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Holley 670 SA or 750 3310 on 340? #259552
03/19/09 09:48 PM
03/19/09 09:48 PM
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Snowing in the north!
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Dart 340 Offline OP
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Have a 340 that is stock with the exception of
some stock head work, air gap RPM manifold and
performer rpm cam. Have been running a 750 3310
for the last year but got a great deal on a street
avenger 670 and was thinking that might be a better
carb for what I have. The Dart is also a 4 speed.

Thoughts and experiences?

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259553
03/19/09 09:57 PM
03/19/09 09:57 PM
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Crizila Offline
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I wouldn't switch. Gonna be hard to beat that 3310 with your combo.


Fastest 300
Re: Holley 670 SA or 750 3310 on 340? [Re: Crizila] #259554
03/19/09 10:10 PM
03/19/09 10:10 PM
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Dart 340 Offline OP
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Will I get better throttle response and vacuum with
the 670 vs the 750? My rear gears are 3:23's with
14" wheels. I've always had a little "dead spot" off the punch with the 750 but maybe I just need
a different squirter for the acc pump.

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259555
03/19/09 10:20 PM
03/19/09 10:20 PM
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landon1 Offline
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i'd go with a 670...i have a 650 on my 440 b/c that's what holley recommends for my engine size and max rpm (5K on a 440) and it's perfect imo

but, if it's all good, i'd leave it alone

Re: Holley 670 SA or 750 3310 on 340? [Re: landon1] #259556
03/19/09 11:49 PM
03/19/09 11:49 PM
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Dart 340 Offline OP
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for my 340 they show for 6K and under the 670 and
for 6500 and up the 750. I know the 670 has jets in
the secondaries instead of the plate.

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259557
03/20/09 07:01 AM
03/20/09 07:01 AM
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Bethel Ct
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AdamR Offline
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You have it, may as well try it.

I believe the Street avengers are also flowed different then the older 4150s and the 670 flows more then 700 cfms.

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259558
03/20/09 08:01 AM
03/20/09 08:01 AM
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dgc333 Offline
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Quote:


Have been running a 750 3310
for the last year but got a great deal on a street
avenger 670 and was thinking that might be a bettercarb for what I have. The Dart is also a 4 speed.





I have a 360 that is producing approximately 370 HP. I have had both a 3310 750 and a 670 Street Avenger on it (as well as a 600 Holley and a 725 Demon).

I have a self imposed 6000 rpm redline and up to that point the butt dyno can not tell a difference between the 670 and 750. BUT, the throttle reponse and below 3000 rpm driveability with the 670 is dramtically better. Plus the 670 gives my 5 mpg more than the 750.

The 670 is wet flow rated compared to the 750 so if it had been dry flow like the 750 it would be more like a low 700 cfm rating. Also, if you look down into the venturis of the 670 you will notice that the primaries are smaller than the secondaries (even though the throttle blades are all the same size). This accounts for the excellent low rpm driveability.

The 670 is staying on the engine until the day I decide to go EFI.


Dave Clement Pembroke, MA 03 PT Cruiser GT Turbo 99 Dakota SLT+ CC 4x4 68 Barracuda sport coupe http://home.comcast.net/~dgc333/
Re: Holley 670 SA or 750 3310 on 340? [Re: dgc333] #259559
03/20/09 08:26 AM
03/20/09 08:26 AM
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Posts: 1,195
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Dart 340 Offline OP
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Dave,

Thanks, that is really good information.

I spend weeks tweaking the 750 last year to get
it to the point it worked well, but it still has
a little dead area on the bottom end. I was hoping
the 670 might give me better low end response.

Thinking I will start tweaking on the 670 and see
what I can get her to do.

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259560
03/20/09 08:35 AM
03/20/09 08:35 AM
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Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
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dead spot usually = lean. Try bumping the the jets or swapping out your PV.

http://www.automedia.com/Building_The_Ultimate_750_Holley_3310/pht200011017h/1

Re: Holley 670 SA or 750 3310 on 340? [Re: Mr.Yuck] #259561
03/20/09 08:43 AM
03/20/09 08:43 AM
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Dart 340 Offline OP
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She's almost an eye burner now at idle, and my plugs are at least brown.... changed the PV about 4
times last fall. I have a 4.5 in there now running
at 9 InHg vacuum. I was thinking maybe the acc pump
squirters might be the culprit?

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259562
03/20/09 08:59 AM
03/20/09 08:59 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
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what squitters are in there now? I had 28's in my 750HP series. The 31's were too big

Re: Holley 670 SA or 750 3310 on 340? [Re: Mr.Yuck] #259563
03/20/09 09:16 AM
03/20/09 09:16 AM
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Snowing in the north!
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Dart 340 Offline OP
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I actually think they are 34's ....

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259564
03/20/09 09:45 AM
03/20/09 09:45 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
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Quote:

I actually think they are 34's ....



wow toooo big. drop them down

Re: Holley 670 SA or 750 3310 on 340? [Re: Mr.Yuck] #259565
03/20/09 10:36 AM
03/20/09 10:36 AM
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Indiana
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YO7_A66 Offline
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Dart 340:
The size of the squirter affects how fast (in relation with the pump cam) the gas will be delivered into the carb. If you are testing with the same cam (as it appears that you are) and no other changes, a "031" squirter will deliver "more fuel faster" than a "025" squirter with the same pump cam. As 72 stated in your other post, your street 340 will like more rpms. A street 340 with its short stroke will not like a large squirter dumping allot of fuel at lower rpms.
What pump cam are you using?
Note: Holley pump cams from smallest cc to largest cc for 30cc pump (black, pink, white, red, green, orange and then the blue is the largest). The pump cams are fun to test with because you can feel the difference after swapping one out. For reference, if you start with a pink one and then install a blue one, you can definately feel the difference in the throttle at lower "cruising" speeds. The blue one might be too much for off idle in a mild sb, but for cruise testing you can feel the difference.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: Holley 670 SA or 750 3310 on 340? [Re: YO7_A66] #259566
03/20/09 11:31 AM
03/20/09 11:31 AM
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Crizila Offline
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You could use a little steeper gear with your set up - maybe in the 3.55 range. Better seat-of-the pants feel ( typical with a smaller carb )doesn't always equate to better over-all performance. Ran a very similar engine set up to yours ( except 360 motor ) with a 3310 in a 4,000 plus pound automatic car and got it to run low 12.70's. Extending the squirter time ( longer duration ) helped for me. I also set the primary float level a little higher ( top of the sight glass ). Also went with a quick fuel secondary plate so I could change jetting easily. Can't remember for sure, but I don't think I deviated much from the stock jetting - maybe 2 sizes richer on both sides. Are you still using the stock sec vacuum spring? I think it is plain steel in color. I believe the stock PV was a 6.5 on that carb. Stick with it if you are idling at 9" - seems a little low? Don't know how fast your advance curve is, but you could try slowing it down a bit and see if that helps.


Fastest 300
Re: Holley 670 SA or 750 3310 on 340? [Re: Crizila] #259567
03/20/09 11:59 AM
03/20/09 11:59 AM
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Posts: 1,195
Snowing in the north!
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Dart 340 Offline OP
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I know a better gear would help, but I found a
great deal on the 3.23 and considering I drive
a lot on the freeway it seemed like a good
choice to go with. It had a 2.76 when I bought
it, talk about a clutch riding killer!

Using the plain steel spring in the secondary's
and the stock PV was 6.5 but changed it to 4.5.
Vac is around 9-10 but the cam has a long duro
and I was told from eddy this is common for
that grind so I do not think I have a leak
anywhere. I will check the shot size to see
what that is and I believe I have the white
cam on the acc pump.

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259568
03/20/09 01:07 PM
03/20/09 01:07 PM
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dgc333 Offline
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Quote:

She's almost an eye burner now at idle, and my plugs are at least brown.... changed the PV about 4
times last fall. I have a 4.5 in there now running
at 9 InHg vacuum. I was thinking maybe the acc pump
squirters might be the culprit?




You didn't mention what you are using for a cam. But anything with more duration than stock typically means more overlap which means you need more intital timing. I running a Comp XE268H cam and I get max manifold vacuum with 17 degrees BTDC for my inital. Anytime you tune an engine getting the timing dialed is the first step.

If you are pig rich at idle with a Street Avenger carb I would say you need more timing. When i went to the 670 it had to be the closest thing to spot on I had ever tried. Tweaked the idle mixture screws, set the idle speed and called it a day and have not touched it since.


Dave Clement Pembroke, MA 03 PT Cruiser GT Turbo 99 Dakota SLT+ CC 4x4 68 Barracuda sport coupe http://home.comcast.net/~dgc333/
Re: Holley 670 SA or 750 3310 on 340? [Re: dgc333] #259569
03/20/09 01:21 PM
03/20/09 01:21 PM
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Dart 340 Offline OP
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Dave,

Cam is 234 int and 244 exh at .050 and lift
is .488 int and .510

the 3310 took a long time to run "acceptable" I
just tried the 670 last evening and it seems to
be pretty close. I still have a little trouble
with idle being high enough the transfer slots
are uncovered a little too much I think, but
advancing the timing should help with that. I
am only at 12 btdc and think I will go up to
16 or 18.

Re: Holley 670 SA or 750 3310 on 340? [Re: Dart 340] #259570
03/20/09 02:21 PM
03/20/09 02:21 PM
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Crizila Offline
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Crizila  Offline
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Quote:

I know a better gear would help, but I found a
great deal on the 3.23 and considering I drive
a lot on the freeway it seemed like a good
choice to go with. It had a 2.76 when I bought
it, talk about a clutch riding killer!




Them trade-offs are always a [Edited by Moparts - Keep it clean] arent they. For a streeter with that gear, the Avenger might be more suitable. Let me know if you ever want to sell that 3310.


Fastest 300
Re: Holley 670 SA or 750 3310 on 340? [Re: Crizila] #259571
03/20/09 02:48 PM
03/20/09 02:48 PM
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Posts: 1,195
Snowing in the north!
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Dart 340 Offline OP
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Give me a few days to see if I can dial the 670 in
and if so I'd sell it to you for a good deal. Lord
knows it's clean and works pretty good.

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