Ok, I am familiar with Clifford and the usual stuff but my question is this; First let me explain my setup; I have a 250 Block #D6DE 6015-AB Head #D5DE 6090 BA Withat information, besides that the block is a 76 and the head being a 75, can you give me like flow rates, compression, valve sizes, cumbustion chamber cc's etc that would help determine hwhat cam would work best when using a Holley 350 cfm, or 500 cfm. I have the 350 now but am willing to go bigger if the gains are worth it. I need to order a cam for sure, and would like to know as well how much I can plane off the head to make some compression. All help is needed thanks. BTW...I am going to be using nitrous...after I get this info I can run a program to get the correct pill sizes for a 50 hp gain. Another BTW; I am building my own custom aluminum carb adapter plane that will allow this head to flow to 1200 cfm. so I need to open up the cam section due to the fact that the valves are smallish, but I'm using an automatic so I can't be using a .600 lift or something wacky big. I know, it's a bit of info, but would help me help you once this carb setup and cam combo works, I can sell it to you all who would like to try it. The plane adapter can be made for 2 2bbl, 2 1bbl,.......look once I get this done and mounted and running, with success, it's going to be cool.
Ronn, more comment than facts but the 200 head will give a small compression increase used on a 250. Porting can be done on this head and pay a lot of attention to the exhaust bowls as well as the intake. With nitrous, exhaust is quite imporant. The juice gets in with the air but the volume of gasses in the exhaust increase dramatically. A cam can be selected to favor the use of juice and still give good low to mid range power on gas. www.Clifford Performance.com should be consulted for you intended application. . A very interesting project. Take it a step at a time and get enough info to plan the combination so it has a good chance of sucess. Good luck.
Depending on the year the 200 and the 250 heads are the same . If you were to use an older 200/170 head (60s - early 70s) you would get a bump in compression but you will need to mill the head because the new head gaskets are two times as thick as the old ones, and you will prolly lose power too because the older heads have smaller valves and a smaller intake log. You would be best off with an '79 - '83 200/250 head milled ~.060 , they have the biggest valves and a much better intake than the old heads from the 60s and early 70s. Another place for ford I6 parts is www.fordsixparts.com they have roller rockers, forged pistons , roller timing chains, headers ect.
