Motor issues.

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moparmarks

moparmarks

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Working on a freshly overhauled 1969 440.
Isky solid cam .557 lift, 296* duration, 110cl. Lash is set at .006
Timing 10* w/ 30* advanced.
Edelbrock CH8 with twin 1406 carbs. New and still factory settings.
We are at about 7000'.
Car does not seem to be running too rich with is odd.
1st issue. At idle the vacuum is very erratic at around 6 in. Needle is bouncing.
The step up pistons that hold the metering rods are bouncing hard with the vacuum. They are hitting their little covers so hard it is making a loud chattering sound.
Does not seem to be and can't find any vacuum leaks. If I choke off a carb it wants to stall the motor.
2nd issue. Using a laser temp gum while at idle. Most header tubes at the flange are running around 240* number 3 is running around 380* and numbers 4 and 6 are round 300*.
Thoughts?
 
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I lost about 6 inches of vacuum moving from sea level to 5k feet, went from 17 to 11 inches and it bounces a bit there too. Add a lot of cam and you are going to lose even more. Not familiar with the Edelbrock metering rod setup.. can you install a different spring? Pull the plugs and see what they look like. Getting my single vacuum secondary carburetor tuned in properly here took quite a few days.

No idea how your header tubes can be that cool.
 
moparmarks said:
Working on a freshly overhauled 1969 440.
Isky solid cam .557 lift, 296* duration, 110cl. Lash is set at .006
Timing 10* w/ 30* advanced.
Edelbrock CH8 with twin 1406 carbs. New and still factory settings.
We are at about 7000'.
Car does not seem to be running too rich with is odd.
1st issue. At idle the vacuum is very erratic at around 6 in. Needle is bouncing.
The step up pistons that hold the metering rods are bouncing hard with the vacuum. They are hitting their little covers so hard it is making a loud chattering sound.
Does not seem to be and can't find any vacuum leaks. If I choke off a carb it wants to stall the motor.
2nd issue. Using a laser temp gum while at idle. Most header tubes at the flange are running around 240* number 3 is running around 380* and numbers 4 and 6 are round 300*.
Thoughts?
Click to expand...
THere are books, articles, and videos about tuning Carter/Edelbrock carbs.
 
A fiend just told me that I have the lash to tight at .006. He said should be .014-.016
I've never dealt with solid lifters on a BB before.
 
[1] Cannot find that Isky cam in my catalog.
[2] Lash would be more than 0.006" for any sol lifter cam.
 
moparmarks said:
Isky solid cam .557 lift, 296* duration, 110cl. Lash is set at .006
Click to expand...
Not seeing any lobes in Isky’s various solid lifter lobe lists with those lift/duration specs. They scream Mopar Performance though. You might want to re-verify and check on the correct lash for those particular lobes on the cam, might need to be a little looser. Those .014-.016 settings are typically tight lash lobe specs if I’m not mistaken. Set cold or hot?
 
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The cam is probably 20 years old.
What do you think I should set them at? I'll set them when hot.
 
moparmarks said:
The cam is probably 20 years old.
What do you think I should set them at? I'll set them when hot.
Click to expand...
Curious, are you running Aluminum heads or iron? Others well versed on lash for sure will have the ideal settings you should shoot for with that cam depending on heads used. Isky does show hot lash for solid lobes ranging from .014-016 up to .028
Depends on what lobes and if it in fact it is an Isky cam or actually an MP cam. Only caught my attention as the lobes are not shown in the Isky lobe list. A consensus might be helpful........But the settings you’re at now are certainly better than .006:thumbsup:
 
906 iron heads with iron non-roller rockers. He bought the motor from a friend and this is the cam info that get got.
 
I'll be working on it today. Need to get the lash right and vacuum issue fixed before I can dial in the carbs.
 
I set all the valves at .015. Vacuum is still around 6 in but is more steady with just a little bit of Bounce not much. On my exhaust temperatures I was incorrect before. Most of them are running around 300 and number three is running around 600. It doesn't look like number three exhaust valve is sticking. I have good compression and can pull the plug wire and notice the change in RPM with killing that cylinder.
 
Nowhere near enough initial timing for that camshaft, double it to 20* and work on the mechanical to hit total.

Probably a dead copy for the 557 mopar cam that wanted .030 for hot lash. Cold lash closer to .022. I set the 528 cam at 020-022 hot, even though the recommended was closer to .030
 
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I bumped the timing to 14*. I also changed the piston springs in the carbs and those settled down.
I'll be back next week to work on it. I'll mess with the timing some more and bump the lash to .022 or so.
I'm concerned as to why #3 Exhaust tube is 600* when the others are 300*
Once I get things figured out I'm having Ray on here setup a distributor for it.
 
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That cam is the old Mopar Perf 296 cam. Lash is 0.028" in, 032" ex hot. With iron heads, you can set the lash cold & it will very close to specs. Vacuum will THEN increase.

Note that the cam has a lot of duration; it will need at least 30* for best idle quality & may require more.
Set lash properly & THEN check exh temps.
 
moparmarks said:
I bumped the timing to 14*. I also changed the piston springs in the carbs and those to settle down.
I'll be back next week to work on it. I'll mess with the timing some more and bump the lash to .022 or so.
I'm concerned as to why #3 Exhaust tube is 600* when the others are 300*
Once I get things figured out I'm having Ray on here setup a distributor for it.
Click to expand...
It is not uncommon to have different header pipe temps its mostly caused by poor cylinder distribution of the intake manifold. In your case #3 is running a leaner AFR than the rest causing that header pipe to heat up. Read the #3 plug it will tell you the story.
Remind me what carb and intake are you using?
 
Not familiar with the characteristics of that intake.
I have seen performance tuners stagger jetted Holley carbs to balance the the AFR between cylinders, never seen it done with Edelbrock carbs. Might be worth a try maybe some of our engine Guru's will chime in with a recommendation.
What does the #3 plug look like in relationship to the other plugs?
 
Soooooooo, your disagreeing with what we have on the motor?????
#3 plug looks the same as the others.
 
moparmarks said:
Working on a freshly overhauled 1969 440.
Isky solid cam .557 lift, 296* duration, 110cl. Lash is set at .006
Timing 10* w/ 30* advanced.
Edelbrock CH8 with twin 1406 carbs. New and still factory settings.
We are at about 7000'.
Car does not seem to be running too rich with is odd.
1st issue. At idle the vacuum is very erratic at around 6 in. Needle is bouncing.
The step up pistons that hold the metering rods are bouncing hard with the vacuum. They are hitting their little covers so hard it is making a loud chattering sound.
Does not seem to be and can't find any vacuum leaks. If I choke off a carb it wants to stall the motor.
2nd issue. Using a laser temp gum while at idle. Most header tubes at the flange are running around 240* number 3 is running around 380* and numbers 4 and 6 are round 300*.
Thoughts?
Click to expand...
The rods bouncing means the lopey idle vacuum is overcoming the spring. Get the Edelbrock tuning kit for your carbs & change the rod springs to a lighter set. Start with one level weaker at a time until the bouncing is resolved. This will keep them from bouncing and will lean out your idle mixture so you can properly tune those guys. I had the same problem with my 408.
 
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