Author Topic: BB manifold still tapping PS box  (Read 7686 times)

sixt9x33rs

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BB manifold still tapping PS box
« on: November 08, 2015, 11:36:38 AM »
I put new motor mounts on my 69 L35 convertible but still have this annoying bumping of the manifold on the ps box. It only happens when the car is in reverse at certain rpms. Not a problem going down the road. I installed correct smog manifolds on the car hoping this would cure the problem. The previous manifolds were wrong and the problem worse. Still have not worked it all the way out. Any ideas?
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

buenymayor

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Re: BB manifold still tapping PS box
« Reply #1 on: November 08, 2015, 12:02:40 PM »
I just looked at my BB 4 speed car, and I've got a good 1/2" clearance between the P/S box and exhaust manifolds. Are you sure you have the right engine mounts/frame stands/cross member? The L and R frame stands aren't swapped side to side, are they?

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #2 on: November 09, 2015, 01:54:02 AM »
I took a mirror and a flash light to make sure I had the right part number frame stands. The motor mounts are right. As far as I know the cross member is right? But can't say for sure. Any other ideas? Something is obviously not right..
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

z28z11

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Re: BB manifold still tapping PS box
« Reply #3 on: November 09, 2015, 03:02:02 AM »
The motor mounts are right. As far as I know the cross member is right? But can't say for sure. Any other ideas? Something is obviously not right..

I think the BB crossmember is offset compared to the small block - just slightly, but might be enough to clear. Checked your underside of the crossmember for the bolt opening ?
Just thinking -

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #4 on: November 09, 2015, 12:57:09 PM »
My car is an automatic. Are there two automatic cross members? SB and BB?
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #5 on: November 09, 2015, 01:00:33 PM »
Just read on the site that the Camaro and Firebird TH 400 cross members look similar but different. I am going to confirm I have the Camaro Cross member. Let you know.
Thanks
Lawrence
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

HawkX66

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Re: BB manifold still tapping PS box
« Reply #6 on: November 09, 2015, 02:35:47 PM »
My car is an automatic. Are there two automatic cross members? SB and BB?
Just read on the site that the Camaro and Firebird TH 400 cross members look similar but different. I am going to confirm I have the Camaro Cross member. Let you know.
Thanks
Lawrence
The 69 Camaro big block manual cross member looks almost identical to the Firebird cross member. The only visual difference I could find is the offset. The 69 Camaro big block auto cross member is completely different though.
Pics came from "TJs" if I remember right.



Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #7 on: November 11, 2015, 12:58:36 AM »
Looks like I have the correct cross member. I measured the distance from the inside of the frame rail to the mounting pad, and the passenger side is approx 1/2" closer than the driver side. So I must assume the offset is correct. Take a look at how close the manifold is to the steering box. Is the manifold deformed? This has me stumped.
Thanks
Lawrence
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

Mike S

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Re: BB manifold still tapping PS box
« Reply #8 on: November 11, 2015, 01:03:27 AM »
Can you see the casting number on the drivers side exhaust manifold? I believe it should be 3909879 if my memory is correct. That has a recess to clear the steering box. I'm assuming the steering box is not loose on the chassis.
Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Under restoration

HawkX66

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Re: BB manifold still tapping PS box
« Reply #9 on: November 11, 2015, 01:38:24 AM »
Did you measure the height of your engine mounts? You said you confirmed they're the correct frame stands too right? I have headers and even they aren't that close.
Dave
69 SS396 X66 L34 M21 BS
Z23 711 U17 Hugger Orange
Semper Fi! USMC 93-02

BSMIT59

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Re: BB manifold still tapping PS box
« Reply #10 on: November 11, 2015, 02:20:17 AM »
Crazy question but could the steering box be incorrect? Are castinings different for manual v power? Z28 v SS or standard shift v auto?
Barry     Old guy but still learning.....
Unrestored 67 barn find
67 SS 350 in process  ( in paint booth now)
Looking for N243673 to reunite V0320MO block and crank

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #11 on: November 11, 2015, 02:29:40 AM »
Did you measure the height of your engine mounts? You said you confirmed they're the correct frame stands too right? I have headers and even they aren't that close.
I bought the listed motor mounts from NPD. I assume they are right?
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #12 on: November 11, 2015, 02:31:31 AM »
Crazy question but could the steering box be incorrect? Are castinings different for manual v power? Z28 v SS or standard shift v auto?
Casting number is correct and the assembly date of the steering box matches the build of the car?
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

sixt9x33rs

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Re: BB manifold still tapping PS box
« Reply #13 on: November 11, 2015, 02:41:47 AM »
Here is a picture from the top side showing the manifold and the steering box.
'69 RS Z/28 Olympic Gold, 711
Flat hood no spoiler, black top, endura, 4:10
POP 39,000
69 X77 Z/28 69 711 Original Paint Unrestored
'69 X66 Convertible Cortez Silver 712 black top Endura, auto, bumper guards, am/fm rear speaker 44k miles

Mike S

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Re: BB manifold still tapping PS box
« Reply #14 on: November 11, 2015, 02:47:30 AM »
 Two questions:
1- "....but still have this annoying bumping of the manifold on the ps box."
   Judging from the above comment I assume this always occurred?

2- Does the fan look centered (Horz. and Vert.) inside the shroud or does it look off to one side.

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Under restoration