Thursday, June 08, 2006


Went into Wales today to see the engineers for the CV spacers.

Used the opportunity to test various settings.... and filled my diff with oil before coming back!

I am slowly dialling into to perfection all over the rpm range, but its a slow process, took me months on the other engine.

Advanced it up a but more again its near max, but might take a bit more 1-1.5deg total - sound as a pound, i'll try and make it knock tomorrow. One thing at a time! Its very vocal with near max advance. I like to get a feel for everything.

I thought the 33 pumps where going on too long there was a gargle noise after about 1second from punching the pedal, fitted 35's and the pickup was much improved as bigger pumps DONT increase fuel level, they dump the same fuel over shorter period, as such punch improved. I leave the pump jet tuning till the very end or when its feeling near good, I will try 38 for a short aggressive pump delivery next...I can then adjust the quanity up or down on the rod and arm mech...and go back down on the jets till it stumbles, go back up a touch and your in the zone.

Found what where great jets last night a bit lean in the heat today was boiling but it ran nicely?! Must be red hot inlet manifolds stealing fuel via burning it off on the way into the ports...Fixed that engine was still a bit rough.

I am gonna make an airbox, but I dont want any restriction in punch so it will be twice the size of the holbay box I had before and painted white to reflect heat.

Moved to BPR8ES plugs tonite seem to have given a smoother flavour, 7 a bit rough? hard to say- but they foul a touch low down due the idle jet issue I will describe in a moment when the jetting is improved further they will be best I think , I gapped them to 1mm which seems better than 0.7mm, smoother and more effiicent feeling...I had my old engine on 1.2-1.3mm gaps or something (have to check my blog!). Its the best its been so far.

I now need to wait for some 120 and 130 air correctors to try tomorrow evening.

At the moment I am on 50idle and 7850.7 holder which is a very rich holder, this is due to the 140 correctors on the 6 tube making the mains a little late in operation they only kick off at 3750-4000rpm or so...As such I am struggling to stretch the idle/progression out to meet the mains without it going a tad rich as from 1000-1500rpm, Lotus used 50 idle and 7 holder on a 2.2L 907 engine!!! My mains are way too retarded.

I hope with 130 or even 120 correctors the mains operate from 2800-3000, I can then drop the main jet size to 115-118-120 or 122? to account for its earlier placement in starting point and rpm range and squeeze the same fuel as used atm over a greater range with a small corrector...Correctors dont just control high rpm mix, they control start point on the mains too - Then I can reduce the idle holder to .1 which gives best off idle mix as seen before...I had it sweet as a nut from 1000-2000 on the 1 holder but have to make concessions as I cannot stretch a 48idle over the required range pon any holder really......

These carbs are crazy, you can tune them a million ways, your result is only as good as bloke doing the work, I aim for a certain style of driving feel, 10 setups will give the same mixture range its just about how it gives power and how it drives....150 correctors make it piss weak in the middle....I like my mains on early and active. Thw way forward is clear.

As such I gave up for now. Jets here tomorrow. When I get the mains on earlier it should liven up the mid range a bit and make the engine take off easier, atm the 6 tube only really operates when you are high into the revs and TPS. It drives well no doubt but I'd like to be more active and cure the off idle fouling a bit...

Lovely weather, half the people who passed me on the lanes tonite stopped to ask if I was ok, if your there in winter no-one stops, if only we had weather like this all the time Britain would be a much nicer place.

No comments: