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My 1971 521


d.p

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Did you see the timing light, it has RPM on it, jumps from 750 to +950 when spraying carb cleaner where the intake manifold meets the head. 

 

Yes I am, dies when I come to a stop, will start right back up and then rinse and repeat almost every time I slow to a stop.   Idle seems to jump around from 600-900 depending on what the truck decides to do at that time.  

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tighten the bolts a little more.I think your good anyways otherwise it wont run that low of a rpm if a bad leak.  If anything you water will be going low as the heat passage in head would get sucked in also.

 

if stops at idle sometimes then clean the idle jet and reset timming again.

adjust the mixture

speed screw should be should be no more than a turn if that.

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Yes it more or less a turn IN ward to hit the trhottle shaft to open the butterfly.

really mine is like a 1/4 after is touches.  If its really turn in alot(like say 2 turns in) that means the idle jet could be plugged and your running on the main circut.

if your not and say 1/4 turn after touching then your idle jet is most like OK.

 

it can be all a combo of a electric choke, mixture, speed screw and timming to get a best set running position. also if anything in a poin ignition wearing out or out of adjustment. 

 

also ck the lower bolts on the intake exhaust.

I have never done the starting fluid in the manifold before I seen your vid and look like yeah thats it. but to me If runs really low rmp its OK but tighening back up is free and this was recently done if I remember right. Thinking its a new intake exhaust gasket. Since you had the head off.

 

As for the statment, "This is never ending"  It usually will be. My Daily driver 12k a year 521 I dont go 2 months w/o something going  bad. Its usually a minor issue of soemthing just wearing out or getting a junk rebuilt parts like a alt or starter (weakkey switch included).

 

My Banzai Flag beater 510  over 8 yrs I have good parts and Nissan Alt ,starter  I never work on except the jet blocks backing out of the Mikunis carbs .But dont drive much either anymore.

 

My yellow convert 510 I sold(YES I sold it) I never worked on that one either. Hardest part was just trying to keep air in the 3 pc rims was a MOFo

 

 

next time my alt goes out Im going to try the Rockauto 35 amper they got ,Says a New Alternator. I know its China but Im going to try it. The Hitachi cores must just be wore out now as I dont get 1 year out of them. starters also.

Im going to try the starter sold Thru TSI Automotive 200$ which is a Denso unit and also sold thru TroyErmish at 510 parts outlet 240$  OF COARSE WHEN THESE GO BAD i WILL TRY

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I tightened all the bolts today and replaced the gasket back when I did the head. I replaced all ignition parts recently along with a pertronix. I will try and mess with the carb adjustments and check the idle jets.

 

Good point Mike maybe that is what’s happening. Will try and spray above it to see what happens.

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I did tighten all the bolts today, cleaned both idle jets and I replaced the intake gasket when I took the head off over the summer.  

 

Something else must be going on because I cant get it to idle right by doing the following...

 

1. Truck warmed up 

2. Idle speed screw touching the throttle shaft + 1/2 turn IN

3. Air/fuel mixture screw 1 turn out from bottoming out

 

If I turn the mixture screw in it bogs, idle gets rough and the RPMS drop.  If I turn it out the idle smooths out but it idles high around 900-1000RPMs.  I basically can't use the idle speed screw because my RPMS are so high from the get go. Anytime I back the speed screw out it isn't making contact with the shaft anymore. If I turn the idle speed screw in the idle climbs which is the opposite of what I want. I think before the idle speed screw wasn't even touching the throttle shaft I just didn't know it which allowed me to have a low idle based solely on the air/fuel mixture screw.   

 

Would a vacuum leak cause all of this?  I sprayed carb cleaner above the intake right around the base of the valve cover and it still surged albeit not as much.  

 

And crash said the same thing, these trucks are a constant battle which fucking sucks if you ask me. 

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I would agree with Mike, it could be getting sucked into the air filter when you spray.

I have most my L blocks idling at 850/900rpms, right now the work truck is at 1000/1100rpms since I changed the cam timing, maybe your trying to get the idle too low.

Try the idle at 900rpms, does it die then when you come to a stop?

Mine will die at 600rpms, that is way to low, it will not idle steady at 750rpms, it has a lope that low.

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I dont have a tack So I dont know if it 750 or not. soemtimes it might be But winter is here and I need it not to die at idle.

I adjust the mixture for best setting then I lower the speed screw if to hight and monitor the timming also. then try get to the specs. or dependingon the Gas issue(pinging) ill set to the dist

 

of coarse it runs better on more advance  but not to much till it pings.

 

just from my experience

ever carbcan be slightly different

 

ck later in 6months and maybe the timming moves a little

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Started over with the carb and got it idling around 825-850 RPMs at 12 BTDC. Idle speed is probably 1/2 turn in and the mixture screw is 1 and 1/2 out. Truck didn’t stall but only time will tell.

I just assumed everyone had theirs idling right 700 but mine runs like shit anywhere close to that.

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Started over with the carb and got it idling around 825-850 RPMs at 12 BTDC. Idle speed is probably 1/2 turn in and the mixture screw is 1 and 1/2 out. Truck didn’t stall but only time will tell.

 

I just assumed everyone had theirs idling right 700 but mine runs like shit anywhere close to that.

 

700rpms is at the low end, mine(ZL23 with dual SUs) in the past has loped real bad at 750rpms, it never died but I had to make sure I hit the gas pedal before I let out the clutch otherwise it would stall, but that is different than what you are talking about.

Just adjust it where it is smooth and then live with it unless it is above a 1000rpms, then you do have an issue if it is not smooth at 1000rpms, unless you have a radical cam.

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fuuuuck at my wits end with this truck.  The idle is anything but consistent.  

 

Sometimes it will idle around 750, I give it a little gas and it drops down to 500-600, other times I give it gas and it sticks at 900+ RPMS.  This is with the air filter off the carb (weber 32/36) and me just pushing up and down on the throttle lever.  If I have the air filter on (w/ return spring)and drive it around it does the exact same shit.  
 

I tried adjusting the idle speed and the mixture screws to no avail, neither of them eliminate this problem so either something else is going or the carb is broken somehow. Anyone have any ideas? 

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Quote  "Sometimes it will idle around 750, I give it a little gas and it drops down to 500-600"  End Quote

 

What happens when it goes from 750rpms to 500-600rpms, does it then speed and start to rev?

What do you mean give it a little gas, do you mean you tap the pedal or do you mean you keep your foot on the pedal and it yet loses rpms?

 

If you have a vacuum leak and have had one since the start you need to revisit every vacuum line, gasket, and devise the engine has, and one that most don't even think about is the PCV valve, this valve should not effect the idle, so remove the hose connected to it and plug it with your finger, if it changes the idle go buy another one.

You also have a Weber, so unless you bought an intake manifold made for the Weber you also bought an adapter, did the adapter have 3 gaskets, one for between it and the intake manifold. one for in between the 2 adapter pieces, and one for between the top adapter piece and the Weber carb, you had all 3, correct?

When and if you had the intake manifold off and put it back on did you use a new gasket?

It is also time to check every vacuum fitting the engine has, if there are fittings that have a cap on them, remove the caps and plug it with your finger, is the idle different with your finger on it compared to when the cap was on it, if it is the same the cap is good, check every vacuum fitting this way, even the ones being used, did the Weber have more than one vacuum outlet on it, one was for the vacuum advance, did it have another one anywhere on the carb, did you put a cap on it if it did?

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Is your adapter plate even or bent. I remember my 510 back in the days and my idle would go up and down and could not find vacuum leak. Then upon taking the carb out, I laid the adapter plate on a table and lo and behold it was uneven. I or the previous owner could have over tightened the bolts.

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Ill try to answer all your questions but here is a video of it what its doing.  

 

37579490825_96ef27816b_z.jpg

 

IMG_4949

 

 

What happens when it goes from 750rpms to 500-600rpms, does it then speed and start to rev?

-No it just idles really low and stumbles around until I shut it off or give it some gas which sometimes brings the idle back up and sometimes doesn't.

 

What do you mean give it a little gas, do you mean you tap the pedal or do you mean you keep your foot on the pedal and it yet loses rpms?

-Hold the throttle for a couple seconds. 

 

With my carb I had to use a tall adapter because of the emissions crap.  So it goes intake manifold > gasket > tall adapter > gasket > weber 32/36.  Vacuum advance comes off the bottom of the weber and its the only one and it goes to the dizzy.   When I had the intake off when I did the head I did put a new gasket on it.   

 

This is what it looks like:

 

35637750146_88a4113c0a_z.jpg

 

Will check the vacuum lines by plugging them.

 

I called webercardsdirect today (bought mine off ebay from them) and they said they would send me a new one. Told me I may have gotten a DGEV that they put a manual choke on because they ran out of DGVs but I doubt that.  I doubt it because he told me the DGVs have studs to hold the top plate down which I have already.  Also don't even know if this is genuine Weber, its stamped w/sticker but I don't see 'made in spain' or anything like that anywhere.  And I cant make heads or tails of who sells or what makes it a 'genuine weber.'

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