mar3

iTrader: (8)

I touched on this subject in the Grose Jets thread and now I'm putting this info out there hoping to find someone who has traversed off the beaten path when it comes to modified Nikki carbs. The engine is a street-port 12A w/ Japanese castings (cleaner and larger exh ports according to Ari...), intake manifold extensively worked over on the engine side---not so much right under the butterflies, relatively new Facet fuel pump--no regulator and "headers" custom bent to Racing Beat recommendations by Ari and Chris over at Rotary Performance in Garland, TX. We didn't touch the carb more than polish the horns because we wanted it to legitimately pass emissions which it did brilliantly when finished. The thermal reactor was ditched and a Random Tech 2-1/2 cat installed on a matching exhaust system bent up by RP. That was 4 years ago. I rebuilt the carb recently and passed emissions but just barely. The cat probably needs to be replaced but some jet tuning is probably needed,too, and here's why I think this. I had a the pwr steering hose develop a slit that would open when the engine rocked when gunning it but normally would just be sealed at idle. With this extra air intake, the beast would run strong. When I replaced this damaged hose, power dropped off considerably on the mid to top end. Prior to fixing this problem, it just barely missed passing inspection with the additional unregulated air coming through the hose. Instead of messing with the basically stock Nikki, I'd like to jump up some CFMs but maintain the emissions capability. If it just barely failed with unregulated air then surely that same air going through a carb mixing it properly would pass. I'd like something in the 425-450 CFM range...any takers? Better yet, any one have such a beast they want to unload??

pineapple racing

If it was me, I would just bore the secondary venturis out and rejet. That may be enough for you. Ari has tried a set of our externally adjustable main jets and loves them. They make rejetting a breeze. The farther you modify the carb the more sensitive the carb adjustments will be to changes in the air from day to day. Ari and Chris are great guys, they have done a good job for you in the past, follow their advice. Too many cooks in the kitchen.... Rob

mar3

iTrader: (8)

So basically, it'll be an import version of a Quadrajet, eh? Nice idea. I'm going to pitch the idea back at Ari again. The last time (4 years ago), he wasn't too keen on the idea because he wasn't sure it would pass emissions with a modified carb. He's racing that turbo'ed injected monster now,so I'll have to find out if they even mess with carb modifications at their shop these days. Would Pineapple Racing still be messin' with carbs? I'll run a search engine to see if y'all done got a website--thanks for the idea on the secondaries...