Not sure about the TB you are talking about. But strokedjeep.com has 64mm bored TB's.
The throttle response is going to be pretty touchy with a 70mm throttle body.
I think it would even be overkill on a stroker. I know that Dino has a 65mm TB and he says its a bit too touchy and doesn't recommend it. My 63mm is a pretty good match with out being overly touchy.
On my old 4.0 I've tried the stock TB, stock TB with taper removed (60mm), and a 62mm TB. With full external bolt-ons and a DIY ported head, the 60mm TB was sufficient and I saw no difference with the 62mm.
On my 4.6 stroker I initially used the 62mm TB and later swapped it for a heavily modified Mustang 65mm TB. I also tapered the TB spacer bore from 65 to 62mm to give a smooth transition to the intake manifold. The 65mm TB made throttle response sharper and it's fun driving on the street, but it's also challenging when driving offroad at slow speed while feathering the throttle 'cause it can sometimes become jerky. The 62mm TB is well balanced for a mild 4.6 stroker.
So with a 4.0 engine, would you say the best bang for your buck is to just take the taper out of your own TB and save the money of buying a more heavily bored one?
I spent $5 for the drum sanding kit I used to remove the taper from my two. I'd like to run a larger TB to see if it would make any difference, but I'm basically just too cheap to do that.
So with a 4.0 engine, would you say the best bang for your buck is to just take the taper out of your own TB and save the money of buying a more heavily bored one?
Probably best bang for your buck is to get a bored TB with the corresponding size replacement butterfly in it from www.strokedjeep.com for less than $100 exchange.