BLACK Z

I think I have narrowed it down to the SA due to cost, please tell me what you know about it since I ned to make up my mind soon, it is going in a 86 Z28 with a gm 350 headers msd 6 al edel perf intake 5 speed 3.45 posi rear. Thanks

EvilCartman

iTrader: (1)

The one I had sucked, never got it to run right. You'd probably be much happier with a regular 650 double pumper especially with a manual trans.

xpndbl3

iTrader: (5)

Tobias05

go double pumper and don't look back. glad i did.

five7kid

iTrader: (14)

Also addressed in your other post about carb choices.

82 Iron Duke

iTrader: (21)

I pretty much had that exact same setup, hated the carb, don't get it

Tobias05

IIRC, aren't the street avenger series CFM ratings a bit exaggerated?

670=600
770=700

and so on?

djtricia

iTrader: (4)

Had a buddy who put a new one on his 68 RS/Z-28 and he hated it. Rebuilt his original Holley and put the Avenger on the shelf.

BLACK Z

How much tuning did you guys have to do with the 650 DP? can I bolt it on and adjust the idle and go? is it going to be jet out of teh box pretty close?

five7kid, I started this post becasue I wanted to narrow it down to the 670 I did listen to everything you said about the 650 dp though.

EvilCartman

iTrader: (1)

You can get lucky and get away with slapping one on right out of the box and have it run great. Most of the time you'll end up adjusting and changing stuff to make it run it's best. It'll probably run and drive around right out of the box but it's best to tune it. Friend of mine slapped an 850 DP on his 350 and runs 11.70's on stock jetting, makes me sick haha

IROCaholic

They are tuned pretty rich out of the box I ran mine for about 2,000 miles before I killed my tranny. I never got it tuned right, but it wasnt terrible. While I am rebuilding I am going to pick up an Edelbrock 600 instead.

EvilCartman

iTrader: (1)

Edelbrocks are even worse lol, friend of mine can't get his to run worth a crap. We've spent hours changing everything, going back to stock and changing stuff again one by one and it's still not right.

IROCaholic

Well I am going with an Edelbrock because I have experience with it. I really want a demon, but I dont have the cash.

SmallTires

iTrader: (4)

I run a 650dp and I had to jet it differently right out of the box because it mwas way to lean for my setup. However most people don't have huge cams like me so it would likely work for you. The holley 4150s are some of the simplest carbs to work on. People are just intimidated by them because it is not your typical AFB style carb which is pretty simple to use as well. As far as the demon goes everyone I know who owned one hated it. They never seem to run right even with the easy idle system they have. When I chose my carb I went to the race track and talked to alot of guys on what they use, and now I rock the holley and am happy I made the choice.

EvilCartman

iTrader: (1)

I'd stay away from Demon till they get their chit together. Bought a Mighty Demon a couple months ago and I'm not very happy with their quality control. Metal shavings in the fuel bowls and vents, boosters not centered in the venturies, burrs left in holes then some holes were undersized. I've spent probably 10+ hours working on getting my carb cleaned up and to spec a bit better. Not what I wanted to do after plunking down $550 bucks.

BLACK Z

Over on the monte ss site they all seem to love this carb and over here no one seems to like? anyone else have anything to add about the carb good or bad?

Is it going to run any better or worse then the Q jet?

IROCaholic

It isnt a terrible carb, but most guys think that since it is more expensive than a regular holley 4 bbl and offers pretty much no benefits that it its junk. One other defect I forgot to mention is that my clear site plugs fell off of the carb within the first month or two. I dont know if others had this prob, but I did.

EvilCartman

iTrader: (1)

I think it's junk for the way my car ran with it on. Night and day difference when I changed it out for a different carb. The sight plugs in mine stayed in but have heard of them breaking off.

cc 82Z-28

iTrader: (7)

I run the 670 on my car and I have had no issues with it whatsoever, that said, you would really be better off, and like the 650 dp since it is geared more for an manual trans and the Avenger is vacumn secondaries is geared for the automatics. Mine worked good right out of the box with only minor adjustments for idle.

BLACK Z

Do the secondarys open that slowly? If I put the lightest spring in it they would open fast, but bog out right? then why does teh DP not bog? How does it give the extra fuel? How do the vac sec give teh extra fuel? thanks

five7kid

iTrader: (14)

The "bog" is caused by the delay between the begining of the airflow through the venturi and the fuel being drawn through the the secondary metering passages.

The vacuum secondaries carbs prevent the bog by "slowly" opening the secondary throttle blades so that the airflow through the secondary venturi will begin drawing fuel through the metering passages before the airflow through the secondaries becomes significant.

Double pumper carbs are just that - they have an accelerator pump for both the primaries and the secondaries. The secondary accelerator pump adds fuel to the secondary airflow as the secondary throttle blades open, and the fuel will be drawn through the metering passages by the time the secondary accelerator pump shot is used up.

sb406camaro86

I'd have to agree with everyone who says stay away from the demon carbs. I ran one on my 400 sbc,and the thing ran great at wot, but idled like crap, it puffed black no matter what i did 2 idle or part throttle.

I sold the carb to a friend with a 81 camaro with a 400sbc but with a higher single plane intake and a manual tranny it seems to run better with that setup. Not that i'd put a highrise intake on a 400 sbc, especially with stock ported 400 heads but that's just me.

I've tried 3 different holleys, 650dp,700dp ,and 750dp and i've found once u get them set right they run great,but if the temp/humidity changes they start to run crappy again. I'm going to try a 750 edelbrock,just cause i've never played with one or a q-jet b4. Figure i'll decide for myself which carb i like better. I think i'll like the edelbrock, cause i don't go to the track nearly as often as i used to and I've got to many other projects on the go to be playing with carb settings all the time.

Remember u can always sell a carb latter and get a different one, whats best for my engine wont be whats best for yours.

BLACK Z

When the secondarys open will it flow as much air and fuel as a dp650?

five7kid

iTrader: (14)

Only if the engine demand opens the secondaries completely.

I don't have it in front of me, but the secondary spring assortment kit comes with a chart that shows how many RPMs it takes to fully open up a VS carb with a given carb & engine size. You'd have to get over 6000 RPMs (if memory serves) to get them fully open with a middle range spring. If you use a light spring to get the secondaries to fully open, you'll probably bog.

BLACK Z

Any tuning tips for this carb?

EvilCartman

iTrader: (1)

So you went with the 670 SA?

BLACK Z

I could not beat teh price, i got it cheaper then I thought, I will give it a shot and go from there.

five7kid

iTrader: (14)

You can go broke saving money, you know. . .

EvilCartman

iTrader: (1)

Well, good luck with it I guess. Talked with a friend of mine tonight and a friend of his had a crap load of problems with the 670 as well...

Electron_Blue

One of my buddys has a 670 and 770 SA..they seem to work decent however on both there were metal shavings in the fuel bowls. Just something you may want to checkout before installing

lowflyr

I ran a 650 demon out of the box with no problems. I've rebuilt alot of holley's and q-jets (not so many q-jets for a long time though). I've tuned them both. But I cannot say enough good things about the demon. Best carb I've ever had. Especially for a vac secondary. This thing ran great out of the box on my last 400. If someone is having big problems getting them to idle or they are puffing black smoke all the time off idle, then they need to check the opening vacuum of their power valve. Replace with one that is appropriate to their application. Also, many people run vaccuum advance at idle, which is not needed and can cause a surging idle. Some people swear they can't get their cars to idle without vaccuum advance, and that is an indication that something else needs to be adjusted. Even a tight torque converter does not need it.....my $0.02

EvilCartman

iTrader: (1)

I've had a 50/50 experience with Demon carbs. First one was awesome, some model before the EZ idle stuff came out. This new Mighty Demon I have now, very unhappy with the crap I've had to do to it, some of things I've already listed in this thread. Idle is fine, throttle response is spot on with the old one, cruise and going WOT are giving me problems though.

joewee350

I ran a Holley SA 670 for a year and had zero problems with it. It ran 2 tenths faster out of the box than my edelbrock 750. I have since swapped to a 750 double pumper after a cam and heads swap. I had a buddy that ran a SA 670 with his manual 5 spd mustang with no problems. He also swapped carbs at the track with a BG 575 mechanical secondary carb. The holley street avenger ran 1 tenth faster in the 1/4 consistently but the BG 575 ran 1 mph faster consistently. I hope this helps you.