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Re: Swapping out Strombergs for SUs

To: "Bruce Cairns, D.D.S." <>,
Subject: Re: Swapping out Strombergs for SUs
From: "Jack W. Drews" <>
Date: Wed, 21 Dec 2005 15:40:27 -0600
I converted my 71 to SU's early last summer. I found that they 
transformed the driving experience of the car.

It idles smoother, it comes back to the same idle speed every time I 
stop at a stop sign, and the engine winds out to redline if I want to 
rather than running out of breath at 4000, and the engine doesn't 
stop if I make a really hard corner.

It takes some fiddling with to get things right -- linkage, vacuum 
connection, choke cable hookup, and emissions hoses. None of these 
problems is insurmountable.

The only downside was the gas mileage, which was reduced from the 
high 20's to the low 20's. I attribute that to using richer needles 
(Volvo)  than were in the Strom carburetors. I just haven't fiddled 
enough with different needles to get a better balance between 
performance and mileage because I drive the car few enough miles that 
it doesn't matter to me.

Extraneous information -- after running flawlessly for several 
months, the performance started deteriorating and finally got bad 
enough that the car would hardly pull itself around the block. I 
spent most waking moments for two weeks trying to find the problem, 
doing everything imaginable. I must have overlooked something, 
though, because I finally took those carbs off and put on another set 
of HS6's, and the problem is gone but the mystery remains.

If you make this switch, you need to orient the tops of the float 
bowls of the SU's so that the float pivots are not on the sides of 
the carbs, but instead one should be at the back and one at the 
front. Otherwise you will have the same problem as with the Stroms, 
with it hiccuping on hard cornering. Having the float pivots on the 
sides causes it to go rich or lean during hard cornering, just like the Stroms.

Bottom line is I recommend the conversion.

At 02:53 PM 12/21/2005, you wrote:
>I'm contemplating replacing the 175CD Zenith-Stromberg carbs on my '74 TR6
>with HS6 SUs.  My main reason for doing so is that, as many of you might
>guess,  adjusting those blasted Strombergs is a pain and word on the street is
>that the SUs are a good deal easire to tune/balance/adjust.  Those who have
>done this conversion, please let me know if you feel it was worth it.
>Many thanks,

uncle jack 

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