Octania

Sorry for the Some Other Brand
It applies to any engine though


1978 Corvette
Elderly Owner has not long to go, we are trying to make it complete right now, by 06AUG2016


frame up rebuild


I did not do the engine, I just put it in. Trying to do initial tune.


Will not idle.
Carb is all gone thru by me and friend, all OK
What do we know?


Fresh rebuilt stock 350 # match motor.
some additional cam we presume
Edelbrock? Intake, headers
HEI stock the vehicle- maybe flaky spark? My timing light only works about half the time, not sure if it's a bad light or this motor.


Fancy shielded plug wires, my sensor is on the unshielded part. Tried #1 and #6 wires. Degreed damper cover, verified that TDC is true to the mark.


REFUSES to idle. Runs OK above about 2000 RPM, so we got the cam broken in OK. Acts like a huge vacuum leak.


Oh, develops ~10" vacuum at best, pretty steady, but again cannot ck it at idle. Vac gage hooked directly to intake tree, ALL other vacuums capped. no extra holes in the intake.


We did find all or almost all intake bolts loose-ish last night. Snugged them. Ihave no idea if the assembler used a gasket or gasket sealer. Engine was assembled 2-3 yrs ago, sat awaiting the project since. We did not open the engine for inspection, just turned it for feel, looked in the plug holes. The engine was stored with all openings taped over.


I am kind of at a loss as to what to do next. Spray ck for vac leaks I guess.


Ck valve lifter motion, maybe a wiped lobe or 2 already?


Total run time has been maybe 1/2 hr. It has yet to idle properly.


idle mix screws started at 2.5 turns out, then I went to +1 for 3.5 turns. No diff, like the idle ckt is not even being used. It's not THAT big of a cam.... I think.

shiftbyear

it may require a valve adjustment. if there was machine work like a valve job or head/block resurfacing, you may need to adjust the valve lash. there may be a youtube video you can research. good luck

Octania

Come on people
the owner is dying of cancer

I rarely ask for help here.

44 views and one suggestion. Thank you shiftbyear
Good call, I forgot they are adjustable and therefore need adjusting upon install.

pretend it's an Olds 350

Next step probably look at the plugs, maybe a compression test.

oldcutlass

Wow I must not of hit post this afternoon.

You have to move the shielded covering out of the way or use a spare plain spark plug wire with your timing light. What is your timing setting? I agree on the valve adjustment. Basically get it warmed and do it with the engine running. Loosen till they clack, tighten till quiet, then a 1/4 turn more. Its messy, but quick.

olds 307 and 403

Either a huge vacuum leak or that cam is not anywhere near stock.

orange442

Sounds like you are retarded! Did you try advancing the timing a little at a time? Remember Chevy advances counter-clockwise!

svnt442

Pull the hose from the brake booster and plug it just to rule it out.

distributorguy

Advance the timing to 16 at idle, vac line disconnected and plugged and leave it that way.
If it still won't idle, pull the valve covers. Assuming this is a hydraulic lifter setup? Back off the rockers on all 16. Tighten them until you can't feel end float in the pushrods - rotate the engine at least 2 revolutions and check each pushrod several times. The base circles on the cam are typically inconsistent, so its easy to get this step wrong. Then tighten each rocker adjuster 1/2 turn and lock it in place. Not a single fraction past 1/2 turn.

If solid lifters, then adjust per cam card specs.

Make sure you have no vac lines hooked up anywhere, even the power brakes. Seal every port. Now if the carb is set up properly it will idle. If not, adjust the float to factory spec. If it still won't idle, add a fuel pressure regulator.

MDchanic

All of the previous advice is good, naturally, and timing, valve adjustment, and confirming no vacuum leaks are all essential, but I will add one more thing to consider:

I know that "Carb is all gone thru by me and friend, all OK," BUT,

Are you ABSOLUTELY CERTAIN that you have used the correct throttle plate to float bowl gasket, and that it is oriented correctly?

I have had this exact problem before, twice, once on a 2-Jet, and once on a '71 Celica, and both times it was an obstruction of the idle circuit by a misplaced gasket.
I do not know whether it is possible to do this on a QJ, but once the other stuff has been re-done and confirmed good, I'd take the carburetor apart.

- Eric

MDchanic

Another thought:

It should be possible to prove or disprove a low-fuel problem (like a blocked gallery) by installing the air cleaner, running propane into the air cleaner intake until the engine speed just picks up, and then slowly reducing the engine speed - if you get more running before it finally stalls, then you should look at fuel issues.
Note that I have not done this before, myself.

Note also that you will need to be outdoors, or have garage doors open and a good fan blowing at ground level, because you don't want any "surprises."

- Eric

Octania

New developments last night
I have never encountered this before


Let's just say I suspected the distributor, in part because I had not gone thru it top to bottom. Rcvd with car, ck'd that it made spark, installed it.


Film at 11:00

Octania

Might not get to the car tonight. Last night... we had trouble getting the NEW [aftermarket] whiz-bang starter to work.... again. Clunk of solenoid but no spin the engine. Then it works again. At least it's easy to get in and out. Not a bad ground, verified. Plus that would prevent the solenoid from actuating. Bad solenoid or starter inside. But, I digress.

If I can figure out how to get a video from the phone to where all y'all can see it I will do that.

Carb is dry, car is out of fuel. Easy fix. I still don't think it's the carb. Not all of it anyhow.

Suspect flaky spark. Confirmed that the engine will start OK, then after oh 2-3 seconds spark is no longer produced and the engine dies. This was found using a spark tester in one of the plug wires while test running it. Lots of spark, like 19mm long, while cranking. Great spark at start and 3k RPM, then no spark and engine dies.

Vacuum is not connected to the dist'r vac. can, we are trying to set the initial timing here.

Verified that behavior is the same with car's dist feed wire removed and my own hotwire installed.

Verified further that the car's wiring continues to supply 12V to the dist'r while no-spark occurs. It's not the ignition switch or related wiring.

So, we are for sure feeding power to the dist'r, which has a good ground, yet, after 3 seconds, no spark. Well, an HEI is pretty reliable and simple.

I took the distributor apart as far as possible w/o removing it from the engine.

Coil looks fine, ohms fine.
cleaned all the wires' terminals.
Tested all wires for continuity

There is a capacitor in there next to the module. It tests OK as far as I know- that is, apply a test light which comes from +12V and the light briefly lights, then goes out as the cap is charged and current diminishes to zero.

Verified grounding of the dist'r housing by means of test light from +V to dist'r housing.

Verified ohms on the pickup coil. Wiggled its wires all over while watching continuity, no problem. Tugged at the wires, no problem. The pickup coil seems fine. Plus, it's not being moved by the vacuum can at all. Yet.

bought a new module for the HEI, installed it. Evidently, dielectric silicone grease is the proper heat sink material supplied with a module now.

Engine behaves exactly the same.
Start, run to higher speed ok, loses spark and dies after oh 3 seconds.

So, previously, when I thought it was a flaky timing light, it was the car's flaky spark, which got worse and worse to the current condition. Oh, and the timing light has always been placed on the unshielded portion of the plug wire of course. Lately it was up at the cap, not at the plug.

This is crazy. The only things left in the distributor are the HV coil- have a spare used one to try- and the pickup coil. Maybe it has a cracked magnet or something. Maybe the dist'r got dropped. I found a new(ish) HEI in the garage that can donate a pickup. I *assume* that ccw vs cw rotation does not matter to the pickup coil. If we dismantle to get at the pickup coil, we can make sure the bushings and shaft are intact and refresh the upper end grease too.

Oh, and I marked TDC better- another aftermarket whiz bang parts fail prevented seeing the TDC zero and other nearby degree marks. I found that I had the distributor set just about exactly right as far as the pickup coil teeth being aligned just as the engine was about TDC and #1 ready to fire and the rotor pointing at what we used as the #1 terminal. Which was off by one location, according to the factory embossed markings on the plug wires retainer ring.

So, at this point, the vacuum thing is unclear but probably simply the engine dying of no spark.

I have enough parts to beat this dist'r into submission.
We are just about out of things that might fail. HV coil and pickup coil. Maybe that capacitor.
What is the BEST way to test a capacitor? Replace it? Maybe my Olds HEI has that item on its wiring.

Other feller went and bought a new / rebuilt dist'r in case we have to go that route. I prefer to keep the car's original part with all its original settings and parts and timing curve. Just replace what it needs replaced to get it going.

Rock Auto has the pickup coil in AC Delco form for about $40.... But I would rather have an old GM part that might possibly be made in the USA. As long as it works.

distributorguy

Sounds like the distributor is 180-out (assembled wrong). This throws off phasing. Pull the distributor, turn the gear 1/2 turn on the shaft, reinstall and reset timing. Your rotor will now be properly lined up with the cap terminals when it fires, and therefor shouldn't stall out on you.
When you hold the distributor in front of you, there should be an index mark (shallow drilled hole) in the gear, facing you. When you look at the top of the distributor, rotor removed, the square index hole for the rotor should be on the left, not the right. This is how you properly assemble this distributor, and it won't run well if its backward.

Octania

A couple problems with that

I did note the drilled dimple in the gear when I went to mark the gear before removing it. The dimple aligns with the rotor's contact. I did the shaft removal with the rotor in place on the shaft. The reason you are never supposed to move the gear from its original position on the shaft is because the hole is never exactly right thru the center of the shaft. The other way around, the hole will not pass straight all the way thru all 3 portions.

But, rotating the gear 180 on the shaft does not change anything in the distributor. Because of the construction of the parts, the distributor is in the same functional position every 45 dist'r degrees- only pointing at a different plug terminal in the cap- the rotor tip vs cap contact relationship does not change by turning the shaft 180 degrees.

if we had dropped the dist'r in a half turn off- ready to fire #6- I know what that behaves like. No run at all. Pop, sputter, spit. What we had was run GREAT at 3k RPM, for a few minutes or maybe 2 seconds, then die of no spark. All with Under 10" vacuum.

Replacing the pickup coil with the one from my Olds dist'r fixed it.... for a minute

Whilst in there, of course, reamed the bushings after checking, cleaned the shaft, replaced the hard grease in the upper bushing reservoir.

ran great for quite a while with the crusty old black GM dist'r cap and the best available HV coil.
when we switched back to pretty new blue Standard Products cap from crusty old cap, same old run 3 seconds then lose spark.

Weird.

Clue:
One of us likes to re-attach every wire every time
one of us likes to get things running simply THEN add back in all the possible trouble sources one at a time.

Neither of us has a good color wiring diagram or bothered to consult the interwebs for what wire does what.
I am quite familiar with the red dist'r feed wire, and GENERALLY each wire has a unique connector that mates the thing that the wire reaches to.

So...
Dist'r feed red (now faded to pink) 12 AWG
Tach wire originally ran thru a capacitor- but with a broke off lead, we removed that radio noise cap and now that harness wire [pink] was run right to the dist'r TACH terminal. Had to swap plastic blocks on the terminal to do that. We did have a working tach, I am told. Off and on.

back to the fail to run issue...

Sick to death of the new mini type starter working OR NOT as it wishes, we pulled it out to find the solenoid was burnt smelling and not at all operable. The motor itself seemed OK but w/o a solenoid it is no good. Off to the store where a "rebuilt in China" real GM-ish starter was obtained. Easy install, no worries. They even took the brand new POS starter as a core.

Put in 100% new distributor/ cap/ coil assembly.
Same behavior, run 3 seconds then die of no spark.

Huh.

I forget how it happened, probably pulled the distributor again to verify that the oil passage [yes, the C brand has an OIL PASSAGE to worry about on the dist'r housing] is correct... but I finally got it to run for a few minutes. Got it warmed up. Idled more or less Ok. Tach wire off. OK, reach over and install the tach wire... and the engine dies. Pull pink tach wire, engine runs. Install it, it will start, run 3 seconds, die. WTH? All this because the TACH kills the engine?

Let's consult the internet
http://repairs.willcoxcorvette.com/1...and-tach-wire/

turns out, the WHITE wire there near the distributor is for the tach. Not the pink wire.
I am sure we have not used the white wire before because it is still covered in green oxidation.
Remove plastic terminal cover, dip the terminal to clean it to bare brass, dry it, grease it, reinstall to dist'r.

Still no idea what the pink wire is for, why it would match the radio noise capacitor tach lead connector originally on the car, or how we had a tach before with the wrong [pink] wire connected.

SO, after days and days of struggling to get it to run right, we finally attained idle of a sort.
We did have two vacuum items still attached- power brake, holds vacuum and plugging it makes no difference... and one 1/4" line down to a carb vapor recovery canister in the fender with 4-5 other hose nipples with hoses maybe or maybe not attached yet. Removed that possible leak and plugged its nipple at the vacuum tree.

The dist'r experience still leaves me stilll convinced the brand C design is poorly executed. Pushing the dist'r shaft UP and holding the dist'r down against it with the clamp is suboptimal.

Current Status:

Idles around 600-700, timing at 6 BTDC per the underhood label
we did go past 200 degrees, no AC system yet either, to almost boiling 240F per the gauge.

FIVE INCHES vacuum seems a little low to me, nowhere near the green zone on the gauge. Drifts from 5-7" Hg.
Have not tried idling in gear yet, except to run the car back into the garage.
Spraying carb cleaner around the intake, carb base, fittings, etc. has no effect, indicating no vacuum leaks.

Oh, and the idle mix screws still make NO DIFFERENCE AT ALL, from seated to 3 turns out at which point they become loose like a kid's tooth.
I can see fuel dribbling from the MAIN nozzles at idle.
Time for the drilling of the throttle plates to get the idle circuit into play?

I am not sure the power piston is drawn down inside the carb, might take the carb apart tomorrow to verify all idle passages. I did find the remains of the carb kit we used on this carb. New float. Throttle shaft not bushed due to not being worn badly.

Found a metal line we can run vacuum to the trans with, will need to T into the vacuum tree in a non-std fashion because of all the non-factory things like the intake- the original line routing hits the air cleaner now.

oldcutlass

The carb is not set up right if its dribbling fuel and running to rich for idle a/f screws to work (Do not drill throttle plates). Need to address this first. Your timing with the hei is way to low. Disconnect the vacuum advance and plug the line. Set your idle to 16-18, or set your total mechanical at 36* at what ever rpm it stops advancing. Mess with the vacuum advance after everything else is corrected as it will probably need to be changed or limited to around 10*.

Octania

OK
I am reading stuff like this which worked well for my 403

http://www.73-87.com/7387garage/drivetrain/qjetidle.htm

Many folks including the Olds factory drilled holes in the throttle plates in order to get them closed enough to engage the idle mixture feed hole yet still get enough air thru to idle.

Very common on Holley carbs, I have seen it all over the place on QJets until just now when I need that info.

Maybe advancing the timing will get the throttle plates closed down enough.

oldcutlass

The drilling of the plates has always been a last ditch effort to correcting the issues with higher compressions and large cams. Your issue is the carb dribbling at this point in time. After that, I also agree that setting the timing higher may help your issue because it will raise the idle speed, vacuum reading, and allow you to set the linkage lower to ensure you are solidly into the idle circuit. Lastly, a properly set up vacuum advance connected to manifold vacuum will enable you to even lower the idle speed setting even more. I have never had to drill the plates on any carb for a relatively stock build and a small cam.

Octania

Well stated, Oldscutlass

today we had enough spark to make the timing light work. I even got the dial back one to work but only at higher rpm.

I can verify that if your spark pickup gets onto the shielded part of the wire it does not work.

At lower RPM's both timing lights were flaky, failing to flash most of the time, or providing multiple flashes which of course are no help at all. I tried #6 and #1 wires, neither was better. I tried it w/o the tach wire connected that caused us a week's delay. Not better.

I marked the balancer at 36 and 0 [TDC]
With the stupid chrome aftermarket timing tab and balancer cover.... the numbers are UNDER the timing tab, so you can see the 30 or 40 off to the LH side... but the numbers you need to see are hidden by the tab. Grrrrr...

So, vacuum off dist'r, light working OK, we started it up easily with the new proper starter, hella high idle due to fast idle due to cold engine... [FI not yet adjsuted] - like 3000 rpm. Set timing to 36 with all mech in and no vacuum. Kick off the fast idle, see what happens.

MUCH BETTER

got up to 15" Hg, steady. Idled down to about 700 RPM

does not overheat now.

starts easily.

Attached dist'r vacuum to a full-vac port on the carb. this increased idle, so I turned it back a little, but that dropped the vacuum again.

Idle mix screws are now capable of affecting the idle and vacuum, a little.

It is so much better now.

We got the trans vacuum routed by means of a 1/4" Copper plated steel tubing that the guys at work donated. Very nice stuff. We tee'd into the vacuum that runs the HVAC or some other stuff. Original steel line long gone, and cannot be out into the top of the vacuum tree anyhow because the nipple hits the air cleaner because the tree had to be elevated an inch or two to clear the carb / brake vacuum because of the non-OEM intake manifold.


Factory underhood label specifying SIX degrees of timing is just no longer relevant.

We did not have to get into the carb and opening up the idle channel restrictions..... yet.

We even took it for a brief road test drive in the neighborhood. Might make the driving deadline of 06Aug

THANKS YOU GUYS for all the help
I have never seen such a thing as wrong wire on tach line leading to a 3 second delay kill of the spark.

I have learned to go ahead and consult the internet and find out the correct color wire. I hope my friend learned not only how to put plug wires on in order but also to attach ONLY that which is necessary at first, get it running, THEN add in things like a tach, which only complicate matters at first.

oldcutlass

Keep your total timing with vacuum advance at 50- 52*. Most engines do not like it above that. Double check your total timing at a higher rpm like 4500 to make sure it does not advance anymore in the upper rpm's. Glad your going in the right direction and hopefully meet your schedule.

distributorguy

Since you blew off the phasing description I already posted because you don't understand it, I'm not sure you'll listen to this either but here goes:
Advance your timing another 5 degrees at idle, then attach the vacuum line to manifold vacuum when you are done. Just try it. You're running hot from retarded ignition timing. Its not a "numbers game" I believe its an issue with cam timing and aftermarket cams. Again, take a minute and just try it. Also, if you continue to have issues tuning, Run jumper cables from the battery to the engine and see if the issue dissipates. You may need better engine grounding, given you already have corrosion issues in the wiring.

Octania

Since you blew off the phasing description I already posted because you don't understand it, I'm not sure you'll listen to this either but here goes:
=====================
I understood it just fine
it's just nonsense, that's all.

rotating the GEAR on the dist'r SHAFT can in no way alter what goes on in the distributor. Maybe if the distributor gear has an odd or prime number of teeth?
You tried to assert that the dist'r gear to dist'r shaft position, of which there are two due to the drilled hole, affects other activities. It does, in fact, not. For future readers, I set forth my take on that. position A is exactly 180 degrees off from position B, and since the dist'r is an 8-banger, every 45' is the same. Plus the part where I noted the dimple when I went to mark the gear, and thereafter made sure to install it as it was before removed, therefore unless is was in the "wrong" position before, it is still "correct" now.

I do appreciate your input and insight though. I will call out incorrect info when it appears.


Advance your timing another 5 degrees at idle, then attach the vacuum line to manifold vacuum when you are done. Just try it.
=================
did all that
that is what worked-
1) getting reliable spark by distaching the incorrect wire from the tach terminal
2) setting timing with mech only at 36
3) attaching manifold vac to dist'r then setting idle and idle mix


You're running hot from retarded ignition timing.
==================
agreed.


Its not a "numbers game" I believe its an issue with cam timing and aftermarket cams.
===================
OK


Also, if you continue to have issues tuning, Run jumper cables from the battery to the engine and see if the issue dissipates. You may need better engine grounding, given you already have corrosion issues in the wiring.
===============
Good call.
I did test for voltage drop battery to engine, when the starter was dying. No grounding problem, it was just a really crappy starter.

She's in pretty good shape now

I would share a video but have to go to work now.

BlackGold

Word of the day!

Octania

learned that one working for Bear Instruments, writing and revising Harley Davidson service manuals. They like that word a lot. I found obscure errors, and even errors in other-language manuals.

distributorguy

Phasing in GM distributors that use an odd number of gear teeth is a very common problem. SBC right? Its not incorrect info. Your rotor position will change when you flip the gear 180 degrees and reinstall the distributor at the same timing spec. The correlation between the cap and rotor is very relevant to coil charge, spark timing, and overall engine tune. The fact that you don't yet understand this does not make it incorrect.

olds 307 and 403

I agree with this for a sbc, an Olds will like around 60, especially a low compression smog version.