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MG MGB Technical - HIF with K&Ns tuning question

Maybe this is a silly question but I am looking at the instructions I have for tuning my HIFs. I am using the Autobooks version as the Haynes one annoys me since it keeps referring you back to the HS tuning bits and saying it is much the same, only different. According to the instructions I do the whole procedure with the air filters off which makes sense to me. I am wondering then why is it when you fit K&Ns do people sometimes need to change needles? I always though it was because the K&Ns breathe better but surely with the filters off altogether you get the best breathing possible?

Les, I know you said you didn't need to change yours. I am hoping that's the case for me too!

Simon
Simon Jansen

Simon. I hope so, too. Roger Parker recommended the AAA needles to me many years ago and it is the best running combination for where I live. When going in for emissions testing, I need to run a slightly leaner set of needles to pass the tests. But, since performance is not as good, they come out of the carbs when I return from the testing.

Personally, I am not convinced that K&N filters are any better than the stock filters for the average hobbyist. But, they do look neat and mine are already paid for.

Les
Les Bengtson

"Personally, I am not convinced that K&N filters are any better than the stock filters for the average hobbyist. But, they do look neat and mine are already paid for."

Yep, that's my situation. I have them already and they look cool. Have no idea if they will make the car perform better though! I heard they improve the throttle response a bit even if they don't add any noticable power.
Simon Jansen

The nicest thing about K&Ns I found was the induction roar, and the fact you can reuse them.
dave

When I removed the filter cans from my 74 B several years ago I used standard paper filters with home fabricated adapters to convert them to open filters. The engine seemed to have a little better response and felt like it had a little more power. I used AAA needles in my HIF-4's after removing the filter cans. I didn't notice any change when I switched to K & N filters a few months later. I have also tried K & N stock replacement filters in a 99 Nissan pickup and a 2002 Mazda Protege 5. The K & N filters didn't improve fuel mileage and I didn't notice any difference in power in either vehicle compared to the stock paper filters. This is a seat of pants feel and not very scientific. A dyno test may show a slight difference, but dyno's don't drive engines in everyday traffic.

FWIW, Clifton
Clifton Gordon

Yes, I agree, but, if you put paper air filter to an cosworth engine he don't work, with K&N filter so much.
Regards
michel

Joe Curto in NY rebuilt my HF-4 carburetors last year (good work) and recommended the K&N conical filters to fit my 1980 MGB. He also said he fit richer needles to match the K&N filters. Now, I'm having trouble adjusting the carburetors; they run rich. I'm slowly leaning them out to get the right color spark plug burn, but it's going slow with just a little change per adjustment. The car runs very well with good power, but rich. Also, the gas mileage at around 20 mpg is not what I'm used to. Any recommendations? Do I need different needles?

Chuck
Chuck Hassler

You may need different needles, or there may be a problem with your ignition system. If the spark isn't hot enough or properly timed, it will run rich. Maybe advance your timing (if you can without pinking) and try the old needles?
Jeff Schlemmer

Thank Jeff,

I'll try the timing advance first. I have a pertronix with a sports coil, so the spark should be hot. The timing is at 13 before on this 1980 engine rebuilt to specs 10,000 miles ago. If the timing change doesn't work, I'll go back to factory needles for the 1973 HF-4 carburetors.

Chuck
Chuck Hassler

This thread was discussed between 14/02/2006 and 15/02/2006

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