Car dies after 20 mins. [Archive] - Chevelle Tech

: Car dies after 20 mins.


jcchevelle
May 30th, 07, 9:50 PM
Well now that my whole distrubitor is changed its HEI, due to my lack of spark when the car got hot, now the car just dies when i put it in gear after it warms up. And im gettin spark now even when it dies.

Never happened before, And to get it to start again, i have to put my foot basically all the way into it and play with the gas for a few second to get it to idle again. then dies immediatley and backfires through the carb when put in gear....what is my problem>? PS the car never runs hotter then 170, its a 355 sbc.

When it gets cold again, im gunna start it and see if it will run in gear while still not fully warm. Ill let everyone know if it runs like that or not.

Thanks guys

gnicholson
May 30th, 07, 10:00 PM
If your sure the timimg is right it sounds like its to lean at idle. check for vacuum leaks and anything you disturbed while working on it. I assume it has a choke and thats why it will idle cold.

jcchevelle
May 30th, 07, 10:09 PM
If your sure the timimg is right it sounds like its to lean at idle. check for vacuum leaks and anything you disturbed while working on it. I assume it has a choke and thats why it will idle cold.

Why, and how would it change all of a sudden? And does that explain the backfiring? Thanks Again

bb489
May 30th, 07, 10:30 PM
I had that happen to me once. car would start fine but after a while it would die. Occasionally I would notice a very strong fuel scent. Ended up that one of my main jets was clogged with clear wrap after I rebuilt it. Even a small amount of debris in the carb can cause all kinds of problems.

jcchevelle
May 30th, 07, 10:56 PM
hey guys, just to make sure, about my timing, heres what i got running, maybe someone can give me some input on what they reccomend for timing.

355 sbc
Sportsman II heads
vodoo cam-- Advertised duration 276/284
Duration @ .050 233/241
valve lift .504/.525
LSA/ICL 110/106

Magnum roller tips
10:1 comp.
i also have a high output mechanical fuel pump, with a regulator set to about 5 psi. ( it always varys..i think from the heat)

i have my intial at about 16-18 with my vaccume plugged at idle, Its and a brand new Proform HEI high performance distributor. sound about right for this engine?

Fried_Guy
May 30th, 07, 11:13 PM
That sounds like a lot of initial. Use whatever works best, don't stick to a certain number. Kinda does sound like a vacuum leak though. Is your vacuum advance hooked up to full or ported? Does it die with the vacuum advance disconnected and plugged?

Bryan59EC
May 31st, 07, 10:46 AM
If the HEI is using existing wiring---that could be the culprit.
Cannot use the existing ballast or resistor wire, need a good 12ga or bigger wire run frrom the ign sw to the dizzy.

Also could be a FUBARed module or coil.

my 59 was doing that (shutting down---no start) and I changed the coil and the module, not a problem since.
Still not sure what the culprit was---have not bothered to check the coil.

Modules can check okay----but when they heat up, can fail.

Bryan

jcchevelle
May 31st, 07, 5:55 PM
If the HEI is using existing wiring---that could be the culprit.
Cannot use the existing ballast or resistor wire, need a good 12ga or bigger wire run frrom the ign sw to the dizzy.

Also could be a FUBARed module or coil.

my 59 was doing that (shutting down---no start) and I changed the coil and the module, not a problem since.
Still not sure what the culprit was---have not bothered to check the coil.

Modules can check okay----but when they heat up, can fail.

Bryan


Bryan, the module and coil are both new, and it was hei to begin with, this is not a swap from points, and the coil is 10 or 12 guage, not a small 16 guage wire or anything like that.

bb489
May 31st, 07, 7:18 PM
Again, make sure your carb is clean inside without debris. I don't think a vacuum leak would only cause it to die when it is warm and timing is timing. Once it is set right, it is not going to change when your car warms up. My bet is either you got a tooth or two off with the rotor when you put the dizzy back in, or your carb is dirty inside and may be holding a needle and seat open causing it to flood and die. The next time it happens, hop out real quick and see if your carburetor inlet and venturi are all wet with fuel. I had the EXACT same symptoms as you and as I said earlier it turned out to be a piece of debris in one of my main jets.

flpackerbacker
May 31st, 07, 9:15 PM
Bryan, the module and coil are both new, and it was hei to begin with, this is not a swap from points, and the coil is 10 or 12 guage, not a small 16 guage wire or anything like that.

don't consider a part good beause it is new!!!!I work in a dealership and replace "good new parts" all too often.in todays age of everything made in mexico or china I take no chances. good luck
eric:beers:

Bryan59EC
May 31st, 07, 11:33 PM
don't consider a part good beause it is new!!!!I work in a dealership and replace "good new parts" all too often.in todays age of everything made in mexico or china I take no chances. good luck
eric:beers:

My 59 Elky had less than 400 miles on a BRAND NEW mallory HEI

yep new parts can be bad

9 mo and a bit over 2000 more miles----no issues (whole car only has 2550mi on it)

Bryan

Ando
May 31st, 07, 11:54 PM
Just make sure when your checking for the "wet spots" its not just about ready to blow your head off... I've had a carb spit fire on a buddy while he was being curious and he lost his eyebrows and bangs... all in one puff!..

Where safety glasses if your going in head first. :-)

Bryan59EC
Jun 1st, 07, 11:04 AM
Just make sure when your checking for the "wet spots" its not just about ready to blow your head off... I've had a carb spit fire on a buddy while he was being curious and he lost his eyebrows and bangs... all in one puff!..

Where safety glasses if your going in head first. :-)

Also no nylon or rayon type clothing!!!!!!!!!!!!!!

My father was burned on about 30% of his body when his shirt caught a
carb burp, and only took an instant for his clothes to melt to his body.
3 weeks in a burn unit---and then had to stay out of the sun for the next 5 yrs.
Had to sell his new boat (27' Scarab), cause he could not take it out anymore to enjoy it.

100% cotton won't melt to you

kirkwoodken
Jun 1st, 07, 1:54 PM
All of what Bryan59EC says: I would still replace the module. I had to buy 4 thermostats before I got one that worked right. Modules are much more complicated. And cantankerous.

Make sure you dist cap is spotless inside; that there is no oil or dirt that could be carbon tracking. Always wear some kind of clean gloves when working on ignition parts to keep finger prints off high voltage parts.

71rat408
Jun 1st, 07, 2:01 PM
You say your getting spark when it dies, is getting fuel when it dies? Could be fuel system issues (ie: heat soak, debris, clogged filter)

bb489
Jun 1st, 07, 2:49 PM
You say your getting spark when it dies, is getting fuel when it dies? Could be fuel system issues (ie: heat soak, debris, clogged filter) Thats what I've been saying. If he is getting spark when it dies I highly doubt it is a coil problem or a timing issue. I would clean the whole carb out and put it back together. Even if that doesn't fix the problem, you'll definatley know for sure that the carb is clean and can look elsewhere for the problem.

kirkwoodken
Jun 1st, 07, 10:13 PM
And one more thing: I once had an engine with symptoms similar to yours. Ended up being a tiny welsh plug rolling around inside the float bowl that I did not see until I took it apart for the 3rd time. Just blended in with stuff in the botton of the bowl. Aren't engines fun?

CHELKAMINO
Jun 2nd, 07, 12:41 AM
This could still be a spark issue?? I had bought a new Accel coil to replace my then (back in 99) stock one in my Elco. When I installed it at the speed shop I bought it from, it ran fine. Once I left and the engine (and coil) got warm.....it would shut off. This happened numurous times on my way home that day, but it would start back up. I checked everything I could think of from carb to wiring. I pulled the MSD Blaster out of my Chevelle and hooked it up in the Elco......never shut off!! It turned out to be a "brand new" bad coil. I returned it for an MSD Blaster, and all is well.

jcchevelle
Jun 3rd, 07, 12:09 AM
hey guys, i appreciate it all, and i think i have solved my problem,- sort of....
First off- dont hate me- i had a small hole in my vaccume line that i did not notice, so when i plugged my vaccume line to set my timing, it wasnt really plugged. That took care of some of the problem

Now, which i think is my carb part of the problem, when i put my foot into the pedal hard, like mash it hard, i get a backfire not too bad, but still. It is a little more excessive above 3500 rpms, but even around 2K it still gives me a little backfire, and the engine stumbles on slight acceleration.

Just as a background, this carb has always given me problems and it needs to be rebuilt i know, its a 750 eddy carb. Now here is my question becasue i dont know anything really on carbs.

I am going to buy a new carb, ive wanted to since last summer, now i have a real good excuse haha. But what do i want? I was leaning towards a holley 770 street avenger or 750 dp, but i really dont know what would be best for me.

my setup is a 355 sbc
sportsman II heads
vodoo .505/.525 cam
Team G hi rise intake (soon changing 2 a performer rpm if it makes a difference)
3/4" spacer
700R4 tranny and a 410 posi rear

kirkwoodken
Jun 3rd, 07, 5:25 AM
Are you sure you don't have a bad plug or bad plug wire? Or broken valve spring? It would be good if you could find another carb to swap to make sure it is a carb problem. You don't want to keep buying new parts that don't fix the problem. If it were mine, I would want to do a compression and leak down test, along with a good visual inspection of valve springs. Things are easier to fix when you know everything is in proper working order.

To run, gas engines need three things, air/fuel mix, compression, and a properly timed spark. As simple as it sounds, your problem will be in one, or more, of those areas. Swaping carbs will eliminate one area, compression and leakdown, another area. That only leaves a properly timed, healthy spark.

Champion used to make a little "glow light" thing that you could put next to a plug wire to see if voltage was going thru it. If you can find one of those, buy it. Shouldn't cost more than $5. It's excellent at finding dead plugs or faulty ign wires.

Don't give up. Very often, when you have a problem like this, you will find out you have more than one problem, maybe three or four. Just keep at it. Leaking intake valves and flat cams also produce the symptoms you are having. There is no allowable leakage on intake valves. If you find one while doing a leakdown test, a valve job is in order.

One more thing: If this engine has been apart before, someone may have left head gaskets hanging in the bores. After you exhaust ALL other possibilities, keep this one in mind. That can make for a really bad running engine that no amount of tuning can fix.

The only thing that bothers me is: all the things I've mentioned wouldn't make your engine stop running when it gets hot, unless you have a valve hanging open after the engine warms up. Check preload on all your lifters one more time. Make sure none are too tight. If you have a "collapsed" hydralic lifter, that could be the problem. I like to push down on the pushrod end of the rocker arm while the engine is runnung to make sure the lifters are working. Even with the clips that keep the oil from squirting all over, it can get pretty messy. Hope some of this helps.

jcchevelle
Jun 3rd, 07, 11:49 AM
Thanks kirk, just to clear up, i dont know if this was clear, the car doesnt die anymore after it warms up, that was due to my timing being way out from the leak in my vaccume line and i realized that it died whenever i put it in gear, now just when it got hot. I thought it was just when it got hot, becuase i would let it warm up before i took it out. But even when i just started it, and put it in gear it died as well. I replaced my vaccume hose,and now it runs and starts fine, everytime i want it to.

This carb that i have now, it runs very rich and its just been a hassle since the start. It would fluctuate in idle and somtimes rev on its own, and i know that it dumps way too much fuel.

My spark is constant, and so is my fuel, i have a pressure regulator with a guage hooked up.

and the motor ran fine, i just rebuilt it last summer. If you can explain how to perform a leakdown test, i will also try that as well to make sure everything internal is proper. Thanks again, Josh