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Sun Apr 29, 2012 10:53 am

Hello i have a 74 with the stock SVDA dist. and I am wanting to put a Harley CV 40 on it but I think that the vac signal that the carb will give will be too much and start advancing the timing too early. Is there any way to alter the Vac. pot on the dist. or to be able to change the signal for the dist. any help would be great.

Sun Apr 29, 2012 11:34 am

you can run direct manifold vacuum,the vacuum control on the SVDA is mainly for emission control.

Sun Apr 29, 2012 3:48 pm

johnnypan wrote: you can run direct manifold vacuum,the vacuum control on the SVDA is mainly for emission control.

Bad advaice.

Sun Apr 29, 2012 5:23 pm

Put a 009 on it . I love that carb I have it on my suzuki samurai it was the best thing I ever did . Tho only bad thing is u have to get the fuel pressure rite I still haven't when it idles it pisses out fuel .

Sun Apr 29, 2012 7:45 pm

mabie just putting a small jet inline with the vacuume source would be close to stock signal

Sun Apr 29, 2012 7:55 pm

Don't do it little cyclone. Incorrect vacuum signature. If you were going to use any distributor, use a 019.

What is wrong with the carb you have anyway? Why do you think you need a Harley carb?

Sun Apr 29, 2012 9:36 pm

I work on Harleys for a living at Des Moines and just b/c i want to. I already had a dual setup on it with the stock manifolds which was a bit of overkill but it was cool to fiddle with it and play with the setup. I took a stock T manifold and had my shipping and recieving guy alter it from a down draft to a side draft and i just have to get a flange adapter which fits perfect. I love this Kehin CV way easy to tune and parts are plentyful. I dont think anything is wrong with my sock carb but it is a bit of a pita to deal with and if in the future i want to do some more mods the cv can handle it no prob.

Sun Apr 29, 2012 9:42 pm

Let me know if you do it . I had a lil problem with the air filter set up but a lil rigging and it was all good .

Mon Apr 30, 2012 8:19 am

joelyons50023 wrote: I work on Harleys for a living at Des Moines and just b/c i want to. I already had a dual setup on it with the stock manifolds which was a bit of overkill but it was cool to fiddle with it and play with the setup. I took a stock T manifold and had my shipping and recieving guy alter it from a down draft to a side draft and i just have to get a flange adapter which fits perfect. I love this Kehin CV way easy to tune and parts are plentyful. I dont think anything is wrong with my sock carb but it is a bit of a pita to deal with and if in the future i want to do some more mods the cv can handle it no prob.

Sounds like fun. Just remember that the flow will be different going from a mechanical to a CV. So that 40 will flow less, thats why S&S carbs are so popular. Duel cv forty's will still flow much better than a stock carb :lol: . I'd go with a thunder slide kit as well.

Mon Apr 30, 2012 2:09 pm

Quote: just b/c i want to

Works for me. I would use a 019 distriburtor though, as opoposed to the stock SVDA, as then the vacuum signature of the carb won't matter.

Mon Apr 30, 2012 4:46 pm

joelyons50023 wrote: I work on Harleys for a living at Des Moines and just b/c i want to. I already had a dual setup on it with the stock manifolds which was a bit of overkill but it was cool to fiddle with it and play with the setup. I took a stock T manifold and had my shipping and recieving guy alter it from a down draft to a side draft and i just have to get a flange adapter which fits perfect. I love this Kehin CV way easy to tune and parts are plentyful. I dont think anything is wrong with my sock carb but it is a bit of a pita to deal with and if in the future i want to do some more mods the cv can handle it no prob.

Randys right that the SVDA wont react the same,with direct manifold vacuum it advances and retards faster but only for the ten degrees or so that the vacuum controls...I ran an SVDA with dual weber ICT's,taking the vacuum signal from the equalizer tube (direct manifold vacuum from both sides)..drivability was great.

Mon Apr 30, 2012 7:45 pm

Quote: thats why S&S carbs are so popular
Well they were popular with the guys that didnt know any better but thats another story. Im not worried about the overall flow or the possible loss of top end power i just want ease of tunning. With the dual CV 40s the low end was kind of sluggish (Expected) but not a huge inprovement in overall power. The jetting could have been off a bit also. Has no one found a vac diaphram that would work "in place of stock" with the manifold vac. like may other setups use? Or I could tap into the vac. signal that raises the slide possibly. would have to see what the reading is at idle and around 3krpm.

"All you need is a ported vacuum source ("ported" means the vacuum is coming from right above the throttle plate); do NOT run this to manifold or venturi vacuum!. Ported vacuum is 0 vacuum at idle, and 15-25" of vacuum at 3000 RPM and 1/8 - 1/2 throttle." From Mallorys website.

Mon Apr 30, 2012 8:12 pm

Easy fix then. Just use a digital manometer to calibrate the vaccum. K&L supply sells fittings that lower vaccum for use with the old mercury manometers. Or as others have suggested use a mechanical advance distributor.

You keep going back to ease of tuning. HD uses standard threads while the big four from Japan use metric. I'm in the biz and I at least have a much easyer time getting metric jets, even come in half sizes. Cheaper too.

Tue May 01, 2012 5:02 am

Quote: You keep going back to ease of tuning. HD uses standard threads while the big four from Japan use metric. I'm in the biz and I at least have a much easyer time getting metric jets, even come in half sizes. Cheaper too.

Kehin is a carb made in Japan for Harley has been since the early 80s.
I work at a Harley dealer as a tech so i have a few jets laying around. Finding jets is not a problem. I have 3 CV carbs as it is.

Tue May 01, 2012 6:49 am

Keep us posted on your progress!. Im interested in hearing how this works out- I also have a 40mm CV Carb laying around not doing anything.

Tue May 01, 2012 11:11 am

I love my S&S Super "B" on my '73 Shovel Bobber...... :D :D :D 1st kick starting........ :!: :!:

Tue May 01, 2012 3:26 pm

joelyons50023 wrote: Quote: You keep going back to ease of tuning. HD uses standard threads while the big four from Japan use metric. I'm in the biz and I at least have a much easyer time getting metric jets, even come in half sizes. Cheaper too.

Kehin is a carb made in Japan for Harley has been since the early 80s.
I work at a Harley dealer as a tech so i have a few jets laying around. Finding jets is not a problem. I have 3 CV carbs as it is.

I know, they still use a different tread. If you have enough jets to tune with then no worries. I forget if the HD 40 has a ajustable accelorator pump. Running 2 should give you enough to keep from having a issue.

Tue May 01, 2012 5:28 pm

im going with only one carb, when i had 2 of them it was a bit sluggish a CV 40 will supply the 1600 just fine.

Tue May 01, 2012 6:11 pm

How does it run with the one? If you have a problems with throttle response increase the volume of the accelarator pump chamber. Works great on dirt bikes after engine work.

Wed May 02, 2012 6:35 am

can you post some pics of your setup? i'd like to see how you managed the intake manifold and how the carb sets on it.
thanks!