Joined: Sun Sep 24 2006, 10:33PM
Location: Lisle, Ill.
Posts: 168
I'm looking for somebody [guy, girl, shop] for a valvejob and some flow improvement in the general northern Illinois area. The current thinking is to throw all my spare change at my recently purchased set of 906 heads to get some compression and better flow, while leaving the bottom end "stock" for now. How much does a valvejob and porting usually cost? The guy I bought them from magnafluxed them and cleaned them. He also said he did some "mild porting," but I want something more along the lines of "wild porting." Any suggestions? And does anybody know how small a 906 combustion chamber can get and still be useable? I'm planning on running a .510" lift cam, and my pistons are .165" down into the bore at TDC. Any math where I can figure valve clearance? Thanks
Joined: Sun Feb 26 2006, 08:46PM
Location: Kingston,Ontario
Posts: 5622
Dave,I spent almost $800.00 Canadian to get my heads "done" I used 452 heads.My gumbers matching 906's are virgins and make a good set of door stops right now.It would have cost $1100.00 plus to get them "done". I redid the 452's 'cause they flow the same as the 906's and have the same size valves.The big plus is they already have the hardened valve seats for today's swill called gaz.Heck I can run on corn juice if I hafta. It would have cost more to do hardened valve seats in the 906's.I am running the original flat-top pistons and had the 452's planed down a little.My compression is close to or at 10:1 My intake sides did not need to be shaved or spaced.
If I had the extra coin,I would spring for the Eddy heads.With your cam choice it would be a thumper!
My guy is a little out of the way-but has a very good reputation.He builds motors for the Poker Run "cigarette" racing boats for people across Canada and U.S. PM me if you are interested
I would bring the heads to someone who works on a lot of Mopars. Like Leaburn said,to put in exhaust seats is gonna cost ya! If you can't have a "pro" port them,leave them alone and put the money in some Ferera or Milodon stainless valves,a good valve job,set the heights and use good springs. .510 lift is not a lot of cam but you are probably getting close to kissing the pistons. I would MOCK the heads up with some clay between the valve and piston,and see what you've got. That is the ONLY way to really tell. One missed shift at about 6000 rpm will bend those nice shinny milodon valves if they are too close.A good valve can bring a cfm flow up 5-7% in some cases.
Joined: Mon Oct 31 2005, 12:48PM
Location: Bakersfield, California
Posts: 1755
Dave, there's a great head guy in Arroyo Grande on the coast by Pismo BEach, but that is in California! He does a three-angle valve job with porting and polishing for far less than $800.00. But, the cost to ship them here and back would make up for that!
Joined: Thu Nov 24 2005, 07:29PM
Location: So Cal.
Posts: 1111
Snotty wrote ... Dave, there's a great head guy in Arroyo Grande on the coast by Pismo BEach, but that is in California! He does a three-angle valve job with porting and polishing for far less than $800.00. But, the cost to ship them here and back would make up for that!
Good luck!
And he knows how to port well? He works on only Mopars, or Mopars are his favorite? I wouldn't trust a SBC (small block chevy) guy to port anything but SBC's.
Joined: Mon Jan 16 2006, 02:52AM
Location: Vantaa,Finland
Posts: 379
Think twice before investing big money in to old 906's. New Edelbrock RPM heads flow as well as 906's with the RPM's price put in to professional port work, they are brand new and compatible with unleaded gas, come with hi perf springs, locks, retainers etc. Even if you have to invest half the price of the RPM's to the old 906's, I think it would be wiser to get the RPM's instead. 906 and 915 heads live or die with the intake short side shape, to port them well you need a guy that has experience with those particular castings to really get them work. The newer "smog" heads are way more forgiving, and pretty easy to port with decent results even by an amateur. They require less grinding around the valve guide too because it's smaller to begin with. There is a lot of good head info in the moparts tech archive; http://www.moparts.com/Tech/Archive/bigblock.html
If you have pistons 0.165" in the bore at TDC, change pistons. With typical 906 heads with 88cc chambers and composite head gaskets, your CR is 7.5:1. Milling the heads for example .080", that already is quite a lot, would only bring the CR to 8.6:1. Using a steel shim gasket would give 8.9:1. Your pistons would still be down the hole the same amount. With .080" milled, you should do something for your lifter preload. Your intake manifold will not fit, and milling all the amount needed out of the intake face of the head may leave the vavlecover rail a bit thin, it can cause problems with the sealing. If you mill the intake, then it will not fit anything else. You must also mill or reform the block endrails; the valley pan will otherwise not fit properly, and there is also a chance that the intake may hang on the end rails near the corners. Your valves will after all this be .080" closer to teh pistons, is there still snough room with the new cam? When you consider how much all this milling and fixing will cost, new pistons may look like a decent solution even if it means rebalncing an deven boring the block. To make the enigne perform with a typical .51" lift cam, that propably has close to 240 degrees at .050" lift, you must have the CR at least around 9:1, ro the engine will be a dog. No low end, and not a very good top end either.
Joined: Sun Sep 24 2006, 10:33PM
Location: Lisle, Ill.
Posts: 168
Wow, didn't realize the headache that came with that head work. I guess I do have to do somethin to the bottom end. 543 time anyone? Thanks for your help guys.
Joined: Mon Oct 31 2005, 12:48PM
Location: Bakersfield, California
Posts: 1755
TNT440_Cbody wrote ...
Snotty wrote ... Dave, there's a great head guy in Arroyo Grande on the coast by Pismo BEach, but that is in California! He does a three-angle valve job with porting and polishing for far less than $800.00. But, the cost to ship them here and back would make up for that!
Good luck!
And he knows how to port well? He works on only Mopars, or Mopars are his favorite? I wouldn't trust a SBC (small block chevy) guy to port anything but SBC's.
It was a Mopar guy that told me about him. I don't know if he's Mope specific, but the racers around here trust him. If I remember right, the name of the shop is West Coast Cylinder Heads. I'll try to verify that.