84' c10 stalls in gear

[Bain]

I know this has been brought up millions of times before because I've spent a ridiculous amount of time reading old threads on the subject but I still haven't found my solution so...

I am working on a buddy"s 84' c10. A while back his original th350 tranny went out on him and he had it replaced with a 700r4. Then a short time later his original 305 blew on him so he bought a 350 from a salvage yard and asked me to help swap it out. Now with all that said the job is almost completely done with the exception that it dies as soon as its put in gear. It will idle in park just fine if the carb is adjusted just so otherwise it spits out of the carb. I have checked vacuum lines a dozen times since that seems to be the number one cause of such a problem and I have sprayed the carb base and intake manifold with starter fluid but still found no vacuum leaks. When I put the vac gauge on it I'm getting a smooth 19 hg from both carb and manifold ports. I've also tried adjusting the carb according to instructions I've read online. Currently I'm all out of ideas. I would suspect the convertor except he was able to drive the truck over to my house without any stall problems. Basically I'm out of ideas so any suggestions would be greatly appreciated. Thanks!

Oh and it has a quadrajet carb on it as well in case that is pertinent.

[j cAT]

Originally Posted by Bain

I know this has been brought up millions of times before because I've spent a ridiculous amount of time reading old threads on the subject but I still haven't found my solution so...

I am working on a buddy"s 84' c10. A while back his original th350 tranny went out on him and he had it replaced with a 700r4. Then a short time later his original 305 blew on him so he bought a 350 from a salvage yard and asked me to help swap it out. Now with all that said the job is almost completely done with the exception that it dies as soon as its put in gear. It will idle in park just fine if the carb is adjusted just so otherwise it spits out of the carb. I have checked vacuum lines a dozen times since that seems to be the number one cause of such a problem and I have sprayed the carb base and intake manifold with starter fluid but still found no vacuum leaks. When I put the vac gauge on it I'm getting a smooth 19 hg from both carb and manifold ports. I've also tried adjusting the carb according to instructions I've read online. Currently I'm all out of ideas. I would suspect the convertor except he was able to drive the truck over to my house without any stall problems. Basically I'm out of ideas so any suggestions would be greatly appreciated. Thanks!

Oh and it has a quadrajet carb on it as well in case that is pertinent.

how did you adjust the carb ? explain your procedure.

what is the idle RPM set at ? what is the condition of the fuel vapor hoses at the intake manifold ? what is the timing set at ?

what is the condition of the EGR ? is this 20 yrs old ?

[Bain]

Well I read to turn the mixture adjustment screws all the way in then back them both out 2 1/2 turns. Then do the same with the idle screws only 1 1/2 turns. Next I started it up and tweeked the idle till it sounded good. It doesn't have a tach so I am just doing it by ear. The carb would spit a little from time to time still so I backed the mixture off a little more because I noticed if I cover the carb with my hand it ran smoother an that seemed to solve the spitting problem but it still died once put in gear. The vapor hoses are in good condition. And the new engine actually didn't have an egr valve installed so I pulled a plug and installed the one off the original. When I checked the timing it was a little advanced from the "0" marks it didn't have the usual plate that shows the 8 degrees on either side so I compared the distance to the one on my camaro and although it's just an estimation it looked to be between 6-8 degrees advanced.

[j cAT]

Originally Posted by Bain

Well I read to turn the mixture adjustment screws all the way in then back them both out 2 1/2 turns. Then do the same with the idle screws only 1 1/2 turns. Next I started it up and tweeked the idle till it sounded good. It doesn't have a tach so I am just doing it by ear. The carb would spit a little from time to time still so I backed the mixture off a little more because I noticed if I cover the carb with my hand it ran smoother an that seemed to solve the spitting problem but it still died once put in gear. The vapor hoses are in good condition. And the new engine actually didn't have an egr valve installed so I pulled a plug and installed the one off the original. When I checked the timing it was a little advanced from the "0" marks it didn't have the usual plate that shows the 8 degrees on either side so I compared the distance to the one on my camaro and although it's just an estimation it looked to be between 6-8 degrees advanced.

to get the 2 mixture screws close you back out the screws 2.5 turns set idle to 800 rpm you will need a tach/dwell meter hook up to the dist cap connector where it says tach . place the tranny in drive . block wheels E brake on. now with this @800 rpm and the screws backed out 2.5 turns you turn each screw in until it drops 50 rpm until you get to the 500 rpm which is the correct idle... this is called the lean drop method this is close , not perfect but it works most times. the other issue is the EGR these are bad when 10 years old they will leak intermittently so replace.. you must also check that the intake manifold EGR bore is not plugged up this happens directly below the carb between the 2 primary barrels . this will effect the idle and smoothness of operation. when opening the egr by hand at idle the engine should stall..

make sure the exhaust heat riser passenger side is not stuck or partially stuck closed .. if broken use a steel wire to force full open.

the timing need be set to 6-8 Deg btdc @1100 RPM. the O should have the tits on each side of it , that are I think each 2 deg or 4 deg each ...the engine rotates in a certain direction the before TDC should be on the side it it rotating. any way if your increasing the timing before TDC the RPM will increase so you will know that that is the proper side of the O mark.

with the computer on these it does change the timing at idle sometimes so the adjustment may need some tweaking ..

plugs are R45ts .045

now if after all this the carb still spits when accelerating the float bowl may be too full and too much fuel is being ingested this is usually a bad needle valve [worn].

the other cause would be the fuel evap system hose has liquid fuel in it and is being sucked from the fuel tank into the intake port. there is a valve the always breaks on the intake manifold that controls this evap fuel vapor canister purge...most bypass this now..

[Schurkey]

1. I thought an '84 pickup would not have a computer--although it should have an electronic accelerator-pump solenoid if you're using the original carb. (Full squirt when cold, reduced squirt when warm)

2. Wouldn't surprise me if the original carb needs to be re-calibrated to work on the 350 instead of the 305. Maybe you'll get lucky. Idle mixture screws should be adjusted with a vacuum gauge. I put the automatic transmission in gear, WHEELS BLOCKED and PARK BRAKE ENGAGED. Adjust mixture screws for highest engine vacuum, then turn each screw in (lean) just a little bit--perhaps 1/8 to 1/4 turn.

3. Spits out the carb? Lean fuel mixture, wiped cam lobe(s), retarded timing are the first three things that come to mind.

4. Assure that the distributor pickup-coil and the carbon button under the ignition coil are in good condition. The OEM carbon buttons can get so hot they melt the distributor cap. Will the ignition system fire a spark-tester? The kind I use comes in two varieties, conventional and HEI. The HEI spark tester has a recessed center electrode to make a larger gap. About twelve dollars; although prices vary.





5. What is the cranking compression of this engine?

6. Any chance the torsional damper and the timing cover advance indicator are mis-matched? If you have the wrong damper for the timing cover, I think there's a 13-degree offset.

[Bain]

Sorry for the slow reply I got a few too many irons in the fire right now so I haven't been able to get back to his truck yet. I do have a dwell tester I've never gotten to use yet so I'll break it in. As of right now it won't go into drive without dying but it seems to change from one day to the next so hopefully it'll cooperate.

[Bain]

Alright, so I went down and put the tach/dwell tester on it today and after letting it warm up I adjusted the idle till the rpms were at around 1000 in park. Then I checked dwell and got no readings at all but I read that on an hei system any dwell reading is meaningless anyway so I don't know if that gives any clues at all. Next I rechecked vacuum readings and I am still getting a steady 16 hg from the intake manifold and the carb going to the vacuum advance. However I found that on the driver side the carb port is only pulling about 7hg. Finally I went ahead and put it in gear since it was idling nice and smooth but it promptly died as soon as i put it in gear. Also as a side note TODAY at least I had to adjust the mixture screws all the way until they were only half a turn out to get the carb to stop spitting while it idled. That's all for now thanks for helping out.

[j cAT]

Originally Posted by Bain

Alright, so I went down and put the tach/dwell tester on it today and after letting it warm up I adjusted the idle till the rpms were at around 1000 in park. Then I checked dwell and got no readings at all but I read that on an hei system any dwell reading is meaningless anyway so I don't know if that gives any clues at all. Next I rechecked vacuum readings and I am still getting a steady 16 hg from the intake manifold and the carb going to the vacuum advance. However I found that on the driver side the carb port is only pulling about 7hg. Finally I went ahead and put it in gear since it was idling nice and smooth but it promptly died as soon as i put it in gear. Also as a side note TODAY at least I had to adjust the mixture screws all the way until they were only half a turn out to get the carb to stop spitting while it idled. That's all for now thanks for helping out.

with the mixture screw adjustment you say now my guess is the needle valve is damaged and the bowl is filled too much.

[Schurkey]

Originally Posted by Bain

after letting it warm up I adjusted the idle till the rpms were at around 1000 in park.

Way too high. Should be more like 750. There should be an under-hood decal with the official specs.

Originally Posted by Bain

Then I checked dwell and got no readings at all but I read that on an hei system any dwell reading is meaningless anyway so I don't know if that gives any clues at all.

Either the meter is not connected properly or it is broken. Dwell on an HEI is significant, but not adjustable. Dwell is electronically-controlled based on ignition coil saturation. Looking at dwell gives a (very) rough indication of coil condition. If the dwell doesn't vary with RPM, the module is defective. If the meter isn't connected properly, or is actually defective, your RPM reading is also suspect.

Originally Posted by Bain

Next I rechecked vacuum readings and I am still getting a steady 16 hg from the intake manifold and the carb going to the vacuum advance.

1000 rpm in Park, and only 16 inches of vacuum? First Guess: Retarded timing. Second Guess: Poor air/fuel mixture. Third guess: Worn engine.

Originally Posted by Bain

However I found that on the driver side the carb port is only pulling about 7hg.

Perhaps a ported-vacuum nipple that has some vacuum because the idle speed is too high.



1. Does the vacuum advance work? If you disconnect the hose from the carb at idle, is there suction at the carb port? Plug the carb port. The idle speed should slow down as soon as the vacuum advance isn't getting vacuum. Should also reduce engine vacuum when the idle speed drops. If you connect a vacuum pump to the vacuum advance hose (or simply suck on the hose) does the vacuum advance activate? If you put your tongue over the hose to plug it, does the vacuum advance hold vacuum, or does it leak?

2. What is the base (initial) ignition timing?

[Bain]

Well I found a problem today with a little luck maybe it'll be the answer to all my problems. I took the distributor cap off today to check the points and make sure nothing was loose and discovered that the advance was really stiff and when you pulled it forward it wouldn't return to normal. It's too gummed up or something for the springs to be able to pull it back. I tried spraying the weights and springs with a little liquid wrench and it helps some it now returns about half way but still sticks. I am now considering replacing the distributor with the one that came off the old engine, I already checked it out under the cap and everything seems to function perfectly and looks good.

[j cAT]

Originally Posted by Bain

Well I found a problem today with a little luck maybe it'll be the answer to all my problems. I took the distributor cap off today to check the points and make sure nothing was loose and discovered that the advance was really stiff and when you pulled it forward it wouldn't return to normal. It's too gummed up or something for the springs to be able to pull it back. I tried spraying the weights and springs with a little liquid wrench and it helps some it now returns about half way but still sticks. I am now considering replacing the distributor with the one that came off the old engine, I already checked it out under the cap and everything seems to function perfectly and looks good.

points in a 1984 engine ??? no way.. this must be a pre 1975 engine.

[Bain]

Sorry not literal points. I was referring to the contacts in the cap not actual old style points.

[j cAT]

Originally Posted by Bain

Sorry not literal points. I was referring to the contacts in the cap not actual old style points.

the advance should move with some force not too easy . usually the cap can allow moisture and with the arcing create a corrosion [ozone] causing the advance to bind, you have to use some penetrating oil to free it up .. then blow off the advance with air .. then put some grease on there. [not much]..

If the distributor cap contacts get messed up fast the distributor bearing is most likely bad. you get rotor wobble effect..

[Bain]

Update: So after replacing the distributor with another of the same type I had available, I re-timed it advanced to about 13 with the vacuum advance (now functioning properly) hooked up. When I disconnect the vacuum advance the timing backs off to about 2-4 degrees. The engine idles smooth again in park and reacts a lot more noticeably to carb tuning screws BUT...it still dies when put in gear although it tries to stay running a lot more than it did. The last attempt I made tonight I set the idle at about 1200 rpm to see if it would catch in gear because I had already tried it at 900-1000 rpm but it still died after struggling to keep up for about 5 seconds. I had a buddy over tonight and had him watch the tach meter and noticed it dropped from the 1200 rpm in park to a touch over 600 in gear. So long story short I stumbled onto and fixed one major problem but it sill isn't the big thorn in my side.

[j cAT]

Originally Posted by Bain

Update: So after replacing the distributor with another of the same type I had available, I re-timed it advanced to about 13 with the vacuum advance (now functioning properly) hooked up. When I disconnect the vacuum advance the timing backs off to about 2-4 degrees. The engine idles smooth again in park and reacts a lot more noticeably to carb tuning screws BUT...it still dies when put in gear although it tries to stay running a lot more than it did. The last attempt I made tonight I set the idle at about 1200 rpm to see if it would catch in gear because I had already tried it at 900-1000 rpm but it still died after struggling to keep up for about 5 seconds. I had a buddy over tonight and had him watch the tach meter and noticed it dropped from the 1200 rpm in park to a touch over 600 in gear. So long story short I stumbled onto and fixed one major problem but it sill isn't the big thorn in my side.

the old distributor did have a problem . the engine stalling when under load at idle not moving would not be distributor with the advance not working since at idle it should not be advanced. the timing should be 7 deg @1100 rpm. the idle should be set to 700 rpm in neutral. when placed in drive should drop to 550-600 rpm. if the engine was running properly you can get these to idle lower like 500 rpm.

I think you have a vacuum leak with this . with a good engine not too worn the manifold vacuum should be 17-21 inches @700 rpm. the vacuum should be steady and not fluctuate... rev engine quickly then release throttle. the vac should quickly drop very low then jump up to the 17 inches .. if it does this slowly then the exhaust or timing is screwed up..

if the vacuum is below the 17 inches you have a leak.. leaks are usually the hoses under the carb . the other leak area is the choke pull off vacuum diaphragms.

many use carb cleaner to clean the exterior of the carb . what this does is damage these rubber parts as well as any wiring.

next is the anti stall solenoid on the throttle stop. this when old sticks then you get this issue as well ...chevy uses electrical control.. buick use a vacuum control.