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Shaggy · 07-31-2003, 04:26 PM

A couple of things,
Port them yourself it is actually quite easy and a set or stock irons are hard to screw up as long as you stay away from the port floor.... not saying to not touch it a little but don't spend any real time on the floor because the more you remove from the floor the tighter the radius becomes on the short side and the more the air has to "bend" to flow through the port. I spent 3 weeks with a dremel porting my first set and have never looked back. I can do a set of irons usually in a day now (gotta love air). My tip o the day on the exhaust side is if you have and extra header laying around cut the flange off of it to use as a tool rest and you to can have perfectly square "professional" looking ports as well.

You can even do the screw in conversion yourself as well, when you take the heads in for the valve job you can ask them to mill roughly a 1/4" off of the rocker pedestals, you need to take a measurement of the thickness of you screw in stud nut and guide plate usually around a 1/4", and then tap them yourself since the hole is already there to tap for a 3/8 stud you just need the tap and as long as you are careful the tap will self align. If you don't take mill off the extra height then you will need a longer push rod to get the rockers to make correct contact. I poor boyed a set of 351 heads for buddy one time and we did the conversion without milling the pedestals and got lucky on a 351w with DOOE head with ARP studs and motor sport guidelines you can run a stock length hardened 351c pushrod (they are a little bit longer).

If you are going with an aftermarket roller rocker then you can usually get away with buying Chevrolet valves 1.94/1.60's, but let your machinist decide that as some I know have a hard on for not doing that. But if he will then you can save a few bucks. Tell your machinist what your cam specs are and what type it is i.e.: roller. hydraulic, solid or whatever, so he can set you up with the proper valve spring rates. I have found that some cam manufactures don't necessarily provide the proper spring rates with there cams... none have ever been so far off that they didn't work and most are dead on but I have come across a couple o three that were to low (early valve float) (typ hydraulic roller tappets) and a couple that were to high (low total lift numbers because the lifter collapses under the strain) (usually hydraulic flat tappets) a pressure for what the weight of the valves or the lifter really like to see. This is an area where experience pays off really well and you must trust you machinist on that one.

That is all I can think of for now, good luck and have fun

07-31-2003, 04:26 PM	#4
Shaggy Registered Member Join Date: Feb 1999 Location: Houston,TX Posts: 466	A couple of things, Port them yourself it is actually quite easy and a set or stock irons are hard to screw up as long as you stay away from the port floor.... not saying to not touch it a little but don't spend any real time on the floor because the more you remove from the floor the tighter the radius becomes on the short side and the more the air has to "bend" to flow through the port. I spent 3 weeks with a dremel porting my first set and have never looked back. I can do a set of irons usually in a day now (gotta love air). My tip o the day on the exhaust side is if you have and extra header laying around cut the flange off of it to use as a tool rest and you to can have perfectly square "professional" looking ports as well. You can even do the screw in conversion yourself as well, when you take the heads in for the valve job you can ask them to mill roughly a 1/4" off of the rocker pedestals, you need to take a measurement of the thickness of you screw in stud nut and guide plate usually around a 1/4", and then tap them yourself since the hole is already there to tap for a 3/8 stud you just need the tap and as long as you are careful the tap will self align. If you don't take mill off the extra height then you will need a longer push rod to get the rockers to make correct contact. I poor boyed a set of 351 heads for buddy one time and we did the conversion without milling the pedestals and got lucky on a 351w with DOOE head with ARP studs and motor sport guidelines you can run a stock length hardened 351c pushrod (they are a little bit longer). If you are going with an aftermarket roller rocker then you can usually get away with buying Chevrolet valves 1.94/1.60's, but let your machinist decide that as some I know have a hard on for not doing that. But if he will then you can save a few bucks. Tell your machinist what your cam specs are and what type it is i.e.: roller. hydraulic, solid or whatever, so he can set you up with the proper valve spring rates. I have found that some cam manufactures don't necessarily provide the proper spring rates with there cams... none have ever been so far off that they didn't work and most are dead on but I have come across a couple o three that were to low (early valve float) (typ hydraulic roller tappets) and a couple that were to high (low total lift numbers because the lifter collapses under the strain) (usually hydraulic flat tappets) a pressure for what the weight of the valves or the lifter really like to see. This is an area where experience pays off really well and you must trust you machinist on that one. That is all I can think of for now, good luck and have fun __________________ A good plan, violently executed now, is better than a perfect plan next week. George S. Patton, General (1885-1945)