Flatspots after fitting K&N filter

Rolling road time, Owen in Abingdons supposed to be quite good but the only person I know who went there was running efi & throttle body per cylinder.

Typical of a Holley on a Rover V-8. Go back to SUs, or fit the Vitesse injection. A new airfilter ain't going to make any difference to the idle speed, unless the old one was blocked solid.

Did the old filter have a hot air pick-up and the new one not? Could have a bit of carb icing-up here.

-- r

Not as far as I could tell, it's a pancake (ring) filter sitting directly on top of the carb. Both took air in from the engine bay. There's a breather pipe from the odd-numbered cylender bank stuck in the bottom of the filter housing, but that's all.

Thats because unlike a fool injected car, a carb can't compensate without manual adjustment/re-jetting.

Put the old filter back on, book a session at a rolling road and take the new filter plus car and get it set up properly.

The message from James Dore contains these words:

Ah, in technical parlance, you've "Buggered it up". I'd put it all back like it was and see if it behaves.

Hah, yes! Bit of a toss-up really, as with the old filter it's a sod to start and keep running initially, and doesn't go as well when warm as the warmed up k&n. I've no idea how long that filter had been on the car, as it came with it so I suspect it was well past it.

I have a free saturday morning, so will investiagte further.

I got given an unused Colourtune kit, if that's likely to be any use - however having never used one, I'm somewhat apprehensive of buggering it further :-D

Cheers,

James Dore wrote in news: snipped-for-privacy@news.ox.ac.uk:

I've got a couple of K and N's on my TR7V8 (running 2 x SU carb's). It starts and runs perfectly on and off choke. The only problem with them is the noise on part throttle, you can hear the air getting sucked into the engine. Sounds a bit like a turbo! I think you need the carb(s) on your car fettled with. I bet it's quite hard to find a rolling road run by someone who actually knows how to tune carb's now a days. The previous owner had the carb's set-up on a rolling road some 5 years ago and I hope to never have to touch them.

Good luck,

Will

Yep - I spoke to Owens in Abingdon as suggested earlier and they do this, but their guy is on holiday next week. Pitstop up in Brize Norton also do rolling road tuning, and the guy I spoke to there was well into it. He did caution that it wouldn't be possible to do outright performance tuning (darn :-), due to the difficulties of keeping the engine cool while on the rolling road, but could smooth it out for driveability. It seems like it's well worth doing anyway, as much for knowing it's set up well.

Your noise issue doesn't sound like a problem to me!!

Cheers,

Well, yes, but that's SUs for you.

Tuning a fixed venturi carb(s) isn't just a case of adjusting a screw or two. It will involve jet selection - and even drilling holes to get the progression right. If you want it work properly. If all you want is maximum power at full throttle than it's quite easy. But getting it run properly throughout the range is a different matter.