Head question

[dirtracertodd]

What are the differences between the IMCA Spec head and the USRA?USMTS spec head? Or are they the same?

[powerslide]

IMCA chambers I believe as cast. USMTS is CNC.

[dirtracertodd]

Ok.. Can someone tell me the performance differences between the two? Is it worth picking up the IMCA heads if the price is right?

[RCJ]

What are your rules?I've always thought the 2 heads are very close to the same and are basicly a track 1 brodix.I have ran the IMCA head in classes with no rules, and angle milled and ported them.They made good power.

[dirtracertodd]

USRA modifieds engine rules.. Just trying to figure out if they would work and what ballpark hp.

[powerslide]

I think the differences are very minimal, the cnc chamber is probably more consistent. Just the rules of each sanctioning body are different so they can get a piece of the contingency.

Talk to the tech man and see if they allow the IMCA heads at a usra track, some may not.

[LateModel B23]

Last season I talked to USMTS tech guy about spec heads unstamped or marked for a different series and he told me that a head cast SPCH is okay to use. He told me if it is stamped USMTS/USRA that means Brodix made and certified it to the correct specs for their series -- BUT you can use a regular SPCH head or one that might even be stamped/marked from a different association and it would be okay, although they might take the head from you and send it to Brodix to be checked and certified.

I asked this question because I had a set of SPCH heads that were marked USAR (not USRA) and he said that as long as they were the Brodix SPCH all was fine, except they were subject to more inspection than a set stamped for the USMTS/USRA series. As it turns our track never did any checks other than for the 8000 chip so it was not an issue.

Like Powerslide says though, I would check with your track tech person and then maybe check with USRA to see what they say.

As far as HP our motor was a 3.875x4.125 (415ci) with a fairly mild roller cam and it was 623hp on alk for fuel.

[RCJ]

Our IMCA legal L/M was around 590,With a better intake and a little head work 626,With no regard for rules over 700.