defiant1

Ok-trying to break in a new camshaft with a rebuilt carb and I am having issues.

Background: Heads rebuilt, new camshaft, new edelbrock performer intake, rebuilt carb w/1 inch phenolic spacer.


Rebuilt the Qjet carb w/electric choke per Cliff Ruggles suggested "recipe". Tried to start the car initially at 0* TDC. It ran for about 3 seconds and died. When it died white smoke/fuel mist came out the top of the carb. Tried a few more times with no luck. The motor sounds like it is "sucking air" then it floods.

The next time I attempted it I set the static timing at 12* BTDC (I ensured I was on the compression stroke).

I thought maybe the choke was the problem, so I clamped the primaries wide open. That caused the white smoke effect almost instantaneously. I then hooked up the electric choke and cranked it. It would crank for about 3-4 cycles and give out the white smoke out the primaries and fuel bowl tube.

The ignition is a petronix III setup- I ensured the tang on the outer edge of the rotor was pointing to the #1 spark plug wire. Checked my wires (I will go check again to make sure).

What is causing the white smoke condition?

Thanks

d1

oldcutlass

If its backfiring out the carb, could the dist. be 180 deg out??

defiant1

I suppose it is possible, not sure how though. There is a matching set of scribe marks on the distributor base and on the edge of the hole the distributor sets in. I was using that as a reference when I had the old setup when setting the timing. I used the marks for the same rationale for the new setup.

Oldsmaniac

I have seen vapors/smoke exit thru top of carbs on engines that have jumped time/timing chain problems. This causes valve opening to be not in sink. The engine cranks with a strange sound as if there is no compression. You may want to check relation of #1 piston in relation to timing mark on balancer and valve position.

defiant1

When the motor was out of the car I checked the balancer relationship with the valves on the #1 piston. And the timing gears and chain were replaced.

When the balancer was at 0* TDC the piston was at the top of its stroke and the valves were both closed.

d1

Oldsmaniac

What is the condition of timing chain and gears?

defiant1

The old timing set looked good considering. And the replacement was a new double roller timing gear set.

Oldsmaniac

Keep at it and hopefully you will figure out what the problem is. Very hard to diagnose this problem in a forum. Keep going over the basics, make sure your valves are opening and closing properly..... your situation reminds me of a weekend trying to start a fresh HP build on a friends 403. Prior to this the engine was bench run flawlessly. On initial try in the car my friends son had the dist 180 deg out and the engine backfired violently. The dist was put in correct and the engine would not fire, only backfire thru the carb and vapors/smoke out of the carb. After trying everything the timing cover was pulled and the cam alignment pin had snapped off and the cam gear was slipping at will. Needless to say valves got bent etc.

defiant1

Yeah, I will keep trying. I will reset back to 0* TDC and re-check everything one more time and give 'er hell.

oldcutlass

I would make sure my pertronix unit is set up correctly and I have the correct voltage at the coil. Then I would start with my initial timing at 10 deg btdc.

Oldsmaniac

Just to be clear you should install distributer with slot on balancer at 0 degrees TDC compression stroke. Rotor needs to point to #1 plug wire. While cranking rotate distributer a little to give some ignition timing...if it starts and runs snug down distributer and check with a timing light for about 10deg BTDC at around 1000 rpm.....this should do till cam is broken in then adjust ignition timing according to specs or preferance.

citcapp

kinda sounds like it is a few teeth off Like a 1/6th turn of the hex oil pump drive shaft.

defiant1

OK-took all the wires off, distributor out, had my helper admit that I might not have been on TDC when we tried yesterday. So, 0* TDC, rotor set at #1 wire and it fired it up.

Got it started for about 20 seconds or so -- had to keep giving it gas as it seemed like it kept wanting to die, which it finally did.

Started it again for about another 20 seconds, could not keep it running.

On subsequent attempts I kept getting backfiring thru both the carb (1.5' flame) and the headers.

So I assume the intake valves are not fully closing. Am I off a couple of teeth on the distributor? Which way do I need to turn it?

Not looking to catch the motor on fire, but spewing gas and flames everywhere is not cool.

Tried retarding the timing while cranking and had no luck...

Any suggestions would be appreciated.

Oh -- and back to my original issue with the white smoke/mist condition, I can only assume I was 180* off.

d1

defiant1

Can I take the distributor out and rotate 1 tooth (not sure what rotation direction yet) and install? Or do I have to set everything at 0* TDC, rotor at #1 wire, etc. first??

d1

B964

Firing order going counter clockwise? They will almost run (barely) if you do it clockwise.

Oldsmaniac

You need to install distributer while timing mark is at 0 degrees TDC compression stroke. Rotor has to be pointing to #1 plug wire. Rotor spins counter clockwise and firing order is 18436572. You need to advance the ignition timing by turning the distributer while cranking to find a spot where it fires and stays running. Are you sure timing chain set was installed properly?

defiant1

Dots were lined up on timing gears, so not sure how else I could have mounted it differently.

OK-what is the best way to ensure I am only adjusting the distributor 1 tooth at a time?

Also, I am assuming I will need to retard the timing, so I will have to turn the distributor CCW 1 tooth???

d1

Oldsmaniac

You do not want to advance or retard the distributer by 1 or any teeth. You drop it in so #1 plug wire on cap is aligned with rotor. To do this balancer slot must be at zero degree mark on timing tab. #1 piston must be at top dead center on the compression stroke. You need ignition timing advance so engine runs properly. You adjust this while the engine is running by loostening dist hold down bolt and turning the dist housing while watching timing tab and balancer with timing light. You prob want 10 degrees advance at 900 RPM. Then tighten hold down bolt. You can advance or retard ignition timing by the direction you turn the dist.

defiant1

OK-then I should be good as I did that already. Just need to keep it running long enough to advance the timing. Can a carburetor cause a backfire condition if it isn't adjusted correctly? I definitely did not have a shortage of gas in the carb.

Oldsmaniac

It is unlikely that the carb is the problem unless it is flooding.

defiant1

OK-hopefully my experience will help others.

I kept reading and also being told to set the rotor at #1 wire and ensure #1 cylinder is at 0* TDC.

I did all that and could not get the motor running. Driving me nuts. So I researched on line and came across a chevy forum that explained how the cylinders related to each other as it relates to ignition timing and the 4 stroke cycle.

So, yes I had the #1 cylinder at TDC, but it was the #6 cylinder that was in the "firing position" and at TDC also when the motor was in this configuration.

So I spun the rotor so it was facing the #6 wire and wallah! The motor took off like a raped ape.

I should mention that this all has to do with the position of the dots on the crank and camshaft sprockets. They relate to each other in the following fashion:

When one of the pair of cylinders are at TDC and ready for spark, the other is at TDC between exhaust and intake stroke. The pairs are:

1/6, 8/5, 4/7, 3/2

So when the:

Crank Dot at - Cam dot at - Cyl at TDC ready to spark:
12 ------------- 12:00 ----------------- 1
03 --------------01:30 ----------------- 8
06 ------------- 03:00 ----------------- 4
09 ------------- 04:30 ----------------- 3
12 ------------- 06:00 ----------------- 6
03 ------------- 07:30 ----------------- 5
06 ------------- 09:00 ----------------- 7
09 ------------- 10:30 ----------------- 2


Basically, lining up the dot when installing the cam and crank gears are only there for the installation portion, but are not directly porportional to the #1 cylinder being at TDC (firing position).

Hope this helps -- I sure could have used this info 2 weeks ago.

d1

coltsneckbob

So what you're saying is that you didn't have the #1 piston at TDC during the compression stroke when the spark it, but instead during the exhaust stroke.

defiant1

Kind of... The #1 piston did not have either the intake or exhaust valve open (valve springs were not compressed). But the piston was at TDC.

Lining up the two dots on the crank/cam gears resulted in this condition.

But yes the #1 piston was not in the firing position. I pulled the #6 spark plug and it was full of gas, and it could not ignite due to the fact I had the rotor pointed at the #1 ignition wire (or I think what everyone refers to as being 180* out).

Shizzy

awesome! glad you got it sorted.

but do yourself a favor and change out the engine oil now. all that cranking and flooding has probably put some fuel in the oil. good way to wipe out some bearings.

MDchanic

And OldCutlass wins the prize!

So now, the question is, why didn't any of us think to explain how to check to be sure that the #1 cylinder was on compression, and not on intake?

It's as easy as holding a finger over the spark plug hole and turning the engine over.

I'm curious (for the sake of improving my troubleshooting skills and preventing this sort of dropped ball again) - when you assembled it, did you set the timing marks on the gears to be directly opposite each other (crank at 12:00, Cam at 6:00), or to be in analogous positions (both at 12:00)? The manual specifies the former (6 & 12), but your table seems to imply that the latter (12 & 12) would be correct.
In theory, when it's at 6 & 12, if you put the distributor in pointing to your intended #1 terminal, it should be right.

If you aligned the gears at 12 & 12 and put the distributor in pointing to #1 instead of #6, this would be the expected result.

I'm VERY glad you got it figured out (and with no help from us meatheads ).

- Eric

Oldsmaniac

Great and now you will never forget the procedure.....When the dots are lined up with the timing gears. The #1 cylinder is not up on compression stroke. If you rotate the crank 1 turn you will be on TDC compression stroke. The finger over the #1 spark plug hole is a good way to check as piston is coming up..... while turning the crank with a wrench.... Trouble with forums is we do not know the expertise of those on the other end and often assume things. TDC compression of #1 must be verified and not guessed at.

defiant1

I am not uber experienced when it comes to motors, but I did follow the advice of placing my finger over the number 1 spark plug hole and waited for the force of air to push my finger off the hole while the crank rotated (via bump start). Then I ensured the rotor was facing #1 wire and the crank balancer was 0*. I tried starting it but only got flames out the carb and headers.

I did this procedures multiple times with varied results. I am sure I even tried it on the exhaust stroke (just in case I was wrong). The motor started at times but only for a few seconds.

The cam and crank dots were facing each other (cam at 6 and crank at 12) when I assembled the timing gears. And your methodology that you described above was what I using as reference. So, when I placed the rotor at #1 and it did not fire up I was confused.

After reading another forum's post, I decided to give that method a whirl based on the when the pistons fire at TDC, not TDC in and of itself. I gave the carb a squirt of gas and it fired right up and ran for 40 minutes at different rpms and only stopped when the positive battery wire burned up (separate forum thread).

No meatheads here, because diagnosing a problem utilizing the internet is not ideal. I have learned more than I could have hoped for from this forum so, I appreciate everyone's input.




I was having problems determining the compression stroke with the finger method. It seemed I was getting a shot of air on both the exhaust and compression stroke. Took the valve cover off to check the compression of springs to help me determine if the valves were open or closed and I was getting the same result (maybe the lifters were not full of oil--not sure). But rockers were loose and springs were not compressed each time I saw the piston come to TDC thru the spark plug hole.

I am sure inexperience played a part but I didn't think I was going to have an issue with timing as it is pretty straight forward.

Thanks for hanging tough thru the thread.

MDchanic

I bet that's part of it. This is one of the places where degreeing the cam would have helped you in the long run - you would have seen the opening with the dial indicator. May also be why you couldn't feel the compression well with your finger - the lifters may have been empty and not pushing the valves very far open. Did you crank the motor at all with the plugs out to get the oil pressure up?

It also looks to me like Joe said the opposite of what I said about where compression is in the initial cam timing position - "When the dots are lined up with the timing gears. The #1 cylinder is not up on compression stroke. If you rotate the crank 1 turn you will be on TDC compression stroke," so don't listen to me .

- Eric

Oldsmaniac

It is always better to turn the crank with a wrench as the bump starter method lets things happen too fast to be sure of things.

MDchanic

For those who like little gadgets, they even make a whistle with a spark plug thread base, so you can hear when you're on compression...

- Eric

defiant1

I actually degreed the cam when the motor was out of the car in order to verify the specs on the cam card. I guess I did not focus much on the relationship of the piston vs. crank/cam at the time. I was just happy the cam matched the specs...

I did not crank the motor with all the plugs out. But I operated the oil pump with a drill for a few minutes to ensure oil was moving where it needed to be (and I found an oil leak on my oil sender switch adapter-bonus). As far as lifters go, they were soaking in oil for at least a couple of weeks.

d1

oldcutlass

Well, I want to appologize for not taking my suggestion 1 more step and explain exactly what 180 deg out meant. Even with the finger method I've found that you have a 50/50 chance in stabbing the dist. in backwards. I'm glad you got it corrected and running!!!!