High flow 1 Series (big window valve) for alcohol. Available sizes include: 2.5, 3.5, 4.5, 5.5, 6.5, 8.5, 10.5 in hg. For example 427125-145, 427125-135 etc.

Application

Tech Tip:

Engine vacuum will hold the valve closed until vacuum drops below the cracking point, measured in inches of mercury (in hg) at which time, the valve will open and enrich the fuel mix.

It is quite common to put very low numbers in multi carb systems. The reason is that if standard single carb valves are used, it will cause the engine to be overly rich. When you are at a part throttle cruise at 55 mph (say, with a 12 in hg of manifold vacuum) and you squeeze into the throttle to go up a hill or pass a car, the manifold vacuum drops (say, down to 7 in hg) and all three power valves open. Normally, this will make the engine soggy & rich, since it has three times the fuel enrichment that it needs.

People will put in the lower power valves to delay the enrichment until nearly Wide Open Throttle. At WOT, the engine can normally consume the additional fuel without puffing black smoke or fouling plugs. The problem with putting -45 power valves in, is that it defeats the purpose of a power enrichment system. The enrichment system is designed to provide a slight increase in fuel flow as power requirements increase. If you install -45 power valves and they do not open until WOT, you lose the benefit of adding just a little bit of fuel when you squeeze the throttle a little.

A better way is to put power valve plugs (or very low numbers) in the front and rear carbs and use a standard power valve in the center carb. The best way is to put restrictors (PVCR or power valve channel restriction, which are small lengths of stainless steel piano wire) in all three carbs, which limits the amount of fuel that is added, not when it is added.

CA WARNING:

Can expose you to lead, a carcinogen and reproductive toxicant. See www.P65Warnings.ca.gov

Specifications

KEY SPECS
MFG. Part #	125-65
Brand	Holley

GENERAL
GTIN Code	Select Size to see
Primary Stage Opening Vacuum	Select Size to see
Sold in Quantity	Each

Ratings & Reviews

4.8

20 Reviews

Overall Assessment

Customers find the product to be of great quality and value for the price. It's consistently described as functioning well for various applications, from street rods to race track cars, highlighting its wide usability. Many users would buy it again, indicating high satisfaction. The product is easy to work with and enhances the power performance of the vehicles. However, fitting issues were reported with a specific model, and the lack of included gasket was a drawback. Generally, customers prefer our product due to its quality, practicality, and affordability compared to others.

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4.8

20 reviews

Most Liked Positive Review

5.0

I definitely will shop here again !

I found out that I needed a different size power valve. I shopped and went with Speedway as I have many times before . I got it super quick and was very satisfied .

Most Liked Negative Review

1.0

Didn't fit my Holley 94 7rt

This item wouldn't bolt in fully. Stuck out too far and wouldn't seat properly. Feared ruining the threads in the carb so did not force the power valve into the seat. Also, how cheap can they get? No gasket provided with the valve. Would cost me as much as my refund by shipping it back to speedway, so I'll just keep it and write it off as a $10 loss. No big deal.

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Needs correct jets and power valve

5.0

9 months ago

Greenville Tx

Verified

Tuning a 350 holley carburetor

Would Recommend

Holley quality!

5.0

9 months ago

Timm

Avondale

Verified

Holley quality! Consistanly top notch!

Would Recommend

i would buy again

5.0

a year ago

evilrado

lincoln ne

Verified

part of owning a carb

Would Recommend

I would purchase this valve again

5.0

a year ago

dbhenryj

k3 illinois

Verified

Speedway motors always have the parts I need to keep my Hot Rod on the road.

Would Recommend

holley power valves

5.0

2 years ago

Flathead

K3 ILL

Verified

the holley power valves work better than some of the other brands

Would Recommend

easy install

5.0

2 years ago

Bob

Verified

good product, out with the old, in with the new, just about that fast

Would Recommend

yes I would buy again

5.0

3 years ago

oldschool

Hastings NE.

Verified

used in my street rod

Would Recommend

great product and great price

5.0

4 years ago

Bob

Fontana

Verified

great service and great product

Would Recommend

I would buy again

5.0

4 years ago

Heath

Verified

Worked as should

Would Recommend

I would buy this again.

5.0

5 years ago

1939ford

Kearney, Nebraska

Verified

Used on a dirt race track car

Would Recommend

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Questions & Answers

2 Questions • 2 Answers

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These will fit a holley 4150 correct?

by Laine

• 9 years ago

1 answer

View Answer

Are these ethanol proof. Thanks Dane

by Okie

• 11 years ago

1 answer

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