i have a 78 280z and a 71 240z .... and i have a header that has ROUND ports and the ports on the HEAD are sorta squared. on the 240Z.... wich is the car i want the header on. could i run the header even if the pors are different? would it run better or no?

 

They make round port & square port headers for a reason... to match the ports on the head. You might be able to use the round header on square ports... but it's not the proper way, and you'll prolly have more probs down the road... like burning through the gasket... and plenty of leaks.

 

You can use a round port header on a square port head but not the other way around.... if im not mistaken the 78 should be a round port head.. just run the headers on that car

 

the thing is im seeling my 78 and im driving the 240z as a daily driver. so i figured hey what the heck il drive it like this for a while then get that l28 block with round ports and boom. i got an l28 with more torque more HP running a header i didnt have to buy and carburatos and im set. thats what im THINKING it should be like right? just replace the block ?..... or are the clutch tranny difff different ?