Bad rocker/ low vaccuum sympoms
06-27-2005, 08:41 PM
#1
Staging Lane
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Bad rocker/ low vaccuum sympoms I just finally fired my ls1 up after swapping in
Stock 99 ls1 bottom end and lifters
Patriot Stage II heads
TSP dual springs
TSP 231/237
Dual Timing Chain
37lb injectors
ported tb
ported maf ends
Ls6 intake
02 manifolds.. 2.5" y pipe and a flowmaster back end
I have some questions tho..I stole a friends tune thats about the same parts
1) It idles pretty good.. at 800 rpm.. is that too low?
2) Will a loose rocker make a clacking noise and make a diff noise at certain rpm like at 5k making a loud metalic noise? or does that sound more like a lifter
3) I shouldnt have any leaks.. but I have only 11 psi of vaccuum at the brake booster.. i couldnt get any vaccuum at the front port of the pcv port.. is this normal? could a bad rocker or two knock this down
should i check any other parts.. plugs? wires?
Stock 99 ls1 bottom end and lifters
Patriot Stage II heads
TSP dual springs
TSP 231/237
Dual Timing Chain
37lb injectors
ported tb
ported maf ends
Ls6 intake
02 manifolds.. 2.5" y pipe and a flowmaster back end
I have some questions tho..I stole a friends tune thats about the same parts
1) It idles pretty good.. at 800 rpm.. is that too low?
2) Will a loose rocker make a clacking noise and make a diff noise at certain rpm like at 5k making a loud metalic noise? or does that sound more like a lifter
3) I shouldnt have any leaks.. but I have only 11 psi of vaccuum at the brake booster.. i couldnt get any vaccuum at the front port of the pcv port.. is this normal? could a bad rocker or two knock this down
should i check any other parts.. plugs? wires?
06-28-2005, 06:19 PM
#2
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I'll knock this to the top for you along with some thoughts:
800 RPM seems fairly normal. You might need to tweak the computer to
accept all the new parts and settings.
A loose rocker is easier to pin point than a lifter issue. If you hear clacking,
there's a good chance the pre-load is incorrect. Turn the motor over by hand
with each cylinder in the firing position (you might need a degree wheel to get
accurate).
At this point, you can check the intake and exhaust rocker for pre-load.
Pre-load can affect vacuum. Camshaft (valve timing) is a huge factor in
manifold pressure. I don't think you have any leaks.
Just one other thing, check your units for vacuum!
800 RPM seems fairly normal. You might need to tweak the computer to
accept all the new parts and settings.
A loose rocker is easier to pin point than a lifter issue. If you hear clacking,
there's a good chance the pre-load is incorrect. Turn the motor over by hand
with each cylinder in the firing position (you might need a degree wheel to get
accurate).
At this point, you can check the intake and exhaust rocker for pre-load.
Pre-load can affect vacuum. Camshaft (valve timing) is a huge factor in
manifold pressure. I don't think you have any leaks.
Just one other thing, check your units for vacuum!
07-01-2005, 11:59 PM
#3
Staging Lane
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thanks for the tips.. i checked all the rockers and they were fine.. the car idles really good now and I think its just a normal noise... dont get to listen to many Ls1s so I have no clue what normal is..
still have low Vac tho.. but i guess that could be the tuning? or timing or some unknown issue..
still have low Vac tho.. but i guess that could be the tuning? or timing or some unknown issue..
07-02-2005, 01:52 AM
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Don't worry about the vacuum, it's probably a product of the camshaft.
Just for example, my last motor had a Crane Energizer with 280 degrees of
adv. duration, and an LSA of 112. At idle, my engine had 14 in./Hg.
This new motor has a Comp 292H-10 which has 292 degrees of adv. duration
and 110 LSA. Now my vacuum is 5 in./Hg.
No brake assist, and falls on it's face idling.
That's just the nature of the camshaft because of the lower effective
compression (too much pressure bleeding off at low to mid RPM).
You can adjust timing to improve the vacuum signal, but you want to make
sure the timing curve is set for best power at high RPM.
There are other methods to tweak vacuum, but it involves dialing the cam,
playing with the lifter pre-load, etc. Pretty advanced stuff.
P.S. Where in Canada do you live?
Just for example, my last motor had a Crane Energizer with 280 degrees of
adv. duration, and an LSA of 112. At idle, my engine had 14 in./Hg.
This new motor has a Comp 292H-10 which has 292 degrees of adv. duration
and 110 LSA. Now my vacuum is 5 in./Hg.
No brake assist, and falls on it's face idling.
That's just the nature of the camshaft because of the lower effective
compression (too much pressure bleeding off at low to mid RPM).
You can adjust timing to improve the vacuum signal, but you want to make
sure the timing curve is set for best power at high RPM.
There are other methods to tweak vacuum, but it involves dialing the cam,
playing with the lifter pre-load, etc. Pretty advanced stuff.
P.S. Where in Canada do you live?
07-02-2005, 12:40 PM
#5
Staging Lane
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thanks for the pointers
it idles and brakes.. i guess I should stop gauge lookin
i live in lloydminster.. its right on the border between alberta and saskatchewan
it idles and brakes.. i guess I should stop gauge lookin
i live in lloydminster.. its right on the border between alberta and saskatchewan
