rob stolz

Can anybody give me some knoledge on street porting my 12a. It has 86 000 km on it and I have the racing beat full exhaust(not street port header but collector)



1. What are the pros/cons of street porting a 12a?

-horsepower gain

-durability

-gas milage

Or more



2. What other upgrades should I make if any while doing this?



3. Where should I get my template from, I plan on doing it myself?



Feel free to tell me more about the after math or the process I am up for, Thank you?

One320B

Doing a street port generally only has minimal "cons".



Pros would be:



-Increased horsepower

-Better midrange-upper powerband



Reliability on a mild streetport doesn't really go down, I've seen a 12A SP w/ 62K on it running strong...



Gains would be about 10% on a mild sp w/ the current exhaust you have. Maybe more depending on your actual port, etc.



Gas mileage will suffer minimally, but that depends on how you keep your foot in it.



Other upgrades, tune the carb more (maybe even get a holley 450 if you go bigger SP)



Racing Beat's templates are decent, thats what I'm using..

mperformance

If you do it also noise level will go up. I would not do it if you don't plan on getting a header.



I currently have a 12a streetported and instead of going mild I would recommend a large streetport, investing in a good header and a 2.5" exhauste system from the beginning with a nice holley or a weber.



This will yield some nice numbers and make it all worth it.





A mild streetport with minor mods will not be worth opening the engine for.

diabolical1

covering your 3 questions:



1. durability can be improved if you so wish, but it will obviously make the overall cost go up. that's an issue you have to deal with on your own because it's your money. this kind of ties into your question on other upgrades. i'd recommend trying to get the most out of your oiling system - SE oil pump, flowed/ported pump passageways, 80 psi rear regulator and a thorough cleaning of your e-shaft passages.



2. you'll probably get 10+% from even a fairly mild streetport.



3. depending on how you drive, you may see better fuel mileage if you keep it fairly mild - if that's the only major change made to your setup. obviously bigger or more thirsty carbies are more likely going to result in increased fuel consumption.



if this is your first attempt at porting and rebuilding, then my only pieces of advice are take your time, be very, VERY patient and don't be power-greedy.

rob stolz

Weird I totally thought I would get like an extra 30-40 horsepower with a street port with the exhaust i have??

diabolical1

think more along the lines of half that HP range for a port-job that you can live with on a daily basis.

BeaterRX7

If your carburetor setup has separate primary and secondary barrels (i.e. stock Nikki, Holley with a divided plenum intake, dual Webers) you might consider mild primary (center) ports and wild secondary ports. It's the same concept as a half-bridge, but you don't even need to bridge the secondary ports, a heavy streetport will work. My current motor is a half-bridge with a heavy streetport on the primaries and bridges on the secondaries, and it's a pain to drive around town. Whenever I get around to building an engine for a daily driver I plan on just cleaning up the primaries and putting a mild bridgeport on the secondaries.