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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Sat Jun 27, 2015 9:50 am Post subject: |
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I made a graph of the cam lift so I could see exactly where the cam was lifting the valves the fastest. After reading a bunch on rocker geometry I like the idea of having the rocker 90* to the valve at the point where the valve is being accelerated the fastest.
I came up with .271" lift on the opening ramp and .320" lift on the closing ramp. Total lift was .543" so .271" would be at half lift, but I'm thinking it would be better to set up the rockers using .320" lift on the exhaust ramp since it's more important to have the valve under control while its closing?
_________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10 |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Sat Jun 27, 2015 12:36 pm Post subject: |
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Mid lift the valve is not accelerating, it is moving at a nearly constant speed.
The acceleration is at the top and bottom of your graph. |
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Stripped66 Samba Member
Joined: May 31, 2005 Posts: 3467 Location: Charleston, SC
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Posted: Sat Jun 27, 2015 12:48 pm Post subject: |
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modok wrote: |
Mid lift the valve is not accelerating, it is moving at a nearly constant speed.
The acceleration is at the top and bottom of your graph. |
PV, eh? _________________
66brm wrote: |
Bodacious wrote: |
Why not just make a custom set of wires with a Y splice in them. Then you could just run one distributor. |
I don't think electrickery works that way |
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FreeBug Samba Member
Joined: March 12, 2012 Posts: 4278 Location: deepest, darkest Switzerland
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Posted: Sat Jun 27, 2015 1:42 pm Post subject: |
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What Modok said. The middle of the curve is where the valve is moving fastest (highest speed), between the acceleration at the bottom and the deceleration at the top (left side of curve). |
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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Sat Jun 27, 2015 2:59 pm Post subject: |
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I made a note of the amount of lift at every 5 degrees of crank rotation, that is the line on the graph. Then made another note of the difference in valve lift between each of those. The area with the most difference in lift per five degrees of crank rotation would be where the valve is accelerating the fastest, right? _________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10
Last edited by theastronaut on Sat Jun 27, 2015 3:02 pm; edited 1 time in total |
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Stripped66 Samba Member
Joined: May 31, 2005 Posts: 3467 Location: Charleston, SC
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Posted: Sat Jun 27, 2015 3:00 pm Post subject: |
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theastronaut wrote: |
I made a note of the amount of lift at every 5 degrees of crank rotation. Then made another note of the difference in valve lift between each of those. The area with the most difference per five degrees of crank rotation would be where the valve is accelerating the fastest, right? |
Velocity. _________________
66brm wrote: |
Bodacious wrote: |
Why not just make a custom set of wires with a Y splice in them. Then you could just run one distributor. |
I don't think electrickery works that way |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Sat Jun 27, 2015 3:21 pm Post subject: |
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"lift per degree" is lift rate, or speed
Acceleration is change in speed.
Imagine that was a graph of you driving to the 7-11 and doing a U turn and coming back. degrees is time, lift is distance from your house.
halfway there the distance is varying linearly with time, so you don't appear to be making any changes in speed, so you'd feel no g-forces.
But certainly would feel some g-forces at the U turn, and appears you accelerated quick and coming back slammed on the brakes. probably typical VW driving behavior LOL
Best to not make any sudden accelerations near your house so add some lash ramps, but once a block away then.......yee haw |
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paradox_pete Samba Member
Joined: August 19, 2013 Posts: 32 Location: 4 Corners
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Posted: Sun Jun 28, 2015 8:50 am Post subject: |
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As others have noted the point on your graph where there is the greatest vertical difference between adjacent data points indicates the highest velocity, not the highest acceleration. It is equivalent to going a steady 75mph on the highway, you are going pretty fast, but not accelerating. Basically, on your graph the places where the line is relatively straight there is little acceleration, and the points where it is curved are where there is acceleration. The point where the curve is "tightest" is where maximum acceleration is occurring. Finding this point graphically would involve drawing lines tangent to the curve at each data point. Where the difference in the angle of two adjacent lines is greatest is where maximum acceleration is happening. |
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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Tue Jul 07, 2015 6:28 pm Post subject: |
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You guys are right, I'm being stupid again. I even originally said "fastest" (meaning speed/velocity) in my first post about RG. Not sure were I got hung up on acceleration as my intent was finding the point where the valve was moving the fastest.
Anywho, the point where the valve is moving the fastest is also the point of half lift, so it wasn't a hard decision of where to set up the rocker 90* to the valve stem. I had to shorten and re-tap my adjustable pushrod since the motor is so narrow, and eventually came up with 10.480" pushrods to get the rocker 90* to the valve stem at half lift (or max velocity). You can see in the pictures that show the pushrod tubes just how compressed the PR tube springs are, it was fairly difficult to get them in place. The cylinder tin needed a good bit of trimming to fit as well. I ordered a set of Aircooled.net's HD aluminum pushrods and had a friend shorten them. He was able to keep them all within .003".
The long block is assembled and I will be picking the flywheel up tomorrow from having it surfaced. The AN lines came in today for the oil filter hoses. I also trimmed the sled tins, and made new industrial tins to fit around the AA Sidewinder header tubes. The visible part of the block is painted with black wrinkle paint, but I shot a light/dry coat of cast iron engine enamel over the last coat of wrinkle while it was still wet to give it a flat grey color. I'm going to add a breather box vented from the fuel pump block off and oil filler, and drain it back to the sump.
I still need to match port one of the intakes and go through the 36's to freshen them up. I'm hoping to have it in the car this weekend, then start hooking everything back up. I'm planning on getting it running with the 36's for now and eventually finding larger carbs to go on it, preferably 45 DRLA's.
_________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10 |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Tue Jul 07, 2015 6:58 pm Post subject: |
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WHOA! I thought sweep the floor would look a bit rougher than that. |
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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Wed Jul 08, 2015 5:54 am Post subject: |
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modok wrote: |
WHOA! I thought sweep the floor would look a bit rougher than that. |
Well, I had most of it already other than the exhaust, heads, PR tubes, and pushrods. Had to buy new bearings, rings, etc of course. The tin is leftover, it looks better in pics than in person. So it's still mostly leftovers. _________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10 |
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Boolean Samba Member
Joined: January 19, 2012 Posts: 1712 Location: Stockholm
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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Sun Jul 12, 2015 6:13 pm Post subject: |
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I bought a set of 32mm venturis from CB Performance and just now have started disassembling the carbs to clean and reseal them. I hadn't really looked over the new vents until now; just noticed they aren't made anything like the original Dellorto vents.
The original vents are flat top and bottom to match up with both the throttle bore and auxiliary venturi. The CB vents have one rounded end, and one end that ends in a point- the ID is opened up all the way to the OD. Also, the smallest section of the CB vents is only ~3/16" wide and located all the way at one end. The smallest section of the original vents are about 3/4" wide and only barely off center.
They can be installed with the thick end at the bottom so they match up better with the auxiliary vent and throttle bore but that puts the smallest section of the venturi all the way at the bottom. That doesn't seem correct as I've always thought that the smallest section should be at the top, closest to the auxiliary venturi. The diagrams of carbs always show the narrowest section towards the top.
So, use these or find another set of vents that are made better?
I do have one near-NOS 48 tri jet. Could find another and use those instead. There's a single NOS tri-jet in the classifieds but its $600 bucks.
_________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10 |
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modok Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Mon Jul 13, 2015 1:26 am Post subject: |
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Sorry, the CB vents are machined wrong and also don't fit right at the bottom.
They are only suitable as raw material for re-machining to fit the 40 and 45mm dells.
I'd be best to get OE 32mm ones from Europe. Or 30mm and bore out to 32 or 33 |
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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Tue Dec 15, 2015 4:16 pm Post subject: Re: Re-Sweep the Floor 1679cc- Heads/Cam/Exhaust? More Top |
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Bought a set of 45's and rebuilt them, added 36 venturis while I was in there. Starting out with 55 idles, 145 mains, and 180 airs.
The machine shop screwed up the flywheel- said the friction surface was off by .035" so they "corrected" it. Which didn't correct it, they threw it off .035". Which also threw it out of balance... Sent it to a real machine shop and they are correcting, lightening, and balancing it.
Hoping to have a full week off for Christmas break so I'll have a chance to get the engine in the car.
Will the engine go in with the sidewinder header mounted, or should I wait until the engine is in to install it? Also, does anyone know roughly how much header wrap is needed to wrap a 1.5" sidewinder?
Link
_________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10 |
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yamaducci Samba Member
Joined: March 30, 2010 Posts: 2335 Location: Mount Airy, Maryland
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Posted: Tue Dec 15, 2015 4:29 pm Post subject: Re: Re-Sweep the Floor 1679cc- Heads/Cam/Exhaust? More Top |
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It may seem like a small thing to point out but when your scratching your head when the engine won't fire just be sure to check the distributor clamp stud and case surface has a clean surface to ground through. Otherwise this "Floor Sweep" Engine is getting carried away as we usually do here. Looks nice. _________________ -John Cox
My 2498 Turbo Re-Build Thread: http://www.thesamba.com/vw/forum/viewtopic.php?p=5578697#5578697
3rd Brake Light Safety Stars- I still have a couple with blue light left. Email me if interested. |
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VWCOOL Samba Member
Joined: June 02, 2006 Posts: 1821 Location: Down under
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Posted: Tue Dec 15, 2015 10:39 pm Post subject: Re: Re-Sweep the Floor 1679cc- Heads/Cam/Exhaust? More Top |
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That flywheel machine job - twice - might reduce pressure plate clamp pressure... resulting in s a slipping clutch |
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theastronaut Samba Member
Joined: November 19, 2007 Posts: 1629 Location: Anderson, SC
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Posted: Wed Dec 16, 2015 8:07 am Post subject: Re: Re-Sweep the Floor 1679cc- Heads/Cam/Exhaust? More Top |
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yamaducci wrote: |
It may seem like a small thing to point out but when your scratching your head when the engine won't fire just be sure to check the distributor clamp stud and case surface has a clean surface to ground through. Otherwise this "Floor Sweep" Engine is getting carried away as we usually do here. Looks nice. |
Good catch, I'll make sure it's cleaned to bare metal. Had that problem with another painted engine a few years ago. Me getting carried away with something... ?
VWCOOL wrote: |
That flywheel machine job - twice - might reduce pressure plate clamp pressure... resulting in s a slipping clutch |
The depth from the pressure plate mounting surface to the friction surface is machined to .830" to make sure the pressure plate clamps properly. _________________ Strive for perfection in everything. Take the best that exist and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough."
-Sir Henry Royce, co-founder of Rolls-Royce
'64 Beetle Sunroof OG Bahama Blue
'63 Beetle Vert
'66 Beetle
'88 Festiva L
'89 Festiva L
'64 Chevy C10
'66 Chevy C10 |
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VWCOOL Samba Member
Joined: June 02, 2006 Posts: 1821 Location: Down under
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Posted: Thu Dec 17, 2015 3:01 pm Post subject: Re: Re-Sweep the Floor 1679cc- Heads/Cam/Exhaust? More Top |
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...excellent |
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Matthew Samba Member
Joined: January 29, 2004 Posts: 1760 Location: Eastern Tennessee
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Posted: Sun Jan 03, 2016 1:25 pm Post subject: Re: Re-Sweep the Floor 1679cc- Heads/Cam/Exhaust? More Top |
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Any updates? I have something very similar coming together. I can't wait to see how yours runs. _________________ 1965 Beetle sedan
Click to view image |
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