I just bought a kit from GMR and i'm dying to fire it up, but here's the issue. Apparently the A/C GMR uses is back ordered and did not ship with the kit, and we have completely installed the top end, cams and it's ready to go except I cannot find an A/C backing plate that will adapt to the HP Inc Throttle Body? We've tried a Zippers Super Sucker, a Ness, an SE New and Old, and an S&S as Steve said he uses, but they all have issues with fitment. In order to get this thing dialed in i'm gonna need a 2-3/4 breather, but so far cannot find one that will fit with the HP Inc T/B without removing the ears, machiningthe back plate and opening it upto fit.

Anyone else run an HP Throttle Body or have a suggestion for an A/C that will fit? I need a hi flow and not some fancy looking thing that doesn't flow. I calledHP Inc twice, and same with GMR and neither appear to answer the phones today? Uggggggh!

 

i had to do quite abit of "machine work" to make mine fit...and it still had problems...so many as a matter of fact i put the stocker back on....what a good move...that stock TB will more than feed your build....it does mine and unless you got some heads better'n the R&R's you wont need that overpriced, oversized 55

 

Just did a similar build with rr's welded head and a 55mm tbody and had 0 fitment issues with the new style s/e backing plate and a zippers air filter. The opening on the backing plate fit the t/b perfect? Can you maybe snap a pic so we can see where the problem is. The

 

GM ~

Another thing to be sure of, with those R&R heads, is that you have pre-06 HD intake flanges (right Byran?). Otherwise, the intake will not be centered around the intake ports and may be prone to leaking air.....

 

Sorry, diregaurd my post as i just reread the initial post and you have the cast heads, not the ported stockers. sorry for the cunfision.

 

Bryan,

I spoke with my mechanic and he states that 55mm T/B from HP is hot. He claims it'll make a bunch more power with that unit and it's totally worth using. He builds a lot of big inch motors and usually changes out the t/b's as well. He also has the issue licked with the a/c as he found a CV backing plate that will work on the T/B. He tookit home tonight and will machine about .0165 from it so that it fits, and it will then be paired with a K&N 2-3/4 filter. Should be ontomorrow and then he's setting the bikeup on the dyno where we have all afternoon to break in the cams, put a few miles on it, and see how this T-Max measures up with the new build.

Helps to have a talented wrench that is also a machinist and runsa fullmachine shop at his home. Awesome builder and lucky to have him close by. I'll take a few pics and some video tomorrow.