Jet height on an hif38

linearaudio · Post by **linearaudio** » Sun Aug 09, 2009 9:21 pm

I can get my head round setting the jet x turns down from level on an HS2, as the jet outer ring is level with the top of the annular section. On the HIF38 the jet outer ring itself sits lower than the "bridge". Is the x turns counted from having the jet flush with the top of the outer ring, or flush with the bridge, in which case 2 turns down brings it level with the top of the ring? As the needle I am working with(ADP) is so far out, I am a bit lost! Yes I will get a AAA needle when I get a minute, just trying to clear this up in my head!

Post by **bmcecosse** » Sun Aug 09, 2009 11:08 pm

Can't say I've looked LA - but having fitted a 3 branch exhaust to mine just in the last few days - with AAA needle in place - I've had to enrichen the idle mix quite a bit -actually as far as it goes - to get it to pick-up nicely. It was probably on the weak side before anyway. Of course needle makes no odds at idle - they are all the same in that area. If I get a minute later this week - i'll take the bell off and have a look - because I want to find out why I've had to wind it up so far!

linearaudio · Post by **linearaudio** » Sun Aug 09, 2009 11:19 pm

Three branch exhaust?? You're getting a bit trendy there! My twisted snake header system is working fine, but having problems with the exhaust getting sucked back in. Must experiment with different exit angles, and sort mixture out, and sort the overdrive box out, and re-connect the heater loop to improve the head circulation.....

Post by **bmcecosse** » Mon Aug 10, 2009 6:56 am

Exhaust sucked back in - to the interior ? I find running with one of the rear windows open slightly + one quarter light open on my Trav stops that. Or at least - if it is sucked in, it's quickly sucked back out! I certainly suggest it's better to have the heater in circulation.
Overdrive - well ....... Actually was looking yesterday at my mate's spare MGB gearbox -with o/d - and it's quite compact !

linearaudio · Post by **linearaudio** » Mon Aug 10, 2009 8:07 am

bmcecosse wrote:Exhaust sucked back in - to the interior ? I find running with one of the rear windows open slightly + one quarter light open on my Trav stops that. Or at least - if it is sucked in, it's quickly sucked back out! I certainly suggest it's better to have the heater in circulation.
Overdrive - well ....... Actually was looking yesterday at my mate's spare MGB gearbox -with o/d - and it's quite compact !

Ahh-Haah!! Now you're coming around! With the Triumph bellhousing it is a much more manageable beast than the Marina monstrosity! All I have to tackle is shifting the starter motor position through 180 degrees to miss the exhaust and I'll be there! Gear lever will come about 2" forward so maybe won't clout the handbrake any more, output flange area just about level with rear of moggy box, 8 1/2" clutch means I won't get "power slip" accelerating from 80 any more!

Curiously, opening rear n/s window makes mine worse, though the quarter light by itself certainly helps. Maybe I ought to get the fuelling somewhere near first, but my thought was that if the aerodynamics are sucking exhaust in, then with a lousy mixture at least I am getting a better "nose" tell-tale of any alterations I make to the exit point. I notice the original exhaust drooped at the back, maybe this was deliberate, not just naff pipe bending. However, a droopy 1 7/8" chromey tailpipe won't look all that...