I have the stock 14102187 "swril port" heads on my car. 58cc? from what i can tell. i have a pair of 12558059 casting heads with the same valves but are "Vortec" and they are 64cc. Will i have any issues switching them over? i also have the crank and pistons from the same engine. The Block was frozen. has any body made this switch? just want to get some info on it before i go ahead and do it. Thanks!

 

well, you will need a vortec intake manifold.

 

059 vortecs are 305 vortec heads and should be 58cc stock.

 

i have a edelbrock vortec style intake for it also. As far as the cc of the heads are i have a parts interchange book and says that the 059 are 64cc and when you google the casting the same comes up.

 

These are the 58cc chambers on my 059s.

 

Wow. They really are swirl port, except that the ramp doesn't wrap around the valve stem boss as much as on 187/191/193/810 TBI heads so the ramp tip doesn't block airflow. I know you ported them and got great numbers, so I expect they run/burn very well. How much effort did you put into reducing the timing advance? And what max advance do you run ? I take it that this is in the van right?

 

how to 305 vortec compare to 350 vortec?

are the 350s way better?

 

They are ALMOST equal in flow stock to stock. The 305 heads have a chamber designed for a 3.735" bore while the 350 heads have a chamber designed for a 4.00" bore. The 305 head is a MUCH better choice than the 350 head on a 305. With the 305 head, you have almost the same flow as a 350 head, keep your compression ratio, and get a much better burn than the 350 heads on a 305.

 

You have read through the thread of my 310 TPI buildup running these heads.

I put some effort into the advance curve while tuning the setup. It ran 30* total timing all in around 4,500 rpm and a very mild rate. It was in the van and ran very well. Today, I think I could have made even more hp/tq with a different cam grind. I would have narrowed the LSA and shortened the duration some.