Mopar 440 block deck height vary

[Jimmy Jakobsson]

Hi! I have built a Mopar 440 to 493cui stroker, Mahle 4340 flatop forged pistons with file fit rings, Compcam xe275hl( 231/237@050 and .525 lift both int/ext), Edelbrock e-street 84cc heads, Edelbrock rpm intake, Edelbrock 800 cfm avs2. Its running great and have a huge low end, no detonation at 93 octane and ignition timing curve 16 degrees initial, 34 full advance at 3200 rpm. Now, im a bit confused over the truth deck height, i have thinking a bit after wards and looking at pictures from the building and so on, the deck height on a Mopar 440 block from all years(my from -77) should have a deck height of 10,725" right? I have a eagle crank 4,150" stroke lenght, eagle H-beam rods 6,760" and this Mahle flat top pistons with a compression height of 1,865". When you counting of compression height(half stroke 2,075"+rod lenght cc 6,760"=8,835" and take that from deck height 10,725"-8,835"=1,89") i shold have a piston with compression height 1,89" to reach zero deck, my piston has 1,865" and i should than have 0,025" left to zero deck right. I have more like 0,043" to zero deck as you can see in the picture i share you almost can see the whole chamfer in top of the bore with piston at TDC. I use Fel pro head gasket with .039" compressed thicknes that gives about 9,48cc, pistons valve relifes 8cc, heads 84cc that should theoreticly give me a compression ratio 10,33:1 and a dynamic at about 8,05:1, but with the real measurement and the piston down 0,043" in the hole i get more like 9,97:1 and a dynamic at 8,02:1, the chamfer on top of the bore probably give a few cc combustion chamber more. Do the 440 block really vary this much? The measurement dont lie so probably. What do you say?

 

[vintage chromoly]

Deck heights will vary.
They will vary from side to side and front to back.

Best to have the boring / honing done on the bores and then mock up a piston / rod at all 4 corners and use a bridge indicator to measure all 4 corners. Mark the results and return to the shop to have the decks milled and “squared”. At that point you set how much deck height you want.

Most factory stuff is way under advertised compression because the pistons are way down in the hole.

 

[91r/t]

When I built mine it was .014 off from corner to corner just checking it with a check drop base indicator, and that was probably pretty good. I had it decked and they had to remove close to .020 to square it all up. I ended up with my pistons .015 in the hole and then used a cometic MLS gasket to achieve my compression ratio I needed.

 

[gkent]

Unless you specifically tell the machine shop what to do, very few will go to the trouble of measuring the crank/rod/piston combo before milling the block. But almost all will mill the block to square the decks. This can be SCARY as my end result illustrates. The machinist didn't measure anything and my pistons stick .016" OUT of the hole !! That's .025" from where it should be !! Had the machinist measured things FIRST I would have supplied another block but now I stuck dicking around with thick head gaskets.

 

[33 IMP]

Yes, they vary that much. Fifty year old machining on an assembly line isn't as good as what is done now.

 

[Jimmy Jakobsson]

Thank you all for your answer and i understand there will be vary from corner to corner on som blocks but this is straight, my machinist check it all and tell me i not need to mill it, also i not needed to line hone it or anything like that, just bore and hone with stress plate, the block is in very good shape, also all the main caps where really tight and thats good to prevent cap walking, the new cam bearings where tight and i needed to scrape them some to get the cam turn nice with small recistance. The deck height just seems to be about 0.018" higher all over, for me it dont do anything it just keep the compression on the safe side for pump gas and that pretty small camshaft for the engine size, i just wondering if this is common? I also use the Fel pro gasket from 440 source that i show in the photo without any problems but i keep wondering if the bore size in the gasket really are as bis as 4,500", i not thinking of it much when i assembled the cylinder heads, can be used up to 4,500" bore size ot stand in the description so it must be than? If it is so than i can add a couple of cc more to the calculation, i calculate it 4,38" i belive.

 

[69Bee]

Deck heights will vary.
They will vary from side to side and front to back.

Best to have the boring / honing done on the bores and then mock up a piston / rod at all 4 corners and use a bridge indicator to measure all 4 corners. Mark the results and return to the shop to have the decks milled and “squared”. At that point you set how much deck height you want.

Most factory stuff is way under advertised compression because the pistons are way down in the hole.

The first thing to do is to align hone the block so that the main bores are round, straight, and to size. The second thing is to square the block, and establish the block height you need. I use a BHJ fixture to square the block, and measure to find the lowest deck. I then mill to get a full clean surface on the deck. Using the piston CD, rod c-c, and 1/2 stroke, I cut for the deck height I want to be at. Then, you roll the block over and match the second side to the first. THEN it goes to be bored and honed. The align hone establishes the crank geometry, the squaring establishes a deck that is parallel with the crank and 90 degrees between the decks. Then it is bored so that the cylinders are perpendicular to the decks followed by honing the cylinders to size. This is the proper order for the machining operations because each operation builds on the last.

 

[vintage chromoly]

Thanks for the clarification.
Good info.

 

[69Bee]

View attachment 881856 Thank you all for your answer and i understand there will be vary from corner to corner on som blocks but this is straight, my machinist check it all and tell me i not need to mill it, also i not needed to line hone it or anything like that, just bore and hone with stress plate, the block is in very good shape, also all the main caps where really tight and thats good to prevent cap walking, the new cam bearings where tight and i needed to scrape them some to get the cam turn nice with small recistance. The deck height just seems to be about 0.018" higher all over, for me it dont do anything it just keep the compression on the safe side for pump gas and that pretty small camshaft for the engine size, i just wondering if this is common? I also use the Fel pro gasket from 440 source that i show in the photo without any problems but i keep wondering if the bore size in the gasket really are as bis as 4,500", i not thinking of it much when i assembled the cylinder heads, can be used up to 4,500" bore size ot stand in the description so it must be than? If it is so than i can add a couple of cc more to the calculation, i calculate it 4,38" i belive.

You should look for another machinist if he is telling you not to align hone & square the block first. This the proper way to do things for the best results. As far as you measurement, a bridge is a better way to do the measurement, but your setup will suffice, but you need to be as close to the center as possible. There will be piston rock, and can give incorrect measurements. From my experience, I have rarely to never seen a block height to match the given spec. I use the spec to get started, but establish the deck height I need for the compression my customer wants.

 

[wyrmrider]

my 6 pack pistons stick out .015 because I had to mill a bunch to take the twist and slopes and chamfers out of the decks
I used marine head gaskets to get the quench where I wanted it
just doing a mininum square or square each side seperatly (but different) just does not cut it

 

[fratzog lover]

You should look for another machinist if he is telling you not to align hone & square the block first. This the proper way to do things for the best results.

100%.

 

[wyrmrider]

you can check to see if you need to align hone or not
Personally I always line bore not hone or line bore then touch up with line hone
are you aligning the cam tunnel with the mains?, doing the cam tunnel first
number 4 cam brg is usually off
doing studs or caps?

 

[Jimmy Jakobsson]

You should look for another machinist if he is telling you not to align hone & square the block first. This the proper way to do things for the best results. As far as you measurement, a bridge is a better way to do the measurement, but your setup will suffice, but you need to be as close to the center as possible. There will be piston rock, and can give incorrect measurements. From my experience, I have rarely to never seen a block height to match the given spec. I use the spec to get started, but establish the deck height I need for the compression my customer wants.

Thanks for answer! When i leave the block to my machinist i told him to check everything up for my mild stroker build and he did, he set up the block and do all the measurements and contact me after that, he say he checked everything up and say i not need to mill or line hone becasue the block is straight and everything align with each other and if im not absolutely want the zero deck its waste of money. I thrust this guy and they have a long history from the 60's so he know what he doing, he just say to me to do the bore of cylinders with a stress plate. I wanted the compression kept down a bit for a pretty mild camshaft so i not care about the zero deck. The engine running great, i broken in the camshaft for 25 minutes on 2-2500 rpm, let the oil out and cut the filter open and no metal at all. I drive it about 200 miles and change the oil again and cut the filter open, no metal. I have driven the engine about 400 miles now without any problem at all so the building must have succed and im happy about it, its my first stroker. I have huge torque and the engine feels really powerful, i have not really beat it yet more than 4500 rpm something, its running great. I just wondered if this with deck height is common, this block is straight but is slightly higher.

 

[Jimmy Jakobsson]

you can check to see if you need to align hone or not
Personally I always line bore not hone or line bore then touch up with line hone
are you aligning the cam tunnel with the mains?, doing the cam tunnel first
number 4 cam brg is usually off
doing studs or caps?

My machinist do all the meassurement and say it was all straight to each other. The cam bearings where all tight so i needed to do some scraping on the bearings. Im using the original main caps, they was all good.

 

[BSB67]

Do the 440 block really vary this much? The measurement dont lie so probably. What do you say?View attachment 881763

I say: sounds like a nice running car, don't look back.

I've seen 440 blocks in the 10.73x's, but not 10 74x's. But that is maybe 10 blocks out of the 1,000,000 they made.

Most piston makers seem to target their piston compression height for zero deck in a 10.700" block. Probably because this gives the owner a lot of flexibility in achieving a desired CD with machining and available gasket options. If your piston ends up too high, it's a litter harder to deal with.

 

[Jimmy Jakobsson]

I say: sounds like a nice running car, don't look back.

I've seen 440 blocks in the 10.73x's, but not 10 74x's. But that is maybe 10 blocks out of the 1,000,000 they made.

Most piston makers seem to target their piston compression height for zero deck in a 10.700" block. Probably because this gives the owner a lot of flexibility in achieving a desired CD with machining and available gasket options. If your piston ends up too high, it's a litter harder to deal with.

Thanks for your answer! Yes the engine running great, no problem at all. I was just thinking back a little. Im happy i succed so good with this build, it have huge torque and that what you use on the street, smooth running on this engine, the rotation is balanced within 1 gram. The xe cam is a bit noisy but that just how it is, little same a diesel/ sewing machine sound , just live with it, the lobes have good wear pattern, it all looks good

 

[69Bee]

Thanks for answer! When i leave the block to my machinist i told him to check everything up for my mild stroker build and he did, he set up the block and do all the measurements and contact me after that, he say he checked everything up and say i not need to mill or line hone becasue the block is straight and everything align with each other and if im not absolutely want the zero deck its waste of money. I thrust this guy and they have a long history from the 60's so he know what he doing, he just say to me to do the bore of cylinders with a stress plate. I wanted the compression kept down a bit for a pretty mild camshaft so i not care about the zero deck. The engine running great, i broken in the camshaft for 25 minutes on 2-2500 rpm, let the oil out and cut the filter open and no metal at all. I drive it about 200 miles and change the oil again and cut the filter open, no metal. I have driven the engine about 400 miles now without any problem at all so the building must have succed and im happy about it, its my first stroker. I have huge torque and the engine feels really powerful, i have not really beat it yet more than 4500 rpm something, its running great. I just wondered if this with deck height is common, this block is straight but is slightly higher.

I did not mean to insinuate that it would not work without doing those operations, I merely meant that it would work better correcting the imperfections that result in production manufacturing. All blocks WILL twist and affect the main bore alignment, it is just a matter of how bad. The decks will NEVER be parallel to the crank and the same height either. We have rebuilt motors like this for decades with little to no problems, but why not correct the problems when you are in there the first time. Mopar engines are a pain for cam bearing tightness. I usually have to scrape every Mopar cam bearing set because of tightness. The engines originally had the cam bearings installed, then line bored for the cam. When precision finished cam bearings are used to replace the originals, you are dependent on the alignment and condition of the cam bores to be good so the cam spins freely. I usually run a ball hone in the block cam bores tor remove any roughness and dress any burrs in the bore and around the oil holes. When the oil holes are drilled, a burr will usually stick up, creating a tight spot when the cam bearing is installed. In a nutshell, if I rebuild the motor, it gets everything done to it because they expect me to stand behind my build. If the customer builds it, I will do as much or little as they want. I always recommend things to do, and why, so that they can make an informed decision on their motor.

 

[wyrmrider]

"I wanted the compression kept down a bit for a pretty mild camshaft so i not care about the zero deck."
Setting compression by moving the piston down the whole is just so wrong so many ways
The factory did that when they went to smog builds and how did that work out
lower power, more heat, worse gas mileage, detonation
glad your i running great but do the dist curve, watch your plug heat range and tune till you are sure you have no pinging

 

[Jimmy Jakobsson]

"I wanted the compression kept down a bit for a pretty mild camshaft so i not care about the zero deck."
Setting compression by moving the piston down the whole is just so wrong so many ways
The factory did that when they went to smog builds and how did that work out
lower power, more heat, worse gas mileage, detonation
glad your i running great but do the dist curve, watch your plug heat range and tune till you are sure you have no pinging

Ok, i know the benefits of a good quench and a closed chamber head and maybe i do wrong to not zero deck but like i say the engine running great. Quench is good to prevent detonation and let the engine tolarate little more compression. 10,04:1 static and 8,05:1 dynamic is in the safe area for pump gas with aluminium head anyway, no pinging at all with a timing curve 16 initial and the vacuum advance up to 30 at idle, 34 full at 3200 rpm, ngk 7, the engine never goes over 180F, i can stand 1 hour at idle if i want, the heat not go over 180F, i use a mechanical water temp gauge