1982 Bronco XLT

[grumpin]

Good news! Good find on the spare truck.

[Weberman]

So I've wondered about this tach. I've calculated my RPM and its 1900, the tach says 3000.

Could the tach be bad or not properly grounded?? The engine sure doesn't sound like 3000rpm so I think the trans wouldn't be slipping.

[ArdWrknTrk]

The tach should have a terminal 'ground here for V-8' but otherwise I can't say that is the cause of your mis-calibration.

Unfortunately the entire instrument cluster changed with the advent of my model year, so I don't have one to refer to.

[Weberman]

Yeah I wonder if at lower RPMs it's closer since it's not that much but as it gets higher it gets further off.
I wonder if the cluster was from a 6 cyl truck? I'm pretty sure I saw rings all around the connectors. Unless they didn't ground it another way. May take it off and create a jumper and see.

[Weberman]

Somewhere it was not grounded. Thought about it and if a 4cyl 2x the RPM, then the 6cyl would be 1.5x. So that would make the 3,000rpm check out for a 2,000rpm V8. Took it apart, made a jumper and took it on the road and sure enough, little over 2,000 for 60mph.

[Gary Lewis]

Glad you figured it out.  

[Weberman]

Time to work on this popping at a pedal position. Doesn't really matter the RPM, just about mid pedal it softly pops, you can floor it and it doesn't pop, it just has the same power as it does when it is making the pops.

Gonna pull the plugs and see

[Weberman]

So I'm beginning to wonder if there is an intake gasket leak, just a small one, that may have become bigger. Or maybe the valves are out of adjustment? I have a video of when the guy sent me the engine, a video of when I first got it in the Bronco, and then now. The now video, it has sounded like that ever since I put the intake back on it. The other videos just sound like each other more and more healthy to me. The only difference really was the passenger head coming off and the intake.

Engine in the car: https://youtu.be/5GZeHthX57o
Engine first in the Bronco: https://youtu.be/yl4Qvca6X0Y
Engine in the Bronco now: https://youtu.be/MCq_wxn5vNI

Also this is what the #1 spark plug looked like, I don't think it looked bad, definitely not rich

[Gsmblue]

When my intake leaked it made a whistling noise.

When i poured some water over the leak the noise would stop and the engine would bog down a bit.

When i pulled the i take the gasket was mush. I never did like that edlebrock gasket and much happier i used felpro the second time around. It was a better fit from the start.

[ArdWrknTrk]

That plug looks fine.
How many miles are on it?

[Weberman]

Yeah I used the nice Fel pros, which is why I'm doubting the intake. But the first two just sound much healthier to me. The vacuum has dropped to like 12 too at warm idle.

The plug doesn't have that many miles, less than 1,000.

[Weberman]

Also didn't think of this either, forgot the engine is also only at like 7* of timing. I have it down that far otherwise it idles high. I forgot I had it that low to idle right, checked it to see if timing slipped. Which I would think could be some air getting by still as the carb is still all the way out too.

[ArdWrknTrk]

I'm not sure what you mean by"the carb is still all the way out"
The engine literally can't breathe if the throttle plates are closed all the way.
So it's pulling air from somewhere...

[nic55kel]

Just a thought but have you checked your PCV valve? It is a controlled vacuum leak.

[nic55kel]

It is possible your cam and PCV system do not play nice together.
A little light reading:
http://www.engineprofessional.com/articles/EPQ315_34-44.pdf

They are obviously selling their valve but it does show how changing things on an engine can have unexpected results.

[Weberman]

The idle screw is all the way out, and timing at 7* to keep it low is what I mean by the carb all the way out. I have a very small amount of adjustment left, wouldn't do much.

[nic55kel]

Your vacuum at 12" Hg is very low should be closer to 15 or higher. I am not familiar with the cam you have but I do not think it is radical enough to bring your vacuum down that much. It may seem counter intuitive but PCV valves let in more air as the vacuum drops (throttle opens). I imagine that you have a different exhaust system on the truck than was on the car and that could make a difference too.

Hopefully you find why the vacuum is so low.

[Weberman]

Yeah I couldn't find many vacuum readings with this cam but the few I did find were 15-17. Don't have cats, exit before rear tires,, glass packs.

May cap the PCV for now and then do the timing to where it should be, adjust the idle screw/arm all the way out and see where it ends up at.

I would think the intake would've shown up before as I've let it idle for awhile and done short quick trips. But I'm wondering if the long drive warmed everything up good and then made the leak worse perhaps and that's why it pops now. I would think a valve train problem would be RPM dependent not a pedal position.

[nic55kel]

Have you tried spraying something flammable (brake clean?) around all the possible places the intake may leak. The rpm will pick up noticeably when spraying near the leak. Just take the obvious precautions although that stuff evaporates so quickly the fan will quickly blow it away.
These problems are what make these older vehicles interesting.

[Weberman]

Well there may be a vacuum leak somewhere but there's bigger problems. Looks like the #5 exhaust lobe is wiped. Went to adjust/check them and when I took the valve cover off and went over to spin the engine, I noticed it barely moved and went and touched it and the pushrod isn't even touching the rocker.