carburation system

[macdodd]

I'm using a edlebrook 4barrel system on a 350 with 305 heads and a 3/4 race cam. Wondering if changing to another system would benefit me as far as better gas milege and/or performance?

[hugger6933]

Probably not. i hope that Edelbrock you have on there is a 600 CFM or else it is gonna be too big for the motor, as far as regular street driving with any hopes of decent mileage. jim

[Mike C]

Exactly which 3/4 race cam do you have...? This is an antiquated term back to the days of Flathead Fords and doesn't help answer your question.

The best thing you can do for fuel economy is lower engine RPM's either through an overdrive transmission or numerically lower rear gear ratio and/or taller tires. There is a big difference also in whether you are running a Performer and a 600 cfm carb or a Victor Jr and a 750 cfm carb.
Posted via Mobile Device

[leftybass209]

We need a lot more information than what you provided. What rear end gears, trans, tire size, dual or single plane intake?

The Edelbrock carb "generally" will provide the best in fuel economy versus a Holley carb of the same or similar CFM. That being said, the Holley can usually outperform an Edelbrock, but that performance usually comes in the higher RPM range, and more fuel consumption. A Quadrajet can usually perform equally as well as any carb, but takes an experienced mechanic as they are a bit more complicated.

I won't debate which will run better because I've seen all of them perform flawlessly from people that know how to tune them.

While the carb is the first piece on the engine that receives fuel, the gearing, trans, heads, and camshaft have much more to do with how much of that fuel your engine will consume.

[trac209]

Originally Posted by Mike C

Exactly which 3/4 race cam do you have...? This is an antiquated term back to the days of Flathead Fords and doesn't help answer your question.

The best thing you can do for fuel economy is lower engine RPM's either through an overdrive transmission or numerically lower rear gear ratio and/or taller tires. There is a big difference also in whether you are running a Performer and a 600 cfm carb or a Victor Jr and a 750 cfm carb.
Posted via Mobile Device

Yeah I was wondering where the other 1/4 of the cam when myself lol

[macdodd]

LOL,,,yea,,,my bad,,,,sorry for the confusion,,,,I'm looking to maybe change out the carb,,,like I said ,,,its running good for a daily driver,,,,so right now, its cool.

[GRX]

3/4 cam ... Wow. Have not heard that in a while. The term often led to people thinking they had a 3/4 inch lift cam. Which we know is very likely not the case. For fuel economy on the street I am a fan of the good old Q-jet. Provided you can put around using the small primaries and avoid kicking in the bigger secondaries. Always had trouble with that one myself Those carbs came stock on engines from 200 to 500 cubes. Trick is tuning it right for your particular application.

[jayoldschool]

Also, WHICH Edelbrock carb makes a difference, too. For example, the 1405 is jetted richer for performance than the 1406 electric choke model (which is designed for more economy). Of course, you can rebuild a 1405 to 1406 specs (and vice versa). I would also agree that the 600cfm is the correct choice.

After carburation is sorted, move on to ignition and exhaust. Then, gearing and overdrive. Then... heads... FI... engine swaps...

[macdodd]

The carb is a edelbrock 1405-1354. Thinking about changing over to a q-jet carb..would this maybe help the milage? And if so,,,,could I use the same intake that the edelbrock sets on now? Thanks,,,

[special-K]

I always get best mileage with Quadrajets. You can buy a spread-bore adapter, but I think a correct intake will flow best. All you really need is a stock intake. You'll be fine if you don't want to change it. I doubt whatever cam you have makes your engine any more radical than what GM built and put a quadrajet/cast intakes on. You need the proper Quadrajet, though, a smaller one

[GASoline71]

The flow of the "305 heads" is also killing your power. It might have bumped up the compression, but the gains are negated by the cruddy flow and small valves of the head itself. Match that with a cam that's waaaaayyyy to big and then you have to put your foot in it more to do anything. Therefore burning more gas in the process.

I agree that a Q-jet will do very well to improve fuel economy over aftermarket stuff. That was their job when they were bolted to these rigs at the factory. But just finding a dusty Q-jet on a shelf and bolting it on won't usually do the trick. You will need one built by a reputable source for optimum economy and performance.

Gary

[macdodd]

I checked with the guy the put the cam in,,,its just a replacement one for the one that was in there.

[macdodd]

Any suggestions as to which q-jet to get? The truck runs good,,,just when you push down to go,,,,just doesn't seem to have the pep it should, unless you really get in it,,of course its been awhile since I had a motor like this one,,,,LOL Starts good,,,once warmed up,,,takes afew more spins to start it,,,had a upgrade starter put in. Has 210 thermostate, have a new one(180) to put in it. Checked the milage awhile back,,,13/15mpg,,on the road at 65mph.

[Boog]

Originally Posted by macdodd

Any suggestions as to which q-jet to get? The truck runs good,,,just when you push down to go,,,,just doesn't seem to have the pep it should, unless you really get in it,,of course its been awhile since I had a motor like this one,,,,LOL Starts good,,,once warmed up,,,takes afew more spins to start it,,,had a upgrade starter put in. Has 210 thermostate, have a new one(180) to put in it. Checked the milage awhile back,,,13/15mpg,,on the road at 65mph.

Bud if you are getting 13/15 mpg in that truck now I wouldn't expect to see much more if any by a carb swap. These things are bricks.

[cdowns]

You can sit with a batch of carbs and spend the money to keep changin em and dick around all you want and in the end you'd be better off sitin in the living room with a bic lighter and just burnin up your cash and end up with that same milage

[geezer#99]

With your motor set up you need all the initial timing your motor will handle.
So, what's your initial timing?

[macdodd]

Oh lord,,,now you're asking something I don't know,,,LOL. He set it when he put the cam in and it starts quick. Of course when the engine is heated up,,,takes afew more turns to start it,,,,,,

[geezer#99]

Originally Posted by macdodd

Oh lord,,,now you're asking something I don't know,,,LOL. He set it when he put the cam in and it starts quick. Of course when the engine is heated up,,,takes afew more turns to start it,,,,,,

Time to buy a timing light and learn how to use it.

[macdodd]

Yea,,,,next week,,,,,

[Wrenchbender Ret]

If you have the Edel. Performer intake, it is made to take the Q-jet or the square bore carb.

[Redline novdog]

The 305 heads are supposed to bump compression ( 1/2 c.r.)? If they are not the 1.94 or 1.85 intake heads or ported,then all is mute. A performer intake and that carb wil help MPG. If you want fuel mileage then start looking at fuel injection.

[GASoline71]

actually... 13 to 15 mpg is pretty damn good for a truck with the aerodynamics of a brick.

Gary

[macdodd]

LOL,,,,,I was concerned about the rpms up high,,,,,65mph=@2800rpms,,but was told , thats not really that bad. Thinking about running up to the Smokies and don't want to mess something up,,,,yea,,I know,,,the thing weights alot.

[GASoline71]

LOL... that's low for an old 350. You're now used to driving modern rigs with supercalifragalistic overdrives and fuel injection.

The 350's of yore ran the freeways over 3,000 RPM's all day long and didn't even work hard.

Gary

[macdodd]

I'm carrying around 28lbs of oil pressure at the same rpms,,,,was told, thats ok too, as long as it stays steady, which it does,,,,running 20/50 oil, gets hot here in Florida,,,LOL