My gasket kit came with one aluminum gaskets for between each of the cylinders and case. The 2nd hand cylinders I bought had multiple gaskets stacked in this space. I assume only one gasket goes there as that is what I see in the Raby video.
Correct?
Also, the kit came with metal gaskets that clearly fit between the cylinders and heads. I'm not used to seeing this used.
Skip these?
How concerned should I be about deck height now?
You need the cylinder base gaskets. I usually put a VERY thin coat of either Kuril C or Permatex "Ultra Blue" on them. (I don't apply the sealant until I'm ready for the final assembly.) You need to determine the combustion chamber volume and the volume of the cylinder above the piston when it's at TDC. Adding those numbers gives you a plugin for one of the charts that are floating around out there. I recommend (and always use) head gaskets, others don't. If you choose to use them, they'll need to be figured into the calculation. The process is important, and not very simple.
Good luck!
The Cap'n
For me it's up to 3 shims can be used between the case and each jug (everything must be equal/same) . I don't use the head gaskets.
You must do the CR math to know how much shim to use, no guessing on this step.
On doing this right it seems that most cases now need to be decked...the bores machined flat
Ok, I measured/CCed my heads. 62.5cc across the board. Looking at the calculators I should see a CR of around 9.1:1 with a deck height of .045.
Thoughts?
Did you double check the CC'ing? That seems higher than normal....I'm thinking 58cc is stockish?
Unless some machining was done to make the chamber larger?
Well, they were all the same. and I did do one twice.
I think I need some serious shimmage. Sounds like closer to 8.5:1 CR would be better....
Correction to my CR. Looks like 8.26:1 will be attainable with .045" DH....
My next step is to get the custom spacers to finally set my deck, then I can install the heads. I think the thing to do will be to make an adjustable pushrod and use it to set the geometry. I have machinist friends who can help make this. I have Cro-mo pushrods so I can set the lifters to zero lash. I'm not used to this as I've usually dealt with Type 1 motors and stock Hydraulic lifter Type 4s.
I'm finding that .045" is around the minimal deck height. Correct?
If I can achieve this then my CR will be 8.26:1. Kind of low but then again I might be a little off on my measurements. I made a tool that helps measure this. One issue I had was that my pistons went .01" prod of the cylinder when I fist installed it. This means that I will need the custom shims or use a head gasket. Not sure what I'll do next. It usually takes about a week to sort all the info/opinions before I make a decision. That clock started last night
So, Crusty says use the gaskets, Jake and Mark are on the no gasket side.
Gaskets or no gaskets?
Should I do a poll?
Should I buy a poll and install it in my bedroom?
My latest build I went with a .035 deck, ho head gaskets and my Comb Chamber measurements gave me ~58-59CCs.
I also took material from the heads when I had them cleaned up for a final Comb chamber closer to ~54 CCs (exact numbers are at home I can check later).
I had a syringe that was exactly 60cc from a veteranarian supply.
I always stopped just short of using all of it.
You can also seal the acrylic disk down with some wheel bearing grease. That might help.
I put koolaid in the water so I could see it better.
Some use power steering or AT fluid.
Here's the numbers I'm plugging in giving me a 8.26:1 CR. Look right?
I'm using power steering fluid and chasing the bubbles....
I'll do it again this weekend with cool aide. That sounds more fun. I should be able to get a 60cc syringe too.
That deck height is incorrect. Mine was.035
Ahhh yes.
And yes I want the CR high. Carbs, race car, High altitude.
http://www.csgnetwork.com/compcalc.html
Anyone wish to chime in on the minimum deck height on these motors?
I'm seeing .030-.045 as the minimum.
I read once where Jake said that less than .030-.027 (depending on parts) and you are rolling the dice, but I cant find the thread.
I had mine at .025-.027 at the end of the last build & got nervous and spaced it to .035
I used a 60cc syringe from a nurse friend and got 61.5cc's on all four chambers. The only real work done on the heads was oversized exhaust value, new seats and some exhaust port tweaking. I used water and ATF to measure with a bosch plug as well.. measured many times and got the same numbers..
I see were you're getting the extra 2.5cc
If you shimmed the base so the piston aligned flat with the top of the barrel, wouldn't the deck height subtract the area you filled to the brim?
I did mine the same as Stu. The disk is flat across the chamber recess like the cylinder is. I sealed it with grease. I think my heads just have had less machine work done over time than others.
I'll PM Jake and report back.
I didn't realize you had a plate in there. Hard to tell at first glance, but I see it now.
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