The vehicle we are working on is an 86 Bronco with the 351 w and a 4 barrel. It is not computer controlled. In the past month I have replaced the heads, timing chain, water pump, ICM box, the pick up for the ignition inside the distributor, rebuilt the carb, removed all emissions, new radiator, plugs, wires, cap, rotor, and redid all vacuum to give the motor only what is necessary, vac adv, egr, brake booster, etc. Timing from everything I have says 10 BTDC. The truck absolutely does not want to run at this setting. The best we can get it to run is at about 5 BTDC. It still pops out the intake and exhaust. The heads that were removed had 4 of the exhaust valves sucked up into the head excessively. I thought sure that was why it didn't want to run. So-here I am at pretty close to $1k into a $200 truck that still doesn't want to run. It has a slight miss at idle. On an 80 degree day you can reach in and pop the key and it runs perfect, except the slight miss. To get it to go over 3000rpm, you have to do it slowly, or it is popping too much to build up the speed of the motor. If you are trying to drive the truck, it actually does act like it wants to take off and run. We have checked and rechecked, set and reset the distributor till we are blue in the face. A couple of experienced people have suggested flat cam? I am exasperated at this point as this is the only totally legal vehicle we own right now. It is to be the wife's daily driver and I really need to get this done. Are there any windsor gurus out the with some insight? We are good mechanics and we have been hashing over this for a good long while now, and I can't keep throwing money at this truck. Any ideas welcomed at this point. Sorry for the long post, I was trying to give as much info as possible. Thanks guys

 

try the 302 firing order.....just might have a 302 cam in it

and make sure all the rockers are moveing while it's running.....might have a bad cam..

 

My son and I just put together a 66' 289,,on initial start up,,fired right off,,but ran rough, and it clicked,,or ticked through the carb when reving up,found #6 cylinder header tube to be cooler,,tried different plug wire,,still dead,,pulled valve cover,hhmm rocker was tight,,backed off to just abit of movement,,fired back up,,ahh better,,but still alittle rough,,pulled both valve cavers,,re-adjusted or checked each rocker,,making sure they were'nt tight( 3 seemed tight,,dont know why, did it by the book),,fired back up,,that was it, the 289 runs great now,,no ticking through the carb when reving, runs smooth,,well except for the Comp 268H cam,,check the valves ?

 

We are thinking a cam and lifters will cure it. There isn't anything else for the timing of the motor that has not been replaced. Also the fact that it runs better at 5 degrees than it does at the recommended 10 BTDC, makes me think this is cam related.

My parts guy, not a punk kid playing with the computer to find the part I need, says he doesn't think it is cam related. I asked why and he said because the popping back thru the carb means that the intake valve would have to be open when it fires on that cylinder. A flat lobe wouldn't do that.

I don't mind buying the cam kit if it'll cure it, but I am getting a little gun shy after buying so much and to no avail. I am hoping that the reason for so few replies on this is because I have covered everything that anyone else would have checked. I'm gonna try to come up with the money for the cam kit here in the next couple weeks, if anyone is curious how this turns out, I'll post back. Thanks for the input-it is appreciated greatly!

 

OK once again....

Have you tried the 302 fireing order????
Did you pull the valve cover and make sure all the rockers are moving the same?

Parts guys are parts guys.......

 

This is my thought too. Were your heads rebuilt or did you get others? If rebuilt were the valve stems cut down to get the proper install height? Check the valve lash to make sure they are closed when they are supposed to be.

 

I bought reman heads at advance auto parts. I believe the company that they were ordered from is called American Cylinder Head. Sorry Hemi Eater, yes we checked the firing order, and we have pulled the valve covers. I wasn't intentionally blowing you off, I just forgot to put that in my last post. I guess I'll rev it up and start pulling plug wires one at a time to isolate the problem cylinder and go from there.

 

yes but have you tried both the 302 and the 351 order...

 

i say the popping is because the rockers were tightened inproperly. seen it before 100s of times. what I usually do is bring the cylinder your adjusting to tdc on the compression stroke, and tighten them till they are tight then back off till there is just bearly any play. do this with all cylinders. then fire the truck with the valve covers off and back them off till it starts ticking. next tighten them until it stops then back off 1/4-1/2 turn. thats how I adjust all hydraulic flat tappet and roller tappet setups.

 

I don't think so...should have 1/4 to 1/2 turn of preload.
if he had adjustable valve train......
I think he is either useing the wrong fireing order or it's got a broken valve spring, stuck valve

if the heads are set up for rail type rockers (extra long valve stems) and he is using pedistle mount then he might have way too much preload, but I would think it would be so much it wouldn't even run.

do the valve stems stick up above the retainer?

 

sorry i miss wrote that, its been a long day lol.. i mean't back off then tighten about 1/4-1/2 turn.

 

If an exhaust lobe is worn off the cam the valve will not open and it will pop up thru the carb. I have had two ARP rocker studs brake on exhaust valves in the past few months
and it pops up thru the carb as you gas it.



hows it going?

 

ALL firing orders checked!!!! I have spent the last 3 days putting a clutch in my Mack at work. I need to recover for a couple days, besides, I have to back brakes to do on my other bronco. The wife drove my diesel to work yesterday and it came back white smokin out the right side and a very loud ticking. I am ready to sell them all and tell her to enjoy the shoe leather express. She's ***kin em up faster than I can fix em.

 

Okay. I got the other bronco's brakes done so I decided to play with this motor again for a little while just to see if there was something we might have missed. I invited a friend over that has a 10 second drag car, thinking surely he could find it. We put the timing light on it again but inside of 2 min. I guess the bulb went out. He timed it by ear and it now seems to run a lot better, at least it can be driven anyway. It has a serious lack of power. It is not popping through the carb now, but where the timing is set, it cranks over so slow you wonder if it's gonna start. I would like to repeat one thing that has me wondering now. When you are driving it, it'll surge for a second and then go right back to the way it's been running. Also, at and idle, cold or hot, it will just die, no coughing or anything, it just seems like someone simply turned the key off. With the hesitation/slight miss, intermittent dying, and the surging, I am beginning to suspect a weak spark, and at times the spark just stops. The only thing that has not been replaced is the coil. Think I oughta take the baster II coil off the 65 and see what happens? Does this sound like maybe a weak spark issue now? I am thinking about now is buying a coil and the cam kit just so I know that EVERYTHING is new from the deck up. What do you guys think?

 

hey try a different carb on it.....can't hurt....