.040 Quench or Zero Deck?

[Steven]

Quench or Zero Deck... where should the emphasis be? I'm confused. I must have read all 14 pages of the decking post five times over.

Is it more important that I get my new Ross piston to zero deck height or get the quench down to .040?

The Ross runs 11.2:1 at OEM deck heights of about .043 in the hole. Wouldn't the compression ratio be rather high if I brought that piston to zero deck?

I can get quench down to about .058 with .012 base and .025 head gaskets but I will still be .033 away from zero deck. Is this ok? What will the compression ratio be?

Or is it better to run no base gasket and the .025 head for a quench of about .048? The piston will still be about .023 away from zero deck. What about compression ratio with this set up?

I can get achieve the desired .040 quench and zero deck height if I run the .043 head gasket, .020 base, and chop the cylinder by .040.

So what is the best way. I have purchesed the .012 and .020 base gaskets and the .043 and .025 head gaskets, so I am ready for any combination.

Which is the proper combination? What should I do?

HELP PLEASE!

Steve

[Steven]

Please forgive the bump. I have to keep this on the front line until someone comes along who has the answers.

Thanks...

[3x440ex]

maybe this will help......

Mr. Dunlap,
After reading your answer to TREX400's question, I was wondering how you get the cylinder volume clearance to 0.040 inch on a 440 engine. I am sure that the head gasket must be different to accept the new sleeve. Also how can I check to see what my compression ratio really is?
Thanks,
oynot400

answer

Decking the cylinder is the proper way to set up your deck clearances. Most head gaskets will be about .040 thick so you try to deck the cylinder so that your piston comes up exactly to the top of the cylinder at top dead center. I suggested going to a thinner head gasket at about .030 (like an XR400 or Cometic's 3 piece steel head gaskets for the 440) and then not using the .020 thick base gasket and this would get you close without having to deck your cylinder. As far as figuring out what your compression ratio is when your engine is completely together, you need to measure the cc's of fluid it takes to fill your combustion chamber up to the bottom of the spark plug hole, make sure your engine is at top dead center and you tip your motor back and forth to make sure there are no air bubbles in the combustion chamber. For example, if you have a 440 motor and it takes 50cc's of fluid to fill it up, you would take 440 + 50 divided by 50 to give you 9.8 to 1 compression. To get a true 11:1 440, you will have to have a 44cc combustion chamber volume. Most so-called 11:1 pistons will have closer to 50cc's. You can get a syringe that measures in cc's at your local pharmacy and you can use just regular motor oil to fill your combustion chamber.


:)

[powerslider]

I would ask the people at Ross on their recomendations for proper setup for the compression ratio you want to achieve.

Steven, what you thinking about now :)

Did you get the parts back from the machine shop yet?

If you did all you need to do gap those rings and install the piston and cylinder (without base gasket if you like not to damage it) and take some measurements on the piston to deck dimensions etc and then take that info along with the dome and head volume cc's and punch it into the calculator at rosses web site.

Try it with the diff gaskets thicknesses and see what comp you get. All you need to do is add the total gasket thickness (head and cyl) and then you can make your decisions.

If you need any of the unknown info for the calc look at the email I had sent you and use those numbers (stroke, head vol etc)

Let us know what you find and decicde etc.

[Steven]

Hey Lenny...

I just don't know which is more important... zero deck or .040 quench.

Thats what I'm hung up on. I'm not to concerned about compression ratio, as long as its under 12:1.

Steve:rolleyes:

Steven the squish is deff important but you sometimes have to give up a little to get a reasonable comp ratio etc so I guess its kind of a trade off with the deck height.

Since some piston mfg's including Ross have adjusted their pin to deck heights to compensate for the below deck set up honda gave this engine you will have a problem with a zero deck and the dome top piston you have.

The only way you are going to get the comp where you want it is to keep it way below the deck or bring the piston up and remove material from the dome. Otherwise you will have more comp than you desire.

You also can only guess at the final nubers until you install and measure the piston and cyl.

AS a estimate you would have around the advertised 11.2:1 with the .043 deck height and the stk .040 head gasket.

If you changed the deck by way of the thinner base gasket and went with the thinner head as well you would reduce the squish (be carefull of your valve to piston clearences) and you would be around 12.2:1.

So as you can see these little things make a diff, so get that thing installed (I personally would do it with out the gasket but if you dont want to install and remove it an extra time you could go with the .012 base gasket to raise the comp a little :) ) and then measure it up so you will know where it is and how to get where you want.

[jaspurx]

so , i get the thinner head gasket idea , but remove the base gasket and use what? high temp. permatex or what? putting it together w/no gasket sounds a little " wrong " to me without some kind of sealant! maybe i`m just dumb.

With the newer pistons and the adjustments to them you dont really need to worry yourself with the silicone or honda bond for the bae gaskets since you will get plenty of comp with the std gaskets.

I think what is happening is that everyone is getting confused with the "old problems" of the 440 kits. I know of more than one example of a 440 that had the wiseco/ims kit that could barely pull the stk motor in a drag etc. and this was due to the fact that it was not uncommon for a 11.5:1 kit to produce around 9:1 with a squish of about 80 or so.

The newer designs that I know of (just Ross but maybe the others also) have lowered the piston wrist pin so as to raise the piston and or added properly sized domes.

So now with the .043 deck height and even stk gaskets you have a very good chance of being close to the correct comp.

[Steven]

Ok then.

I'm going to run the .012 base and .025 head gasket and leave the cylinder alone. That should give me a deck height of .033 and a squish of .058.

Leny, can you calculate the C/R with the above based on your measurments.

Thanks, Steve.

It will only be possible to get close at best but still will need to know your exact bore size (prefer in inches).

[Steven]

??? 89mm

[Ketch]

Lenny How do you get the Gasket you talk about do get them from costmic or dealer or white brothers?:) Jimmy

The thinner gaskets are made by Cometic and you can get them from C&D (actually a little less $$$ than buying from cometic).

440 89mm (3.508)
+4mm
11.2-1
#99709
302

430
88.6mm (3.488)
11.1-1
#99774
300

440
88.97mm (3.503)
11.2-1
#99772

Just want to be sure we get the correct cyl volume etc.

[Ketch]

Thank you Lenny I didn't know Jimmy

[Steven]

Lenny, I guess is 3.508in (89mm) bore.

What C/R does that get me with the .012/.025 gaskets?

[Colby@C&DRacing]

Lenny you are the man ( I showed him everything he knows) :D Just kidding you guys have done some good research. My hat goes off to you guys for getting real answer not just spreading hear say:)

[Steven]

Hey Colby, I bought my Hotcam Stage II, #45 pilot, and outerwear from you guys at C&D. Thanks for letting me pick your brains yesterday. Your service is top notch. Kudos to Dusty as well.... I think that was her name.

So Lenny, figure out the c/r yet?

[Colby@C&DRacing]

Steven I was glad to give you any info that I have. That is what I am here for. Just hope that I can help. I enjoy talking with you guys.

Lenny you are the man :devil :cool:


Bore in 3.508
Stroke in 2.7559
Head cc's 38
Gasket Thickness in .025
Deck Height (Put .0001 for zero deck) in .035
Dish or Valve Pocket [-] or Dome [+] cc's 8.6+
Number of Cylinders 1

Displacement Cubic Inches 26.64
Compression Ratio 12.22


ross pistons.com (http://www.rosspistons.com/)

[Steven]

WOW!

How does .013 less quench get me to 12.2:1?????????

Ross rates the piston at 11.2:1 with XR400 gasket thickness which I thought was a .018 base gasket and .030 head gasket (compressed).

If I run the .012 base and .025 head, I'll be at 12.22:1??????

Is this right Leny?!?!

Steve

The confusion may be from the gasket thickness.

I thought the stk head was .040 and base .020 and used those numbers as reference.

You will deff know more when you get it all torqued down, and can make some decisions then.

For the calc I had used the .025 head and deducted .008 on the deck height w/.012 base to get the results shown.

If you like maybe go to ross's site and try it with the thicker gaskets and see where you "may" end up.

[jaspurx]

but if the piston i bought 6 months ago is a true 10:1 , then if i run the thinner gasket i get a li`l more compression for cheap considering i`d have to replace those gaskets anyway! but not sealing where the basegasket goes sounds kind`a wrong? so then i have a question for colby@c&d : whats a gasket kit ( the thin one ) going to cost me?

[Steven]

they are inexpensive, call them