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MG MGA - Can't get full throtle with Hif

Hi All.
I have fitted a pair of 1 1/2 HIFs to my 1860cc B engined A Coupe. I replaced the HS4s from the 1600 A engine but now can't get full throttle with the gas pedal.Any ideas where the problem may lay?
s page

Hi S
do you mean you cant get full power?

Or do you mean that the throttle butterflies are not opening fully?

Take the fuel filters off and take a look into the carb venturis to see if the butterflies are wide open when the pedal is pushed fully down.

If they are not, then there is problem with the accellerator cable or the linkage adjustment.

If the butterflies are wide open then you have probably got a fuel flow or fuel mixture problem.

It could be that the ignition timing is very retarded but I would check the carbs first.

Colyn Firth

I just spotted this on Facebook, may be useful for you.

There is a lot of info there.

Colyn Firth

Sorry I wrote the post in a hurry and I new what I meant. The problem is with the newly fitted HIFs when the the throttle pedal is fully depressed the butterfly are not fully open. I have taken off the bottom pedal stop which made some difference I understand there is a top stop as well but I have been otherwise engaged.The question might be do the HIFS need more pedal travel than the HS4s due to different ratios of lever lengths on the throttle spindle on the carbs.
s page

Not absolutely certain, but I think the answer is yes. I believe the MGB throttle pedal had a longer output arm for more cable travel. But I don't have one handy for measurement.

I assume you still have the MGA accelerator cable setup even though you are using HS4 carbs. Here’s a John Twist video that may help.

JL Cheatham

This thread was discussed between 26/11/2017 and 28/11/2017

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