how can i tell if i have a 48 or 52mm throttle body on my 88' 350 tpi??? are there any numbers or codes or do i simply measure it? if so, where do i measure?? thanks

 

Measure it (where the plates are would be easiest and not require removal), but if its stock, its 48mm.

 

the stock 48mm is usually cheap casting. Most aftermarket TBs have decent to nice finishes.

 

ok, i just measured the rear of the TB and im getting 50mm for each blade????
the casting #'s are '17075921' on the bottom and '17085051' on the side....
theres also '1835 huy' on the side also...
am i measuring correctly when i measure the back instead of the front??? i went across each blade and not directly across the entire face, end to end... thanks

 

i think its a 48mm but not sure, here are a few pics:

 

one more...

 

here are the #s on the side and bottom

 

IIRC there's a larger machined area at the back side, you need to measure more where the blades are or the blades themselves. Looks stock to me though.

The numbers are just GM part numbers, so that tells you it was/is a stock throttle body and the only way it would be anything other than 48mm is if someone bored it out larger than 48.

 

IIRC ??? whats that mean?

 

Thats 48mm TB.

 

ok thanks, looks like ill be selling it, need to upgrade to a 52mm

 

I went through these guys and it works well:

eBay Motors: TPI 52mm bored/port throttle body 85-92 Z28 TA Corvette (item 8072670660 end time Jun-15-06 18:58:24 PDT)

I had them rebuild and rebore mine.