650 double pumper on 289?

[Mustangfeverrr]

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???

[monkeystash]

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. 

[cmayna]

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.

[Kats66Pny]

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.

Same here. I have a 700 (I think or maybe its a 750) DP on Gert and she sucks a lot of gas.

[janschutz]

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 had the same issue with my double pumper.  I switch to vacuum secondaries and it fixed my bog!

[Mustangfeverrr]

OK, thanks guys. Kind of confirmed my initial opinion.

[silverblueBP]

I have a 650DP on my 289 and it SCREAMS[1] 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.

1.	when it's actually running

[6t6red]

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]

6t6 Let me know if you want to get rid of your old 600!

[6t6red]

6t6 Let me know if you want to get rid of your old 600!

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]

I have a 650DP on my 289 and it SCREAMS[1]

1.	when it's actually running

You can remember that long ago?

[silverblueBP]

 



No, but I do watch the videos to remind me.

[70_Fastback]

You can remember that long ago?

HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!
HA  HA  HA !!!

[silverblueBP]

hater

[AzNick]

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.

[guruatbol]

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

[pprince]

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.

For street driving your friends were right. For the track though you made it perfect :)

[guruatbol]

For street driving your friends were right. For the track though you made it perfect :)

The heck of it was, it was my daily driver too!

Mel

[blown66]

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..

[pprince]

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.

[whisperer]

This is just my opinion, but Holley 4150/4160s are very much misunderstood. What is the List Number on your 4150 650 DP? There are a few oddballs out there but the 650 and 600s typically share a common main body, both of which have a 1-1/4 primary and 1-5/16 secondary venturi. The main difference in the carbs is the base plates, the 600s having 1-9/16 throttle plates on primary and secondary, and the 650s having 1-11/16 on primary and secondary. You can make one into the other by changing the base plates so instead of selling your 650 and buying a 600 just buy a 600DP base plate if you are so inclined. That said, changing the size of the base plates will have little effect until you run out of CFM capability at top end. Changing the size of the venturi will indeed have a strong effect on lower RPM performance. A smaller venturi will pull harder at low RPMs but will run out of capability at higher RPMs, and visa-versa.
  The rest is just tuning that you will have to do with any carb. Something to remember is that a smaller carb (venturi) takes a smaller set of main jets to achieve the same mixture on a particular engine. It doesn't mean you use less fuel, it just means that the CFM requirement of the engine is the same at a given RPM, and the velocity through a smaller venturi is higher and "pulls harder" on the fuel through the main jets. (Smaller venturi, higher vacuum signal).
  It's very important on a 4150/4160 to get the power valve sized correctly for the engine. On a near-stock 289 you will have plenty of fuel on a DPDF 600/650 4150 as long as the pump shots are timed correctly. I'd start with 125-65 or possibly 125-50. These will operate when the vacuum signal drops BELOW 6.5 in. or 5.0 in. respectively. (125-65 = 6.5 in., 125-50 = 5 in. and so on.)
 If it was mine I would just bolt on the 650 with a 125-50 power valve and probably install down-leg boosters in the primaries and install 65s and 75s main jets to start. Then it's just tuning from there.........