1970 302 idle, run, timing issues

[Drewski+82]

What up fellow ford fellas? I’m new to this forum, so be gentle with me. What I’m about lay on y’all is going to be a lot so bare with me, we’ll get through this.

WHAT IT GOT
I recently bought a 1970 SWB F100 302 w/C4 from a friend. The engine INTERNALS are STOCK. All of the following is new stuff that was added by previous owner….
-Edelbrock AVS2 1901 500cfm carb w/ auto choke
-Edelbrock alum intake
-mech fuel pump
-distributor w/ vac advance(on manifold vac)
-Edelbrock max fire coil pack w/plugs(.035) & wires
-water pump & thermostat
-alt
-alum radiator
-valve cvrs
-fuel tank
-On the exhaust, cats were cut off and cherry bombs installed(the in cab exhaust drone is horrible)and there are 2 exhaust leaks with clamps installed.

WHATS THE ISSUE
The truck starts up perfectly, idles around 1000 rpm and is responsive when I rev motor, but when I put it in gear it dies. I can not get it to idle below 1000 rpm without it running rough or wanting to kill. When adjust timing on the distributor, the vac advance is hitting the radiator hose. I have tried multiple times to uninstall/reinstall the dizzy to give more room for adjustment with no luck. I feel like I’m a tooth off on the distributor.(recently found out the vac advance is F-ed and needs replaced).
When idling the exhaust fumes from the tail pipe are strong, the valve cover breather on the 1-4 side has a good bit of smoke coming out, and if I pull the oil dipstick a little smoke comes out(this leads me to believe a rebuild is on the near future). I checked/changed the spark plugs I noticed they were coked up. So thinking that I’m too RICH, I cut back on the idle mixture screws as far as I could. When I adjust idle mixture screw on the 5-8 side I see NO CHANGE in vacuum psi, but when adjusting on the 1-4 side vacuum psi changes as it should. I thought maybe the fuel pump psi might be too high, but it puts out 4-5 psi @ idle. Also, therefore is a hissing noise coming from inside the carburetor at idle.

WHAT I’VE DONE
-Broke down/rebuilt carb and adjusted per Edelbrock specs
-pulled/drained/washed out fuel tank
-replaced ALL rubber fuel hoses(not hard lines from cab to engine)
-replaced fuel filter with inline Edelbrock filter(between pump discharge and carb)
-replace spark plugs(first set was coked up)
-checked timing mark to TDC multiple times, remove valve cvr to verify
-adjust points in distributor
-uninstalled/reinstalled distributor(set 10 BTDC and 32 vac@2500)


Help me out fellas. I’m dying to get this buggy on the street

[DuckRyder]

Do edelbrocks have transfer ports that could be un covered like a Holley if idle is set too high?

Is the distributor just a parts store rebuild, or something nice? Are you sure 2500 is enough to have all the advance in?

The no change in vac on the 5-8 side is puzzling, I’d suspect a vac leak or perhaps a damaged carb, sometimes people will crank down on idle screws and damage the seat cast into the carb.

Do you know what converter is in it?

[Drewski+82]

Edelbrock has transfer slots and there is a recommend setpoint for them in which my carb is set.

Distributor is nothing fancy probably store bought.

As for vacuum advance, 2000-3000 rpm range is where it would kick in.

I have already had to replace the carb manifold because the previous owner broke the idle mixture screw tip off and lodge it in the seat. The only other thing I could think is that I could have a miss fire on the 5-8.

I’m not sure as to what converter you are asking about, but if you mean the catalytic converter there are zero-manifold, pipe, cherry bombs

[DuckRyder]

Toque converter.

[Drewski+82]

I don’t know, I think the transmission came from an early mustang

[DuckRyder]

While I collect the rest of my thoughts,

Assuming it is safe to do so - what happens if you drop it in gear without your foot on the brake and let it roll off?

You don’t have a friend with an extra known good carb do you?

[Drewski+82]

What’s the logic behind putting it in gear and let it roll off?

[DuckRyder]

It helps eliminate a too tight or defective torque converter.

When you sat it’s a stock bottom end - stock what? Truck or passenger car and approximately what year?

Also when you say it runs rough if you try to idle below 1000 - is it choppy like camshaft choppy or just missing? Are you positive no one has stuck a cam in it?

[cep62]

how much vacuum is it pulling when you're adjusting the carb ?
You have an aftermarket intake , maybe a vacuum leak
spray good carb cleaner around the intake when it's running and see if it changes idle.

[DuckRyder]

BTW.



Disclaimer: I’m not an edelbrock carb guy nor a small block guy, but.

So clearly the no change in mixture in the one mixture screw is a problem and assuming that the internals are in fact stock the 1000 idle is way too high.

Questions/ ideas.

You said the vac advance is bad? It this Is to a manifold runner it could be a vacuum leak. Remove the hose from the manifold and plug it. (In fact I would keep it that way until figure out what’s wrong.)

Check thoroughly for vacuum leaks paying particular attention to the cylinders fed from the 5-8 side of the carb (it’s probably not 5-8) .

If you can find no other reason for the lack of change on the mixture screw I would replace the baseplate containing the mixture screws or the carb.

I don’t think that the distributor has much to do with your issue, however typically on a ford you drop the distributor in with the vac advance can pointed straight forward on #1 tdc or timing mark. This should get you the needed timing adjustment without hitting anything. 2500 is not nearly enough to get total timing unless the distributor has been recurved, but for purposes of this discussion it does not really matter. You may be getting a few degrees of advance out of the centrifugal advance at 1000 though, so if you can idle it down to 750 or so recheck initial.

Verify the marks on the balancer as well.

If this is a cheap rebuilt points distributor I would replace it with an electronic distributor.

CEP has a good question about how much vacuum it is pulling (and is it steady).

[6Delta]

I had much the same setup on one of my Rancheros, except for I had the 1st generation AVS and a Pertronix ignition/distributor. I wonder if you could have a bad intake gasket leak (manifold to head or carb spacer) causing a problem? Also, with no knowledge on the cam or actual mileage, your harmonic balancer may have slipped a bit and you may not be close on your initial timing. ( Don't forget early Fords had that crappy timing gear that wore often and screwed up the cam timing over time.) Check the vacuum readings closely and if need be you can rotate the timing of the spark plug wires to achieve a little more room if the advance mechanism is hitting and stopping the dist. from rotating enough. Watch the Edelbrock videos closely and you may need to order a needle and jet kit for fine tuning. I am close to sea level and my carb was close out of the box. I became fond of it after a while.

Also the PO did not remove any catalytic converters as they were not in use in 1970. For the "drone" just route the exhaust farther back and either behind or out the side . Not under the bed. Good luck.

[Drewski+82]

Thanks y’all for the reply’s.

-Thursday evening I uninstalled/reinstalled my distributor and was able to get the distributor positioned so the vac advance was facing the front of the truck. I now have no issue with adjusting the timing
-Friday morning I bought a carb rebuild kit and rebuild it. After getting the carb installed and adjusted I had the truck idling at 900 rpm’s. I sprayed carb cleaner around and saw no change in vacuum psi. It was responsive when I rev’ed it, however when I put it into gear it bogged down and killed. I was able to start it up right after and it idled perfectly. I tried holding the brake with one foot, had the other foot over the gas, and put it into gear. As it bogged down I gave it a little gas and was able to keep it running. But when I stopped giving it gas it killed.

[DuckRyder]

Still think you are fighting the torque converter, 900 is still to high for a stock bottom end, should be more like 500 in drive.

Were you able to affect change in idle with 5-7 side mixture screw now?

We asked quite a few other questions, noteably what’s your idle vacuum reading and is it steady? If not steady how does the needle act?

[Jbarnes79]

I had a similar problem and found a nasty vacuum leak at my brake booster.

[cep62]

are you sure your tach is accurate ?
some have settings for 4,6,and 8 cylinders.