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Discussion Starter #1
I'm new to this car and this working on cars in general. 383 stroker and it has been running great for the past 2 months. Fires right up and runs strong. I disconnected the battery and put new speakers in the front and back and a new head unit in that I ran of the BATTERY terminal on the block because the original battery power for the head unit was not there.

Start it up and it idled fine but had a bad miss. Feathered it and restarted it a couple times and got it worked out and it ran fine for a cruise. Next day same thing with same result. Took air cleaner off and saw power wire to electric choke was disconnected. Reconnected and no change. Today same issue but today wont even keep an idle and no noticeable fast idle. some burping and few backfire like sounds in with the carb

So does this sound like a fuel issue with the carburetor or spark and what is the first steps an armature newbie can try. Carb is a Demon either Street or Road...older one with no stamped model information. Any possibility the power feed for radio or disconnecting the battery messed up the MSD box or MSD coil?

help appreciated for a newbie
 

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Give us a list of your combination.
Make, model, year, more about power train and accessories. And anything else that you changed or messed with during the speaker work.
 

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In addition to replying with what Fred asked for, I would suggest you verify the electric choke is actually functioning properly. Next time before you start the engine (and before you put the key in the ignition or step on the throttle), remove the air cleaner and note the position of the choke butterfly. Now step on the throttle one time and the choke butterfly should move to a partially or completely closed position depending on temperature. Start the engine and let it run, within a few minutes the choke should begin opening and eventually open all the way in approximately five to seven minutes.

Let us know?
 

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Discussion Starter #4
Thanks for the response.

Its a 1968 383 stroker with an edlebrock 383 stroker top end and a demon carb of unknown model. 4 speed. MSD wires, distributor, MSD box with 6000 chip and MSD coil. Everything else is stock other than spring stack and traction bars and rebuilt 3.73 rear end. Nothing else was messed with during the speaker work other than the neg battery cable disconnected and a power wire to the BAT tab on the block which I have since dis connected to rule that out.

I do think that the electric choke had the butterfly in the almost full open up/down position yesterday but I will check that out.
 

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Can you post a picture of the routing of the wires for the MSD box. Also when powering the radio do you mean you ran the 12+ to the battery terminal in the fuse box? Make sure you have the 10 gauge red and 10 gauge black wire from the MSD box to the + and - battery terminals. Get a pair of spark plug wire puller and when you have the car running pull 1 spark plug at a time to see if you notice a change in that cylinder. Reinstall the wire and move on to the next one. If you find one that makes no change in the way the engine idles check ohms with a multimeter. Then look at spark plug and replace if necessary.
 

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Discussion Starter #6 (Edited)
Ok so I removed and cleaned the fuel filter. It was fine. I took the air cleaner housing off and pushed the throttle with the engine off all the way and get nice squirts into the carb. It seems to be idling ok but has a miss at around 2000rpm and is sluggish on a tap of the throttle and burps/pops and backfire at the carb. No smoke or backfire at the exhaust. Attached are pictures of the set up under the hood. I plan to get a timing light in the next day or two and try to go down that path to at least make I have spark at all the cylinders.

So ruling out fuel delivery at this point does this still sound carb or now sprark/timing related....also keep in mind it was running great with no issues at all from the time I got it until parking it the other day and getting in it two days later. It worked through the problem and drove fine twice but now is not drivable at all So whatever happened just happened.




 

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If you haven't already, I would check for any loose wires around the battery. Especially that crimp connector on the positive side of the battery.
 

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Discussion Starter #10
Ill check everything over again.

Could this all be from the electric choke not working? Cold the butterfly is not moving to a closed position. I am going to test the electric choke but I have a feeling its not working.
 

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Possibly, but I would tend to think not. I believe it's more of an electrical connection thing, since you were playing with the wiring. The choke was not hooked up before, but ran fine? I don't think it's cold enough for the choke to be needed, but I don't know what your engine needs.
 

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Discussion Starter #12
I was also getting fast idle before and definitely am not now so I'm thinking the electric choke connector falling out is when things may have started.

I am getting around 12 ohms on the electric choke....from what I found that way to high. also the butterfly is stuck in one position and will not move. I cannot manually push it closed.

The only electrical I have touched was to disconnect the negative battery terminal and then run the power for the radio to an unused tab on the front of the fuse block that had power all the time.
 

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Discussion Starter #13
Can anyone tell me what ohm reading they are getting on a working Demon/Holley style electric choke?
 

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a miss at around 2000rpm and is sluggish on a tap of the throttle and burps/pops and backfire at the carb.
u may not have moved any HT leads...To get a back fire thru a carb u NEED an ignition while a firing cylinder is open...
This can only be caused by a couple spark plug wires wrong
or a valve mis adjusted and open...
or cross fire between HT leads
or broken, cracked dirty Dizzy cap rotor.

Check #1 is set to fire on compression stroke (thumb on #1 spark plug hole to feel for the compression stroke)
Check and re check HT lead order.
Inspect rotor/ cap inside and out with a magnifying glass looking forand arc trails / cracks... then clean
Run motor on a dark night and feel/ watch for any arching...

Remove the MSD unit, and with it in hand, walk out of the garage, place your hand as far behind u as possible, then bring your hand in a very fast arch, releasing the msd unit at the right to to accurate it in a manner for greatest distance and height.
Return to the garage and car.
The reasons why, I have expressed several times in old posts.
 

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Only thing I ask is could your msd box be shorting out internally?
Second, I don't see where you have the msd box grounded.

Last, Steps, You know something I would like to know about R&R the msd and walking outside the garage with. Can you share? I am thinking something in the lines of polarity?
Usually when I walk out of the garage and back its because something that hacked me off and I need to cool off. :mad: Know what I mean? Might pick up any tools I threw out in the drive way too.
 

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Discussion Starter #16
This whole thing is just getting so bizarre. Tonight after several days of not starting the car it started like it had no choke which is rough and no fast idle like it used too no matter what temperature. (its 90deg here today) Then it idled and drove ok but very sluggish and no throttle response. But no miss or popping out of carb or any of the earlier issues and I changed nothing but loosened electric choke gave it a slight turn clockwise and tightened the electric choke back down.

I really don't think that electric choke is working because it will not close the butterfly even for a second when the key is turned to on. 12v power verified to it.

I think with the miss gone today I'm back at carburetor. My timing gun will be here tomorrow but could the choke be causing the sluggish behavior of the car?

Apologies I am obviously very green here.
 

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Find some way to tie open that choke, wire , tape or what ever, if you have to disconnect that power source to the choke but don't let it touch ground, tape it too. Make sure the choke flap is open , that should kill the fast idle cam.
You have eliminated the choke issue.
Try to run, if you still have problems, do what Steps mentioned. If you still have issues, I would suspect the msd box is fading away. This happened to me but on the road.

Most electric chokes have a heat coil inside of some type, after they heat up, they break circuit , there is no longer any effect that 12v source to the choke. At least that's what mine does.
 

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MSD multispark distcharge.. it will fire a spark plug mutli times in case the 1st spark doesn't ignite the mixture... at low street cruise rpms only.
Any rpms above this there is not enough time to fire several times...
If the spark, without MSD, doesn't fire 1st time every time , that means the Ign system/ HT / Plugs need some maintenance because of lack of maintenance or some bloody idiot ripped a HT lead off a plug, not by the cap.

Add to that a bloody ugly red box that clashes with any colour scheme under the hood, unless a MSD red...and a heap of wires floating around when one is doing one utmost to clean look the engine bay...

Or put another way, a good HEI, with a good set of Top gun spiral wound HT, change every 10 to 12 yrs and a change of plugs every 3 or 4 yrs, will do just as well.. on daily driven mileage.
Its like fishing.. the more knots, swivels and BS u put between the main line and hook the bigger the chance that big 30kg + king fish is liable to break u off...
 

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Discussion Starter #19
Thanks for the inputs. The stuff about no MSD box makes a lot of sense. Does the 383 stroked engine need it though?

Also what does HT mean?
 

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Thanks for the inputs. The stuff about no MSD box makes a lot of sense. Does the 383 stroked engine need it though?

Also what does HT mean?
MSD box is what lots guys run, I even run a 7AL, but I don't have mine painted hooker red.
You need some type of ignition , whether just a pointless distrib, HEI coil in top .
You need something. So its your call. Any chance someone has a msd set up and you could borrow to test?

H/T? I think Steiner meant is plug wires, some people call them hight tension cables. A good set of spiral wrapped plug wires will work. You can test these wires you have. I normally use an ohmmeter to test resistance in ohms per foot. Here is the link on what to look for. http://www.msdignition.com/page.aspx?id=3302
A 383 does not command an MSD box no more than a 283 ci does, Sometimes I consider these things romance items for bragging rights but I got one and not bragging, its what I have run for last 20 years . Had one go out due to water leaking into it, acted like what you are describing. Worst, it failed on me during a photo run at the Texas Motorplex speedway, officials had to push me off the track, talk about embarrassed.:(.

Steps, correct me if I am wrong on the H/T
 
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