Time and Tune 460 w/an edelbrock 600 and msd ignition
We are working on getting our '84 F250 4x4 w/a 460 and eldebrock 1406 up and running and have hit the next stage - time and tune.
In previous posts about a good carb combination for this truck, the eldebrock 1406 seems to be a decent carb to run. Now I have to figure out how to tune it.
The truck came with a MSD 6AL ignition box, MSD distributer and maybe a rev limiter (another box set up to a large tac in the cab - which I'm sure means the previous owners ran the truck into the ground). All of this looks old, but works. I much rather go back to a stock configuration, but that will wait for a more time and money situation to materialize.
I took the carb off, did a basic tear down and cleaning. The electronic choke is set to (2) clicks back and the mix screws are set (2) turns from being fully seated. The idle is set at 1000 rpm. I have the vacuum line in the driverside connection and blocked off the passenger side. I did this as its the side that is actually pulling a vacuum when the truck is running.
The truck starts right up, but I'm sure I can get it to idle better.
I bought a vacuum gauge and timing light.
What is the tuning procedure?
Where should I set the timing?
What is a good vacuum range?
Re: Time and Tune 460 w/an edelbrock 600 and msd ignition
Ok, not knowing what else has been done, timing chain set back to earlier specs (straight up, no retard) and what kind of distributor modifications have been made, the best I can do is give you the stock settings. Timing spec is 8° BTDC with no vacuum on the advance diaphragm, but 10° BTDC won't hurt. Idle speed is 600 rpm in drive if an automatic, should be the same with a manual trans. This would be after getting the timing. one item, if the idle is at 1000 rpm with the vacuum advance disconnected, lower it first.
On the timing, it is a pain to see on these with all the stuff in the way, the pointer is passenger side low down and the balancer marks run from 30° BTDC to 10° ATDC.
Good luck with it, unfortunately for the next few days I will not be able to (a) access Alldata and (b) a bit busy.
"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 1994 Taurus LX
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413
I run the 750 Eddy on Big Blue, but recently built a 1406 for my brother's little 350 in his '55 and decided to run it on BB for a test. It was stock and it ran great. In fact, as I told him, if it wasn't destined for his engine I might have left it on.
In my case I liked the choke at about the index. But that varies by engine.
And I do not like using manifold vacuum to my vacuum advance. I like "ported vacuum", which is probably the one you capped. That port only gives vacuum after you start to open the throttle, and especially with an automatic tranny (your sig doesn't say what you have) that's important.
Ignition advance can be in the range of 6 - 12 degrees BTDC, and that depends on whether you have EGR and what your distributor's advance curve is like. But it is limited by spark knock under part-throttle with a load if you have too much advance. So maybe start at 8 or 10?
As for the idle speed, I like mine more like 650 or 700 RPM. And you get there by iterating between adjusting the idle mix screws and the idle speed screws. Adjust the mix screws 1/4 turn at a time, probably out if you are starting at 2 turns, to get higher RPM/vacuum. Alternate back and forth between sides. You are looking for max RPM or vacuum, which is the same thing, but while keeping the R's down around the 650 - 800 range with the idle speed screw.
And a good vacuum range is about 20" at idle. But that depends on the cam you have. More aggressive cams drop the vacuum, while a stock cam usually gives about 20 - 22".
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/soon-to-be ZF5/3.55's & EEC-V MAF/SEFI