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deck height measured over the pin differant side to side?

Started by 1340evo, May 01, 2021, 11:12:11 AM

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kd

Like Ohio said, there has been many suggestions for you and all along the same line. You are fortunate enough to have a high level of understanding in the conversation and have asked some good questions. Some of these folks make a living building lots of engines and do so with high respect for them and their work. There seems to be a general recipe aimed at what you are looking for. When a chef gives you a recipe you don't substitute salt for sugar or whole wheat flour for pastry flour. I think if you reread your thread you'll figure out where you need to go. You have your engine in a state that it will be easy to do.  It would not make sense to experiment if you can do what is proven to work. 

I also would suggest you talk to the shops and builders that have offered their advice and see what you can get going to move you forward.  Confirm before you buy anything else and source the parts you still need through one of them or from where they suggest. Things like gaskets are available in several thicknesses and any machining should be based on what is available for assembly to get to the sweet spot. Select your target and don't compromise without good alternatives that work.

I sense you may be feeling overwhelmed with all of the weird measurements.  I get that and know the feeling as many of us do or have.  Take a deep breath and talk to the folks that can help you.  They have already stepped up to the plate.  Some times too much information is just that,.... too much information. Your Evo plan is a common one that has existed for years and a safe no PMS (no mood swings due to fuel, temperature etc.) engine recipe has been offered.  Try to get an understanding of the reasons and safe parameters.  Put the pieces together sensibly and not helter-skelter or because it's all that is available down the street.  That's a common problem no matter where you live.  You will have a sweet running Evo you will be happy with for a long time.  I know you want it done right now but that may be an expensive mistake.
KD

Hossamania

I don't know for sure, but adjustable pushrods will probably be a good idea, especially if the heads, deck height, and gaskets are changing.
If the government gives you everything you want,
it can take away everything you have.

1340evo

Thanks KD and everyone for helping out here, not a lot of free advice in the UK and machining / parts cost a lot!

I'm not wanting to do anything with the jugs now they are re-bored and honed for the new pistons, that in turn have been balanced to the crank and rods, just in-case I damage them. (the builder should of done all this! I did ask him to address the cylinders but he refused saying its not a good idea??)

If I get .030 heads, that gives me squish at .035 front and .039 rear. would this cause vibration (could equal out on the base gasket using one at .016 and one at .020 to get both to .039). So not zero deck, but within the .030-.040 as suggested.... or get a .010 base and a .014 base if they exist to get me to .033 so a -.003 deck?)

Then I'll get the heads to 78cc as above.... sounds like a plan??

At this will I need adjustable rods?

Don D

Don't trip and fall over .004 difference. Leave it alone and just cut the heads

1340evo

Really... I have .016 and .020 base gaskets now.. Just thought it would be best to equal them out... or get .010 and .015 that I've seen?

But thatks for that.. you don't think .004 will impact on anything...

so stick with the .016 bases on both... .030 head and heads to 78cc  :chop:


I'm assuming you can mix James bases and Cometic heads... just follow the instructions for the head gaskets.. correct?


Don D

If you already have the deck heights close by gaskets, .004, carry on and cut the heads.
I personally cut the barrels, it is simple with the tooling I have. But respect that access to that may not be great in other places.

kd

Like Don says, getting it close with gaskets is good to go for your purposes. There should be no problem mixing the manufacturers of gaskets and yes, the head gasket instructions are the ones to follow.  Be hospital operating room clean on the surfaces at the engine and the gaskets.  Oily finger prints can handicap the sealing ability of both.
KD

rigidthumper

You asked a question:
And corrected for the cam ev27 gives

7.98:1   ? what ever that means?



Static compression is the ratio of total volume with piston at BDC (AKA V1) vs remaining volume with piston at TDC (AKA V2), so the compression would start as soon as the piston starts upwards.  Corrected compression takes into account the compression doesn't actually start until the intake valve closes, so it only includes piston swept area after intake valve close in the V1 measurement.

I was taught that 10x the corrected compression ratio would be a "ballpark" octane requirement in a carbureted bike- so a corrected CR of 8:1 would need ~80 octane fuel. John's recipe sets the CCR @ ~8.4:1, so would be drama free with any commercially available fuel.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

1340evo

Thanks Thumper. I understand now :)

Can you get 0.027 MLS head gaskets for the 89 evo engines?

That would get me to .036 worst case :)

1340evo

Just thinking a bit more on this one, it would be better to trim the barrel bottoms like I asked the shop to do in the first place! Then I can use the gaskets I've bought already.
I can't get the swing on my lathe as its too small, but could take it to work and do it there.
They are finished and honed now so must take care, but if I take .001 cuts I should be able to do it without damage.

guess they don't have to be torqued down to do it... can't see how you could

Thinking is a piece of wood turned in the chuck to the exact ID of the bore that runs just short of the barrel end. then a wooden disc with a ctr in it to push it into the shoulder at the chuck end... and as I say, very small cuts ?

jsachs1

Quote from: 1340evo on May 07, 2021, 03:24:51 PM
Quote from: jsachs1 on May 07, 2021, 03:04:49 PM
Last 3 sets I did with EV 27 cams, 80". I set the chambers at 78 cc., 0 deck, .030" MLS gaskets, stock flat tops. No PMS, happy customers. :up:
John

Hi John, thats interesting. I have .042 squish and I'm kind of stuck with it as no .030 MLS available in the UK right now. (.016 base and .036 head)... but 78cc is less of a shave of the heads.
so if I'm at 81cc now, how much do i need to take off?... and did they run std rods etc  ... 

no PMS?.. whats that?

cheers.
Somewhere in the area of .018" to .020" total removed off each head should reduce chamber volume by 3 cc.. :wink:
John

1340evo

Okay, thanks... will do.

I guess then you need adjustable rods

rigidthumper

Depends on the lifters used- most have .200" total travel from top to bottom, and the stock components usually put the lifter plunger depth about .100" down (basically centered in the lifter) when at room temp. This gives enough room for normal operation during expansion when hot, and contraction when freezing. From the factory,  stock, you have ~ zero deck & a .045" (when compressed)  thick head gasket. If you switch to a thin head gasket, say .030", and still a zero deck, the pushrods will now be .015" deeper in the lifter. Not an issue. If you shave the heads, that amount will push the plunger deeper still. Using adjustable pushrods will allow you to set the depth where you wish. Using stock is fine, as long as you know where you will end up, and are comfy with that.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Don D

May 09, 2021, 05:55:46 AM #63 Last Edit: May 09, 2021, 06:50:01 AM by HD Street Performance
If you don't have the tooling $$$ to properly hold the barrels forget the lathe. I made mine but even the raw materials cost ~700.  Consider modified toe clamps to hold the cylinder on 123 blocks and cut the top. Not centered on the bore axis but better than wood the the spigot bottom as a datum.

1340evo

Quote from: rigidthumper on May 09, 2021, 05:47:14 AM
Depends on the lifters used- most have .200" total travel from top to bottom, and the stock components usually put the lifter plunger depth about .100" down (basically centered in the lifter) when at room temp. This gives enough room for normal operation during expansion when hot, and contraction when freezing. From the factory,  stock, you have ~ zero deck & a .045" (when compressed)  thick head gasket. If you switch to a thin head gasket, say .030", and still a zero deck, the pushrods will now be .015" deeper in the lifter. Not an issue. If you shave the heads, that amount will push the plunger deeper still. Using adjustable pushrods will allow you to set the depth where you wish. Using stock is fine, as long as you know where you will end up, and are comfy with that.

Its funny you say zero deck when torqued down. When I'm measuring my deck I'm clamping it down with plastic tubes under the head nut and with a .016 base gasket, would get -.005 & -.009 pistons in the hole... If I torqued it down to spec would you get this moving any do you think? I'm not using the base gasket to measure this, I'm putting the cylinder straight onto case faces anl lightly clamping up so calculating the in-hole dim... I actualy get .007 and .011 proud when measuring.
So under full torque, do the cylinders compress a bit.. and if so, how much?

This is 30 mins in the garage and what I was thinking. It's .060 oversize now so would need putting in the chuck and making true on the machine at work. Push on the barrel and load it with the base ring. if only taking .001 at a time it would work, but I'd need to clock the base before cutting as its obviously coming from trhe bore C/L...  Mad idea??


kd

When you reach the torque spec the studs begin to stretch within a  predetermined range that doesn't actually separate the molecules but provides constant tension. The plastic pieces you are using are generally just fine.  The tension on the studs transmits clamping force that is sufficient to accomplish your goals.  The barrels will not compress under the spec torque (but with torque plates will stabilize the shape to the form they run in.

(When the engine heats up under running conditions the barrels will grow taller and the studs will try to follow with the result that there is better sealing of the base gaskets.  For this reason you always bring the engine up to temp before beating on it.  The leaking base gasket syndrome seen with Evo engines can usually be attributed to not letting the engine warm up before getting on it.)

IMO, not using a base gasket when determining deck height. is the way to go.  There is no confusion about whether or not the gasket is compressed enough to give a real world dimension.  Just know that most gasket dimensions are in place and torqued to spec numbers.  Cometic for example says their MLS and steel gaskets will measure to the dimension stated as installed and torqued.

As far as your question about the machining fixture, Listen to HDSP about the process.  A good machine shop should be equipped with the tools to secure the barrels and do a proper clean-up pass or so to get your dimensions.  They will also have the measuring equipment to ensure you get back what you asked for.
KD

Billy

If you have a faceplate and a bullnose live center large enough, friction drive the cylinder between the two in your lathe with the spigot in the live center, you don't need to get it very tight to take .001-.002 cuts on the bottom of the cylinder.
Lazyness is the Mother of Invention

1340evo

Thanks KD, thats how I understand it, so should be good.

We don't have a face plate, but thats the idea with the wood. Maybe cut down length wise so it located about 1" into the cylinder. I can bore soft jaws to hold it, true the face of the jaws, locate the wood and size it to the bore, then mount the cylinder on the wood and use the MDF shim between the jaws and the top of the cylinder. Then as you say, use a bull nose ctr to make it all tight enough to drive. I could even put a peg between the MDF shim, between the jaws and into a stud hole to give extra drive... that sounds like a plan...  :)

Obviously the liner is cast iron so need to take care with that so I don't crack it.. only .075 in places... ever put banding or a big pipe clip around it to hold it??

mK2 ready to go. Using the old gasket as protection in place of the MDF as that wasn't that accurate on thickness?... and pegs for drive. Cut down the 3.5" dia bit to about 3" long... 2" in the jaws, 1" out and use as above..


kd

Be careful to not cut a sharp inside corner radius up against the liner when you cut the surface.  A sharp corner is a recipe for a cracked liner.  The piston rocks at the bottom when it changes direction.  The side thrust works the spigot and a sharp inside corner is where a crack can appear.
KD

1340evo

Yes, noted. infact there is a gap between the liner and the cases so you don't have to go fully to the cast iron, not to mention the large taper on the case bores.

One thing that does worry me is how thin the liner is to put a ctr in there. its only thin in places and the bore is not exactly round as its done between torque plates so you'll get point contact. May be best making a cup locating off the OD and putting the ctr in that.
Will have to see what the face is true to first.. If they don't clock within .001 when set up, I'll not do anything with them and try jig it another way.

Obviously need both to be doable before I do any so will check both before I put the tool in ;)

1340evo

Job done. No wood, no soft jaws, no tail stock, just bung it in with some card on the bore and it will be fine  :smileo:

And it was.. so now have them .004 different in length to match the rods  :smiled: and the additional few tho off to get the right squish.

Heads next, but they are easy to do

1340evo

okay, so re-checked tonight and with my .016 bases and .036 heads, I'll end up at 0.035 squish on both :) .. looking back sqish is quoted at .030-.036 so in the top end of that... (I could still get .030 heads and then have .029 squish... but no, lets stay as we are)

So next the cc... is 78cc a good place?

1340evo

Heads skimmed, so should be both at 78cc now... .023" off one and .027" from the other... may as well be spot on whilst we are at it ;)

Now to take them all in bits again and de-burr, clean  :crook:


kd

KD

1340evo

Cleaned off today and CC'd them, both spot on 78cc :)   now in plastic bags read to fit