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Old 03-29-2019, 10:16 AM
  #39726  
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Originally Posted by SrTelemaster150
WHOA, WHOA, WHOA, hold your horses there pardner.

You are comparing apples to oranges.

THAT is a SB Chevy that has an adjustable rocker pivot mount. That video does not apply to any engine that has a fixed rocker pivot like our Saitos, or SB Chryslers Fords etc.




While the geometry does change, the net valve lift will not change a significant amount when the change is at the pushrod/rocker interface . As long as there is sufficient adjustment available, there would be little benefit in changing pushrod length.
I believe I said that to Pete in a reply

Jim
Old 03-29-2019, 10:26 AM
  #39727  
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Originally Posted by the Wasp
I believe I said that to Pete in a reply

Jim
As usual, after missing a days worth of posts, I failed to read all of them before replying.
Old 03-29-2019, 10:29 AM
  #39728  
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Originally Posted by SrTelemaster150
As usual, after missing a days worth of posts, I failed to read all of them before replying.
LOL I do that too much

Jim
Old 03-29-2019, 10:42 AM
  #39729  
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Originally Posted by Captcrunch44

30% nitro
18% oil
Originally Posted by Glowgeek
30% nitro in a high compression 180? Try FAI fuel (0% nitro) or maybe up to 10%. Having high compression advances the ignition timing and doesn't require high nitro content. You could be experiencing detonation using 30%. Check your glow plug for a deformed coil and/or little bumps on the wire.

Things that advance ignition timing in glow engines:

Higher compression
Hotter glow plug
Higher nitro
Higher oil content
Higher prop load
Try 30% nitro O'Donnell Speed Blend with 8% oil in an FA-180HC running CDI

Holy moly will it howl! Hit nearly 9000 RPM with an 18 x 8 Dynathrust prop.

Boy oh boy was it ever thirsty though.

Last edited by SrTelemaster150; 03-29-2019 at 10:58 AM.
Old 03-29-2019, 10:46 AM
  #39730  
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Originally Posted by FlyerInOKC
Purrs like a kitten!
But it snarls like a tiger when you open the throttle.
Old 03-29-2019, 11:00 AM
  #39731  
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to add, even tho the rockers have an adjustment, the angle of the longer rod will change, as he suggested in my video, the result will be more lift


is there any info on Saito's Rocker Ratios ??

Jim
Old 03-29-2019, 11:04 AM
  #39732  
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Originally Posted by SrTelemaster150
But it snarls like a tiger when you open the throttle.
LOL Pete will like that

Jim
Old 03-29-2019, 02:58 PM
  #39733  
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Originally Posted by the Wasp
to add, even tho the rockers have an adjustment, the angle of the longer rod will change, as he suggested in my video, the result will be more lift


is there any info on Saito's Rocker Ratios ??

Jim
Just measure the distance from the center of the rocker pivot to each end and divide the distance from center of the pivot to the center of the valve stem pad (A) by the distance from center of the pivot to the pushrod socket. (B)

The geometric change will be insignificant since the pivot point toes not change. To compute the change use the square of the B - the square of the deck reduction (C) to get (D squared) A/D will give you the new rocker ratio.

Last edited by SrTelemaster150; 03-29-2019 at 03:50 PM.
Old 03-29-2019, 03:26 PM
  #39734  
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Default Saito FA82 CR Mod

New data just in. Measured three more times and no need to average as the difference was unmeasureable (visually). There are two differences in how the measurements were taken than previous; I was much more careful about dripping drops everywhere and I adjusted where I was aligning the syringe plunger to the graduation marks.

Previously taken measurements:
Combustion Chamber: 1.80 cc
Glow Plug (Type F): .030 cc
Mechanical Swept Vol: 13.97 cc
Mechanical Compression: 8.63:1

Latest measurements:
Combustion Chamber: 1.75 cc
Glow Plug (Type F): .030 cc
Mechanical Swept Vol: 14.05 cc
Mechanical Compression: 8.89:1

Conversion shows that my 82 is an 85.7 LOL!

Here's the thing, I have no way to calibrate a graduated 3cc syringe so take the volume numbers with a grain of salt. The CR however is probably very close to real because it's a ratio between swept and combustion chamber volumes.

Clearances:
Cylinder skirt to case relief: .017" . I have removed .015" from the bottom of the cylinder skirt in preparation for milling as much as .020" off the case deck if needed.

Valve to Piston:
Mechanical valve to piston interference occurs if the case deck is milled down .036". For now I will be limiting milling to .020" so no problems there.

Cylinder fin to Cam Gear Housing:
A small notch was cut in one cylinder fin to allow clearance for lowering the cylinder.

Compression Ratio:
The starting CR is approx 8.89:1. I will be shaving .013" off the case deck initially yielding right at 10:1 CR. From there I'll increase CR until I'm happy or something breaks.

Goal:
Currently both of my FA82's spin an APC 14x6 at 9200 rpm using 15%/17%. I'm looking for 9800 rpm without increasing nitro content.

Lonnie

Last edited by Glowgeek; 03-29-2019 at 03:29 PM.
Old 03-29-2019, 03:53 PM
  #39735  
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Originally Posted by Glowgeek
New data just in. Measured three more times and no need to average as the difference was unmeasureable (visually). There are two differences in how the measurements were taken than previous; I was much more careful about dripping drops everywhere and I adjusted where I was aligning the syringe plunger to the graduation marks.

Previously taken measurements:
Combustion Chamber: 1.80 cc
Glow Plug (Type F): .030 cc
Mechanical Swept Vol: 13.97 cc
Mechanical Compression: 8.63:1

Latest measurements:
Combustion Chamber: 1.75 cc
Glow Plug (Type F): .030 cc
Mechanical Swept Vol: 14.05 cc
Mechanical Compression: 8.89:1

Conversion shows that my 82 is an 85.7 LOL!

Here's the thing, I have no way to calibrate a graduated 3cc syringe so take the volume numbers with a grain of salt. The CR however is probably very close to real because it's a ratio between swept and combustion chamber volumes.

Clearances:
Cylinder skirt to case relief: .017" . I have removed .015" from the bottom of the cylinder skirt in preparation for milling as much as .020" off the case deck if needed.

Valve to Piston:
Mechanical valve to piston interference occurs if the case deck is milled down .036". For now I will be limiting milling to .020" so no problems there.

Cylinder fin to Cam Gear Housing:
A small notch was cut in one cylinder fin to allow clearance for lowering the cylinder.

Compression Ratio:
The starting CR is approx 8.89:1. I will be shaving .013" off the case deck initially yielding right at 10:1 CR. From there I'll increase CR until I'm happy or something breaks.

Goal:
Currently both of my FA82's spin an APC 14x6 at 9200 rpm using 15%/17%. I'm looking for 9800 rpm without increasing nitro content.

Lonnie
What algebraic formula are you using to compute CR?

Are you adding the chamber volume to the swept area before dividing the sum by the chamber volume?
Old 03-29-2019, 04:05 PM
  #39736  
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Originally Posted by SrTelemaster150
What algebraic formula are you using to compute CR?

Are you adding the chamber volume to the swept area before dividing the sum by the chamber volume?
(Swept Vol + Comb Chamber Vol + Glow Plug Vol) ÷ (Comb Chamber Vol + Glow Plug Vol)
Old 03-29-2019, 04:29 PM
  #39737  
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Originally Posted by Glowgeek
New data just in. Measured three more times and no need to average as the difference was unmeasureable (visually). There are two differences in how the measurements were taken than previous; I was much more careful about dripping drops everywhere and I adjusted where I was aligning the syringe plunger to the graduation marks.

Previously taken measurements:
Combustion Chamber: 1.80 cc
Glow Plug (Type F): .030 cc
Mechanical Swept Vol: 13.97 cc
Mechanical Compression: 8.63:1

Latest measurements:
Combustion Chamber: 1.75 cc
Glow Plug (Type F): .030 cc
Mechanical Swept Vol: 14.05 cc
Mechanical Compression: 8.89:1

Conversion shows that my 82 is an 85.7 LOL!

Here's the thing, I have no way to calibrate a graduated 3cc syringe so take the volume numbers with a grain of salt. The CR however is probably very close to real because it's a ratio between swept and combustion chamber volumes.

Clearances:
Cylinder skirt to case relief: .017" . I have removed .015" from the bottom of the cylinder skirt in preparation for milling as much as .020" off the case deck if needed.

Valve to Piston:
Mechanical valve to piston interference occurs if the case deck is milled down .036". For now I will be limiting milling to .020" so no problems there.

Cylinder fin to Cam Gear Housing:
A small notch was cut in one cylinder fin to allow clearance for lowering the cylinder.

Compression Ratio:
The starting CR is approx 8.89:1. I will be shaving .013" off the case deck initially yielding right at 10:1 CR. From there I'll increase CR until I'm happy or something breaks.

Goal:
Currently both of my FA82's spin an APC 14x6 at 9200 rpm using 15%/17%. I'm looking for 9800 rpm without increasing nitro content.

Lonnie
What did you use on the piston crown to do a real world valve to piston crown clearance check?
Old 03-29-2019, 04:49 PM
  #39738  
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Originally Posted by SrTelemaster150
What did you use on the piston crown to do a real world valve to piston crown clearance check?
No clay or anything, removing the piston is not necessary for that measurement and I didn't want to unseat the ring. Instead I first measured the full opening distance for each valve. Next I removed the pushrods and rear cover then measured the the distance from the big end of rod to the case rear cover opening at TDC. Next I wedged the rockers to bring both valves to there full measured travel and slid the piston up until it stopped against an open valve. Lastly I remeasured the big end of rod to case measurement and took the difference.

As it turns out I later noticed the cylinder skirt - case relief issue and had to remove the piston anyway just to sand the bottom of the cylinder.
Old 03-29-2019, 04:51 PM
  #39739  
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SrTelemaster150

Just measure the distance from the center of the rocker pivot to each end and divide the distance from center of the pivot to the center of the valve stem pad (A) by the distance from center of the pivot to the pushrod socket
yes I understand that part, but because I will have to eye it I wont get an accurate measurement, and I rather not be wrong in doing so, and I have been wrong enough over the years


The geometric change will be insignificant since the pivot point toes not change. To compute the change use the square of the B - the square of the deck reduction (C) to get (D squared) A/D will give you the new rocker ratio
what ?? LOL

Jim
Saito engines, if you are good to one, and you let it go free, it will come back to you
Old 03-29-2019, 04:59 PM
  #39740  
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Originally Posted by the Wasp
SrTelemaster150


what ?? LOL

Jim
Made perfect sense to me Jim, you better hurry and catch up...lol
I hate when Algebra gets in the way of my Geometry!
Old 03-29-2019, 05:10 PM
  #39741  
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Originally Posted by Glowgeek
No clay or anything, removing the piston is not necessary for that measurement and I didn't want to unseat the ring. Instead I first measured the full opening distance for each valve. Next I removed the pushrods and rear cover then measured the the distance from the big end of rod to the case rear cover opening at TDC. Next I wedged the rockers to bring both valves to there full measured travel and slid the piston up until it stopped against an open valve. Lastly I remeasured the big end of rod to case measurement and took the difference.

As it turns out I later noticed the cylinder skirt - case relief issue and had to remove the piston anyway just to sand the bottom of the cylinder.
why can't you just bring up the piston to TDC and allow the valve to drop in the cylinder and see how far it goes ? you should be able to measure it.

Jim
Old 03-29-2019, 05:14 PM
  #39742  
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Originally Posted by the Wasp
why can't you just bring up the piston to TDC and allow the valve to drop in the cylinder and see how far it goes ? you should be able to measure it.

Jim
Could have but didn't want to try to get the retainers/keepers back on without removing the piston.

Also that method doesn't tell how far the piston can move up before striking the valves. This is because the valves are at an angle to piston travel.

Last edited by Glowgeek; 03-29-2019 at 05:25 PM.
Old 03-29-2019, 05:29 PM
  #39743  
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Originally Posted by Glowgeek
Made perfect sense to me Jim, you better hurry and catch up...lol
I hate when Algebra gets in the way of my Geometry!

LOL you know, my dad was a borderline math genius, really!! but when I rebuilt my 327 I showed him the stock cam and the performance cam I was going to use, he asked me why is it "that the stock cam's lobe is "higher" than the racing cam's lobe" I told him that it's simple, the racing cam has a smaller base circle, he smiled and called me a little s***

Jim

Last edited by the Wasp; 03-29-2019 at 05:44 PM. Reason: I forgot the s for s***, oops, edited again for the smile ;)
Old 03-29-2019, 05:38 PM
  #39744  
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you will just have to use clay or play doh

Jim
Old 03-29-2019, 06:14 PM
  #39745  
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battery discharging question,


guys, I am cycling two 3000 milli amp 6 cell 7.2V NiMH packs that I use on my engine starter, I have a great charger, a Reedy 1216C2 charger,

at this point this one pack has been discharging for 88 minutes, the pack voltage going in is 7, 77 volts,
well, I have the charger set to pull 2.4 amps yet the pack has only been pushing 1.4 amps out,

even tho the volts are 7.77 couldn't I still have a bad cell ?

Jim

Old 03-29-2019, 07:38 PM
  #39746  
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If you want to find a bad cell with NiMh, charge the pack full then hook up the starter and load it. If you have a bad cell the voltage on the pack will drop quickly and not recover. That shock of drawing high amps will drain a bad cell in a matter of moments. Don't stall the starter, just slow it with your hand or something that will spike the amps.
Old 03-30-2019, 02:29 AM
  #39747  
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Originally Posted by the Wasp
why can't you just bring up the piston to TDC and allow the valve to drop in the cylinder and see how far it goes ? you should be able to measure it.

Jim
Hard to do while rotating the engine through TDC

Originally Posted by Glowgeek
Could have but didn't want to try to get the retainers/keepers back on without removing the piston.

Also that method doesn't tell how far the piston can move up before striking the valves. This is because the valves are at an angle to piston travel.
^^^What he said.^^^


Originally Posted by the Wasp
you will just have to use clay or play doh

Jim
Clay or Play Doh doesn't work on such small surfaces. Been there, dine that.

I use .015" dimensional "pattern maker's wax". It comes in sheets and has an adhesive back that sticks well to the small piston crowns.

In such small engines .015" is plenty of piston/valve clearance.

Last edited by SrTelemaster150; 03-30-2019 at 02:34 AM.
Old 03-30-2019, 02:48 AM
  #39748  
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The swept volume is constant, it should not change unless you change the bore or the stroke.
Old 03-30-2019, 02:49 AM
  #39749  
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Originally Posted by SrTelemaster150
Hard to do while rotating the engine through TDC

Clay or Play Doh doesn't work on such small surfaces. Been there, dine that.

I use .015" dimensional "pattern maker's wax". It comes in sheets and has an adhesive back that sticks well to the small piston crowns.

In such small engines .015" is plenty of piston/valve clearance.
Using wax, clay etc and rotating over a fully assembled engine allows for a dynamic valve interference measurement. The way I measured it is a static measurement and doesn't account for the fact that the valves are only partially open at TDC during the exhaust stroke and not at all during the compression stroke. Still, it allowed me to see if there was room to drop the cylinder without removing the piston.

Last edited by Glowgeek; 03-30-2019 at 04:27 AM.
Old 03-30-2019, 04:49 AM
  #39750  
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Wow you guys
i haven’t got this much info sents I took A&P school.
Is someone going to put this in a book or pdf that can be down loaded so a guy like me can refer too.
I have a couple 91’s that I could mess with.

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