So from the start, vacuum line repaired?now time the motor by ear, keep advancing,bit by bit,at operating temp,shut off and restart,until it bucks on the starter,then back off a bit,or with vacuum gauge,stop at highest reading
5.7 SBC Surging on acceleration and under load in gear only.
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!
-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!
21 - 40 of 61 Posts
Ahh. I'll look closely at the Balancer. What's your thoughts on the rest?
Haven't got to that repair... seems the vacuum line is sealed to the modulator... can't patch it... gonna have to get a new modulator.So from the start, vacuum line repaired?now time the motor by ear, keep advancing,bit by bit,at operating temp,shut off and restart,until it bucks on the starter,then back off a bit,or with vacuum gauge,stop at highest reading
One way to check tdc, take bolt out of balancer, keyway will be straight up @ 0 or180,then check rotor pointing at no1,or no6 @180 out, another idea, before bolt removal,use breaker bar on bolt,go back and forth,see how much timing chain stretch you have
I'm assuming you mean looking at the rotor as I am using the breaker bar. If so, Yes, I have done that multiple times, and It seems very tight. Maybe someone replaced the chain and was off on their install? All other information is noted.One way to check tdc, take bolt out of balancer, keyway will be straight up @ 0 or180,then check rotor pointing at no1,or no6 @180 out, another idea, before bolt removal,use breaker bar on bolt,go back and forth,see how much timing chain stretch you have
Ok, I'll give... fix the vac. leak... do my test... but the rotor position at TDC... any thoughts geo1? noting also that I saw combustion between header and exhaust mating point.
-----Looking back at this post I wrote last night, I realize that I actually took the distributor out at one point and tried to set it closer to where it looked correct. It didn't run well at all when I did that so I just put it back.. I think before I worry about that trans modulator I am going to come home straight after work and follow those valves closely when turning the crank... I think it's my issue.View attachment 110089
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.
- 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...
About the balancer . . . it should be called a vibration reducer. There's a rubber membrane between the inner hub fixed to the crank and the outer weighted ring with the timing mark on it. The rubber absorbs the power stroke of each piston reducing inertial vibration to the valve train. When the rubber deteriorates the outer portion (and the timing mark) can rotate relative to the crankshaft, throwing the timing mark off.
You can attempt making a new #1 cylinder TDC mark in the outer portion of the balancer as a workaround but if it's still slipping around you can still get timing off. The only real solution is a new balancer.
Ted
You can attempt making a new #1 cylinder TDC mark in the outer portion of the balancer as a workaround but if it's still slipping around you can still get timing off. The only real solution is a new balancer.
Ted
About the balancer . . . it should be called a vibration reducer. There's a rubber membrane between the inner hub fixed to the crank and the outer weighted ring with the timing mark on it. The rubber absorbs the power stroke of each piston reducing inertial vibration to the valve train. When the rubber deteriorates the outer portion (and the timing mark) can rotate relative to the crankshaft, throwing the timing mark off.
You can attempt making a new #1 cylinder TDC mark in the outer portion of the balancer as a workaround but if it's still slipping around you can still get timing off. The only real solution is a new balancer.
- Ted
I set my initial timing with my timing light at 10 DEGREES and its smooth idling.
The point of my post is what you point the timing light at. How do you know the timing marks are where they are supposed to be? Is your balancer one solid piece?
Ted
Ted
Did a valve adjustment on the truck and now it won't start... It may be a while till I get back to it.
How probable is it that the balancer has spun? Is this common?
How probable is it that the balancer has spun? Is this common?
How did you do valve adjustment, feeler gauge way or 1/2 to 3/4 turn way? As to the balancer...if its never been replaced...likely enough.
I have had this same issue and tried a to z. I replaced the fuel pump 6 different times. In the end it end up being the housing that holds the fuel pump in the tank.)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!
This older truck has a mechanical fuel pump. The suction is only at the sock at the bottom of the tank... I put fifteen gallons in it after cleaning the debris out of the tank. No change.I have had this same issue and tried a to z. I replaced the fuel pump 6 different times. In the end it end up being the housing that holds the fuel pump in the tank.)
3/4 turn... then 360 out... 3/4 turn on the rest... but...How did you do valve adjustment, feeler gauge way or 1/2 to 3/4 turn way? As to the balancer...if its never been replaced...likely enough.
I returned it back to TDC Number 1 and noticed almost all pushrods in this sequence were still loose. I went for another round. 3/4 turn on everything again but only after I barely tightened it back to no spin on the pushrod. Was this second go around wrong?
-My reason for doing it again was that I "assumed" that there was a ton of caked old sludge at the several contact points between cam and valve. I figure I smushed that crud out of there and needed to tighten again.
Yeah...well as long as we arnt hitting valves...turns by hand, no hard spots or tinks, when you tried to start it? Hydraulic lifters bleed as they sit...allowing slack. They are probably cranked way to tight now. I would do the factory adjust now, then see if I could start it...then, do it the way I said earlier....
1.Warm engine
2.pull valve covers
3.start engine, making sure all is clear
4.roll adjuster back until valve starts to clack...
5.roll adjuster forward slowly until clack goes away
6.do this for all valves
7.shut down engine and let cool
8.roll another 1/2 to 3/4 turn on all adjusters, staying the same across all adjuster's either 3/4 for all or 1/2.
9.start and check
10.assuming all is well replace valve covers.
Another option... Do a compression test and back off low cylinders.
Or back all of them back, the last 3/4 turn adjust you made...but I think (with what you just explained to me, that you did) (I should have numbered steps as I did for you this time, so I'll take part blame for not laying it out well) the first option, though the most tedious is probably the best.
1.Warm engine
2.pull valve covers
3.start engine, making sure all is clear
4.roll adjuster back until valve starts to clack...
5.roll adjuster forward slowly until clack goes away
6.do this for all valves
7.shut down engine and let cool
8.roll another 1/2 to 3/4 turn on all adjusters, staying the same across all adjuster's either 3/4 for all or 1/2.
9.start and check
10.assuming all is well replace valve covers.
Another option... Do a compression test and back off low cylinders.
Or back all of them back, the last 3/4 turn adjust you made...but I think (with what you just explained to me, that you did) (I should have numbered steps as I did for you this time, so I'll take part blame for not laying it out well) the first option, though the most tedious is probably the best.
Ok, I'll go with one full turn back and try to start it. Then a half turn if it doesn't start. Oh, but first I'm going to make sure I've got spark.
Then I will certainly take you up on your method.
I guess I didn't grasp the concept of the hydraulic lifters, and maybe they are slam wore out anyway.
Then I will certainly take you up on your method.
I guess I didn't grasp the concept of the hydraulic lifters, and maybe they are slam wore out anyway.
Your truck, your job, but I suggest going the long rout at this point...
Yeah, thats what i meant. Ima go ahead and back em off a full turn instead of just 3/4th. Once it starts ill plug and chug on your process... or do you mean something else?
I meant go ahead with the factory setup (feeler gauges), that should allow it to start...prob have some clack though, then go forward with valve adjust procedure that works. I.e. the feeler gauge way should get you close...then get it right after that.
Oh, yeah. Gotcha. Dirp. Back to the former, I found out that that vacuum to the modulator is replaceable... also, I'm still in search of a cheap vacuum tester... I'm pretty busy these days so it may take me a couple daysto acquire one. In any case, i looked at the balancer and it looked like the rubber has split in some sections... but i watched the rockers travel when nearing and passing . TDC and they seemed well centered on TDC. Which I assume this proves timing is spot on. I'm hoping that my adulting doesnt interfere with finishing these few adjustments tonight.
21 - 40 of 61 Posts
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