high idle and no power up top

[77Datsun620]

ok I'm new to Datsuns, and just got a 77 KC, it starts up just fine, but has a high idle, with no tach, i would say 1000-1200 RPM, once i take off, its ok till 3000-3500??( if even that high) then it just has no power what so ever, Alot of the vacuum lines are gone, so im gonna start replacing those first, it appears to have all the smog stuff still attached and i dont feel like removing it, would rather just fix it right. From what i have found here, it sounds like the dizzy isnt getting enough vacuum? to advance and retard the timing as needed? And also i seen that someone said that i can find wiring diagrams at the620.com( that includes all the underhood lines alla my vacuum lines), any help would be great, ill get it right sometime, but with all of your inputs, i might get it right on the first try :D thanks in advance.

[datzenmike]

If you look on the valve cover side of the stock Hitachi carb, there are two vacuum ports. The one to the front should go to the vacuum advance on the distributor.(the other goes to the EGR) Remove the hose from the carb and take off the distributor cap. Apply vacuum to the hose by sucking on it and observe that the distributor advances. Hold the vacuum and note that the distributor does not return until vacuum is released. Check that hoses are secure and no leaks. This will test that the vacuum advance is apparently working.

 

The rear vacuum hose goes to the EGR. Check that the hoses are tight and not leaking.

 

Check that the carb mounting bolts (12mm) are tight.

Inspect cap, rotor, plugs and wires, and or replace.

Get the timing checked.

[77Datsun620]

I'll def try the hose to the carb and try the vacuum to see if the dizzy advance moves. The carb is tight, i have all the stuff for a tune up i just bought a fuel filter, fuel pump, new vac lines, plugs, wires, cap rotor, coil and a new resistor, and the motor has a newer rebuild on it, so ill whip out the Timing light, it should be 10 BTDC? Im hunting down a haynes manual atm,( lol dont know if it will help any) so if i check all that i should fix my problem /crosses fingers Lol if i cant get it over 3000 RPM, all the hillbilly's with there giant Ford F450 4 door diesel dually's will run my little ass Datto over XD

[datzenmike]

Unless you are in California, you will need new points too. This should eliminate any ignition related problems. No power over 3K could be fuel delivery problem at the carb. 10-12 degrees will work.

[77Datsun620]

It looks like a Cali truck maybe, im in TN now and bought the truck locally, It has a little black box inside the dizzy, so it should be EI? I dont think its a fuel problem, that ittle hitachi pumps fuel fine. The truck has a cat on it also, doesnt look factory, but neither does the exhaust( its got dual pipes out the back :lol: ) Thanks for the help BTW my name is Mike also ;)

[datzenmike]

The '77 California truck had a cat and remote igniter EI dizzy. Check under dash, above the pass side kick pad. There should be a black box a bit larger than a pack of smokes.... that's the remote igniter box. If the distributor has a small black (match)box on it's side it may have been replaced.

 

Mike is a good name.

[77Datsun620]

Ill look tomorrow since i have the interior out of it atm for new car cleaning and fixing, so it will be easy to see if i have the remote igniter. Ill take so pics and post them, then it will be easier, how do i post pics here? Photobucket?

[datzenmike]

Photobucket yes.

[77Datsun620]

I finally got to do some work on my truck, fixed a few vacuum lines and low and behold the idle dropped quite a bit, and once i got the cheap ass Autolite plugs out and did a full tuneup, It sounds like the idle is right where its supposed to be.

here is a pic of the inside of my dizzy

[77Datsun620]

Datzunmike you out there? I got to work on my truck finally, fixed the vaccum leaks and the idle dropped alot its way better now thanks for the help :) atm i have the timing mark at 11 and its ok there, but the truck just has no upper end to it, as i said i dont have a tach, so i cant say for sure, but from the factory it said 112 hp @ 5600 rpm, it doesnt sound like it get close to 5600, it feels to be 3500-4000 and its outta steam? any ideas? other than the fact that its a smog L20b with a W58 head.

Or is it just that im use to having V-8's, and the only other 4 cyl i have owned have both been supercharged, so maybe im not use to a low hp motor? It has nice pickup in low RPM's, It has what looks to be a rebuilt factory carb, and the PO said it was rebuilt, but we all know how that goes without having paperwork to back it up :rolleyes: and anybody is welcome to put in their $0.02

[Guest DatsuNoob]

I assume you got the 4 speed? Friggin tractor gears :eek:, If you wanna go a little faster and have the ability to save a little gas by driving at lower RPM's, I'd suggest considering changing your gear ratio. I think Datzenmike or Datsunaholic posted a list of GR's with different tranny and rear end options.

Maybe even de-smog that engine too. Mine seemed to run better without all that EGR crap and a weber kit from ebay. Just my 2 and a half cents

[77Datsun620]

Hiya Noob thanks for the response, but most emission stuff is gone, and its a 5 speed. its not the gearing, its the powerband of the motor that doesnt feel right, just seems like it runs outta power to early

[datzenmike]

Datzunmike you out there? I got to work on my truck finally, fixed the vaccum leaks and the idle dropped alot its way better now thanks for the help :) atm i have the timing mark at 11 and its ok there, but the truck just has no upper end to it, as i said i dont have a tach, so i cant say for sure, but from the factory it said 112 hp @ 5600 rpm, it doesnt sound like it get close to 5600, it feels to be 3500-4000 and its outta steam? any ideas? other than the fact that its a smog L20b with a W58 head.

Or is it just that im use to having V-8's, and the only other 4 cyl i have owned have both been supercharged, so maybe im not use to a low hp motor? It has nice pickup in low RPM's, It has what looks to be a rebuilt factory carb, and the PO said it was rebuilt, but we all know how that goes without having paperwork to back it up :rolleyes: and anybody is welcome to put in their $0.02

 

Been on hollidays. 11-12 degrees is fine. The smog head still flows pretty good. One posibility is timing chain stretch. This will effectively retard the can giving to the lower RPM while robbing from the top. To check for chain stretch see :

 

http://forum.ratsun.net/showthread.php?p=38197#post38197

[77Datsun620]

im gonna remove the valve cover soon anyway for paint. It is supposed to have a rebuild on it, but who knows, i would hope if they rebuilt it they got a new timing chain :rolleyes: ohh and also, i was cleaning under the hood, on the passenger side, there are 2 black wires coming out of the big harness that runs across the core support, the 2 wires look factory and are both in a metal eyelet connection but werent hooked to anything, any ideas? they look to be ground wires for something.

[datzenmike]

Even a new chain may be on the wrong numbered hole.

[datsunfish]

If you have a hitachi carb check the secondary throttle linkage.Mine acted that way.I came to find the arm from the vacuum pot had come off so I was only running on the primary.

[Guest DatsuNoob]

im gonna remove the valve cover soon anyway for paint. It is supposed to have a rebuild on it, but who knows, i would hope if they rebuilt it they got a new timing chain :rolleyes: ohh and also, i was cleaning under the hood, on the passenger side, there are 2 black wires coming out of the big harness that runs across the core support, the 2 wires look factory and are both in a metal eyelet connection but werent hooked to anything, any ideas? they look to be ground wires for something.

 

Looking into the engine bay from the front of the truck, which side are these wires? L or R?

[datzenmike]

If you have a hitachi carb check the secondary throttle linkage.Mine acted that way.I came to find the arm from the vacuum pot had come off so I was only running on the primary.

 

Good point too! Or just plain stuck or not working.

 

Also check that the mechanical advance weights aren't stuck. I guess revving up with timing light on would show if the advance is working. Maybe leave the vacuum line off so you don't mistake the vacuum advance for mechanical. I had a dime once and the plate under the points with the three ball bearings was 'stuck'. Greased with vasaline (know a bit more now) but it worked. The difference was like night and day!!

[77Datsun620]

Looking into the engine bay from the front of the truck, which side are these wires? L or R?

 

standing at the front of the truck, they are on the left side, just above the headlights. look to be a ground of some sort

[77Datsun620]

Datzenmike, where on the dizzy would these ball bearing be? i have a photo of my dizzy higher up in the thread. and here are some pics with the crank pulley on 0, this is where my cam is sitting. the timing chain is nice and tight.

let me know what you think.

[banzai510(hainz)]

if your poisitive you got it to 0 on crank and chain tite

the marks should line up to what 521gatherer has posted(photo) on the cam timming.

intake lobe should be close to the 10oclock positio,exhaust 2 o clock.

 

620.com has my vid i made and shows all this on timming chain issues. if you watched this you would awnser most of these questions

 

But if this truck was running fine before you got it then the timming chain is fine.

If you bought the truck as is and this was allready a proplem then maybe they put the chain in off a tooth or the oil pump spindal/distributor drive could be off also.

 

 

right off the bat I see that the dimple where a new chain link would(the dimple) go is farther down than normal. usually is more in the 2 o clock position up higher. if this motor is really lined up to ) on the crank.

 

 

great photo 521 gatherer

photo 1 ,should be close to this or V slightly to the right is fine also that I have seen depending on the quaility of the sprocket. Some have bigger V notch than others

phot0 2 Note Im using #2 timming but the location(the dimple) should be close to the same when its at TDC. Your sprocket show #1 dimple farther down meaning the cam is to adv(im guessing right now but off hand this is what I think going by the looks of things)

photo 3 look at the intake lobe its close to the 10o clock poistion behined the sprocket

[77Datsun620]

Ok, i went to look for my v notch on the cam sprocket mine has a small v, but it is lined up with the notch on the cam retainer, so i would assume that its lined up ok( and the truck has always ran Hainz ) but i noticed in the pics above, that the 1,2,3 on yours is set with the 3 on the top the 2 on the right, and the 1 down, mine is 3 to the left, 2 is on top, and 1 is to the right

 

would this be why it makes power in lower RPM's, versus Mid to High RPM's?

and i would watch your video Hainz, but with dialup its a no go :mad: damn country living :lol:

[banzai510(hainz)]

what ever # is near the 2 o clock position thats what your cam is put on the dowel(behind the fuelpump ecentric and washer).

going by the photo and what you tell me that is #1.

 

I have set mine to #2 before and be honest I cant tell the difference myself.

 

I myself never acually seen your type of sprocket with multiple inspection holes. But assume there is no other nearby V notch located right next to it behined there. Since its 1 2 3 I assume it will only have 3 V notches.

 

But if your positive its on Top Dead Center and the V is lined up then I say the cam is mechanically timed.

 

But really if this rig was OK like you said earlier then its not a mechanical timming proplem.

Now anwer this!!!!!!!!!!!

was everyhting ok before this happened. Then it could a carb issue. Vacuum secondary stuck on carb?Did you swap anything out and didnt tell us.

 

you have to be very specific on this otherwise Im going to ask you to pull the distributor and see if it lines up like this at 0 TDC

notice that its like in the 11.28 position(Look closely) ans when distributor is installed it should point almost excactly on #1 plug wire and the points should be open(if it has a point distributor)

also ck to see if distributor didnt turn to one side of the timming plate or can only run on one side of the timming plate. Loosen the 10mm bolt on timming plate and turn it to say 10deg using a timming light.

[77Datsun620]

ok here is the deal, i bought the truck, it ran fine, just the idle was very high, and most of the vacuum lines were gone. once i got it home, i hooked up the vacuum lines and the idle dropped down, now it idles great. The truck runs really good, no misses, knocks, pings or any of that. Like i said higher up in the post, its fine till about 3500-4000 RPM (idk for sure, no tach) then it just kinda runs outta power, it doesnt buck or act like its starving for fuel, im use to V-8's, and all my previous 4 cyl have had superchargers, I just think for an import motor, it should have more power up top. and look at the pic of my dizzy, i dont have points? do i? it looks like EI in there, and there is a black box inside on the pass side, in between the cab and dash( the remote box)? Everything looks good on the carb, and my timing is at 11

[banzai510(hainz)]

be honest i think everything is fine mechanically and probaply timming(electrical wise)

Duh I see your dizzy now!!!!!!!!what was i thinking, points??????

 

maybe can you give a speed while driving when this happens.?

 

all I can think is the sencondary not opening up on the STOCK carb. (make sure you stick your finger in the carb and make sure it moves)

fuel filter?

fuel float in carb?

carb linkage binding? Open to full max?

 

make sure the valve lash is adjusted

 

otherwise "I DONT KNOW"

Like Jeff Spicoli said, to MR Hand.

 

I DONT KNOW!