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Old 06-30-2006, 08:51 AM   #4
Les, slight limp
Board Member
Join Date: Sep 2005
Location: clayhanger, uk

The 2 groove head i did was supposed to be text book somender singh, 1 groove pointed at the plug from the squish area aligned between the valves, i had a spare k-jet head that was no use to me so used it for test purposes, i tried a couple of powered ways of cutting the first groove with varying degrees of disaster, hence the triangular file, i realise it cut the grooves a couple of mm to wide at the top, the file is far bigger than i'd recomend a fit person to use but because it was large it meant i could slowly do the job myself, there seemed to be a sizeable squish area alongside the plug and on reflection decided to put a smaller one there as well, no scientific basis for it at all, it just looked right, a quick rub with a brass brush and on it went, i didn't even clean the plugs, if the grooves were going to work they'd do it in spite of me, not because of me.

First impressions were pretty underwhelming, what you don't realise is that you can now drive your car like a diesel but it takes a while before your brain registers the fact that 30 mph in 5th is quite normal for a grooved head, just the job for pootling around in traffic, that's one of the problems with it, your car won't sound the same or drive the same, it's much much smoother, it's quieter and sounds more like a six than a four, the volvo harshness has gone, it's somehow more refined.

I couldn't get it to ping/knock even at 30 degrees advance, i had to advance it that far with the engine running to get it to start, the kick back is wicked anything past around 23 degrees, we finally had some 90 degree weather and i got a slight low ve ping at 30 degrees, obviously i only advanced it that far to test knock prevention.

I had to lean the carb out after doing the grooves to get the tickover down, this made no difference to the actual running of the engine, the carb was brand new when i bought it 6 months ago and had new jets etc for a 2.3 as it was off a b18/b19?, i'd estimate, and i've run the grooves a good while now that fuel economy is up 10% at least.

My wife likes it, i'm in the process of teaching her to drive, the grooves make it virtually stall proof, great for a nervous learner or a bloke with a gammy leg.

the grooves actually call for having the c/r raised or turning the boost up to realise the full benefits, all my tests were done on 95 ron unleaded, i think thats about equivalent to 88 ish american, it's normal supermarket piss anyway nothing special.

Tickover = idle, there is no idle adjustment left on the carb so the only way i can get it down is by leaning the mixture.

95 ron is the europe wide standard for ordinary petrol, 98 ron is the better stuff and the race petrol is about 110 but thats also leaded.

Last edited by Les, slight limp; 06-30-2006 at 06:12 PM..
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