Edelbrock carb tuning

[c1500sbc]

IMOP you are lucky to get one that worked that good out of the box.

Now you get to enjoy your ride! Congrats

Thanks! Curiosity, have you had bad luck with the street avengers?

[1980RS]

IMOP you are lucky to get one that worked that good out of the box.

Now you get to enjoy your ride! Congrats

Thanks! Curiosity, have you had bad luck with the street avengers?

I know I have with both the 670 and 770. Both had hesitation problems and were dogs performance wise and with the sec side no opening now I know why.

[MikeB]

I got a great deal at a local parts store on a new Holley Street Avenger 770. It fired right up out the box. Idled at 1200 during warm up and down to 750 after the choke opened. I bumped the idle speed up along with the fuel pressure to 7 psi and it’s a runner now! No more bog off idle or at WOT. Super smooth transition circuit and the fuel curve is on the money. I don’t know if I’ll have to touch a thing on it! I’ll drive it for a day or two and see how everything goes. Vacuum at idle went up a little as well over the Edelbrock. AFR at wot is right where I want them. I can’t say if it makes any more peak power but I can say it’s definitely stronger throughout the rpm range. I’m super happy with it!

I had a similar experience after going from an Edelbrock 1405 carb that worked just OK, to an old skool Holley #80783C 650CFM 4150 series. After setting only float level and idle mixture, it worked great with no other changes. Messed around with jets, power valves, and pump cams just for the heck of it, but eventually went back to stock. It is probably my all-time favorite carb for a mild-mid performance street 327-383. Wish I would have yanked it and reinstalled the Edelbrock before I sold the car!

[c1500sbc]

IMOP you are lucky to get one that worked that good out of the box.

Now you get to enjoy your ride! Congrats

Thanks! Curiosity, have you had bad luck with the street avengers?

I know I have with both the 670 and 770. Both had hesitation problems and were dogs performance wise and with the sec side no opening now I know why.

You had problems with the street avenger too? Man, I read nothing but good things about them!

[shadango]

http://mewagner.com

A fully adjustable PCV valve.. Also can be setup as a "fixed orrifice" type PCV valve..

Put the drills away.. I mod my own cause I'm cheap but would like to try one of these..

Hope no one minds that I am reviving/hijacking this year old thread...lots of good info in this one, and I figured why make everyone repeat themselves...LOL

I, too, have been fighting an Eddy for years....its a 600 cfm 1405....

The engine is a chrysler 318 (727 auto). The engine was a "pig in a poke" in the roller 72 Barracuda I picked up.....setting in the car but not running. I was told it is a stock shortblock aside from a double row timing chain and a milodon oil pan. It has J heads and a Mopar purple cam -- no idea on its specs but it's lumpy and has low vacuum for sure....I ended up putting in a 2400 stall just so I could get this engine to idle enough to drive when I first assembled the car. It really likes the top end of the RPMs. Low end, with 3.55s trutrac, she is a bit of a dog.

Its probably too much cam for the car and the heads are too big --- J heads (from the 340 engines) were a popular go-to back in the day for Mopar guys looking to hop up the 318, but from what I have read they actually drop the compression ratio, so its not the best way to go. That said, I have never gotten around to doing a proper matching cam and head swap (life is always in the way) and they are on the car. Been running that way for well over a decade since I got the car together.

When I first got the engine it had a 750 Eddy on it and I had all sorts of issues......so at some point on the advice of others I swapped in the smaller 600 Eddy. Spent hours playing with rods and jets and springs and got her to a point where I think it works.

Runs fine when you stomp on it.....up top she really pulls hard......

But one problem I have had for over 10 years is its idle.....I know the big cam affects that.

At idle, the idle screw has to be turned in to the point where the transfer slots are exposed.

So when driving and coming to a red light for instance it wants to idle really low and almost stall in drive, so I will shift into neutral. That brings the revs up to a more comfortable, non-stalling idle. But if I touch the throttle at all in neutral AT ALL, it idles up to around 1500 or so and wont usually come back down......shifting back into drive at that RPM is hard on the driveline.

But if I don't touch the throttle at all it will idle OK...I can shift back into drive and go.

Setting the idle speed higher to compensate for the in-gear low idle makes the idle too high in park and result in run-on when shutting down and just make the neutral idle issue worse.

There is an elusive sweet spot that I had found after hours and hours of rods, jets, springs, timing , etc where this doesn't happen as much but it often gets lost....Had it set "perfect" for a while but after a recent carb rebuild/cleaning last summer i just cant seem to get it back.

So to the point of my post....drilling holes and PCV valves.

Back in the day I had considered drilling the holes in the primary blades to address the transfer slot issue, but worried about how I would refill them if they didn't work out as hoped...so I didn't. I figured epoxy MIGHT work. Some said "solder them" but I was worried the solder or epoxy could come off and end up inside the engine. Replacing the blades on this carb doesn't seem like an option...I even reached out to the techs at Edelbrock, who insisted I didnt need to drill the burtterflies and that put me into a long period where I tinkered with the jets/rods/springs/timing. I didnt want to ruin the carb. So once I found that sweet spot I left it alone.

I also came across an article in a magazine back then about adjustable PCV valves...but never followed up on that since the engine was running ok at the time. It seemed then, and evn now, to be a more obscure way to approach this issue......

Well, now that I am facing this issue again, and saw another tech article in a Mopar magazine where some other lost soul had the same issues and the very experienced tech guy suggested (you guessed it) drilling the butterflies.........

This woke up all the same thoughts from a decade ago. LOL. So I googled and came across this thread.

F-Bord 88, you seem to be a staunch advocate of the adjustable PCV valve INSTEAD of drilling.....at $129+shipping that valve you linked to is pricey.....but will it be a cure to my issue, you think? I am cheap too, but don't have the patience to try making my own and do not mind buying this gizmo if it works.

I have again been tempted to drill the holes and see what happens. Like the OP ended up doing, I have contemplated scrapping the Eddy for a Holley setup.

But this adjustable PCV valve, if it could save me that hassle, might be a way to go. Just not sure if this is a snake oil kind of thing or if it really works.

The PCV valve I am using is a parts store item for the 318, which I know means a STOCK 318......but does the PCV valve REALLY affect idle etc that much to warrant a $130 adjustable one?

[weedburner]

I too played with drilling the throttle blades on a Carter/Weber/Edelbrock style carb. I ended up going back to non-drilled blades, then adding a home brewed adjustable feature to a cheap off-the-shelf pcv valve. First I cut one apart to see what was inside...



Then I gathered as many similar ones as I could find locally, then cut them apart to see what the differences were.

NAPA# 2-9229 (the body of the valve is stamped 2088) GM 4/6/8 cyl '85-'95
Spring free height is .775"
95 grams compressed .300"

NAPA# 2-9333 (the body of the valve is stamped 2221) Ford 5.0 & 460 '87-2002
Spring free height is .800"
110 grams compressed .300"

NAPA# 2-9210 (the body of the valve is stamped 2072, pictured in previous post) GM 262/350/454 '80's thru the '90's
Spring free height is .775"
117 grams compressed .300"

There are different pintel shapes and tapers.
All the above have the same dia holes in the internal "washer" that the pintle slides into.
2221 and 2072 use the same pintle with 4 cutouts in the large "nailhead" end and a short taper.
2088 has a pintle that looks like a sawed off nail, no cutouts in the nailhead and a very gradual large dia taper where it slides into the "washer".

I also had two other valves in hand, but they were special order from my local store. I didn't get them until after i had made my valve, so i never bothered to cut them apart. They were...
NAPA# 2-9230 (stamped V187) '80-'87 Chevette
NAPA# 2-9246 (stamped 2108) '74-'79 350/400/454

All the above valve bodies share the same 3/4" body outside diameter where they plug into the rubber grommet, and feature the same plastic elbow that is pushed onto the top of the valve body. From the outside they all look identical.

I took one of the valves (don't remember which one) and made it adjustable by adding a long screw to the top of the valve's plastic elbow. That added screw allows me to adjust the minimum flow position of the valve's tapered piston, basically turning the valve into an adjustable orifice unit at idle without disabling it's reverse flow check-valve feature...





Here's a link to a page about the car that I use that valve on. I've been using that same valve for over 10 years now on several different engines in that car, still works great. The car still uses a carter/edelbrock 625 carb, but now on a screaming 9000rpm street/strip 355. Scroll down to the bottom of the page to see the current configuration of my adjustable pcv system...

http://grannys.tripod.com/20102.html

Grant

[rustbucket79]

Shadango

Do a compression test and put a vacuum gauge to see the idle vacuum. This is the most important step.

I’ve dealt with a few ill conceived engines on the dyno, here’s what you need to do. If you have less than 150 # cranking and 7” vacuum (arbitrary numbers) you can make it idle better with more base ignition timing. (While limiting mechanical advance so you still only have 36 maximum) On the worst offender I eventually just locked the distributor and dialed in 34 degrees. With 140# cranking it starts fine and idles better considering this engine only had about 5” idle vacuum. You can also try manifold vacuum on your distributor but if the vacuum is too low it may not pull in any timing.

[F-BIRD'88]

If the idle manifold vaccum at idle ,in gear is very low.
Lock out the diz mechanical advance curve.
Now the mech adv is fixed. (It does not change with rpm.
Set the now locked tming at 34-35 ° btdc.
now warm it up and reset the carb idle screws.
It should idle much better now with the increased idle timing.
Then you can use vaccuum advance on either full manifold vac port or "ported vacuum" port on the carb.
(I use ported)
Big cam in 318 with low cr): Advancing the cam you got will help low end torque.
100° to 104° intake c/l.
You can ID the old Purple Shaft mopar cams by cam lobe lift.
You should have bought at least a 3500 stall.
more is better.. the advertized stall will be for a typical 340-360-383 mopar.. So on a 318 the realized real stall speed will be lower... So be generous when choosing a converter for a lil 318 or 273..LA.
A 4000-4500 real stall speed on a cammed up lil 318 LA is not too much.

Locking out the diz mech adv curve will help a lot.
Do this first. The big lumpy cam needs a LOT OF IDLE TIMING @idle. that does not drop off in gear.
On the PCV you can probe to see that the valve inside is staying in the "closed" low flow idle position when idleing in gear.

Use a ignition power interupt switch to interupt spark power to aid hot re-start with now locked out diz.

There are tons and tons of different spec PCV valves
but no published specs.
Do these mods FIRST.

[F-BIRD'88]

A low compression 318 with high perf 340 heads would be killer with a mini roots blower on the street.
Weiand 142-144-177. Edelbrock- TFS- Magnuson 122H.
If old Purple shaft cam be sure it is advanced in the motor.

Now your lil 318 can beat up on those pesky chevs.
Get some 4.30-4.56 gears for it too.

[F-BIRD'88]

A much better cam for you:
Comp cams XE262H-10 #20-222-3
262/270 218/224@.050". .462"/.470"
110LSA. (106/114). install on 104/116 centers for 318 cid TORQUE. (2400 STALL-3.55 GEARS. lame CR)
great with 100-150Hp nitrous.
Try it

[Geoff2]

Shadango,
The most important thing you need to focus on to fix your problem is timing at idle, & you haven't mentioned it.....
F-88 has given good advice.
Your combo could need as much as 50* of timing at idle [ yes, 50!!! ]. However, it will probably be less. I have seen idle rpm increase 300 rpm by simply turning a dist to advance idle timing. The rpm increases because the engine is making more hp. In your case, this would reset the t/blade/tslot relationship, might not be perfect, & holes in the t/blades might still be reqd. PCV needs to be working properly before you start drilling holes.
So, always get the idle timing dialled in BEFORE touching the carb.
As F-88 said, a good way on a street engine to get the reqd idle timing is to use Man Vac Adv [ see link below ] MVA. Chrysler missed the boat on MVA & used the useless PVA.
You MUST use an adj VA unit with a low vac cam. Adjust the Allen Key fully CW. If your current dist does not have a VA unit or provision for an adj VA, a dist that does is the best present the Easter bunny could deliver....
Most VA units can add up to 30* of timing.

Scroll down to post #6.
www.hotrodders.com/forum/vacuum-advance ... 47495.html

[rgalajda]

Has anyone suggested checking the size of the idle jet ?