Holley: Rocking ratio of 50cc pump arm -VS- 30cc. - Team Camaro Tech
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post #1 of 11 (permalink) Old Dec 26th, 08, 12:37 PM Thread Starter
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Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

As I keep buying and selling Holley carbs, I keep swapping out parts for my dual Holley 450's on my tunnel ram. I want to run the 50cc pump arms because they look so beefy and cool. What I'm wondering is if the arms have the same profile (rocking ratio) as the 30cc arms or are they different? I do realize that the 50cc setups have a different pump cam....just didn't know if the arms are different too or that they would work fine on a 30cc pump housing? Thanks!


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post #2 of 11 (permalink) Old Dec 26th, 08, 02:53 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

dubs, I'm pissed right now!.....I answered your question and it got deleted!
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post #3 of 11 (permalink) Old Dec 26th, 08, 03:37 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

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dubs, I'm pissed right now!.....I answered your question and it got deleted!
You also solicited him for parts which is something you have been around long enough to know not to do and every time you start a new topic there is a reminder of... No reason to get mad, follow the guidlines, post over and PM your parts request...

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post #4 of 11 (permalink) Old Dec 28th, 08, 10:56 AM Thread Starter
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

I guess I missed that one Ron. I did find out that they are the same though. PM me if you had a question.


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post #5 of 11 (permalink) Old Dec 28th, 08, 12:13 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

I was thinking of changing the 30 cc on the front of my carb to a 50 cc any thoughts on this one....

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post #6 of 11 (permalink) Old Dec 28th, 08, 02:22 PM Thread Starter
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

Are you talking about just the arm or the actually housing? I think it would depend on your combo. Just remember....most carbs with a 50cc pump have them on the rear and not the front. That would be a ton of gas, especially on a street driven motor. You would be better off to at least start by testing different pump cams and squirter sizes before swapping to the 50cc setup. It can give you a real "lazy" throttle with too much gas. What makes you want to throw around changing in the first place?


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post #7 of 11 (permalink) Old Dec 28th, 08, 02:35 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

Quote:
Originally Posted by dubs68camaro View Post
Are you talking about just the arm or the actually housing? I think it would depend on your combo. Just remember....most carbs with a 50cc pump have them on the rear and not the front. That would be a ton of gas, especially on a street driven motor. You would be better off to at least start by testing different pump cams and squirter sizes before swapping to the 50cc setup. It can give you a real "lazy" throttle with too much gas. What makes you want to throw around changing in the first place?
A buddy of mine tightened the spring and it helped some but did not fix it totaly it still has some hesitation when you slap the throtle.Do you think if I change the arm it will help...

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post #8 of 11 (permalink) Old Dec 28th, 08, 02:48 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

I ran a 50cc on an 800 that I had years ago, throttle was terrible until I figured out it was the pump volume and ratio, even with cam swaps it never fixed it. Dropped back to the 30cc on the front and 50cc on rear and it worked great. I wouldn't suggesst running the 50 on the front, there is no reason to do this! Go with what has worked for decads...the 30cc on the front and try the 50 on the rear if you want.
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post #9 of 11 (permalink) Old Dec 28th, 08, 02:58 PM Thread Starter
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

In other words.........+1

LOL


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post #10 of 11 (permalink) Old Dec 28th, 08, 03:50 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

I replaced the 50cc rear one with a 30cc setup on my 850 Holley (454 engine). The 50cc for most people isn't necessary.
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post #11 of 11 (permalink) Old Dec 28th, 08, 05:21 PM
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Re: Holley: Rocking ratio of 50cc pump arm -VS- 30cc.

Quote:
Originally Posted by david calligan View Post
A buddy of mine tightened the spring and it helped some but did not fix it totaly it still has some hesitation when you slap the throtle.Do you think if I change the arm it will help...
Anytime the main system is starting late with an oversized carb..the transient will need to be crutched with a bigger pump shot.How you attain that is vehicle specific.There is no one size fits all fix.It could be the spark curve,valve timing events,looser converter etc etc.There is one given tho imo..if peak HP is not your ultimate goal.the smaller the carb that satifies your performance needs will deliver better driveability,crisper throttle and usually an increase in mpg to boot.For a street deal..you need 2 carbs.One on the car for cruising and one on the bench for saturday night grudge matches.
fwiw..I like primary reo pumps atop big roots blowers.Once again..vehicle specific.

George
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