tr7triumph.com

I currently have a tubular manifold K&N pancakes and bal needles
now i know if you just have the tubular manifold i would'nt need bal needles
but i may put the original filter box back on if i do
i will probably get rectangular K&N filter for it.

My question is... Will i need to revert back to the original needles as the new filter will be flowing much more freely



http://mytr7.weebly.com/

What will dictate the needle requirement gaz, is the quality of the air filter you use. The K&N filter will probably require the BAL needles.

I had to use BAL needles in a stock 7, with a stock exhaust, when I used Ramflo air filters, which are extremely free flowing.

Hasbeen

There are two parts to getting air/fuel through the engine. One is getting the mixture into the engine, free flowing air filter like K&N (you can fine tune this by porting intake manifold). Once it's in the engine you have to get it out. This is more important as the hot exhaust gases have a bigger volume than the cool air going in. This is best done by a tuned tubular exhaust (equal length tubes resulting in a spaghetti looking arrangement). A 4 to 2 to 1 arrangement gives better mid range than a 4 to 1 arrangement which is better for high rev range. The design of the tubes and where/how they join creates a reverse shock wave that can help extract the exhaust hence the name "tuned" exhaust. Doing just one of these things gives a fractional increase as just as you want less restriction of mixture going in you also need less restriction of the large volume of the exhaust going out. A free flowing "sports" exhaust is also needed after the header to continue the low restriction. This free flowing air path needs the carb needles that can supply the fuel to keep up with the 14 to 1 ratio desired, the BAL needles can do this.

As the rectangular K&N filter will be free flowing you shouldn't have to change needles. The difference in air flow between pancakes and the air box itself would be marginal I would think.


- - - - TR7 Spider - - - - - - - - 1978 Spitfire - - - - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - - Yellow TCT

There's only one way to find out, well two;
• Check the car's set up an a rolling road;
• Find someone knowledgeable who can set up the carburettors without a rolling road.
Everything else will be a complete waste of time and money [}:)]

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<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
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[quote]<i>Originally posted by Beans</i>

There's only one way to find out, well two;
• Check the car's set up an a rolling road;
• Find someone knowledgeable who can set up the carburettors without a rolling road.
Everything else will be a complete waste of time and money [}:)]
/quote]

I hear that. Rolling roads are scarce as hen's teeth here on the island but a friend knew somebody that has one so set his Spitfire up on one to the point where he sandpapered a spot on the needles to get rid of a flat spot (too lean) at a specific rpm range. Probably wouldn't pay if you had to pay for the rolling road time. Somebody in the club said they were pretty expensive here.


- - - - TR7 Spider - - - - - - - - 1978 Spitfire - - - - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - - Yellow TCT