View Full Version : Throttle

Trevor Triumph
08-09-2004, 07:30 PM
We installed a 1296 engine in our MKI Spitfire. I transferred the needles from the 1296 engine to the 1147 HS2s. According to Victoria British the carbs and jets are the same for each car but the needles are different. The car starts well but immediately goes to what sounds like full throttle in stead of idle. As near as I can tell the throttle plates are closed. Any thoughts? We've been with out a running Brit car since the middle of April and we are getting eager to drive the car. T.T.

08-10-2004, 12:04 AM
I probably should stay out of this as I know nothing of these carbs, but maybe I can offer encouragement until some real help logs on. It does seem to me though that if the butterflys are closed that the engine would have to be drawing air from some place to rev up. Good Luck and take heart as I'm sure you are close to a solution.

08-10-2004, 03:35 AM
Hello Trevor,
I take it no work has been done on the carburettors except for changing the needles?. I would ensure that the throttles are fully closed, especially that the choke fast idle screw is clear of the cam. You can get a very high engine speed on no load with relatively small throttle openings. It may only be one carburettor that is the culprit, so you can block each air intake in turn to find out if that is the case.


Simon TR4a
08-10-2004, 12:32 PM
Agree with both of the above, since it's a new installation check that no cables are kinked, back off the throttle stop screws, check the manifold is mating against the head properly with no leaks.
Remove air cleaners and see that pistons are dropping all the way.
Even if the needles are wrong that will only create a mixture problem, not what you describe.

Trevor Triumph
08-11-2004, 03:45 PM
Thanks for your help. Part of the problem went away when I shortened the return springs connecting the throttle to the manifold. Now the throttle plates slam shut completely. The engine idle speed dropped to under two thousand RPM. I think between the timing and carb adjustment I think I can the engine to behave correctly. Thanks again. T.T.

Trevor Triumph
08-14-2004, 07:43 PM
The engine/ carb thing is settled but the will be off the road again due to bearing noise. On start up it often sound like our Austin diesel. Looks like bearing all around. DARN!! T.T.

08-14-2004, 10:03 PM
Double Darn, but don't be discouraged. I was able to put main and rod bearings in my TR7 myself, but had waited too long and the crank was already ruined. The Spit may be even easier to do than the 7. For sure when you do get your car on the road it will have been worth it. Good Luck

08-17-2004, 12:10 AM
That 1300 is getting hard to come by so take good care of that crank(the racers use them up pretty quickly), get it done right.
MD(mad dog)