i have a fresh 355 with an edelbrock 600 cfm manual choke carb.
I am going for a long trip soon to break the engine in but I was wondering how to tune the carb correctly for maximum power but decent gas mileage. Before anyone tells me to read my edelbrock owners manual....I already did..1000 times and the instructions are too generalized..not specific enough for every step.

I dont want to tune it with a vacuum guage because it wont be valid due to the low vacuum at idle of my performance cam.
My initial timing is 8*...so I guess thats initial(8) + mechanical(10) + vacuum advance(20).
Any methods that anyone has experienced good results with would be great.

Thanks in advance..

 

I've never had a Performer or Carter AFB. So, I don't know any specifics.

However, the vacuum gauge is still a valuable tuning aid. Sounds like you're assuming it is only used for adjusting the idle, which isn't true.

 

Get the edelbrock calibration kit for you specific model I.E. 1406, 1407... Jet the carb up by 2 jet and needle sizes at a time until your running to rich, then back it down one jet size. Make sure you use the correct springs as well, i think i had the best performance out of the light orange springs. As far as the timing goes, i would bump the initial up and remove some of the vacuum and mechanical. 38 total is where my 383 performs the best. What type of dist do you run? If its an hei, get a recurve kit and throw those heavy stock springs as far as possible. put the lighter springs on so the timing comes in a bit faster. This is all dependent on you cam profile and purpose of the car, I.E. Drag car, street car, road racer. For example a drag car, you want the full timing right off idle, road racer you want the timing to come in gradually across the rpm band. As far as idle settings, jet the carb, set your timing and then mess with idle. If you bump up the initial timing, it will probable idle a little smoother and you will have a stronger vacuum signal. I've been tuning a long time, I've always used a vacuum gauge even on my 600 hp 383, that pulls @ 2.5 to 3 hg at idle. Remember, the idle circuit is just that, just for idle it has nothing to do with your jetting.

 

I have that moroso centrifugal advance weight kit with three diff colours. I will look on their website to determine which is the lightest and install them..

ok so what do I need finally..
a calibration kit(how much$) for my 1405 and I will get the orange springs.
What should I set initial timing to???? 10* maybe..or what

and yes its an HEI

 

The carb kit comes with the springs. Set timing at 10-14 degrees. As far as the distributor springs, You have three sets, when I say lighter I mean lighter spring tension. You will notice that the springs have different diameter wire used, the smaller the diameter the lighter the spring pressure. The lighter the spring pressure the faster the timing will come in. As in the first post, drag cars, you want the lighest spring pressure( Timing in fast), street car(Timing in gradual) use stiffer spring. Hope this helps.

 

One more thing, when setting your timing remove the vacuum hose from the distributor and plug the hose. After you set initial, unplug it and put it back on the dist.

 

1. Unplug vacuum hose
2. set initial timing to 12 degrees
3. Experiment with springs and weights to get 36 total(14 mechanical) and NO more
4. once that's set reconnect your vac advance
5. Determine your elevation and get a tuning kit
6. Use the chart in the instructions to set Power Mode and Secondaries according to the rule 2% leaner per 1500 feet.
7. Find the leanest cruise mode number that is in the same row on the chart for your Power mode setting.
8. Change to those settins making sure not to change the power mode. If you do, compensate for it with the secondaries.
9. If the motor cruises steady with no surges but there is a bog at light thorttle and then the motor kicks back up after you give it more gas, change to a higher rated staging spring(stock is orange 5 in HG go to the 7HG one)
10 If there is any pinging, back off the vacuum advance.

This should give you the best tuning you can get from an Edelbrock Carb. I did all this with an A/F gauge until I got it just right. Hope this helps.

 

Or this way, basically you will get the same results.

 

thanks alot guys, i ll give it a shot

 

Quickest and easiest solution is to just tune by ear. Swapping metering rods and jets takes a lot of work and a lot of math (to do properly).

Just tune the idle by setting the idle speed screw (I prefer 750-1000rpm for easy starts and warmups). Then adjust the mixture screws by adjusting from a base point (with car off, tighten all the way in and back both out 3 turns). Adjust one side until you hear a slight rpm reduction, then adjust the other side the same way. Reset the idle speed, and ear-tune again again until it's idling smoothly.

Another tip that works wonders for me is over-advancing for long trips. Basically, I just turn the distributor about 5-10 degrees CCR, until it runs a little higher and smoother. I can get 400 miles on a tank with my 350 with this trick. Just be sure to retard the distributor before you shut off the car. Otherwise, you might crank down the battery before you remember the advance.

 

 

Yeah thats also a way to do it, I wouldn't. You will end up having to do it the right way sooner or later. If you do it this you'll end up running to lean or rich, you'll get lean pops of idle, possible lean out at higher rpms... As far as the advancing the dist, wouldn't do that either with todays gas, you could have problems with detonation, car will run hotter.... Save yourself some problems and do it right the first time. These tricks worked well back in the day when you could get some good gas, those days have passed...

 

Advancing a little for highway runs doesn't pose much of a threat. As long as you don't hammer on the gas, detonation won't be a problem.

I admit, nothing beats metering the carb, but if you don't know how or lack the equipment, you can still choke out plenty enough performance with a few tricks.

 

I AGREE....