carb angle

@marinatlas:
Thanks for the frame sketch. Not enough detail to prove top and bottom frame tubes are parallel, but scaling the sketch (something I only do as a last resort) shows them to be parallel.

@dynodave
Your comment

"Only one thing I consider...what is the FUEL level at the center of the carb i.e. emulsion/jet tube.
I have never been convinced the floats are symetrical and have used a fuel sighting tube to verify fuel level entirely in line with the center of the carb. Why would anyone care about fuel or float other than where it matters?"


is exactly what I said in reply #12 above, but in different words. Thus, we agree on this.

Re: carb angle
I keep getting 20 degrees with my adjustable protractor. Here is a sketch of head (side view from left side) showing the manifold mounting surface inclined 20 degrees from the vertical, which corresponds to 20 degree air/fuel flow from the horizontal. I cannot get 28 degrees on the intake manifold, but the intake rocker box measures close to 28 degrees.

carb angle


Slick
 
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Atlas engine tilted? 650ss and atlas cases are exact same casting#. Barrel height the same. head casting is the same, only the 4 bolt pattern is wider. engine plates different???? Different head steady bar part# length longer for atlas?

I agree Dave. Although the cases have different numbers (650SS vs Atlas) they are the same outside dimensions.
My parts lists (64 & 66) show the following are common parts for 88ss, 650ss and Atlas:
24990 - Frame only
23868 - Plate, head steady
15621 - Plate, engine, front
20700 - Plate engine, rear, left hand
50229 - Plate, engine, rear, right hand
With all these parts the same how can the Atlas have a different engine angle?
I find it a concern when someone emphatically puts forward their opinion (myth?) as fact - laying a trap for some poor unsuspecting bastard to fall into.
The same person also stated catagorically that the slimline frame was different (lighter) for the Model 50 than the ES2 - wrong again - both have same part number 23052
I think we should all make the effort to identify and "red flag" fake news
 
Slick & Dave
I took my 650ss head off to get a more accurate measurement of downdraught at the face of the manifold - I agree with Slick's 20 degrees
Cheers
Rob
 
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I've been measuring floatlevel via a sight tube at the motor side of the carb with good results....making several checks while the motor is running and every few miles. I will see what happens when I move the sight tube to the center of the carb.
 
so if the angle is 20 degrees I could make a manifold approx 16 or 17 degrees to account for the rider compressing the rear shocks.
 
Could it be that the motor appears to lean back because some daft yank convinced the factory that they needed a fat 18" rear wheel instead of the 19" one that the bike was designed to handle the best with?.
 
The downdraught ports together with the wider splay on the exhausts was credited with the better breathing (over the earlier head) that gave the DD SS its performance lift. The AMC team were not impressed though with the Norton design and immediately set about changing everything to make it better .(Combat anyone?)
 
@marinatlas:
Thanks for the frame sketch. Not enough detail to prove top and bottom frame tubes are parallel, but scaling the sketch (something I only do as a last resort) shows them to be parallel.

@dynodave
Your comment

"Only one thing I consider...what is the FUEL level at the center of the carb i.e. emulsion/jet tube.
I have never been convinced the floats are symetrical and have used a fuel sighting tube to verify fuel level entirely in line with the center of the carb. Why would anyone care about fuel or float other than where it matters?"


is exactly what I said in reply #12 above, but in different words. Thus, we agree on this.

Re: carb angle
I keep getting 20 degrees with my adjustable protractor. Here is a sketch of head (side view from left side) showing the manifold mounting surface inclined 20 degrees from the vertical, which corresponds to 20 degree air/fuel flow from the horizontal. I cannot get 28 degrees on the intake manifold, but the intake rocker box measures close to 28 degrees.

View attachment 4425

Slick

TS-robss
I redid a measurement a few minutes ago on the bench with barrel top level...concede 20/21 degrees at port face
 
I recently took a commando intake manifold and shaved 5 degrees off each end. It looks good, is barely noticeable, and appears to hold the carb level. I will take the bike off the bench friday, set it on the ground on both wheels and shocks installed for the final inspection. I wish I was more computer literate so I could post pictures. I can do it via email. Also a friend will stop by Tuesday and perhaps he can post them.
The flange could possibly take another one degree of shaving before it is gone altogether.
 
Couldn't wait, took the Norton off the table and had someone sit on the bike so I could see if amals were level or not. It worked out great.
 
Our Atlas has a level carb. The manifold is an aftermarket one ,Norville or RGM. The factory single carb manifold was different and still showed the carb at a reduced downdraught.
 
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