I saw in one of your posts that you got 190hp out of a 12A using the stock manifold and a streetable exhast. What kind of set up did you use on that beast? That is exactly what I would like to do to my Autocross car. I am just starting my rebuild now and plan to port the motor, but I would kill to know how you did that using the stock manifold. It was my impresion that 150hp was the top you could get with the stock manifold. Thanks

 

I didn't. I was re-posting something that someone else posted to a mailing-list.

I personally wouldn't bother trying to make any power with a dead-stock manifold unless rules require it. As it comes from the factory, it's so bad that you can realize decent gains with even rudimentary work if you apply a little brainpower before breaking out the porting tools.

A properly ported stock manifold with a Nikki carb can actually make more power than a 48IDA with 38mm chokes. Chew on that one for a while

 

Are there any links or sites that have info on porting the manifold as you sujested here. I have a manifold from a 79 and a 83 so I don't mind screwing one up in an atempt. Thanks

 

Speaking of porting, how difficult is it to just disassemble the engine myself, and port it myself (tools, labor, knowledge, skills required, etc...)?

 

adamp: http://personal.riverusers.com/~yawpower is a good place to start.

357: The engine really are fairly simple. If you've ever field-rebuilt a lawnmower engine, then the rotary will present no hassles. Invest in a manual (even a Haynes or (gack) a Chilton's will do) and study the engine disassembly/reassembly section so you know what you're up against.

 

As long as you have a good set of wrenches, plyers, sockets, an engine lift, and screwdrivers you are good, you might want to get a micrometer. it is fairly simple to do just make sure you work in a very clean area and you are really orginzed.

peejay: thanks for your help

 

Hmmm, well, I have everything but the engine lift, but I might be able to use a small hydraulic crane from my dad's lab. Do i just need to run nylon straps around the engine to make sure it supported? also, with regards to the porting itself; what is the recommended method for removing the excess material, and what about dimensions of the port? Thanks again.

 

I heard this statment a few times over the years and thought it was B/S untill i got one super modded.

It is great!! Mine was made as a once off but the guy is now doing them for other guys, because there heaps cheaper than what a weber is over here.

it is a 12a nikki on a rx4 13b inlet manifold on a large extend ported 13b

 

No, there's two small hooks on the engine, one by the distributor, and one on the passenger side of the engine near the firewall that you hook a chain through.


Die grinder, for sure, and the dimensions are dependant on how big of a port you want. I'd suggest going to www.racingbeat.com or similar, and looking for porting templates, if you're not familiar with the process, as you can easily screw up a perfect engine by crappy porting...


Jeff

 

Atkins rotary has a real good video on rebuilding a 13b. It's only like 30 dollars. I bought it and it's very detailed. I'd recommend watching it a few times before trying to rebuild.

: