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PMO jetting on 3.0 S cams

Hi guys,

does anybody of you have any advices what jets I might use for this setup?

3.0 engine with 10.3 cr, S cams, twin plug, headers

I know thatīs not the perfect choice but the carbs are 40 PMO. I donīt have 46 for now so I need to make the 40 work.
The venturis are 36mm, I have F11 emulsion tubes. It would be great if I can keep those. The jets currently are 55 idle, 155 mains and 190 airs and itīs running way to lean. Can someone give me a direction?

Many thanks Malte

Old 04-29-2017, 04:49 AM
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Carburetor Jets

Quote:
Originally Posted by MaRu View Post
... itīs running way to lean. Can someone give me a direction?
Many thanks Malte
Malte - where is it lean (lower RPM, upper or throughout)?
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Old 04-29-2017, 06:43 PM
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I would disagree. 40mm PMOs are ideal for that setup.

Velocity is where you'll make the power. 46mm are best suited to 3.2 and up

Are you sure it's lean? You'd have plenty of fuel with that combination.

If even step down to 145 main jets.

RR



Quote:
Originally Posted by MaRu View Post
Hi guys,

does anybody of you have any advices what jets I might use for this setup?

3.0 engine with 10.3 cr, S cams, twin plug, headers

I know thatīs not the perfect choice but the carbs are 40 PMO. I donīt have 46 for now so I need to make the 40 work.
The venturis are 36mm, I have F11 emulsion tubes. It would be great if I can keep those. The jets currently are 55 idle, 155 mains and 190 airs and itīs running way to lean. Can someone give me a direction?

Many thanks Malte
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Old 04-29-2017, 07:09 PM
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What's the symptom that makes you believe it's too lean? And under what conditions (RPM, load, etc.)?
Old 04-30-2017, 04:42 AM
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You need to do some dyno runs at PT & WOT to see where its lean and precisely by how much.
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Old 04-30-2017, 07:29 AM
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Thank you very much, and I am sorry for the later answer!
I havenīt checked it with my laptop with AFR readings yet because I am working at the suspension and canīt drive the car . With a CO reader I am good at idle (3,4 %), but as soon I raise the rpm it goes down to0,5% CO and partly starts backfiring. But when all of you say it shouldnīt be that bad for starting I will finish the suspension check AFR while driving and if this seem to be good I will go to a dyno shop

Old 05-01-2017, 11:44 PM
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