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Discussion Starter #1
Hi all
Hope your all well and playing safe.
I have a1970 Torino Thunderjet with Performer rpm inlet.
motor is missing on 1 and 6.
tried different distributors, leads, plugs and carbies. Both have good compression and cam lift
It will fire 1 and 6 only when it’s that rich it smokes the shed out. Set the carby 770 vac sec Holley correctly and 1 and 6 stop firing.
Tried a 600 and 650 no change. With a 1000 dp it runs but is way to rich.
been at it every weekend for 2 months nearly ready to burn it.
Regards
Stephen
 

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1 and 6 are connected to the same side of the carburetor.
Are you sure that you have no vacuum leaks?

SJ
used 2b RHP


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Discussion Starter #3
1 and 6 are connected to the same side of the carburetor.
Are you sure that you have no vacuum leaks?

SJ
used 2b RHP


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Yes they are on same port on carby and directly opposite in distributor
Tried 3 carbs and 2 distributors. It is definitely fuel but I’m missing something.
 

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Is it possible that the Eddie Performer RPM is an issue? Anyone else have one on a 429?
This really sounds like a vacuum leak of some sort.

SJ
used 2b RHP


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Is it possible that the Eddie Performer RPM is an issue? Anyone else have one on a 429?
I ran one for many years. The flange is designed to accept both a Holley square bore and a Q-jet. This design results in an odd shape with a very narrow sealing surface which can result in vacuum leaks when using a Holley. I believe Edelbrock makes a plate to address this problem. Might want to check for vacuum leaks at the carb base.
 
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With the firing order being 15426378..1 and 6 are paired together in that when 1 is at top dead center so is 6..What you have is a broken valve spring on 1 or 6..It causes the weak valve to draw in the fuel mixture for the other cylinder..Just pull the valve covers off and take a good look at the springs..Gotta look at the base of the spring because that is where all the pressure of it being squeezed will take the most stress..This happened to me..
 

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Discussion Starter #8
I’ll check them again. However the heads have just been rebuilt with new valve springs.
I have located the Edelbrock plate that is used on the Performer RPM when using the square bore carby. New gaskets Loctite Non Harding no 2. Still no difference.
it has to be vacuum!!
 

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Have you hooked up a vacuum gauge to it.? With a leak, it will vary at idle..but with something wrong with the valve train, it will twitch in rythem with the idle rpm
 

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If I remember this right..this happened to me back in the 70s..It was a broken exhaust spring..As the piston draws down on the intake stroke, it would crack open the exhaust valve and suck exhaust back into the cylinder..messing up the fuel mixture..That is what my faint memory is telling me..I have run out of ideas..I am pretty sure then that the springs are good..It would pulse(gauge) if valves were weak with a broken spring
 

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Hi all
Hope your all well and playing safe.
I have a1970 Torino Thunderjet with Performer rpm inlet.
motor is missing on 1 and 6.
tried different distributors, leads, plugs and carbies. Both have good compression and cam lift
It will fire 1 and 6 only when it’s that rich it smokes the shed out. Set the carby 770 vac sec Holley correctly and 1 and 6 stop firing.
Tried a 600 and 650 no change. With a 1000 dp it runs but is way to rich.
been at it every weekend for 2 months nearly ready to burn it.
Regards
Stephen
I would think you have a vacuum leak at the bottom of the port under the manifold on 1 and 6. If the heads or block were decked and the manifold wasn’t cut, or vice- versa, you could have non parallel mating surfaces. Causing a leak. Take manifold off and measure the angles on the block and manifold, and check width across bottom and top of heads vs manifold. My 2 cents worth.
 

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To check for a large vacuum leak under the intake.

Remove pcv valve and tape valve cover grommet. Check for any suction at the other valve over.
There should be NONE.

SJ
used 2b RHP


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Discussion Starter #16
Well I’ve battled on and found a collet half out on no6 inlet valve. I couldn’t see this unit I removed the rocker. Replaced it with a new one and presto 1 and 6 are firing again. However I now have another issue perhaps it should be the start of a new thread?
I’m fairly good with Holley carnies and normally don’t get beaten by one. However now I have a motor that doesn’t stall when the idle mixture screws are wound all the way in. Two different carbies a 770 Street Avenger and a 650 Vac Sec. 2 different power valves in both.
Normally this is a sign of a failed power valve but not this time.
Regards
Stephen
 

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Discussion Starter #17
If I remember this right..this happened to me back in the 70s..It was a broken exhaust spring..As the piston draws down on the intake stroke, it would crack open the exhaust valve and suck exhaust back into the cylinder..messing up the fuel mixture..That is what my faint memory is telling me..I have run out of ideas..I am pretty sure then that the springs are good..It would pulse(gauge) if valves were weak with a broken spring
Not a broken valve spring but a loose collet! Thanks!
 
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