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crank ventilation effects on mixture

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Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Good to know, and most helpful! Thanks. I may as well remove that as well...maybe venting to atmosphere and blocking ports on the carbs will kill two birds with one stone, so to speak!

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Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Any advice regarding my previous question about choke versus needle size? If pulling the choke at cruising speed doesn't improve the running, would changing the needle possibly make a difference? (Do they function in different ways?)

RAORR Robert Orr
Ridgeville, IN, USA   USA
1953 MG TD
1967 MG MGB
Hi Peer. I have not read every post on this thread. Has anyone suggested points bounce? I had this on my 67B. I reset the points and problem gone. I was clued in by a search on this site. Might be worth a try.

Hope you find the problem.
Bob Orr

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Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Hi Bob. I investigated this in the past. Three distributors later I think I can rule it out. Running one of Jeff's now.

pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3657321 by Poundingsand Any advice regarding my previous question about choke versus needle size? If pulling the choke at cruising speed doesn't improve the running, would changing the needle possibly make a difference? (Do they function in different ways?)

I suspect you are lean at light throttle which can be caused by a vacuum leak, weak dashpot springs or incorrect needles.

What happens when you pull the choke out while the engine is surging? Does it get better or worse?

Adrian



Home built Eaton M62 Supercharger with 9psi boost, "stock" high ratio rocker arms, 8:1 compression, Piper 270 cam, ported head, matched manifolds, CB Performance computerized ignition.

Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Adrian, I will test it again today...doing valve lash now. But as I recall it didn't make a difference in the past.

Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Okay folks. Spent the morning adjusting valves. Number 1 was slightly tight, rest were good. Next was dialing the carbs a little richer and checking timing after warm up. Idle was around 15btdc. Drove it and had lag. Just for giggles I dialed in a little more advance while checking dor linking.

Back to the freeway, and it feels a lot better. I actually passed a few cars at around 78mph. (Although its pretty slow to get there) so freeway now feels pretty good. However at idle its running rough and hunting and smells rich. Acceleration feels about the same...

Time to check needle sizes??? Other suggestions?



Edited 1 time(s). Last edit at 2018-01-06 01:32 PM by Poundingsand.

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Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Hoping for some feedback. Pulled the carbs apart. Needles are AAC. Springs no idea what color. Pics attached. One spring is 5" and the front carb spring is 4 3\4 uncompressed...

Jets seem super low...around 3-4 mm...


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ice Avatar
ice Gold Member Larry Ice
Lawrenceville, GA, USA   USA
Is one spring thicker than the other? Maybe just an illusion? Springs are supposed to be same dia. and length



Iceman

Atlanta GA

60 AH MK1
62 AH MKII
67 Midget
71 Midget

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Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Hey Larry. In the pic they are sitting next to a ruler. One is definitely longer than the other.

What color springs should I have? And any thoughts on my jet size?

Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
They seem the same thickness. With carbs mounted and air cleaners off when I push the pistons up and let them go they drop at the same rate.. Also just checked compression warm. All cylinders are 155-165.

I think I need to try different needles. Hope someone can advise.

ice Avatar
ice Gold Member Larry Ice
Lawrenceville, GA, USA   USA
Actually, I meant wire size that make up the spring, are they the same? Different wire size would cause problems trying to synch the dampers.

Sorry, never messed much with different configurations of needles. For most purposes, I don't think you can go wrong with the stock needles. I would keep everything with the carbs stock or you will soon find yourself nit picking results. Again, look to the plugs to tell you what is going on inside the engine. Go run it some and relook the plugs.



Iceman

Atlanta GA

60 AH MK1
62 AH MKII
67 Midget
71 Midget

pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3657560 by Poundingsand They seem the same thickness. With carbs mounted and air cleaners off when I push the pistons up and let them go they drop at the same rate.. Also just checked compression warm. All cylinders are 155-165.

I think I need to try different needles. Hope someone can advise.

I wouldn't bother... unless a Google search indicated they were the wrong ones. Lowering the jets will make the mixture richer. So will stronger springs. You can find a procedure to check the "weight" of the springs online. Find out the model of your carbs and then you can determine which needles and springs are correct for your year.

Adrian



Home built Eaton M62 Supercharger with 9psi boost, "stock" high ratio rocker arms, 8:1 compression, Piper 270 cam, ported head, matched manifolds, CB Performance computerized ignition.

Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Hi Larry. Caught that after I read your post. They seem same wire thickness just different lengths.

Adrian, the carbs are AUD404s. Not sure of the springs. The issue is I run rich on the bottom end and lean on the top. Adjusting for one screws up the other.

On the other hand maybe i am asking for more than these cars usually give???? I just want a decent freeway cruising speed. Haha

Poundingsand Avatar
Poundingsand Silver Member Peer Ebbighausen
Los Angeles, CA, USA   USA
Adrian, also my jets are currently about 3mm below the bridge in the carb throat...seems excessive no?

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