Hi,
I was going to finish this swap and write an article to hopefully be
published in Spitfire & GT6, but I'll go ahead and give you some
details. I considered converting to HS4s, but I live in an emissions
state and one of the top 10 worst air cities in the US, (Raleigh-Durham
NC). So I decided to undertake a swap that would allow me to keep my
emissions intact. The swap has gone fairly well so far and I hope to
have it completed and running this weekend. I am using an HIF6 that I
got from Mini-mania rebuilt on sale at $159.00. My car is a '79, but I
used a large flange '76 manifold to mount the carb. The '76 has a large
square flange which allows 2 new stud holes to be drilled and tapped,I'm
only going to use 2 studs to mount the carb. The inlet was bored to
1.75 in. and the hole in the top of the manifold was drilled and tapped
13/16 by 14 threads per inch, to accomadate the brass elbow that the
U-shaped EGR pipe screws into. I did some testing before hand to get a
baseline. Currently my car with the Stromberg and all the emissions
will run 0 - 60 in about 13.5 seconds and 30 - 60 in third gear in an
average of 9 seconds. I have a '76 high compression engine with a street
cam installed. Once the installation is complete I will test it again
and let everyone know the results. My only concern is getting the
needle in the right ballpark. I have two approaches that I am going to
try with that. The first is to use a very lean needle and the
colourtune plug and measure the height of the piston at different rpm
and file the needle to richen the mixture as necessary at that poin (the
car would be up on blocks and I am going to try to load the engine using
the emergency brake, The only problem I have is that I doubt that I can
get the piston to rise more than 3/4 of the way before I hit 6000 rpm.
My second Idea is to use the needle recommended for a similar sized
engine with the same carb as shown in the back of the weber manual, for
example there are a couple of Austins listed I beleive that are about
1700 cc that use a single HIF 6. Also several people use a single HIF 6
on A - series engines (1275 cc) in different states of tune. By
comparing these to the Stromberg needle that I have now (BIDL) I
hopefully can guesstimate a good starting point. Any SU gurus that have
recommendations please chime in.
Glenn Trunnell
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