1986-87 Buick Grand National / 1989 Pontiac Turbo TA
Throttle Body & Plenum Machining Services
A 62 mm throttle body is one of the upgrades that helped my stock motor and turbo 1986 GN break into the 11's in 1997.
Flow Test Results
Stock TB flow is 480 cfm on the intake test, and 398 cfm on the "blow through" test.
A 62mm TB will flow 541 cfm on the intake test and 464 cfm on the exhaust test. These figures were on a 62mm TB with the shaft unmodified. The Half Shaft mod will increase flow even more.
(test result details taken from Jay Jackson's webpage)
Throttle Body Features
Bored from 57mm to 62mm but this TB will flow equal to a 65mm TB
Hi Temp Paint
Tapered entrance (bell-mouthed)
Polished Throttle Plate
Low profile stainless screws
Half shaft mod
Bore increased by 5 mm (.200")
This throttle body was machined after being powder coated
Powder coated TB Pic courtesy of Jim Chaudrue
Note: The bake process following powder coating causes the aluminum in the TB to become softer so when machined, the surface finish will not be good. If you wish to have your TB powder coated, it needs to come here first to get machined then have it powder coated and then the shaft seals can be installed and the TB can be assembled.
Check out Jims webpage at www.phillyturbosix.com
Plenum Features
Clean and bead blast inside and out
Remove EGR Boss
Machine opening to 63mm
Round over lower edge of entrance
Removed EGR Boss
Blend transition from enlarged opening to rear
Thinking of adding an RJC Racing Powerplate to your plenum?
The modification shown here has no negative effect on a Powerplates CFMs.
Throttle Body Machining - $125
Includes:
Disassembly
Clean
Beadblast
Machine throttle body to 62mm
Bellmouth TB Entrance
Install new shaft seals
Mfr custom fit polished 6061-T6 throttle plate
Modify shaft to improve flow (half shaft mod)
Chase all threads prior to reassembly
Plenum Machining - $75
Includes:
Clean/Beadblast/paimt with hi-temp cast aluminum paint
Machine plenum opening to 63mm
Remove EGR boss
Round over trailing edge of plenum opening
Throttle Body Shaft Seals $20 pr/shpd
FYI, GN shaft seals don't always go in straight but a little sanding in the seal pockets w/a Dremel and small flapwheel makes the job much easier & with less chance of crushing the seal.
You can visually tell if the seal went in straight by checking to see if the outer part is even with the seal boss all the way around
Seal Correctly Installed
Seal has been crushed on installation. Guaranteed to leak
Crushed Seal
GN Throttle Body Rebuilding $65
Inlcudes Clean & Beadblast, install new shaft seals, paint w/hi-temp ceramic paint
Price Includes shpg to a US Address
NEW!!
Check Out Our Turbo Services
Page
Throttle Body Thread Sizes
TPS Threads - M4.5 X .75
Shaft Retaining Clip Threads - M4 X .70
Vacuum Block & IAC Boss Threads - SAE 10-32
Limited Time Offer ~
11" X 14" Buick GN Cruise Picture
I have about 6 of these left
$20 Shpd in US
Any questions please email stevemonroe@cox.net
Free priority shipping in CONUS
24 hour turn-around in most cases
Canadian shpg $25 one item or $30 for both
( for gaskets, shipping address & more information )
Pay by Paypal, cash or money orders
Paypal address: stevemonroe@cox.net
MISCELLANEOUS
Replace your lost / broken spacer while these are available.
Heavy Duty Shaft - Spring Spacers $10 each incl shpg
~ FYI ~
Here's a picture looking down into a stock unbored TB mounted onto an unmodified plenum. I put some red layout dye on the plenum to help show how much mismatch there can be on these parts.
If you aren't ready for a 62mm TB upgrade, I suggest you at least port matched these parts.
I Buy Cores
84-87 Buick GN's or 1989 Pontiac TTA's
T-Bodys / Plenums
Bolts most often requested by Do-It-Yourselfers
