Project: Iron block 5.6

[vandor]

Are you suuuuuuuure you have done your math right?

It's just that on a 4.5 the pistons stop a few mm shy of the deck and it has a CR of 8:1. You have more cylinder displacement and a smaller combustion chamber. I would think just these two would give a significant compression bump. Add to these that the block will be decked a few mm and it seems you'd get a huge CR increase. Of course I have not done the math, so I may not know what I'm talking about...

OH WAIT - do you have dished pistons? Maybe that's it.
bye,

Csaba

[Tony H]

On your engine the pistons are down the hole 3.15mm to 3.6mm at TCD but that is not typical. Usually the piston is a small amount out of the hole. Looking at the manual it varies from .1mm to .75mm (.004" to .03")depending on the engine.(except for the 117.981 to .984 which is yours) so I can see how you would wonder about achieving .040" of clearance.
BTW the 5.6 pistons do have a 30c dish. You are correct-if they were flat the CR would be WAY too high. The area around the dish is flat and creates the squish area.

[Tony H]

here is a picture of a 5.6 piston I found on the net. This is not my engine. The large 30cc dish on the US engines adds so much volume to the combustion chamber that even with 3.5 heads the cr is 10.0:1.

[Tony H]

Finally got some time to check the deck height. On the one piston I installed I have
.023" out of the cylinder so I either need to take .014" off the piston tops or use thicker head gaskets to get to .040" clearance.

[Palolo]

From post #1:

Originally Posted by Tony H

I'm starting a new thread concerning my project to build an iron block 5.0 engine since it's progressed from concept to actual construction. I am removing about 28g of weigh from the pistons by machining the tops down to accommodate the longer stroke.

A lot has probably changed since then, but seeing your recent "shave (height) off the top" or "thicker head gasket" for clearance decision reminded me of it... Would you have to take more off the top, or have you not shaved the weight off yet?

[Tony H]

Once I get it all together and see if all cylinders have the same deck height I will decide what to do. I plan on having it balanced anyway. I found a company that can put larger fire rings on the thicker 4.5 head gaskets so I may go that route-that would be the most simple solution.

[Tony H]

Took a few quick pics. Need to paint the block-I think the original color was black-not sure what sheen since the remaining paint is so old. I decided to machine off the excess .014" from the piston tops to get .040" squish. If I use modified 4.5 gaskets I will end up with .052" plus trying to have them get the fire rings in exactly the correct location would be difficult.
Also shown is a method I came up with for removing the rod caps using a tailpipe expander. They come back with the caps on and removing the caps without damaging the bearing surface can be difficult. The white plastic is 2" PVC that I cut and causes the expansion to only act in one plane.

[Frank Reiner]

Tony H:

Do my eyes deceive me; is it an illusion? Has the block been sleeved?

Frank

[Tony H]

Hi Frank,
No it's just bored. The round marks at the top of the cylinders were left by the fire rings on the head gaskets. Looking at the specs for the iron block M117 the deck height I ended up with is in line with specs but the iron block engine uses a much thicker head gasket and I am using a thinner 5.6 head gasket.
The machinist honed it tight so the pistons would not rock when I measured the deck height. The piston fits but is very snug. I bought 2 5.6 engines to get 8 pistons the same size-some were 0, +0, 1, 2. I ended up with 8 "1" size pistons which are the standard size.

[Tony H]

I have become intrigued with the possibility of using 5.6 heads on my project due to the larger ports and intake valves. I bought a pair of 5.6 heads yesterday and dropped them on the block and they seem to fit just fine except the cam tower head bolt holes are off about 1/8”. A little machine work could fix that. All the other head bolts line up. All the important holes(coolant, oil) are close enough to work as is or a little match porting to line up.
One thing I noticed is the combustion chambers are large (compared even to the 4.5 heads) so that will drop the CR some. I did a super quick measuring job and came up with 50-55cc volume. The valves protrude past the head parting surface so getting the measuring plate to seal was a chore. i will need to make a custon plate with notches to clear the valves.

[Frank Reiner]

Originally Posted by Frank Reiner

Tony H.:

Please recall the head gasket pics that you posted. There are five bolt holes that are slightly relocated for the aluminum block engines (the third row up from the lower edge of the head). That relocation is the result of those five bolts being angled by 1deg.,52min. from perpendicular to the block surface.
Those are also the bolts that pass thru and hold down the cam towers. There appears to be sufficient metal (in the heads of the aluminum block engines) available to re-drill those five holes at 90 deg. to match the iron blocks, if one were of a mind to do so.

Why were those bolts relocated? To shift the stress distribution at the top edge of the cylinder bore, in an effort to minimize distortion of the bore caused by tightening the bolts.

Tony,

Above is the text of Post #32. It seems to me that there are two ways to approach the angled bolt situation: 1) redrill the 560 head at 90 deg. to match the iron block head, or 2) plug the bolt holes in the iron block, and drill and tap it at 1 deg. 52 min. to match the 560 heads.

[mercmad6.3]

Perhaps you would be better off leaving the pston crowns protruding and use a thicker gasket to maintain the squish and compression at the samwe time while using the 560Heads?
420 or 500 heads..they have the same size ports as a 560 but maybe a smaller combustion chamber?. If you keep your squish volume down as low as possible you can use a high compression ration. Trouble only occurs when compression ratios are high with a too large an squish volume.
M100 6.3 pistons pop up a full millimeter and sometimes up to two millimeters on the euro engines and the pistons dont have a dish. If tyou do strike preigntion problems down the track,fit a high pressure water injection system.

[Tony H]

Ron-I have to use 5.6 head gaskets due to the larger bore and they are about .049". I have some used gaskets to check the compressed thickness. As a plus I will reduce the dish volume by about 2cc by taking off .014". I don't want to do any decking/milling on the block/heads and upset the valve train geometry and timing.

Frank-yes I think redrilling the heads would be the way to go. There is plenty of material.

I had some time to clean and really look at the 5.6 heads and compare them to the 4.5/3.5 heads. As I expected the intake ports are much larger and the intake valves are larger. The exhaust ports are slightly larger but the exhaust valve stems are thinner(9mm VS 11mm). I really cannot find any reason they will not fit the iron block with some minor machine work. The only disadvantage is the larger combustion chamber. Welding and reshaping combustion chambers is commonplace and it is a simple old school wedge combustion chamber so reducing the volume is totally viable. There is a lot of dead area that could be filled in without shrouding the valves to get 10.0:1 CR. I pretty much have all the details worked out now and just need to get the car complete so I have something to put it in. I’m not going to permanently assemble the engine until just before I plan to install and run it. I have even though of installing my old 3.5 and get it running good on Megasquirt/EDIS and then transferring it to the 5.6 so at least it will run when I first start it.

[Tony H]

Made a custom plate and accurately cc'ed the 5.6 head-50cc which results in a 9.11 cr. (28cc dish volume, .048” head gasket, .008 deck height) I'm going to put the timing cover on and insure everything lines up. Comparing the 4.5/5.6 head gaskets the 5.6 heads line up with the 4.5 timing cover. Am I in uncharted waters at this point or has someone used 5.6 heads on an iron block engine?
I measured the old head gaskets and there was .001” compression compared to new.
As a bonus the 4.5 alternator bracket fits the 5.6 head. I can’t remember if any of the power steering bolts to the head-I will check over the weekend.
At this point I think I will just go with the 560 18/19 cams. They have more lift than the 4.5/450 cams and were intended for that engine. Being hydraulic it will be quieter. They are plentiful in the Pick and Pulls here.

[dirtyharry]

do 18/19's have more overlap then 52/53's I think 52/53's have something like 20 odd degrees of overlap... duration and lift are one thing, but the overlap is really gunna make it with increased displacement mid-high in the rpm's. which intake manifold are you gunna run? I suggest polishing the inside of a D jet manifold, for increased port velocity, huge runners make for low velocity and therefore weak exhaust scavenging. at least that's what I'm doing to my manifold, plus a few other odd mods to the motor... is it possible to put a M117 crank in a m116 block for like 4 liters or so? or a destroked m117 for 4 liters? not that you should change your whole project around I'm just curious.. I suppose that stuff is all interchangeable, I guess I'll just try it. what clutch are you going to run? I doubt the stock one, even though pretty large in diameter is enough to support more then 250ft/lbs.