I bought a pair of 906 heads a while back to use on my 440 and just got around to having them magnafluxed. The guy doing the work gave them a good looking over and says the heads have been shaved .060's and said a stock intake may not fit right and that the stock push rods won't work either. Is this true, do I have to buy different push rods and intake. I didn't really want to stick a crapload of $$$$ into the motor,,,, just wanted to keep it stock and cheap, it has 60k miles. I had to switch heads because one of the 452's that were on it had a crack. If I need different intake and push rods I'll probably just get a different pair of heads again

you can mill the intake to fit, i don't remember the formular for this, been a long time, but i would guess if you took .015-.020 off each side of intake it would fit fine. also i have several sets of 452, 906, 915, heads been saving for many years.

sam-missle

You have an easy enough fix, just take the intake to a competent machine shop and have the intake rails cut. The main objective is to get the bolt holes and intake ports back into closer alignment. Also, your pushrod issue. You can get some shims to place under the rocker shafts to restore the preload to your lifters because of the .060 +/- that has been taken off the deck surface of the heads. Most all cam companies offer these for engines that dont have adjustable valvetrains(Olds,SBF,BBChry.,etc)for those occasions such as yours. Or, you can bite the bullet and get adjustable pushrods or rockers. Three options, take your pick, anyone of the three is pretty easy!

Actually, it's better to machine the heads for the intake. If you do the intake, it will become a part just for those heads. If you machine the heads, any intake should fit from there on but before you machine anything, do a mockup to see how things fit. there's been times when I've milled heads and the intake actually fit better than before. factory machining isn't always perfect. And shims for the rocker shafts should work but are you using the old worn pushrods and rockers? Those are a wear item too and depending how many miles you have on them. Also, you can CC the combustion chambers to see about how much they were milled. Stock 906 heads usually check out around 90cc. A .060 milling should reduce CC's by about 13-14 cc.

If they have been shaved .060 , then .084 must be removed from the bottom of the manifold & .060 removed from the sides.

What will it do if the intake is used the way it is without milling anything? The guy I got the heads and aluminum intake from said they was only used for a short time. The heads were only used until the paint got a bit discolored. That must be why he sold them. The aluminum intake bolt holes show bolt thread markings on one side of the hole so I'm assuming he tried using it the way it was and it didn't fit right. What length of pushrods would I need to make up the difference?

If the mismatch is severe, performance will be affected because of port mismatch and if you are getting thread marks on the intake, the ports well probably be that way. If the heads were milled .060", then the pushrods should be .060 shorter but like I said before, a mockup will tell you what have for sure. Good luck...

if your heads have been flat milled, you do not have to cut the heads on the intake side. flat milling lowered your heads .060, and widened the "V" where the intake sits, which changed the match up of your ports, milling the intake manifold .020 on each side will lower the intake so your bolts and ports are in alignment. when doing this i like to use the thick mr. gasket intake gaskets. if your heads were angle milled, then you would have to correct the intake face on the head. just because .060 has been removed from your heads does not mean you need .060 shorter push rods, there are to many variables involed to come to that conclusion.

sam-missle

You can mock up your engine with the heads set on the block,for more accuracy you need to use head gaskets as well(but no need to torque them). If the intake is an open plenum, you can shine a flashlight into the runners and see if there is a very bad port alignment for yourself. You will have to make the decision yourself as to what you can live with. You can slot the bolt holes with a die grinder and then dress them up with a cartridge roll afterward. You still will need to address your issue with the heads being cut by .060 +/- and shim your rocker shaft or change the pushrods and /or rockers!

Widened the V? Take .060 off the top of that V and then measure across it to see if you just widened it....as for the pushrods. Mopar calls for about a .050 preload and if you just 'lowered' the heads .060, that preload will increase and will probably not let the valves close. But like I said, do a mockup. It doesn't matter what surface you decide to mill for the intake...the head surface or the intake surface, you'll end up in the same place but if you mill the intake, it will no longer work on unmilled heads.

Any chance they make a head gasket that is .060 thicker than stock which would set the heads back to stock height so nothing would have to be milled and the original pushrods would still fit,,, or isn't it that easy?

Stock Mopar used a steel shim @ about .020. Aftermarket composition is ..040. You might try Cometic as they advertise any thickness but they ain't cheap but good products never are. Have you CC'd the heads to see what the chamber volumn is? They may not have been milled .060 . A quicky want to check them is use a 100cc horse syringe....

with head gaskets set the heads on engine, measure the top of the V. now remove the gaskets and set heads on the block, measure again, the top got wider!!!!!!

sam-missle

The 'V' is the block right? Take off material off the top of each leg of the V (block decks) or take material off the chamber side of the head. The deck of the V (block) just got closer to the crank centerline, right? The ports of the head just got closer to the crank centerline too, right. It doesn't matter if you take material off the deck of the block or off the head, everything just got closer to the CCL. Lob off 3" off of the top of that 'V' or 3" off the head. Now please tell me how the V got wider. It doesn't matter if you take off .010" or 3" off the heads or off the block, you just put everything closer to the CCL. The 'V' gets smaller and smaller with each cut and the smaller the V gets, the smaller the intake needs to be. If you can't see that, I'm sorry.....

You are absolutely correct on all points of discussion! Maybe it would be easier for sam to visualize, if you explain it from the standpoint of making the intake fit the cut heads. If he agrees and understands the intake needs to be cut to match the cut heads(as a possible solution), then the "v" of the uncut intake will naturally be reduced if you cut each intake rail by a specified amount.....it seems he has the concept, he just might not be expressing in words the same way he his thinking.