ok so im rebuilding motor, basically back to factory, except i think ima upgrade the oil pump and pan...anyway i was thinking about having a local shop do some port and polish on the heads, since sending them off is just going to cost to much. But what i was wondering say its a simple clean up of the ports how much does that affect the way the car runs? Im pretty sure it needs to be tuned to gain from the work done, but is this one of those things where i can sneak by without tuning it? just cuz i kinda want to wait to dyno tune it for when i get the sc done.

 

If they don't know what they are doing it can slow the car down. Jeff Stafford (NMRA) gained 3 tenths in the quarter from a headswap only where his earlier ones were ported wrong. I am getting a dyno comparison shortly where a set of Stage 3 heads from a big name company were installed on a mild NA motor and lost power everywhere with 15RWHP at the peak. Unless they have experience just have them stock rebuilt with some good bronze guides IMHO.

Most inexperienced shops take a look at that swirl dam and think its the first thing they need to cut on. Touch it lightly just at the top and you will lose 10% of low lift flow and 5CFM at high lift, not to mention you then have to add more timing in the motor at the same time which means the motor is not as efficient as before with the combustion. Touch it correctly and you can gain near 20CFM in the mid lift region but you better be prepared to do some RPM to make up for the low to mid RPM swirl loss.

 

so basically stick with the mustang guys who port and polish. i was going to do mph stage1 but still 900 bucks plus shipping. im more worried about how much the shipping will cost me because the price isnt bad. and same other question, if i put a stage one, can i get away without tuning? obviously no gains without tuning but will it hurt the way the car runs? and cant you just clean up around the valve guide and not have a negative affect?