datsun-roadsters
[Top] [All Lists]

Re: Solexes

To: "Datsun Roadster Mailing list" <datsun-roadsters@autox.team.net>
Subject: Re: Solexes
From: Ronnie Day <ronday@home.com>
Date: Thu, 12 Apr 2001 12:05:42 -0500
>Ah, the old debate between Solexes and SUs kick up again. I have driven a 
>solex car and an SU car. I think that both types of carbs will give great 
>performance, but each is designed for a different application.

>Vic Laury let me drive his SU car and I felt it had every bit as much power 
>as my solex car until it got into the 5k plus range. The solexes pull all 
>the way to redline and I have yet to see an SU car do that. Consequently, 
>the SUs offer better accelaration through the lower gears, while the solexes 
>have "dead zones" until you climb over 2500 to 3000 RPM. Once in that range, 
>the solexes roar to life.

As I've often stated, for cars that are street driven regularly, IMHO SUs 
usually offer snappier performance everywhere except at higher RPM. I 
also would be willing to bet that many dual throat sidedraft setups don't 
work as well as they could because the carbs aren't in good condition, 
aren't set up and jetted properly or both.

There's much about the way SUs work that make them forgiving and almost 
self adjusting, whereas tuning the Solex/Weber style carbs can be tricky. 
I wonder how many folks know how or are willing to take the time to do it 
right? First the mechanical condition of the carbs and the float levels 
have to be right. No amount of fiddling with jets will compensate for 
problems in those areas. And the linkage has to be working properly, too. 
Then you can start worrying about jetting. Of course these same things 
need to be right with SUs, too.

My point? I recently came across a booklet on Weber jetting that I 
learned a lot from. The booklet is actually the tuning guide for a Weber 
jet block that's designed to be used on Holley 4 barrels with removable 
float bowls. A good portion is devoted to jetting. The basic concept is 
that you tune from the bottom up and it makes a lot of sense after you've 
read through the process since each successive circuit builds on those 
below it in the RPM range. Done right there shouldn't be any holes in the 
acceleration curve, certainly not big ones. Makes sense to me. The 
procedure includes step by step instructions and symptom charts as 
guides. 

I scanned the booklet and am in the process of recreating it as a Word 
file. If anyone wants a copy, email me directly and I'll send it when 
it's finished. Should be done in a week or so. If there are a large 
number of requests, I'll find a way to post it for D/L since the 
listserve strips attachments.

FWIW, Ron

Ronnie Day
ronday@home.com
Dallas/Ft. Worth
'71 510 2-dr (Prepared Class Autocrosser)
'73 510 2-dr (Street Toy)

<Prev in Thread] Current Thread [Next in Thread>