1300 engine

[Doebag]

Hi, without wishing to double post, I have started a thread about my 1200 Herald [Sorry, link no longer available]

At the moment it has a late 1300 Dolomite engine and single rail gearbox fitted. An O/D or 5 speed conversion is planned, but is the conversion from the single 1 1/2" SU carburettor to twin 1 1/4" [as in 1300 spitfire ] worthwhile. I am guessing twin 1 1/2" would be overkill for a 1300 engine

[Toledo Man]

I presume you're referring to HS4s. This conversion is worth doing. I've done it on my Dolomite 1300 and I also used the Dolomite 1500 exhaust because the bore is slightly larger and the manifolds are matched to each other.

[Nick Jones]

If you are not doing anything else to the engine I'd stick with the single 1.5" SU.  You'll not see any performance improvement except at very high rpm.  Low speed running and economy will be better with the single.

I did back to back trials with a highly tuned 1300, 1 x 1.5" SU, vs. 2 x 1.25" SU, vs. 2 x 1.5" SU.  Really not alot of difference between the first two and the 2 x 1.5" only showed benefits over 5,500 rpm ish.  That particular engine revved to 7000.....

Nick

[Doebag]

Nick
that is the answer I was kind of expecting. I do not intend any engine mods, just the O/D or 5 speed alteration with 3.89 diff if needed.

[Casper]

http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl?m-1339360948/