MGB and HIF44 SU Hesitation

[jdhorton]

Hi All-
77 MGB- Replaced my ZS carb with a Moss SU HIF44 carb. I have serious hesitation on acceleration, but excellent running at higher RPM's. Idle is smooth. Has anyone had a similar experience?
Any help is greatly appreciated. (THANKS!)

[rick_ingram]

I ran an HIF6 from an Austin Marina (similar to the HIF44) for several years on my MGB. I used a BBQ needle...which do you have?

[DrEntropy]

Where's Eric when we need him. [img]/bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif[/img]

[jdhorton]

Hi-
Thanks for the info. This is a Moss item. Do not know what needle came with it. Anyone familiar with their offering?
Thanks, Jim

[DrEntropy]

Another thought: what oil are you using in the damper?

... and check the needle for starters.

[jdhorton]

I'm using Castrol 20W-50 in the damper. 'She' runs well (very) with the choke out partially. I adjusted the idle screw (on the choke linkage)to maintain correct idle speed. Should I be able to read the needle ID by withdrawing the piston with the piston intact, or will I need to remove he needle? (That may be and ""idle"" question, since I will pursue the needle ID whatever is required...) Thanks, Jim~

[Dave Russell]

I used a BBQ needle...

Is that like a spit as used on an outdoor grill?
D

[rick_ingram]

I used a BBQ needle...

Is that like a spit as used on an outdoor grill?
D

Well...it's too large for a Spitfire...and doubt if it would be very useful in a Weber.

[img]/bcforum/images/%%GRAEMLIN_URL%%/cheers.gif[/img]

[DrEntropy]

I'm using Castrol 20W-50 in the damper. 'She' runs well (very) with the choke out partially. I adjusted the idle screw (on the choke linkage)to maintain correct idle speed. Should I be able to read the needle ID by withdrawing the piston with the piston intact, or will I need to remove he needle? (That may be and ""idle"" question, since I will pursue the needle ID whatever is required...) Thanks, Jim~

Needle needs to be removed from the piston to read the "I.D." BUT!!! You just hinted that the choke plays into this. You MAY find that just enrichening the mixture will sort the problem. Locate the HIF mixture screw (a "shrouded" cross-hatch one, in a bore on the side) and run it in a quarter-turn. Drive the beast and note the changes.

I can't recall if "in" (clockwise) or "out" (counter-clockwise) is the richer... I *think* the "in" is the enrichment. Hopefully a more post-emissions familiar member will pap up and define it more accurately.

[jdhorton]

Many thanks to DrEntropy for the good advice on the enrichment adjustment on the HIF44. While it did take considerably more turns than anticipated, the "in" (clockwise) adjustment does, indeed, result in a richer mixture. The B is running very well and I am still making fine tuning decisions almost daily. Very pleased with the operation and response of the HIF44, and I'm glad that I decided to give it a chance.
If anyone knows of an SU (or other) publication/manual containing (more) complete details of the HIF44, I will greatly appreciate the name of the pub(!). I'm sure that I should learn more about the setup and tuning as soon as possible.

Thanks again for your help DrEntropy :O).