Author Topic: Build thread for my 865  (Read 8743 times)

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Gremlinsteve

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Reply #15 on: September 08, 2020, 09:27:16 pm
I’ll take question and comments yes


Gremlinsteve

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Reply #16 on: September 08, 2020, 09:29:34 pm
Regarding the valve. I’m not happy with the exhaust valve I’m sure they had a reason to run a nail head valve.  Maybe to gain area under the valve for low lift numbers

I’m wondering what a tulip valve will do in the exhaust side


Gremlinsteve

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Reply #17 on: September 08, 2020, 09:50:47 pm
Well some of my backcut angles did literally nothing. Port is whistling like crazy. Mac tool guy said holy crap what was that....! Lolol.


Lots of velocity


Gremlinsteve

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Reply #18 on: September 08, 2020, 09:52:43 pm
A 1 inch sharp edge orifice flows 88-90 cfm. Our intake ports flow a hair under 190. The intake opening is 1.125x 1.060. You do the math.  I’m gonna try a couple more things to see what else I can get. 


ace.cafe

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Reply #19 on: September 08, 2020, 10:09:48 pm
I’ll take question and comments yes

Okay.
From the flow chart we are seeing essentially a shift in flow away from low lift and toward better high lift flow.
I am using .354" figure as max valve lift with S&S cams.

It is doing real well at .250" and higher.
There is a significant drop of 10 cfm at .100" lift.
Not too concerned about the smaller drop at .050" because not much flow is happening yet.
Your average flow over the working lift curve is only 2cfm over stock. If you could pull up that dip at .100", you could increase the average flow to 4cfm over stock.

Do you have any cause isolated for the drop at .100" lift?
At what lift does the valve clear the short side chamber wall by .200"? Maybe there might be some shrouding by the chamber wall at low lift, but clears out as the valve moves further clear of the chamber wall?
« Last Edit: September 08, 2020, 10:14:26 pm by ace.cafe »
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Gremlinsteve

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Reply #20 on: September 08, 2020, 11:43:15 pm
No cause isolated yet other than experimenting with valve angles


Gremlinsteve

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Reply #21 on: September 08, 2020, 11:45:32 pm
Stock bore versus a roughed in marking where the 865 kit will place the bore


ace.cafe

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Reply #22 on: September 09, 2020, 12:01:37 am
Looks like there is room on the chamber wall for unshrouding on the short side if the chamber wall is too near the edge of the valve.

We always used .200" as a minimum figure for that.
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Gremlinsteve

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Reply #23 on: September 09, 2020, 12:40:39 am
Yea
I’ll unshroud that area.  Trust me I’ve just begun


Gremlinsteve

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Reply #24 on: September 09, 2020, 01:55:53 am
Plus room for mor valve job. The lap line is still not the best


derottone

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Reply #25 on: September 09, 2020, 08:15:22 am
Stock bore versus a roughed in marking where the 865 kit will place the bore

The 865 bore appears to be very close to the water jacket channel.
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Gremlinsteve

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Reply #26 on: September 09, 2020, 05:58:59 pm
I have a video of the head on the bench
It has a beautiful sound.  Sorry I can’t post it


Gremlinsteve

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Reply #27 on: September 09, 2020, 08:53:36 pm
Yes. The 865 bore is just at max

The bore size increases by right at 1/2 inch or 13mm

Here is the exhaust side.   Going to keep plugging away at this thing


Gremlinsteve

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Reply #28 on: September 09, 2020, 09:02:05 pm
Candy


ace.cafe

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Reply #29 on: September 09, 2020, 10:31:21 pm
Nice looking short turn!
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