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Just wont light.

2K views 16 replies 8 participants last post by  Nsomnia 
#1 ·
Got a junkyard dog 400 that I slapped together yesterday. Ran 12v to the dist and starter so I can crank it on the stand.

Dash of fuel down the intake, decent spark, and should be getting compression even if its 30 years old. Just wont light up. Some small amounts of smoke out of a few cylinders but nothing more.

Im going to try slapping a carb on to make sure fuel delivery is a bit more optimal and giving it a half hour to air out. Then I might try putting on a different distributor (you never know) failing that im lost.

Lined tdc up with the balancer and looking into the combustion chamber and it was 180 off and got a carb fire so I switched it around and now this... any suggestions?
 
#2 ·
Um yeah, it`s not going to start or "light up" as you say without a carb on it, with a open intake it`s pulling in almost all air and air as you know won`t light off without fuel, the carb is the mixer device that mixes the air fuel ratio, without a carb it`s not supposed to do anything.
 
#5 ·
It started on the stand when I got the carb on.

Now that its installed, it wont start at all. I verified TDC with the balancer (worked on the stand) and installed the plug wires all right (checked about 10 times by now) and played with the timing retarded and advanced as well as straight up. It seems to want to spit-back out of the carb for some reason.

I loosened the valves a little bit thought maybe an intake was sticking open to no help.
 
#7 · (Edited)
I suspect the valves are too tight, especially if you used the "thumb and forefinger TWIST method" of setting them.

Here's the bulletproof way to do it. Pull the valve covers and spark plugs. With your thumb on #1 plug hole (driver's side, front), turn the motor over clockwise with a socket on the damper retaining bolt on the crank until you begin to feel pressure on your thumb. Continue turning the crank while watching the timing tab and bring the crank up to TDC where the tab lines up with the groove cut into the damper. This will put you on TDC #1 firing position where the valves are closed and the lifters are on the heel of the cam lobe.

Starting at #1, jiggle the pushrods up and down with your forefinger and thumb and tighten down the rocker nut on each one until there is no play. Tighten the rocker nuts an additional 3/4 of a turn (270 degrees) or like from 12 O'Clock to 9 O'Clock on a clock face. Now, put the socket on the crank nut and turn the crank clockwise 1/4 turn (90 degrees), like from 12 O'Clock noon to 3 O'Clock on a clock face. This will put #8 cylinder on TDC firing position. Adjust both rockers on #8 cylinder (passenger side, rear). Now, turn the crank another 1/4 turn and adjust #4 rockers (passenger side, second from the front). Turn the crank another 1/4 turn and adjust #3 rockers (driver's side, second from front). Turn the crank another 1/4 turn and adjust #6 rockers (passenger side, third from the front). Turn the crank another 1/4 turn and adjust #5 rockers (driver's side, third from the front). Turn the crank another 1/4 turn and adjust #7 rockers (driver's side, rear). Turn the crank another 1/4 turn and adjust #2 rockers (passenger side, front).

Use only the "jiggle up and down method" of determining play in the pushrods. Twisting them will give you the wrong lash because THEY WILL END UP TOO TIGHT.

To summarize, bring each cylinder up to TDC firing, jiggle each of the pushrods for that cylinder up and down until all play is removed, tighten each rocker down an additional 3/4 of a turn after all play is removed.

The reason for removing all spark plugs before beginning is.....
1. To make the motor easier to turn over.
2. To prevent the crank from "rocking back" against compression of the next piston in the firing order comin' up the bore and giving you an erroneous reading.
 
#8 ·
123pugsy said:
Distributors probably installed 180* off.
If I installed it 180 degrees around it backfires REAL nice.

THere is definitly more play than suggested, so they cant be tight, the rockers will move around a little bit. But I will definitly adjust them like that tomorrow, thanks for the walkthrough, much appreciated!
'
Edit: being too tight would explain the carb spitback when everything is installed correctly.
 
#11 ·
Light it up!!

It sounds like you are firing at or after top dead center. Line your timing mark up about 13 to15 degrees before tdc. Make sure both valves on #1 are closed. Pull your distributor cap and make sure your rotor is lined up with #1 spark plug wire on the rotor cap. Clean cap and rotor with non flammable electrical cleaner and put back together. It should fire!!

Bob
 
#12 ·
Turns out my battery cable was sparking against the starter housing causing what I assume to be a voltage drop for the distributor and stops the motor from cranking. A big short basically.

Im gonna rewire the starter with proper terminals and see what happens then, isolate all the possible problems.
 
#13 ·
Im still having issues.

Had it running good until I bent a pushrod which broke a lifter, it still ran. Finally noticed when it quit and wouldnt start again and replaced the lifter.

Now she wont start at alla nd when I try to start it it makes it sound like its hitting something inside the engine, not quite like having timing too advanced but similar, a grinding crashing kind of noise. Changeing timeing makes no different.

It is a weak battery but its charged however the spark is kindve weak so I replaced the distributor and coil (same cap however, could this be an issue?). It gets a spark, its a weak blue one which I figure should still start it andI've even tried new gas. Any ideas?
 
#14 ·
Nsomnia said:
Im still having issues.

Had it running good until I bent a pushrod which broke a lifter, it still ran. Finally noticed when it quit and wouldnt start again and replaced the lifter.

Now she wont start at alla nd when I try to start it it makes it sound like its hitting something inside the engine, not quite like having timing too advanced but similar, a grinding crashing kind of noise. Changeing timeing makes no different.

It is a weak battery but its charged however the spark is kindve weak so I replaced the distributor and coil (same cap however, could this be an issue?). It gets a spark, its a weak blue one which I figure should still start it andI've even tried new gas. Any ideas?
Is there any oil in the motor if there is is it getting oil presure???????
 
#16 ·
You must be psychic. I checked the dipstick and it took 3.5 liters to top er up. I wonder if there are oil stealing gnomes up here in canuckistan, I put 5 quarts in when I built er.

Turned over alot smoother for a second and actually sounded like it wanted to light but now its back to a horrible grinding-binding noise. Maybe the starter gear isnt disengaging and its not letting it turn freely? WHat else can I check?
 
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