[junktrucker]

Ok, so I am new here, but I am not new to this truck. I have a 1985 Chevy Scottsdale C30. This thing is a pig, and acts accordingly. I've been all over this truck since I got it a year ago and my head has been itching over it so much that I've developed a balled spot. That said, the title explains it. I can't get this thing to surge here in the driveway, at all... period. and the only way I can test my "fixes" is to drive outa my subdivision to the local stretch and romp on her, which is where she decides to conform to her true nature; a no good, fumbling, bucking, squealing pig that wants to do anything BUT what I ask from her. Here's what I've done so far.
-New Mechanical fuel pump
-Cleaned out the gas tank
-Rebuilt Carburetor
-plug wires, and plugs
-oil change
-checked timing.... over and over again.
**cant find a true VIN CODE M Emmisions label for this truck.
-New coil, cap, rotor, ignition module
-HAVE NOT REPLACED DISTRIBUTOR
-Tested pick up coil... Checks out ok.... hmmm...
-Checked timing slack by watching rotor when turning crank by hand... no sign of significant slack.
-Drilled out fuel mixture screw covers... adjusted and adjusted... and adjusted.
-Checked vacuum advance mechanism for operation... yeah, it does.
-egr... oh yeah, the egr is there, but all ALL other emission stuff removed by previous owner.... pfft, fool.
-A/C system removed as well
-Cheap reman 63amp alternator put in place. tested yesterday at local dumbnut parts store... they say its fine.
-New PCV valve... yeah, I went there.
Now, my thing is, when I stomp the gas. it acts like it starts to rev up, the rev disappears and reappears several times, but not consistenty. the harder I push the gas the more pronounced it is. but it doesn't change a bit. It just does not like more than half throttle at all. and I'm lucky to get half throttle most of the time.
Please get me outa the pig farm. it stinks in here!

 

[geo1]

Can you do a vacuum test and post back, you covered everything else,darn truck

 

[junktrucker]

I've been a bit buzzed tonight... which ports? I did notice that it seems I've lost vacuum more recently than this situation occurred.. testing by feel, I noticed the ports on the carb aren't sucking as hard as they used to... I think I caused this issue by f*ing with the tranny vac. solenoid.. I think I remember ripping the boot that goes into that solenoid... or what that is. anyway.. i'll plug that tomorrow and figure out how to check vacuum too. I've got to go get a vacuum guage... you might be on the right track... if that vacuum to the tranny was already deteriorated to the point where I barely wiggled it and it fell apart, all while I was trying to put a reman starter in... maybe the vacuum's been, well, not sucking enough, which would suck.

 

[geo1]

And is there any backfiring in carb?I had a 84 carbed truck , similar problem,head gasket was leaking between two cylinders,and only when I got on it

 

[geo1]

Modulator I think,get your connections tight,any line with vacuum at idle will work

 

[junktrucker]

I'm not sure... the only way it surges is on the road, and it certainly backfires out of the exhaust... scared the evil outa me once. but I don't hear a cough or spit from in front of me. Btw... this thing backfires so hard that it blew out both mufflers (literally blew the mufflers like a soda can in a freezer)... I decided to cut the pipes to just before the mufflers.

 

[junktrucker]

modulator? the trans vac switch is called the modulator... or?

 

[geo1]

So unburnt fuel igniting in exhaust, tailpipe black and sooty?

 

[junktrucker]

Oh, btw, I've sprayed starting fluid all around the engine... no bog caused. I know there can be internal leaks but I couldn't catch a bog from that test... I did catch my distributor on fire once when I sprayed that stuff near it... that was a pleasurable experience.

 

[geo1]

Use water in spray bottle,much safer,ha

 

[junktrucker]

yes, unburnt fuel at exhaust tip. And on that note, while I was looking for stray sparks from ignition components today, I noticed that where my header is leaking on the passenger side, I can see that in the miniscule gap between the exhaust port and the header, there is visible light caused by ignition. I thought that to be strange, but I'm guessing that combustion may complete as the exhaust valve is opening.

 

[junktrucker]

Use water in spray bottle,much safer,ha

NO FUN!

 

[geo1]

Lifters adjusted too tight,valves not seating 100%?a bad vac line should make you run lean and bit higher than normal idle,a lifter adjustment might be a problem,odd, but stuff happens

 

[junktrucker]

ok, so grab my feeler gauges and pull valve covers... u thing that's my surging issue? like I said, it doesn't surge in park... only driving down the road and pretty much at half throttle or better... I can rev this truck like a racecar in the driveway and it b-lines it to beyond redline...

 

[junktrucker]

BTW, what's my vacuum at idle (Near 0 at WOT I believe)?
I should sign off for the night, and I'll pick up at my earliest convenience. It's the only vehicle I WANT to drive this winter... not that it is necessary that it runs, but I hate it when the things I've got don't play their roll.

 

[Zach Smith]

BTW, what's my vacuum at idle (Near 0 at WOT I believe)?
I should sign off for the night, and I'll pick up at my earliest convenience. It's the only vehicle I WANT to drive this winter... not that it is necessary that it runs, but I hate it when the things I've got don't play their roll.

15-18 for vac, should be steady (not bounce)...and no on feelers...GMs valve adjust procedures suck...always off (for 5.7 and 4.3)...just warm engine, pull v covers, run engine... (You will lose some oil and make a bit of a mess if you don't have modified v covers for this) back off valve till "clacks" slowly tighten till clack goes away...do this for all valves (16 times) shut down engine ,let cool. Turn all valves 1/2 to 3/4 full turn (do ALL the same). Replace valve cover, check oil. Unless you have solid lifters...

 

[Zach Smith]

You can get an idea of what is happening by checking your plugs...what do they look like?

 

[geo1]

It was in another thread, but what if you're harmonic balancer spun?and you're timing is retarded, just throwing ideas out there,but do tighten up that vacuum line

 

[junktrucker]

It was in another thread, but what if you're harmonic balancer spun?and you're timing is retarded, just throwing ideas out there,but do tighten up that vacuum line

Can you explain "Spun"? I Will look into that. I have a timing light, and I'm about to explain what I saw setting TDC for valve adjustment... Bear with me.

15-18 for vac, should be steady (not bounce)...and no on feelers...GMs valve adjust procedures suck...always off (for 5.7 and 4.3)...just warm engine, pull v covers, run engine... (You will lose some oil and make a bit of a mess if you don't have modified v covers for this) back off valve till "clacks" slowly tighten till clack goes away...do this for all valves (16 times) shut down engine ,let cool. Turn all valves 1/2 to 3/4 full turn (do ALL the same). Replace valve cover, check oil. Unless you have solid lifters...

I'm in the process of doing just that. And I think I've stumbled upon an issue...

You can get an idea of what is happening by checking your plugs...what do they look like?

I checked the plugs, and as they've been since I got her, they are lightly sooty with carbon. Not oil soaked, white, damaged, etc..

AND FOR THE REVEAL. I think I've stumbled on a potential problem, but I ran out of good weather to finish looking... It started raining... I wanted warmth... and a beer. Anyway, I set the engine to TDC NO.1 and found that my rotor is pointing almost down the centerline of the truck (Belle is here name). I've got the valve covers off, but like I said, it started raining so I didn't proceed to check if the timing seemed skewed. I'm assuming if my timing is off (IE: jumped a tooth), then My valves would move differently than what TDC shows.

- The rotor is point just southeast of centerline at TDC
- If I try to adjust the distributor anywhere near that location with NO.1 spark plug... the engine runs like (insert poo emoji)
- I'm Confused about "spun Harmonic Balancer" as of yet, but I'll look into that.
- Does anyone see their rotor pointing just southeast of centerline? or should it be more east... like if you place a stop sign on center line and it should be closer to the southeast most point of the sign.... I guess I should upload a picture at this point.
- I tried to stand as close to centerline when I took this picture, so...

 

[geo1]

Spun,meaning the outer layer slipped on the inner layer,Wich is separated by a rubber like membrane,that deteorates over time,so the line on the outside ring for the timing lite is off