I finished porting my 12a last week. I'm waiting on my new bearings to get here now.

I was planning on running a Holley 650cfm carb but I don't have the money to buy all the necessary equipment to go along with it right now. Now before I ask my question I have searched this and I haven't come up with a direct answer. So here goes. I was wondering if I could just get it running for now with the stock Nikki. I know that it will run, but I'm worried about it leaning out too much.

If anybody can help me out with this I would greatly appreciate it.

 

I doubt itll lean out, esp N/A. From the factory Nikkis are jetted rich for the emissions/cat to work.

 

not 100% sure on this but to me and can't lean out too much. reason being if you have your nikki, which will flow at a maximum number of CFM, and the fuel that goes in there suffices it, no matter how big your intake ports are, it can't draw more than that. .. but just guessing here ...

 

Youneed to keep the revs low during break in. Especially because of your new bearings. Count on spending 1500 miles no higher than 3k.

The Nikki should be fine for break in. I've used undersized carbs before. Keeps the revs low. Pay attention to engine temp. If it gets high, shut it down.

 

Three responses in three minutes. We're doing pretty well this morning.

 

So I don't really have anything to worry about except for being slow. One more question though, why would it want to run hot?

That break in period is going to suck. I'm so excited about finally having it running, I'll get a video of it as soon as I get it running.

Thanks for your help!

 

Hey Carl, you think running the stock Nikki would be fine for a full bridgeport for break in?

 

I'm running a YAW nikki on a 13B... Runs like a champ.... pulls real good upto redline in every gear and hits 110 no problem QUICK. I have one of those cheapie A/F meters and it never sees lean when I'm getting into it.

I bought the motor and setup from a forum member and I believe all he did to the carb when going from 12A to 13B... (which I would think would prob' be the same as 12A to 12A halfbridge) was up the secondaries one jet size.

 

Yep,just one jet size up on the secondaries.It was a stock port 13B after all.

The Yaw nikki (and presumably the Sterling Nikki) flow over 400cfm,which is WAY more air than the stock unit.This is probably enough for a bridged-ported 12A,but the stock Nikki probably couldnt make any power on anything more than a mild streetport 12A.Even a stock-port 12A can make more power when something bigger than the stock nikki is bolted on,which shows you how much they strangle the engine from the factory.

Engine temps can be higher than usual during break in because there is quite a bit more friction being generated as the parts rub and grind into each other,creating new sealing surfaces.Plus,when an engine is installed is when your likely to disturb,damage or otherwise upset coolant and oil hoses,sensors and gaskets.So its always a good idea to check and recheck everything under the hood after an engine install and during the break in period.

 

It'll be fine. A buddy here ran a nikki on a 12a 1/2 bridge and it ran beautiful. Your only loss is you won't get the most out of the engine. great for break in and daily driving in the meantime though.