Every web page I've looked at says the R1 Mikunis are CV carbies, not flat slides. The Mikuni CV carbs used are smaller than stock SU's, which are CV too. I wouldn't bother with them.

Why won't your HIF's work? The area 15% jump in airflow over HS6 SU's + they handle better. Get them sorted out. (Are they HIF6 or HIF7's?)

The one piece iron manifold is better than the aluminium manifold if it does not have the secondary throttles which are rarely seen in Australia.

The head has already been worked extensively with double valve springs and opened up ports.

Well I hope it's not a B20E head which has been opened up, they are too big already.

The valves are bigger than normal, the stems of which are thicker than the valves on the 74' B20E engine I have.

How big are the valves? It takes a porting genius to get bigger than 44mm inlets working well & I don't like the sound of Holden valves. Are they one piece stainless or stock two piece? You need to get you head flow benched, Ask Volpro how much to flowbench it.

Get the 5-speed in ASAP, it saves fuel no matter what engine you have.




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Three 164's, Two 144's, One 142 & a partridge in a pear tree.