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650 double pumper on 289?

M

Mustangfeverrr

Member
I'm thinking about finally upgrading my '66 C-code, A/T coupe (with 3.00 gears) to a 4-barrel.
I know that about 500 to maybe 600 cfm is optimal for a 289, but I've got a nearly-new Holley 650 double-pumper that I was thinking about tossing on with an Edelbrock intake. This would probably be the only performance mod made, with the exception of maybe some K-code exhaust manifolds.
Is the 650 really going to be too much carb? Can it be made to work well by jetting down, or...? Is anybody else running this with good results, or is it really just plain ol' not worth the time???
 
With 3.00 gears and an auto, I'd stay away from the double-pumper. It'll bog like crazy if you floor it from a stop (and probably a roll too.) If it were a 650 with vacuum secondaries, I'd say go for it.
 
I'm currently running a 750 DP on Shag's Cleveland and I'm really considering down sizing to a 650 with vacumn Secondary. DP's are gas guzzlers.
 
"cmayna" said:
I'm currently running a 750 DP on Shag's Cleveland and I'm really considering down sizing to a 650 with vacumn Secondary. DP's are gas guzzlers.
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Same here. I have a 700 (I think or maybe its a 750) DP on Gert and she sucks a lot of gas.
 
"monkeystash" said:
With 3.00 gears and an auto, I'd stay away from the double-pumper. It'll bog like crazy if you floor it from a stop (and probably a roll too.) If it were a 650 with vacuum secondaries, I'd say go for it.
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I had the same issue with my double pumper. I switch to vacuum secondaries and it fixed my bog!
 
I have a 650DP on my 289 and it SCREAMS[nb]when it's actually running[/nb] BUT....my engine is built for higher rpm and wfo operation. I would agree with others that you don't need it for your application.
 
I have a 600DP and I purchased a 600 with vac. secondaries to put on mine after I find some shorter throttle linkage. Glad to know it should make a difference.
 
"65fast" said:
6t6 Let me know if you want to get rid of your old 600!
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Will do. The carb is missing the choke plate and shaft. I removed it when I had this engine in my 85 GT that I raced. Jegs has the linkage that I need for the other carb but I keep forgetting to order it.
 
"apollard" said:
You can remember that long ago?
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My buddy's built '66 289 fastback bogged down with a double-pumper...yikes, that was high school...1986 or 1987. I had a Holley 600 secondary vacuum, which he switched to, and he had no complaints.
 
I had a 66 coupe with a 289 in it in 1980. I was running a 4 spd and the engine was very nicely built. It routinely ran in races up to about 7500 - 8000 rpm. No fooling!

Anyway, it ran some pretty high compression and some radical cam, topped off with a single 4V tunnel ram. On that was a nice 850 double pumper. It ran hard and fast! Well, for the times. I have stuff under the hood right now that is close to how it ran.

Now, at the time I had many friends into racing and they all told me the TR and 850 was too much, until I kicked there butts on the track! So, many here will tell you the 650 is too big and a gas guzzler. I say depends on your setup.

In the old days when I ran that, I took the 850 off and bought a 650. I slapped the 650 on there and the car ran noticeably slower! It did however run without making your eyes water!

I think that now I have a different setup and the rpms aren't nearly as high, but the 600 Edlebrock on both my cars is just awesome! When I took the Holley (600 vacuum Secondaries) off the 65 and put the Edlebrock carb on, it just bolted up and the car had much more seat of the pants off the line and much more top end.

So, take all our advice and digest it and then buy a carb. If you like it great, if not get rid of it and get a different one. I like what I read about the Summit carb...

HTH,

Mel
 
"guruatbol" said:
Now, at the time I had many friends into racing and they all told me the TR and 850 was too much, until I kicked there butts on the track! So, many here will tell you the 650 is too big and a gas guzzler. I say depends on your setup.
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For street driving your friends were right. For the track though you made it perfect :)
 
back when I had our blown 66 running I ran two 600 dp that where blue printed for our altitude here with a mild cam and 68 302 heads & boss 302 block heads with chevy valves and adjustable top end and a 3:50 rear gear and a 4spd with a 2:78 first gear had no problems ran like a champ it even got 11 mpg on the hyway..I would say a 650 would be just alittle to much inless you had some race heads and cam then maybe..
 
Carbs are all about compromise.

If you go too big they work great at 6,500 rpm but suck on the street. Too small and they work great on the street but you sacrifice top end power.

A nominally hopped up 289 will work great with a 500cfm carb.
 
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