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Shag's 3rd carb already? - WTF?

cmayna

cmayna

DILLIGARA?
Donator
That's right dweebs, I just finished installing and doing a test run on Shag's 3rd Holley.

History:
1st carb - 750DP (no choke) - A major gas guzzler
2nd carb - 650DP (no choke)- Little better mileage but it was a bear to warm up in the mornings. Besides, it was one of those shinny ones with just didn't look right for the green turd.
3rd carb - 650 vacumm secondaries with electric choke - Now this one I like !! Hopefully I can put this carb issue away. Test drive tomorrow to JeffTepper's abode.



:thu
4-040211120630.jpeg
 
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Craig,
In my younger days i had an XA GT coupe, (an OZ Torino), 351, Hi flow 2H sig erson cam, Weiand Xcellerator, 600 Double pumper, twin point mallory dissy, toploader, 3.25 gears.
Over 11 years i mucked around with a few carbs but i always came back to that 600.
I agree that overcarbing causes more problems than anything else.
Steve
 
Come over to my house!! I am home and want mote details I may follow your lead on this one.
 
hmmm... that looks nice. I was getting ready to pull the trigger on a silver Holley Street Avenger 670 for my chebbie. Aside from the color and 20 cfm difference, I wonder if there is any major design or performance differences between the two. I do like how the 650 you have looks more period correct.
 
Yeah that shinny stuff was just a little too much and we all know how much we stare at our carbs on a daily basis.

:thu

Another reason why I went with the 650 is because it has a dual inlet which the car was already setup for that.

But no matter what happens, these carbs are a very easy plug and play. One day I might try a 600 but for now I want
to give this 650 a try.
 
I have a 770 Street Avenger on my 429 and it's 10 years old now. No problems with it. Very reliable and I averaged 16 mpg on the Power Tour with a 2.79 rear gear and no OD. I think vacuum secondaries make better street carbs because if the engine don't need it they don't open.
 
"cmayna" said:
That's right dweebs, I just finished installing and doing a test run on Shag's 3rd Holley.

History:
1st carb - 750DP (no choke) - A major gas guzzler
2nd carb - 650DP (no choke)- Little better mileage but it was a bear to warm up in the mornings. Besides, it was one of those shinny ones with just didn't look right for the green turd.
3rd carb - 650 vacumm secondaries with electric choke - Now this one I like !! Hopefully I can put this carb issue away. Test drive tomorrow to JeffTepper's abode.



:thu
4-040211120630.jpeg
Click to expand...

Ok Craig, I have had nothing but trouble with the Holley carbs built after 1985. So I have switched to the Edlebrock and have never looked back. For the street they are wonderful and work awesome on both Captain America and Ed.

I think if you do some searching on here and VMF you will find that Johnpro agreed with me.

Mel
 
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This is a hi-jack but, on topic.

I went with the original 650 Holley for my car but, it has an electric choke as well. I am still working on the wiring on my car and was wondering where did you tap for the choke lead?
 
"GTchris" said:
This is a hi-jack but, on topic.

I went with the original 650 Holley for my car but, it has an electric choke as well. I am still working on the wiring on my car and was wondering where did you tap for the choke lead?
Click to expand...

A 12 volt source when turning the ignition key is good.
Don't take it from the plus on the ignition coil !!!!
Maybe you can take it from the trans wiring harness??
Or a seperate wire from the fusebox. :confu
 
I got one too... got it at Advanced Auto Parts... 369.99 online, but if you enter P20 in for a promo code, it comes down to 295.95. Print out the order form, and they'll match the price at the local store too.

What brand feed line are you guys using? It seems like there are a few choices and some don't fit right if i recall correctly...
 
I might be stirring up a hornet's nest here... and I do agree that it is a bad thing to over carb an engine... :char

But I have a pet peeve with the combination of the carb sizing equations and the math of marketing.

If you use the supplied equations, and adjust for volumetric efficiency you will get an airflow requirement - but here is the catch - that is airflow at wide open throttle where ideally you should have close to zero manifold vacuum. Keep this in mind...

Now for the marketing math... every carb manufacturer I know measures CFM for 4 barrel carbs at 1.5 inches of vacuum for historical reasons. If your car has 1.5 inches of vacuum at wide open throttle your carburetor is acting as a restriction! If you do the math, you will find that a 800 CFM carb measured at 1.5 inches of vacuum is really about a 630 CFM carb at 0 inches of vacuum.

If you go by the supplied equations above and do not account for the "marketing" flow numbers, I guarantee you are leaving power on the table. :hs

I'm not saying that it is good to over carb an engine and I admit most street cars don't see prolonged wide open throttle operation; but if you are going to use equations, be sure all the terms match...

Good luck,
-Rory
 
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