Point Gap Size In 289?

[jmcallis]

Hey guys,

I'm new to the Early broncos so I haven't even gotten my manual yet. So does anyone know what the point gap is supposed to be for my 66 289 4spd? I want to confirm it is set correctly. The engine has a slight backfire when I back off from full throttle.

Thanks

Jason

 

[STLKIKN]

According to Chilton...

.034 gap for the plugs

.017 for points

6 deg btc for timing

 

[jmcallis]

Thanks a ton.

I'm going to check to entire system tonight. I want to be sure as much as possible that my carb needs a rebuild before I pull it off.

Jason

 

[Broncoholics]

If you have 3" exhaust or some leaks you can get some small back fires when the throttle is released quickly.

Does the truck ever want to keep running when you shut the engine down?

Could be too far advanced on the timing.

What carb do you run?

 

[dbolsenga]

hay you can set the points at .017" and this will get you close but it will be wrong.

the way to do it is to pull the plugs and leave them out! pull the seconary coil wire.

so you dont get zaped.

use a dwell meter so you can set the dwell angel. dwell should be at 29 degrees.

to do this key on use remote starter switch hooked up to the solinoid. spin the engine over and set the points.

once the dwell is set put it back together set the timing then balance the carb and you should be good to go. remember on an old ignition system dwell effects timing.but timing will not effect the dwell.

 

[jmcallis]

Hey guys,

thanks for all the feedback. I figured the dwell is off. THe points are right in at .017 but I still get a weak engine. Runs like a 4 banger. I will try the dwell test. What was that about balancing the carb? How should I start that, do you mean just be sure the rpms are right? Any other thoughts to check? Cap, wires and plugs are all good. My carb is the stock 2 bbl. Some gas has leaked through the accelerater pump piece in the front of the carb. I tightened to screws and it appeared to stop. The truck never stays running when I shut it off, idles great, and starts up great warm and sometimes a bit rough in cold start.

Thanks again guys,

Jason

 

[jmcallis]

Hey guys, thanks for all the info so far. I was away from my computer and I couldn't remember the dwell angle for my 289 (29 degrees). So I have another question. When I do the plugs and coil wire removal do I need to pull off the vacuum advance tube too? My points seem to be at .017, but the dwell was at 18 and then it would vary to low 20's. I image that the dwell being that far off would cause a real performance problem. I will take another stab at dialing in the dwell before I adjust the valves. I hope that solves my lack of power problem.

Anyone out there know what the valve clearance specs are for a 66 289? Should I have hydrolic lifters, not solid right?

Thanks a ton guys!

 

[Broncoholics]

You take off the hose to the vacume advance when checking the timing. Not sure ont he dwell.

 

[dbolsenga]

if its stock you have hydro lifters

to set the lifters you should realy have a book that will walk you thru it.

 

[jmcallis]

Yeah, I just got the diagram on which valves to adjust and when. Looks pretty simple. I also found that the book suggested that with the 289 you should adjust the valves every 10,000 miles. How many of us do that? I'll post how it turns out on Sunday.

 

[jmcallis]

Hey I'm looking at my valves right now. They should be .022 cold or .018 warm. I can only get a .005 feeler gauge under the appropriate valves when I have the crank in the right possition. The previous owner was a punk, so do you think he just over tightened the 289s valves or could the gaps closed up over years of non-adjustment? I was going to just back off the bolts and reset the gaps. Does that sound correct?

Thanks for your feed back.

 

[dbolsenga]

go back to your book if this motor is stock it should have hydrolic lifters which means there is no valve lash.