardad


This is the kind of thing I was talking about in my earlier post. You need to machine the block to correct the problem.

If the block is straight and flat, machineing the deck won't help. Because the piston hieght is at fault. Or maybe the length of the rods are uneven. You would need to measure each piston's deck height and then machine each piston to match.

[6 packin]

Originally posted by Mopardad


This is the kind of thing I was talking about in my earlier post. You need to machine the block to correct the problem.

This is not how I would do it. The correct piston and copression height is the only way to go, When you deck say a 8:1 440 engine with factory pistons, well this may be fine, but you have limited your self with only that piston or the same CMP height. Then you run into things like pushrod length trouble, Head gasket sealing, itake sealing problems, why bother, if it costs $150 to deck the block then your buy new cheapo pistons replacments for $200 thats just a waste of money, just buy the correct pistons that your friendly local machine shop suggests, after you explain to him what you want. The KB's 237 are very easy to achieve over to 12:1 with a set of closed chamber heads, what else do you want? That same engine will make more power than a pop up dome pistons running 13:1 with better tunabilty, less detnation and timing. quench is good, but not by cutting a nice 440 engine. You will be spending more money in the process of decking and buy cheapo pistons, just to do what a set of $325 pistons will do with all the negitive side effects........is it sinking in? I know were there is a 440 block that has been cut so much that the guy cant run the 6 pack replacment pistons, do to a postive deck height, that sucks, its a 69 HP too.

[crankshaftkid]

Thanks rumble....and 6 packin is right on. I never deck a block unless it needs it and most shops won't just check one for ya. A poor mans way of checking a block for square is to install the same piston and rod in all four corners and check the deck height at all four corners but this won't tell you if the crank is ground off or not but will tell you something ain't right. I have a dummy shaft that I bolt into the block instead and mic from the deck to the shaft. That tells me if the block is square. If it's .003 or less for a bracket motor, I don't mess with it (also, I've had blocks sent in to be squared and it came back worse!). This same shaft also helps to tell me if it needs align bored. I have found heads that varied more than 5cc per chamber too. I haven't messed with many small blocks but have messed with big blocks but have had pretty good luck with them being pretty straight but have found heads to be off a good deal. There's much to learn about engine building and the more you learn before digging into it, the better off you will be.

[Mopardad]

I'm talking about machining to the factory specs. Factory seem to always have enough out of spec to be able to square a block up & bring it back to spec. Done to specs the rest of the assm. will be right on if they are correct also.

[rumblefish360]

It's not allways that simple Mopardad. But if theres enuff there, then you'll be OK. But the blocks and other parts aren't cast with that much extra to start with as so that this can be done. If your taking metal off to bring it back into spec, where was it before? Over spec?
If you can get the machine shop to make sure the piston sits equall in all hholes and have the heads bolt on without a mia match in bolt holes, great.
Go speak to your machinest. Maybe if he's feels like hes in a good mood, he'll take a half hour or so and show you how it's done.
My old guy was an older fella and did this for me sometimes when it wasn't to crazy with bizness.

[Mopardad]

Rumblefish or you other guys, you need to find a machinist who wants to build a good block, not just get paid for his time. The shortblock in my son's Daytona was machined by Andy Jensen, if you don't know who he is then you don't know anything about the streetcar shootouts here on the East coast. The factory blocks are normally very much off spec & that is where the extra metal comes from. I don't think it is simple to achive a block that is square, but I know a good machinist that can do it & does do it. When you start cutting piston tops to keep compression heights the same when the block is the thing that is wrong you are just adding a crutch. Two wrongs don't make the engine right. Don't believe me, fine, go talk to a real engine builder, not some hack.

[amxauto-x]

Originally posted by amxauto-x
If the block is straight and flat, machineing the deck won't help. Because the piston hieght is at fault. Or maybe the length of the rods are uneven. You would need to measure each piston's deck height and then machine each piston to match.

Mopardad, re-read this post.

[perfmachst]

hello, couldn't help it. had to add my comments on block squaring.
I run in NHRA stock eliminator. to really get it all straight and perfect, these are the steps involved; 1) measure the block corners. 2) measure the pistons and rods. 3) have thecrank indexed and stroke equalized. 4) resize the rods to the same length. 5) machine the pistons to equalize the C.D. 6) remeasure
the total rod/piston combination, all should be equal length.
now the block can be cut square to the crank line as much as needed for the deck height you need. this will provide you with
a blueprinted short block. also, the factory blocks will be way off.
hope this, helps.

[23T]

I love it when some chebby guy tells me he has a balanced & blueprinted engine. I ask who did it and how much, price is always cheap and I have to ask" Do you know what blueprinting an engine is?" Usually same answer- " I got the parts/price list, C/R ratio, balance sheet, etc" Makes me wonder off LOL, I would bet there are not 10(true) balanced and blueprinted engines running on the street in all of the USA

[rumblefish360]

Rumblefish or you other guys, you need to find a machinist

WHOA!, I just don't see a whole lot of meat on the block to go playin with. If you need to square up your block, knock yourself out! Go do what you gotta do to get what you think you need. By all means, don't let me stop you.

Don't believe me, fine, go talk to a real engine builder, not some hack.

My guy does many local NASCAR engines. Nuff said.
But, then again, any ass can claim this. Andy Jensen who. Don't mean jack to me cause he ain't gettin my money. He's doin what he needs to be doin. (Wish I could say the same, but the islands for a perment vaction is a little off right now)
Squareing up your block. You need, it do it. Nuff said.
Then again, maybe you need a better block.

When you start cutting piston tops to keep compression heights the same

If your doing this, somethings wrong.

I don't think it is simple to achive a block that is square, but I know a good machinist that can do it & does do it.

Your right, it's not simple. Go pay the man.

Don't believe me, fine, go talk to a real engine builder, not some hack.

A real builder, hummmmmmm what qualifies you to judge this. Some clown puts together a good engine and he's great, but some other guy does the same job but doesn't enter the same race or big event and he's a hack?

streetcar shootouts here on the East coast.

Sure, have here as well. A few guy from the track take there 9 sec cars out to the street.
We got your flavor. AT the track or in the back roads.

[creative1]

SIC 'EM, rumble!!!

[bwlizard]

Way to go, Rumble !

[Mopardad]

Rumble, heres a little note I copied from another list. I think it applies to you.

Never argue with an idiot, they will drag you down to their level and then beat you with experience.

[cuda66273]

1. Deck and square the block.
2. Index the crank
3. Bush and redrill the rods to the exact length.
4. Size the rods
5. measure the head volume

Get out the calculator and do the math.

Now your ready to order the correct piston with the appropriate pin heigth and the correct gasket.

[bugsy]

Easy there boys! I haven't seen an argument this heated in a while! My two cents worth is:a) that the term blueprinting is WAY over used. It is a term usually employed by someone inexperienced, or someone experienced who doesn't want to take the time to explain to the inexperienced. To actually bring EVERY dimension (and NOTE) into blueprint specifications is not usually done. Most people do what the application requires, balanced by what they can afford (there are cheaper hobbies). b)
Cuda66273 is correct (he has the cridentials to bask it up). Everything has to be right to be the best. If you don't check it, you might be lucky and win the lottery, but otherwise someone else will eat your lunch.

[bugsy]

Easy there boys! I haven't seen an argument this heated in a while! My two cents worth is:a) that the term blueprinting is WAY over used. It is a term usually employed by someone inexperienced, or someone experienced who doesn't want to take the time to explain to the inexperienced. To actually bring EVERY dimension (and NOTE) into blueprint specifications is not usually done. Most people do what the application requires, balanced by what they can afford (there are cheaper hobbies). b)
Cuda66273 is correct (he has the cridentials to back it up). Everything has to be right to be the best. If you don't check it, you might be lucky and win the lottery, but otherwise someone else will eat your lunch.

[hedgehog]

Don, can you get a cometic gasket for a 2.2l at .040" or so? I currently can only find them at .067".


Thanks