[mike82]

This is driving me crazy.
Just fitted a new engine to a 79 project I'm working on.
But the sob wont start.
It just keeps popping through the carb.
I have set timing as per Lars's papers,
bought no1 cylinder to tdc on compression stroke lined up the dizzy but it still pops through the carb.
The engine is a newly rebuilt unit which i bought and did not rebuild.
Do you think that i may need to degree the cam first before doing timing.
Any ideas.

 

[rjent]

Check your high tension leads for correct firing order. Who made the engine? Make sure what your cam firing order is on the cam (whether it is a "corvette" firing order or chevy firing order).

How are you finding TDC on #1?

 

[The Torch]

Checking the cam might be a good thing assuming (and not trying to kick you here) that the firing order is correct. Who ever built the engine could have gotten the cam at 180* from where it should be

 

[mike82]

Check your high tension leads for correct firing order. Who made the engine? Make sure what your cam firing order is on the cam (whether it is a "corvette" firing order or chevy firing order).

How are you finding TDC on #1?

I lined up the timing mark on the balancer,when the no1 cylinder valves were on compression stroke(neither valve moved).Then droped in the dizzy and the rotor was in the no1 cylinder position.

The engine was built to go into a camaro,so you might be right about the firing order,i thought all small blockks were.
18436572
is there another firing order?
:cheers:

 

[Elduderino]

rotate the dist 180* and see what happens, who knows????

 

[jotape650]

:agree:

 

[6880 Mike]

Answered your post at the other place.

:thumbsup:

 

[010752]

Checking the cam might be a good thing assuming (and not trying to kick you here) that the firing order is correct. Who ever built the engine could have gotten the cam at 180* from where it should be

I don't get that. :huh:

 

[Strider]

The engine was built to go into a camaro,so you might be right about the firing order,i thought all small blockks were.
18436572
is there another firing order?
:cheers:

Learn something every day??? Didn't know that a corvette and a chevy had different firing orders?? Knew some cams have changed a couple of cylinders but never new chevy and corvette differed.
I would try advancing the distributor, turn the housing counter clockwise until the starter starts to have trouble turning over the motor.
Poping through the carb to me sounds like REtarted timing.
I always advance them to the point where the starter is starting to have trouble.

 

[010752]

Here are some other firing orders for chevy v8, but usually used for racing for a max gain of less than 10 hp. Doubtfull this is the case here.

1-8-4-2-6-5-7-3
1-8-7-2-6-5-4-3
1-8-7-3-6-5-4-2
1-5-4-3-6-8-7-2
1-5-7-3-6-8-4-2
1-5-7-2-6-8-4-3
1-5-4-2-6-8-7-3

Check that your valves are not set too tight too. That can cause some popping and cloud the issue.

 

[mike82]

Thanks guys looks like my weekend is mapped out for me.:thumbsup:

 

[rjent]

Learn something every day??? Didn't know that a corvette and a chevy had different firing orders?? Knew some cams have changed a couple of cylinders but never new chevy and corvette differed.
I would try advancing the distributor, turn the housing counter clockwise until the starter starts to have trouble turning over the motor.
Poping through the carb to me sounds like REtarted timing.
I always advance them to the point where the starter is starting to have trouble.

Smart engine builders understand the benefits of a 4&7firing order swap camshaft, which exchanges the 4 and 7 camshaftlobe timing in small and big block Chevrolet engines. While some builders have realized significant horsepower gains, all of them experience the exceptionally smooth torque curve possible with this new firing order technology.

source

I only posted this because I have seen it before. The 4/7 swap is actually a Ford firing order and supposedly balances the pulses better (less crankshaft stress). It is a long running controversy. If an engine builder is told an engine is for a Vette, sometimes they put the 4/7 swap cam in because it is considered a Corvette firing order. :thumbsup:

 

[big2bird]

rotate the dist 180* and see what happens, who knows????

:agree: $10. says your out 180*

 

[Fred Mann]

I've heard of cams that required a different firing order, but not just changing spark plug leads around. The factory LS6 manifold that I have has the standard firing order cast into it...18436572.

As you brought the crank around to TDC and the No. 1 valves are both closed (no tension on the rockers if the valve adjustment is right) then you're on No. 1 TDC. The cam can't by out by 180 degrees, the only relationship between the cam and crank is through the timing chain. When you install the timing chain with a new cam, that's when No. 1 TDC is set. If the marks are lined up between the crank gear and the cam gear, that's it. When you do the initial valve adjustment, you have to have your head screwed on straight and check that the lifters for No. 1 are on the cam base circle at TDC. If you brought the crank around to what you thought was TDC on No. 1 and the lifters weren't down on the cam base circle, then you are on No. 6. You would just crank the engine around again to get TDC on No. 1. Correct me if tha's wrong.

If you lined the dizzy up exactly with the No. 1 tower location on the distributor, you probably have retarded timing, since the spark will jump to the terminals before things actually line up.

 

[010752]

I lined up the timing mark on the balancer,when the no1 cylinder valves were on compression stroke(neither valve moved).Then droped in the dizzy and the rotor was in the no1 cylinder position.

The engine was built to go into a camaro,so you might be right about the firing order,i thought all small blockks were.
18436572
is there another firing order?
:cheers:

That should have worked.

Here is an easy way to do it without having to take the valve covers off.

Gut an old spark plug.
Stretch a balloon over it and install by fingers into #1 cylinder.
Turn the engine over with a socket on the front of crankshaft.
When the balloon starts to fill with air, you know you are on the compression stroke.
Forget about balloon and continue to turn the crank by hand until the tdc mark lines up to approx the 10° btdc mark on the pointer.
Aim the dist rotor leading edge to the #1 terminal leading edge on the cap/dist.
Rotate again to double check before installing plug/wire.
Should get you close enough to run.


If it won't run in that position, then either
-wires are not correct
-an old balancer has slipped
-cam/crank timing is wrong (may be off a tooth on chain etc)
-valves may be set too tight
-have differently timed cam installed (wrong firing order)

 

[69vettester]

I lined up the timing mark on the balancer,when the no1 cylinder valves were on compression stroke(neither valve moved).Then droped in the dizzy and the rotor was in the no1 cylinder position.

The engine was built to go into a camaro,so you might be right about the firing order,i thought all small blockks were.
18436572
is there another firing order?
:cheers:

I agree with those that have said To "turn the Dist. Counter Clockwise a little at a time until the engine fires.
But...
If it doesnt start up then Try This, its an easy way to tell that your Cam gear was installed correctly without removing the timing cover.

Remove the #1 Plug. Turn the balancer clockwise until 0* starts comming up. Put your finger Over the #1 plug hole. Air will start blowing out the hole as the mark comes up and will stop as the mark goes past 0* "TDC". If this doesnt happen, Your crank gear was likely at 12oclock and your cam gear was intalled at 12oclock That is 180* off" and the #6plug will be at TDC when the balancer mark is at 0*.

Another way of saying that is "the Timing gears must be installed with the crank Gear at 12 oclock and the Cam gear at 6 oclock.

Keep posting Im the curious type and interested in How you solve the problem..:cheers:

 

[010752]

I agree with those that have said To "turn the Dist. Counter Clockwise a little at a time until the engine fires.
But...
If it doesnt start up then Try This, its an easy way to tell that your Cam gear was installed correctly without removing the timing cover.

Remove the #1 Plug. Turn the balancer clockwise until 0* starts comming up. Put your finger Over the #1 plug hole. Air will start blowing out the hole as the mark comes up and will stop as the mark goes past 0* "TDC". If this doesnt happen, Your crank gear was likely at 12oclock and your cam gear was intalled at 12oclock That is 180* off" and the #6plug will be at TDC when the balancer mark is at 0*.

Another way of saying that is "the Timing gears must be installed with the crank Gear at 12 oclock and the Cam gear at 6 oclock.

Keep posting Im the curious type and interested in How you solve the problem..:cheers:

If you don't like that position, then rotate the crank another 360°.


Do you like it better now. ???

 

[big2bird]

 

[Elduderino]

Have you tried to just rotate the dist 180*? Ill bet thats the problem.

You mention you set the timing mark to be TDC and looked at the valves on number 1? You know if its at TDC on the exhaust stroke, the exhasut valve has just closed and the intake valve is just starting the open. So it really looks like they are (and actually are ) both down... You really need to verify TDC on the power stroke by putting paper or your finger on the plug hole whils someone turns the motor over. That ballon trick looks pretty good too.

 

[mike82]

Well guys,
heres the latest
tried rotating the dizzy 180 degrees just made things worse.

But while i was bolting the dizzy down,
i had the drivers side valve cover of,
i noticed that the valves on #1 cylinder while on tdc on compression stroke were not level,
the inlet valve was lower than the exhaust valve,
so i loosened all the valves on all 8 cylinders,
and the s.o.b fired straight up.
That was the most beautiful sound i have ever heard in my life.artyon:
So it looks like the cause of the problem was due to the engine builder over tightening the valves.
many thanks for your ideas and help.
:cheers: