LT1 throttle body dia?

[astroracer]

I just picked up a polished aluminum cold air kit off eBay (for cheap) for my wifes '94 Formula. The connectors are blue... The car is red. I am looking for red connectors and need to know what diameter adaptor to get to go from the TB to a 3" tube...
I can take everything apart this weekend to figure it out for myself but I thought I could get this stuff ordered if any of you knew the adapter size.
Thanks
Mark

[ThreeHonks]

stock throttle body butterfly is 48mm. even for an aftermarket 58mm throttle body, the plenum area is still very close to the same size as stock. Most people use a sewer coupler sold at home depot (I forget part number but it works well) I can post a pic of mine if you want it.

[JoeliusZ28]

stock throttle body butterfly is 48mm. even for an aftermarket 58mm throttle body, the plenum area is still very close to the same size as stock. Most people use a sewer coupler sold at home depot (I forget part number but it works well) I can post a pic of mine if you want it.

wait, are you saying you got yours from home depot? I thought that was factory.

[ThreeHonks]

no thats not factory. the stock one has bellows in it which I guess hurt flow. plus the one I have looks a lot better being smooth and gloss black

[JoeliusZ28]

alright ill have to check out home depot then. i was actually going to ask you what your part number was on that when i did my LS1 lid

[ThreeHonks]

if u need it I can dig up a part number for it. let me know

[JoeliusZ28]

nah I want to use the home depot piece.... unless your saying that has a part number?? Pretty sure i could find it though.

[ThreeHonks]

yeah it does have a part number. the home depot product is made by Fernco if that helps

[DETROITMUSCLE]

I have a piece of Fernco you can try out Joel, its still in the bag with the reciept as I have my stock bellow on the car.

[JoeliusZ28]

I have a piece of Fernco you can try out Joel, its still in the bag with the reciept as I have my stock bellow on the car.

Cool thanks. but you might need it by the time i get around to my lid project lol. Getting the PCM swap done is a much higher priority for the time being. that and i still dont have an aftermarket lid to try fitting. Just a stock lid with the oval inlet/outlet....whatever you'd consider that

[Schuby87]

Cool thanks. but you might need it by the time i get around to my lid project lol. Getting the PCM swap done is a much higher priority for the time being. that and i still dont have an aftermarket lid to try fitting. Just a stock lid with the oval inlet/outlet....whatever you'd consider that

I tried the Fernco and didn't like it. It is too thick, a little too short, and didn't bend at all, even when I boiled it to soften it up. You would be better off just getting a silicone coupler.

[astroracer]

I pulled the stock bellows off the car last nite to measure the circumference of the TB and look what I found... Whoever installed the bellows last did a hell-of-a-job. The whole bottom edge got folded up into the air stream. It's been that way for a long time. It does not want to return to shape and the bellows is ripped at the ends of the folded section... Nice, Real nice.

A pic from the bottom.

Who knows how long the motor has been sucking dirty air through this tear...

[astroracer]

After finding the bellows fiasco I wrapped a piece of tape around the TB inlet, cut it to length and measured it on the bench. 12.5 inches. Divide that by 6.28 and multiply by two and you get 3.98 inches. The "diameter" of the throttle body is 4".
A 4" to 3" adapter coupling is what I need.
Thanks Guys!

[JoeliusZ28]

My stock intake bellow has the same problem. I spent some ridiculous amount of time, like 3 hours reinstalling that piece trying not to get it do that. Finally I thought I had it right - only to take it off this winter and find it messed up like that again. I'm done with that piece, they tear and fold too easily and cause way too many problems. Not only is that a restriction, its capable of throwing your tune off being ahead of the MAF.