I tried a search but couldnt find any threads: What is the size of opening in the LT1 intake manifold behind the throttle body?

Going with a cc503 cam and was thinking about upgrading to a 52MM TB, but wanted to know if i would need to have the bore increased in the manifold.

 

52mm

 

And whats the size of the stock LT1 throttle body? Is it 52mm as well?

 

i BELIEVE IT IS 48MM OR 47MM

 

Stock TB is 48mm.

 

Im in the process of installing the following and would like to know if 52 will work or if i'll need to step up to 58mm

cc503 cam
1.6 pro mag
pace setter mids
mail order tune

 

You will be fine with a stock size TB. If you want, you could see some gains in getting a 54mm stock TB. There is a guy on ebay that does them and he will give you some money back if you send him your stock one. I think I remember reading that a couple people here were happy with his service.

 

So is the general idea... that its not bad to upgrade to 52-54mm, but a 58mm would be over kill?

 

I've seen more people have problems with the aftermarket throttle bodies and they don't provide much, if any, better results.