Holly 670 street avenger

[bigfoot]

I was looking at a 670 street avenger holly carb..vacuum secondary with electric choke....do they have jet extentions in the rear ??do these carbs work for drag racing too..I have a 347 ford..thanks

[bigjoe1]

Not a good choice ! Look at the Quick Fuel line up. Depending on lots of things, a 750 might be a better choice ( 450 HP or higher )


JOE SHERMAN RACING

[racear2865]

Bigfoot
Listen to Joe and stay away from the Avenger. It most definitely is not as good as the Marvels "Avenger" movie.
reed

[chevyfreak]

It most definitely is not as good as the Marvels "Avenger" movie.
reed

Haha. Lol. I take it you also a marvel fanatic. Hehe.
chevyfreak.

[bmcdaniel]

A friend of mine just put one of these on his 347. They are definitely different to tune than the old Holleys. Holley's advertising says you can run it right out of the box with only minor adjustments because they are "wet flowed" at the factory. Wrong. The float levels were set way too high. Had a problem getting it to idle, too much air coming in the secondary. What worked best to set the secondary throttle blades was to back the adjustment screw all the way out, turn it in until it just touched the tang and then add 1/4 turn. Forget about going by the transfer slot exposure. One of the primary idle mixture screws has no effect. The car goes on the dyno next week, we'll see what happens.

[In-Tech]

Holley also did a neat trick that screwed up the idle circuit, especially when dual carb'd. If you have problems getting it to idle lean enough and the transition from there is fubar, take close up pics of your primary metering block and we'll help fix it.

[Tuner]

The easiest thing to do is change the primary metering block to one for an 1850. Some genius "designed and calibrated" (LOL) the "670 Avenger" with a "backwards idle" metering block on a normal idle body and base. The metering orifice in which the tip of the mixture screw goes is .104" instead of .063" and the needle has a very blunt tip. This metering block arrangement is used in the "backwards Idle" emissions carbs and is intended to be an adjustable air bleed, not a fuel control adjustment as it is in the "normal idle" carb. The large hole and blunt needle make it so a very small turn of the mixture screw causes a very large change of A/F and also results in a situation where normal temperature extremes from cold start to operating temperature and the resulting expansion and contraction of the metering block causes erratic changes in A/F. Holley should warranty a new correct metering block and mixture screws to everyone who has one of these carbs. This same stupid mistake is in other list number 600 VS carbs, starting about 25 or 30 years ago.

[bmcdaniel]

The easiest thing to do is change the primary metering block to one for an 1850.

Is the 1850 metering block a direct install or are modifications required?

[Tuner]

The easiest thing to do is change the primary metering block to one for an 1850.

<br abp="656">Is the 1850 metering block a direct install or are modifications required?

Direct replacement. It should work OK. Like any carb situation it could be improved with fine tuning, but at least the idle adjusting screws should respond normally.

[bigfoot584]

Believe this is the block Tuner speaks of.

alst-1.jpg

[bmcdaniel]

Yep, got an old 1850 sitting on the shelf, we'll give it a try.

[Blue Malibu]

Do what Big Joe suggests and go with a Quickfuel and don't look back.
I have virtually stopped building carbs because of using the Quickfuel carbs.
They are easy to adust for any combo out there.
The one we use the most is the budget friendly SS series.

Andy

[bmcdaniel]

OP, sorry for busting into your thread, I can start another if need be.

We put the 1850 metering block on. There is now "some" adjustability on the primary idle mixture screws but I think it would still like to be a little more lean. The screws are almost all the way in, I didn't want to bottom them out, the idle just keeps improving as I lean it out. We gave another half turn on the screw that adjusts the secondary blades to try and get more air in the carb. Didn't make much difference, I guess because of the 4-corner idle. BTW, this is a dual plane manifold, if that matters.

[bigfoot584]

For testing find some wire about the size of shipping tag wire and
cut 4 pieces about 3/8" long bend in the middle into a vee and place
each one in one of the ifr and the other end float in the hole next to it,
if it helps try two each if it feel right leave it or you can use some
math and figure what a new ifr should be if you want to replace them.

[jmarkaudio]

OP, sorry for busting into your thread, I can start another if need be.

We put the 1850 metering block on. There is now "some" adjustability on the primary idle mixture screws but I think it would still like to be a little more lean. The screws are almost all the way in, I didn't want to bottom them out, the idle just keeps improving as I lean it out. We gave another half turn on the screw that adjusts the secondary blades to try and get more air in the carb. Didn't make much difference, I guess because of the 4-corner idle. BTW, this is a dual plane manifold, if that matters.

Thread your idle feeds, info below. Then you can more easily make them smaller.

http://racingfuelsystems.myfunforum.org ... ?f=25&t=18