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 Post subject: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 6:45 am 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 223
Anyone running k&n air filters on their SU carburetors? I don't believe they have the built in velocity stacks like the factory housing does. What is the effect of running these without them, anyone know?

Jay


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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 9:39 am 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12728
Location: CT
:mrgreen:

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1970 240Z


Last edited by Frank T on Fri Sep 22, 2017 2:44 pm, edited 1 time in total.

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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 9:39 am 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12728
Location: CT
SUs will run without velocity stacks, but you'll never get full performance without them. Stacks are necessary to accelerate the airflow into the area of the carb ahead of the throttle butterfly, where the idle jet is. Without them you can't get a perfect idle, nor optimum top end performance. The carbs are built to depend on a long fast airflow the whole length of the carb. You can't achieve that without stacks. I tried for several years, added a set of Bryan Little's velocity stacks inside my air filters and saw an instant performance increase. Whole engine sounded happier.

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1970 240Z


Last edited by Frank T on Fri Sep 22, 2017 9:41 am, edited 1 time in total.

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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 1:20 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 223
I was thinking that might be the case. Does Bryan still still them?

I run a stock housing but my friend runs K&Ns, and he's been having trouble holding an idle. I have been trying to get him to Vinny's for tuning and I think ultimately that's where he will end up, but as I'm thinking about his car I thought there might be an issue there.

Does Bryan still sell them?


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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 2:23 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12728
Location: CT
I don't know if he still has any or not. I bought one of his final sets and he has just recently sold his Z ( :shock: :x ) so he doesn't need any more of them. I think there might be a PARTS FOR SALE post on here somewhere; I'll try to find it.

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1970 240Z


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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 2:45 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12728
Location: CT
HERE'S BRYAN'S POST FROM ABOUT 5 YEARS AGO:
* * * * ** * * * * * * * * * * * * * * * * * ** * * * * * * * **
Datsun Z Garage
FOR SALE: sets of unique 240Z air horns

Posted: 06 Feb 2013,

(I'm making these horns available to CTZCC members before I put them on the popular big auction site)

Conventional wisdom is that a stock 240Z air cleaner flows well and needs little improvement. But several years ago I took a close look at my own stock 240Z air cleaner and saw three things that worried me.

1) At the bottom of each air horn there is a sharp crimp.
2) The rear gasket overlaps the hole.
3) The rear housing “centering” on each carb was sloppy.


Some might consider this picky. But considering how much time we spend trying to improve and our engines and enhance performance…and how sensitive SUs are to the quality of the airstream…leaving an obstacle-course like this in place didn't make sense. It seemed an easy fix…replace the stock air cleaner with a pair of K&N™ chrome filters with “full radius” air horns inside.

Image

But the only full radius pair I could find online were 50mm long…which almost touched the inner lid of the K&N™…too restrictive for me. Engine wisdom is that you should never run a sidedraft carb without an air horn as it kills the airflow…so running the K&N™’s by themselves was not an option.

Next I located some full radius SU horns sold in the UK which looked promising, until I found the rear flange only fits on British SUs…not Hitachi SUs. There were some cheap “stub stack” available but again…they only fit British SUs. So I was stumped when I realized that no one makes short full-radius, performance air horns for 240Zs.


THE SOLUTION
For those of you who know me…I don’t like running into a brick wall during a project because the right part doesn’t exist. So I contacted a U.S. manufacturer with a three-decade reputation of building air horns used in the 24 hours of Le Mans, Sebring, and Daytona. I shipped them a 1970 SU carb to use as a template asked them to custom fabricate some air horns to my specs. The result was a shipment of beautifully machined 38mm "full-radius" air horns with the correct rear flange for a 1970-72 240Z SU carburetor.

GOALS ACHIEVED

• Identical height to the stock horn.
• Nearly seamless airflow transition into the intake manifold.
• More clearance and airflow when used inside K&N™ and ITG™ 240Z air filters.
• Best of all…they can be installed into a modified 240Z stock air cleaner…replacing the stock horns to provide a stealth-induction system(!) Click here http://datsunzgarage.com/ctzcc/horns/air2013.pdf for a pdf on the process.


SMOOTH, SMOOTH AIRFLOW
Image
Image
PERFECT MATCHING! Compare this to the stock horn at the top of the page!
Image

TO SUMMARIZE
These are not cheap knockoffs or offshore toys. These horns are quality 6061-T6 aluminum alloy bar-stock spinnings made in the US exclusively for me…you won’t find these anywhere else on the planet. Detective work might clue you in on the manufacturer but don’t be fooled when you see similar models…even the manufacturer doesn’t make them in this short length.

Do they increase power? Sorry, I haven’t done a dyno comparison between these and the stock horns to make any claims. But don’t take my word for it that these are better than stock, do some reading on the effects of full radius air horns and the difference between long and short lengths and you be the judge.

PRICES
• I’m selling these for $115 a pair + $8.00 shipping. Included with each set is a new pair of properly sized rear SU gaskets sized for these horns. I only have a limited number of horn sets and once they are sold out I WON’T ’get anymore fabricated…so get ‘em while they last. First come first served. PM me through the CTZCC site to find out how to order a set using Paypal. I can only ship to the US and Canada, sorry.

• New SU gaskets. I had these fabricated overseas by an American gasket company in Asia. Made out of a fireproof material in the correct thickness. $5.00 a pair + $1.50 shipping.

Image

HORN DIMENSIONS: 38mm high, 88mm OD across the bell, and 44mm ID where it meets the carb. The outer bells have a dull matte finish and the bell interior is smoothly machined. I haven’t tried it but metal polish and/or a buffing wheel would likely give them a mirror finish.

INSTALLATION NOTE: The clearance between the bell edge and rear flange is too narrow to get a standard 8mmx16mm length bolt in. And a shorter 8mmx12mm length won’t fully engage the threads in the SU. I suggest a pair of 8mmx 25mm studs loctited in each carb with a locknut on the horn flange. Safety wiring them in would be the ultimate in security. You’ll have to decide what method works best for you as I can’t held responsible for a fastener vibrating loose.

Image

Image

_________________
Bryan Little
Datsunzgarage.com
* * * * * * * * * * * * * * * * * * ** * * * *

I DON'T KNOW HOW TO MAKE THE PHOTOS SHOW HERE. YOU CAN FIND THE ORIGINAL POST WITH PICTURES UNDER THIS FORUM, DATED FEB/2013

Frank T

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1970 240Z


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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Sep 22, 2017 5:07 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 223
Thanks Frank. I sent the information along. I got the pictures from a page on Bryan's website.

Jay


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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Oct 06, 2017 7:30 am 
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Joined: Sat Jun 01, 2013 5:38 pm
Posts: 535
Location: Orange, CT
Does anyone know if Bryan packed it in after his car sale?
I’m looking for a set of these to buy or make a copy of or a CAD file I can have them machined with.

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Nov/70 late series one HLS3014777 Sunshine Yellow 919


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 Post subject: Re: K&Ns on SUs
PostPosted: Fri Oct 06, 2017 4:23 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12728
Location: CT
No word from him for over a month. Maybe he'll show up for the picnic; Maybe not. I don't think he attended last year?

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1970 240Z


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 Post subject: Re: K&Ns on SUs
PostPosted: Sat Oct 07, 2017 7:13 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 223
I hope he does, I'd like to meet him. Would have liked to see his Z in person too.


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