If you read my earlier post I had just installed a new GM Goodwrench 350 in my 86 IROC, and I had added a non computer controlled HEI dist. w/ the stock CC q-jet. I was getting 10 mpg and thanks to some people's help I bought an Edelbrock 600cfm Remanfactured carb. After going 120 miles w/it I am now getting 13.5mpg, a definate improvement. Here's the question anyone think that might go up once the motor loosens up. Oh one key note I don't have OD.

 

You have 2.73's ? Right ?


If So, You should be getting better than that Highway, even W/o OD.

Is you Vaccum advance hooked up ?

If So, Is it ported or manifold Vaccum?

I Run mine on Ported But Ive heard that running it on Manifold gives Better Milage, I dont quite understand that however.

How is the Carb jetted ? Idle mixture set ? All these things can effect milage signifigantly.

As far as it going up when the motor loosens up, I couldnt answer that as Im Not familiar with brand new engines




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

The vacuum advance is hooked up, what's the difference between the 2 vacuum advances(ported and manifold) I'm not sure which I have.. With the carb. being remanufactured the jets came preset so I figure it should be in the middle. Yeah I have 2:73 gears.

 

what is your initial and total timing?

what is the vacuum reading at idle on the port that you have your vacuum advance hooked to?


ported vacuum comes from a port on the carburetor that depends on airflow through the carb to produce vacuum. This is darn near useless.

manifold vacuum is a port that connects directly to a space under the carburetor and supplies vacuum equal to that inside the manifold. This is a good source to provide full vacuum advance at idle, cruise, or decceleration. This provides the best economy.

 

ouch, I was getting about 15 with the same setup and now am getting 17 with the qjet. Sounds like more tuning is in order.

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1983 Camaro Z28
Goodwrench 350ci V8, Edelbrock TES Headers, Flowmaster Catback, MSD 6al and Blaster 2 coil, Edelbrock Performer intake, (Edelbrock Performer 600cfm carb.)- went back to q-jet!!! T5, 373 rear, Eibach springs, Cervin Vega speakers, Rock. Fos. Sub, Pioneer CD,
email-chris4421@hotmail.com
-------------------------
"I used to be a Mustang Guy! I didn't know the power of the dark side!!"

 

opps, just noticed the no OD part.

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1983 Camaro Z28
Goodwrench 350ci V8, Edelbrock TES Headers, Flowmaster Catback, MSD 6al and Blaster 2 coil, Edelbrock Performer intake, (Edelbrock Performer 600cfm carb.)- went back to q-jet!!! T5, 373 rear, Eibach springs, Cervin Vega speakers, Rock. Fos. Sub, Pioneer CD,
email-chris4421@hotmail.com
-------------------------
"I used to be a Mustang Guy! I didn't know the power of the dark side!!"

 

I had the same setup as you but with a 224 224@.50 cam. once broke in i got about 10 mpg. with a spring change it got about 14/15 i think i changed the springs from orange to yellow or vise versa.
for future i suggest changing to a holley "stock setup" I get about 18 city and 22 highway and alot more power!

 

Well I can't change my springs b/c that will void my warranty.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

 

Changing the springs or rods won't void the warranty, changing the jets will.

 

warranty?
I hope you guys are kidding right?
LOL

 

Opening it up to change the jets does supposedly void the warranty, although anything that would make you want to return it would be probably apparent within the first few minutes of running it.

 

ODB my man, splain me dis.

Having the vaccum advance into porten vaccum will yelid litte/no advance at idle, and increase advance as the throttle opens, right ?

Plugging it to regular vaccum will yelid full advance at idle, and diminished advance as the throttle opens.

If im right there, then wich is better for performance ?


I would think the former...




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

first statement: Yes

second statement: Yes

third statement: you get better performance from the vacuum advance plugging it into full manifold vacuum like I said earlier. I think you may be confused about the purpose of having a vacuum advance in the first place. It is to provide spark advance at (low load) conditions, and has nothing to do with WOT performance of the engine.

 

ODB,

OK, just to make sure I've got you right here:

You're saying that if I hook my vac advance up to a manifold vacuum source, which of course gives me full vac advance at idle, that I'll have better performance? I can understand at low end, but what about mid and high range?

I just tried it hoping that it would help my situation, but I couldn't get the timing even close. Am I going about this wrong?

If I am at full vac advance at idle, and I can get the car to idle at a decent speed, it won't change my over all will it? Won't it cause the car to run hotter at idle since the advance is greater than normal?

 

.

[This message has been edited by Pablo (edited March 20, 2001).]