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Vintage oval Samba Member
Joined: September 13, 2004 Posts: 25 Location: Colorado
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Posted: Fri Nov 25, 2011 4:49 pm Post subject: 1500cc Okrasa |
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I'm finishing up a 1500cc Okrasa 36hp motor with custom handmade linkage and would like some help jetting the Solex P40-11 carbs. The motor is 74mm x 80mm. Cam is 265 Dur, .322 Lift and the compression Ratio 8.5:1. The ventures are 32mm.
I'm in the Denver area and I'm thinking of using 122.5 mains, 180 air correction, 965 pilot. Has anyone used the P40-11 on Okrasa heads before that might be able to give me some suggestions on the jetting?
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alanhall Samba Member
Joined: February 18, 2006 Posts: 115 Location: Northern California
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Posted: Fri Nov 25, 2011 6:22 pm Post subject: |
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Don't have experience with the Okrasa heads, but the jetting you are suggesting is standard for a split shaft 40PII-4 on a late 912 Porsche, 1600cc 9.3:1 CR. Might be a little rich for 1500 cc in Denver, perhaps a 115 or 120 main might work better. Are your carbs solid or split shaft? Engine looks great by the way!! |
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Vintage oval Samba Member
Joined: September 13, 2004 Posts: 25 Location: Colorado
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Posted: Fri Nov 25, 2011 7:33 pm Post subject: |
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Thanks for the info. The carbs are solid shaft. I have both split and solid shafts but decided to use the solid shaft as they look more period correct for the motor. I was trying to build something that looks it could of been built in the mid to late 50s |
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splitpile Samba's Worst Speller
Joined: May 03, 2000 Posts: 5927 Location: back to living where hell meets the suface
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Posted: Fri Nov 25, 2011 9:57 pm Post subject: Re: 1500cc Okrasa |
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Vintage oval wrote: |
I'm finishing up a 1500cc Okrasa 36hp motor with custom handmade linkage and would like some help jetting the Solex P40-11 carbs. The motor is 74mm x 80mm. Cam is 265 Dur, .322 Lift and the compression Ratio 8.5:1. The ventures are 32mm.
I'm in the Denver area and I'm thinking of using 122.5 mains, 180 air correction, 965 pilot. Has anyone used the P40-11 on Okrasa heads before that might be able to give me some suggestions on the jetting?
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Beautiful _________________ Stocking distributor of "The Funky Green Panels"
www.BUSTORATION.com metal and more for your bus
"no more hacking my sig line" |
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gimmesomeshelter Samba Member
Joined: May 08, 2004 Posts: 1466 Location: San Carlos, CA
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Posted: Fri Nov 25, 2011 10:22 pm Post subject: |
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Hello-
I'm so jealous!
I bought some Zenith carbs recently, but now I'm having second thoughts.
Cheers,
Paul |
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grueni Samba Member
Joined: November 03, 2008 Posts: 582 Location: Germany
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Posted: Fri Nov 25, 2011 10:27 pm Post subject: |
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very beautiful. in first thoughts i would say the vents could be too big for this engine in low and mid range. _________________ 1960 1584cc turbocharged, 35,5/32 (11,117s 1/4mile ) |
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Vintage oval Samba Member
Joined: September 13, 2004 Posts: 25 Location: Colorado
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Posted: Fri Nov 25, 2011 10:53 pm Post subject: |
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I also have a set of 28mm ventures that I can try out on the carbs if the 32mm take away too much from the low end and mid range. |
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Roadcow Samba Member
Joined: November 14, 2003 Posts: 1012 Location: Stockton, Ca. area
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Posted: Sat Nov 26, 2011 12:23 am Post subject: |
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Talk with Richard Troy, I used his Okrasa 1500cc with those same carbs at Bonneville 2 years ago. Ran 92 mph in my Ghia. Beautiful engine. _________________ 71 Westy Roadcow
67 Panel
63 Bug
66 Ghia Bonneville 2014
74 Ghia Vert
69 Bonneville Ghia 150 in Chico
69 Bonneville Ghia in Ireland
80 Cabby 2.1 16v
98 Passat |
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alanhall Samba Member
Joined: February 18, 2006 Posts: 115 Location: Northern California
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Posted: Sat Nov 26, 2011 12:39 am Post subject: |
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Just for comparisons the jetting used for solid shaft 40PII-4 on the 356 1600 Super 90 motor was: 115 main, 32 venturies, 57.5 idle, 1.8 idle air, 50 pump, and #25 emmulsion tube. The jetting used for the solid shaft, sand cast 40PII-4 on a 1500GS 4-cam motor was 102.5 main, 30 venturis, 50 idle, 1.5 idle air, 50 pump and #33 emmulsion tube. The sand cast 40PII-4 were similar but a somewhat different design compared to the later die cast 40PII-4 carbs. |
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oldbusboy Samba Member
Joined: June 25, 2006 Posts: 604 Location: Bowen Island, BC Canada
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Posted: Sat Nov 26, 2011 2:41 pm Post subject: |
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That motor looks awesome!
Sorry, nothing to add to the jetting question, but I'd love to see a video of that running.
Trevor _________________ 1968 porsche |
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Louis Samba Member
Joined: September 26, 2007 Posts: 423 Location: canada BC
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Posted: Sun Nov 27, 2011 2:08 am Post subject: |
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where did you get the manifold?
cheers! |
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Vintage oval Samba Member
Joined: September 13, 2004 Posts: 25 Location: Colorado
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Posted: Sun Nov 27, 2011 6:14 am Post subject: |
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I got the manifolds from Speedwell USA. |
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Jacks Samba Member
Joined: July 15, 2006 Posts: 2348 Location: San Clemente, Ca.
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Posted: Sun Nov 27, 2011 11:27 am Post subject: Re: 1500cc Okrasa |
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Vintage oval wrote: |
I'm in the Denver area and I'm thinking of using 122.5 mains, 180 air correction, 965 pilot. |
What is a 965 pilot? |
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Louis Samba Member
Joined: September 26, 2007 Posts: 423 Location: canada BC
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Posted: Mon Nov 28, 2011 12:33 pm Post subject: |
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any phone number for speedwell?
i emailed him from his website but no answer.
love those manifold... want them! |
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Louis Samba Member
Joined: September 26, 2007 Posts: 423 Location: canada BC
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Posted: Mon Nov 28, 2011 12:35 pm Post subject: |
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are those carbs too big or they work great for this motor?
anyone want a set of pbic32?
cheers! |
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gimmesomeshelter Samba Member
Joined: May 08, 2004 Posts: 1466 Location: San Carlos, CA
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Posted: Tue Nov 29, 2011 1:53 pm Post subject: |
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Hello-
Regarding your choice of ventruis, how do you want your car to drive?
Do you prefer to step on the gas at 2K and have something happen? If so, try the 28mm venturis first. If you prefer to let all the other cars pass you by until you finally reach 4K, then go with the 32mm. Given the modest duration of your cam, I suspect that the 32mm venturis may be a bit of a mismatch. Keep in mind that Pre-A Supers came with 26mm venturis for for normal driving, and used 29mm for racing.
Cheers,
Paul |
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rcraigbug Samba Member
Joined: July 12, 2004 Posts: 240
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gimmesomeshelter Samba Member
Joined: May 08, 2004 Posts: 1466 Location: San Carlos, CA
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Posted: Mon Jan 23, 2012 10:37 pm Post subject: |
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Hello-
Have you made any progress with your carbs?
Cheers,
Paul _________________ "I would rather have questions that can't be answered than answers that can't be questioned."
Richard Feynman |
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earthquake Samba Member
Joined: January 10, 2008 Posts: 3984 Location: SANDY VALLEY, NEVADA
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Posted: Tue Jan 24, 2012 12:32 am Post subject: |
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That motor is beautiful but it should be hung on a nicer stand...
Just kidding
Casey _________________ 74 CLASS 11 LOOK-A-LIKE
69 DUNE BUGGY
79 INTERNATIONAL SCOUT II
05 SCION XB SERIES RELEASE 2[#437]
95 Chevy C3500 dually
98 Ford E150
Link to Kelly J. Nolte 3/20/53 - 11/6/08
https://time-zonelabs.blogspot.com/p/about-kelly.html
DEATH TO CHINGERS!
[From a military recruitment poster in the novel "The Stainless Steel Rat" By Harry Harrison] |
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Vintage oval Samba Member
Joined: September 13, 2004 Posts: 25 Location: Colorado
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Posted: Wed Jan 25, 2012 10:27 pm Post subject: Venturs |
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Here is an update on the ventures. I am looking a drivable engine, not a race engine so I am thinking of going with 26mm ventures. These will give me around 4500 rpm limit and will give torque in the lower range which I think will make it more drivable in the city. Anyone have any experience with selecting ventures for a 1500cc engine with two dual carbs? |
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