Valve Train Geometry with Cam., Beating a dead horse. Options

[jaredmcginness]

Hey guys,

Making headway on my 1911 build (no pun intended).

I have a few valve train questions. I've researched this a good bit the last few days and read a couple informative threads on here with some info (including one by @nditiz1 that went through a very similar issue)

I am trying to not over complicate this, so my tiny brain can make sense.

I was having an issue with my rockers, posted a photo of my heads on the 914world facebook group and got a great response from J. Raby with a lot of helpful info.
It seems I bit off a bit more than I can chew with valve train geometry.
(I understand he wrote a dissertation about Valve Geometry a number of years ago, but I cannot seem to find it.)

It does not surprise me that the fella/shop who built my bottom end didn't go into too much detail about this. He basically laid the numbers out and said "If I have X amount of cam lift, we need to machine the heads for dual springs to achieve X amount of clearance. All there is too it."

Maybe there is a bit more involved than that. (IMG:style_emoticons/default/smile.gif)

Specs:
-1911 (96x66mm)
-51cc heads - fresh.
-Scat c35 .495 Lift
-Scat solid lifters
-Scat dual HD springs, head machined.


Recommended additional purchases by Jake:

All available at Type4Store
-911 Swivel Foot / Machine rockers .060
-Solid Spacer and shims. Byebye rocker spring.
-8mm HD studs for strength.

Question:
With all of this added, it seems like the heads will be much more sound, and be able to handle the possibly over-sized lift on the cam.


-I have seemingly completed a proper valve adjustment using the "Lobe per lobe" technique. (I.E. Intake 3 fully open, adjust opposite rockers on 1) I cannot find a lot of info on the right way to do an adjustment with a large cam. Thoughts?
My TDC mark on the flywheel doesn't match up with the valves due to the ramp of this cam. (I think I understand that right)


-Does this geometry affect my pushrods? They SEEM to be working fine at their length. Do I need "chromoly"? Is this for strength and + cut to size?
I read all these threads on the Samba of guys running large cams with stock rods. (probably my engine builder posting that stuff (IMG:style_emoticons/default/biggrin.gif))

I would just like to do this right the first time.


(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1599592477.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1599592477.2.jpg)


Sounds like this motor is going to run like scat if I don't wrap my head around this and study a bit more. I'm really proud of what I have learned so far building this 914.
But I am just at the tip of the iceberg.

Feel free to just tell me to use the search function. (IMG:style_emoticons/default/beerchug.gif)

[jaredmcginness]

Hey guys,

I posted this info in my build thread, but I figured it is better suited here, incase anyone is following for their own type 4.
Update: been awaiting a lot of parts for my valve train. Everything has finally arrived!


With that said - and having read and taken notes on Raby's novel on Valve Geometry about 7 times - I began.


(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600822307.1.jpg)


I ground the 1.7 rockers about .060. Started with ~ .504 and ended with around .437 on all of them. Filed flat and deburred on the buffing wheel.

I counter sank them to fit the Thorsten Peiper, Made in Germany swivel feet. (I didnt go OEM ((sorry Jake)), I paid $117 for these - about 1/3 the price of OE - we'll see how it goes. I couldn't find anything bad on these, unlike the El Cheapo $38 ones.) I also chased the threads after this photo.


(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600822307.2.jpg)


I assembled the rocker assembly, HD studs, solid spacers, fresh HD washers.

One question I am looking for a few answers on:
Spacers on the rocker assembly...
Am I shooting to line the adjusters up with the valve, (by moving spacers left or right, and stacking between - see photo) dead center as close as I can, then shim later at half lift if needed?

Or just assemble the rocker shaft, evenly spaced washers and shim under the studs as needed later.


Should it be this layout?:

Stud|Rocker|SHIM|Spacer|SHIM|Rocker|Stud


Current layout is:
Stud|Rocker|SHIM|Spacer|Rocker|SHIM|Stud


I have a gap of .006 currently. I may be overthinking the assembly layout, may not matter at all.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600822308.3.jpg)



I don't have a washer between every piece in the assembly. I'm told and am thinking this is OK... yes?

For mounting my magnetic base, I made a quickie bracket. For the hole pattern, I overlayed my intake gasket, and copied with a sharpie.

I haphazardly cut it with my grinder, as I ran out of wheels... Pretty sad for a professional sheet metal mechanic. (IMG:style_emoticons/default/lol-2.gif)


(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600822308.4.jpg)


(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600822308.5.jpg)


Base mounted GREAT! Super solid!


(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600822308.6.jpg)


This is about as far as I got this evening...
(IMG:http://www.914world.com/bbs2/uploads_offsite/i.imgur.com-23209-1600823044.1.jpg)

I lined up the dial indicator. It looks pretty co linier right now. I want to get the angle dead on. Next is preload, then find full lift, and so on so forth.





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Thanks all!

Jared