#
It is currently Thu Sep 18, 2014 11:16 am


Post a new topicPost a reply Page 1 of 1   [ 9 posts ]
Author Message
 Post subject: Fitting CV carbs from a motorcycle to a car.
PostPosted: Sun Jun 01, 2014 10:54 am 

Joined: Thu Apr 24, 2014 11:00 am
Posts: 11
I was asked to do a thread about my 2t which has been converted to run on bike carburettors.
I went this route for a few reasons.

1. Im a motorcycle technition so this type of carbs are familiar to me.
2. a set of webbers with manifold to bolt up are £1000 GBP+
3. Cv carbs work well at any revs/throttle openings and help a cammy engine drive well at lower revs,also once set,dont need touching.
4.they give about the best economy of all carbs when well set up.
5. I had a set of NOS 40mm kehin carbs from a zzr100 which cost me £80.

The downside was I needed to make a manifold to fit them up. Not such a bad thing.

I dont have any pics of the process of building the manifold,but it goes like this....
I took an inlet manifold gasket as a pattern,and cut this shape from 5mm thick steel,also blocking the water outlet from the head to the manifold.The bike carbs only need heating if being used in below zero deg C temps.
I would have liked to use alloy,but i dont have access to a tig welder.
Then I made a jig to locate the position of the throats of the carbs and shaped the runners from there,from 2mm thick stainless steel bends of 38mm dia.
Silicone hose reducers join the carbs to the manifold. There is a take off on one of the runners for the brake booster. A electric fuel pump from a yamaha is ideal to supply the 3psi the carbs need. A mechanical one like the original on the car will cause flooding,as it will overcome the smaller floats. The electric bike ones can flow well at low pressure,and are pressure sensitive so shut off when the floats are full. You can blank off the fuel return.
Then you need to fit up a throttle cable and choke cable.
Obviously a 1600cc car engine(ive got the 2t)will pull a bit more air each stroke than a bike,so you will need to tune the fuelling. Many bike carbs have needles which can be raised or lowered to adjust midrange fuelling. The lower range/idle fuelling is done by the mixture screws,and full load is controlled by the main jet. Stock jets are usually in the 1.6 mm range. I took them to 2mm (which will probably be rich) and dyno from there.
I used a ramair filter kit,which comes with a blank 1mm thick backing plate and you cut it to fit the type of carbs/bodies you have.
I know they are not entirely period correct,but they just work.

Here are the piccs i do have.

Manifold with vac take off for brake booster.

Image

Test fitting

Image

Fitting air filter backing plate to remaining part of the bikes airbox. The trumpets remain inside the filter.

Image

And all fitted.

Image


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Mon Jun 02, 2014 6:21 am 

Joined: Wed Apr 11, 2012 1:43 pm
Posts: 22
Location: Portugal
nice job!
it was a 2T-B engine? or single carb?

_________________
Image


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Mon Jun 02, 2014 6:45 am 
User avatar

Joined: Sat Feb 05, 2011 5:53 pm
Posts: 316
Location: Bay Area, California
Terrific!

Have you driven the car yet?


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Wed Jun 04, 2014 5:02 pm 

Joined: Wed Oct 22, 2008 5:33 pm
Posts: 96
Location: Manila, Philippines
Cool! How does it run? No issues at all? I want to do this on my 4af engine


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Thu Jun 05, 2014 10:06 am 

Joined: Thu Apr 24, 2014 11:00 am
Posts: 11
Yea it runs great. Id reccomend the conversion to anyone. It just takes a bit of care and knowledge of the carb tuning and there should be no probs. Like every thing its about the setting up.
You need to install the carbs at the same angle they would be mounted on the bike,to get the floats shutting off correctly. You need a good manifold with no leaks,correct fuel pump and a dynojet kit or similar to tune them .Thats it.


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Thu Jun 05, 2014 10:08 am 

Joined: Thu Apr 24, 2014 11:00 am
Posts: 11
CCoelhone wrote:
nice job!
it was a 2T-B engine? or single carb?


It was a single carb. 5speed . :D


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Thu Jun 19, 2014 1:53 pm 
User avatar

Joined: Mon Jul 15, 2013 7:11 am
Posts: 64
Not to sound like a certain British Top Gear presenter, but what would make more power? CV or DCOE carbs?

POWAAAAAAAAAAHHHH, hehe.

_________________
Real men have "carbs"


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Thu Jun 19, 2014 4:42 pm 
User avatar

Joined: Tue Oct 02, 2012 4:06 pm
Posts: 3
Have done the same with my 2TC but running a set of 93 CBR900rr carbs with a Dynojet kit (Highly recomend made engine run way better!!!!). have been running this setup for about a year, made my manifold from a exhaust header off of a Dodge. Also made a manifold set for a 68 Datsun Roadster with a 2L he has a set of CBR1000 carbs on his with a Dynojet kit. The roadster has a big lobed cam, he was running side draft carbs that came stock on the car, very loppy and ran rough. after we put the set of motorcycle carbs drafted to the side, car ran 100% better idled like it came off of the factory floor purrrrrr.......

thanks,


Top
 Profile  
 
 Post subject: Re: Fitting CV carbs from a motorcycle to a car.
PostPosted: Sun Jun 22, 2014 10:23 am 

Joined: Thu Apr 24, 2014 11:00 am
Posts: 11
Gene wrote:
Not to sound like a certain British Top Gear presenter, but what would make more power? CV or DCOE carbs?

POWAAAAAAAAAAHHHH, hehe.





Neither will make more power, assuming throat size is the same IE 40mm.
The CV carbs benefit you by only opening dependent on engine demand, so you get no bogging down if you open the throttle too quickly. There is no accelerator pump to deal with.
Being from a bike which has a cam to manage from 1000 rpm to 12000 rpm, means they work particularly well on a road car with a lumpy cam,adding driveability lower down.
Yes you'll need to re-jet (or dynojet)


Top
 Profile  
 
Display posts from previous:  Sort by  
Post a new topicPost a reply Page 1 of 1   [ 9 posts ]


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  


Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
610nm Style by Daniel St. Jules of Gamexe.net