Just finished a full rebuild and hope you guys can help me with a few questions. Truck runs and drives great - fires right up

Question 1: Timing - Originally had the initial timing 10 degrees BTDC, fired right up but idle was high and driving throttle response wasn't great. Right now timing set to 7 degrees ATDC and the vacuum advance is advancing with rpm increase but didn't record total advance - engine runs great like this. ...engine has 3 miles on it, bored 30 over, HO roller block. Does this sound good?

Question 2: Carb adjustment - I have a four barrel Edelbrock 1403 500 cfm electric carb and out of the box all I did was gently bottom the fuel and air mixture screws and opened both 1 1/2 turns out and adjusted the idle down. Does this need any other adjustment? Runs great set like this with no hiccups, flooding, backfires and acceleration is quick no hesitation.

Question 3: Brake pedal - Right at startup the brake pedal firms right up but when pressed there seems to be a bit of travel and mushy feel. The truck stops fine but seems like you'd really have to use some force to lock them up / / (haven't tried to). During a maiden voyage around the neighborhood engine stalled and the pedal was almost to the floor and all pedal firmness was gone (going about 20 mph). Is this normal for a brake booster'd '83 with 32" tires? Only brake parts not replaced were the booster, proportion valve and most of the steel lines.

 

F100 or F350? 300 CID or 460? Helpful members will want to know.

 

My bad - truck is an 1983 F150 with a HO 302 roller.

 

7 degrees ATDC? That engine should barely run at that setting. If it runs good fine, but it sounds like some miss-matched pieces there. If you get a piston stop and screw it into #1 cylinder, you can verify that 0 TDC is really top dead center for #1.

 

On your carb adjustment, I am not sure why so many people are afraid to adjust the mixture screws. They always turn them the recommended turns and then are afraid to adjust them afterward. That recommended adjustment is only there to get the engine running. You always fiddle with the adjustments after you get everything dialed in and it's warmed up. Turn one of them in till it runs worse, and the turn it out till it runs the best. Then do the same for the other screw. And then go back and do over the first screw and the do the second screw again.

 

My rebuilt 302 is a Frankenstein in that exhaust manifolds, distributor, Dura Spark II, tins, mechanical fuel pump are all '83 vintage, but the block, crank, rods and heads are from '96 - '98. Everything else is new aftermarket. When assembling the timing gears I had the marks facing each other at 6 o'clock and 12 o'clock. I verified TDC was truly TDC as I had a dial gauge on the piston top before slapping the heads down (marked balancer installed at time - correct). Here's something that just came to me...though I set the timing with the advance vacuum line removed and pluged I later checked the timing with the advance vacuum line installed. Is it possible my new stock replacement distributor retards to 7 degrees ATDC at idle (800 rpm)? I'm going to recheck timing with the vacuum line unplugged and then plugged.

 

Will give this a try thanks for explaining!

 

The standard procedure is to check the timing unplugged. But on most Fords, after it's warmed up and idling slow, most have the vacuum advance hooked to ported vacuum. This means there should be no vacuum going to the distributor at idle. If you have vacuum at idle, then you are plugged into the wrong port, or your idle speed is too high.

And on all cars and trucks, if the vacuum advance does activate, it "advances" the timing. This gives you a higher BTDC or Before Top Dead Center number. If you fire number 1 cylinder earlier or more in "advance", you are firing it more BEFORE the piston gets to the top. ATDC or After Top Dead Center is another word for "too late" the piston has already gone past and is on the way back down.

If you rev the engine just a little so you have vacuum on the advance unit, you should be able to plug in and then unplug the vacuum line and with the timing light watch the mark move more BTDC with it attached, and less BTDC with it unplugged.

 

What do think about the brakes? Thanks!

 

Have you tried re bleeding them, starting at the furthest brake drum , also check booster with mityvac tester , the booster non return valve can crack and make sure you've got a good rubber in booster. And good air brake hose. Cheers.

 

I'll triple check everything and re-bleed and see if that helps. I did a new non return valve and grommet. Would my booster possibly be faulty for not keeping pedal pressure firm when the engine stalled or is it normal to have the pressure drop off during a stall?

 

If you have all new pads they can take quite awhile to bed in also the brand and compound . I think when you mentioned the pedal was nearly on the floor and engine stalling that you would have had very low vacuum , you are lucky easy to pick up rebuilt booster if it is no good , a lot of freight for me , make sure you have got a good strong idle , good vacuum . No good if its a two footer at the intersection .Cheers

 

Sounds a lot like the vibration damper is horked, making timing marks pretty much useless too. It's not really 7° ATDC or it would run like ****. Did you replace damper as part of the rebuild?

When you get the damper/marks situation straightened out: Disconnect and plug the vacuum advance port on the carburetor or intake. Run it up with a light and check/adjust the distributor to see what you have. The important thing is where it ends up, not really where it starts - Figure around 34° BTDC is what you want to see it top out at, more if she'll stand it, with pump gas, somewhere around 3000 RPM. The initial number isn't critical at all, something more than 10° and less than 20°. Now if you use your truck to haul gravel, you'll have to be more conservative on your advance curve.

Take some test drives and advance or retard as required for your engine. Every engine is slightly different.

When you are satisfied with the mechanical advance, then re-connect the vacuum advance and adjust the vacuum can ONLY, for part throttle cruise acceleration ping. A slight part throttle rattle every now and then is OK.

That's just the initial bench setting, guaranteed pig-rich, so engine will start. When it's good and warmed up you can make a more or less final adjustment, at least seasonal. Follow the carburetor tuning instructions and lean the idle mixture out as far as practicable consistent with a smooth idle. Those needle jet screws are precision cut, just a slight turn will move the idle air fuel ratio a whole point. If engine is idling rich it will tend to "load up" and reduce idle quality after a minute or so, and the plugs will tend to foul.

 

I didn't have a timing light when I bought my current truck, & for a while I timed it just by advancing to the point of pinging, then backing off enough to eliminate the ping. I didn't realize until I put a timing light on it, that this was giving me an initial timing of 4 degrees ATDC.

I knew that the previous owner's mechanic had done a DS-II conversion on it........but I didn't know that he (or someone) had also put lighter advance springs in the distributor, but not set it up correctly. The timing curve was extreme & was advancing so fast that the initial timing had to be at 4 deg ATDC to avoid pinging caused by the mechanical advance.

Maybe you have something similar going on with your replacement distributor.

Another factor is that these distributors have varying amounts of mechanical advance; I have a spare 302 motor with a distributor that gives 42 crankshaft degrees of mechanical advance (plus vacuum & initial).
To know what you have, you need to either strip down your distributor to see the stamped number on the reluctor arm (this number gives the degrees of distributor shaft advance, which is half the crankshaft advance), or use a timing light to see the advance range, while the engine runs.

 

The rear brakes are usually responsible for a lot of the pedal travel. I would go back and jack one side up in the rear, and get a screwdriver and put it in the slot in the backing plate and adjust the adjuster till you can't turn the back tire(make sure the parking brake is off). Then back the adjuster off till you still have some rubbing, but you can turn the tire by hand. Then do the other side in the rear the same way. See what it does after that.