Located a pair of GT40 heads I will be picking up this weekend and need a little help. I want to have them completely tore down, tanked and completely reworked with high grade parts. I'm trying to figure out if I should let the machine shop provide all the parts or would I be better served ordering up the parts myself and handing everything to the shop at once. I know I want 1.7 rockers, upgraded springs and new valves. If I supply the parts, what else do I need to include? Never worked on heads before, so I need a little help making a list.

 

let the shop order all the parts; they will probably insist on it anyway.
they are probably going to get a much bigger discount than you can, and you wont burn through a bunch of fuel running around to pick them up.

 

+1 Give them your specs and let them find the parts. If you must have a certain model/brand of something give them a link to a place to order it if their supplier can't provide it. Then check the invoice when they're done for line items of these things.

 

It depends what you want done. But, the component list is: intake and exhaust valves, valve seals, valve springs, spring retainer, spring retainer locks. The heads might need a valve guide or more replaced if they're worn out. For rockers, you set those up once the heads are bolted to the block. I'd never so much as changed a valve seal and assembled my gt40p heads in one evening. The shop should be able to grind your valves and do any guide work without requiring that they finish assembly and supply parts.

Edit: Are you going to bigger valves? A nice spring upgrade for your heads that won't require machining of spring seats can be found at Alex's Parts. It will include locks and retainers and he can set you up with good viton valve seals. It's a very economical kit. For roller rockers I recommend the Crane Cam kit. They clear the factory truck valve covers and are the correct 5/16" pedestal mount. With a minimally decked head, block, and near standard head gasket you might not even have to shim them for correct lifter preload with stock push rods (obviously check this during assembly).

Doubled edit: The heads should be decked for head gasket longevity. Bonus, better squish & a hair more compression.

 

I would tell machine shop what I wanted and let them get everything cause if there is a part failure and you brought them the part it's your baby. As said above just look over invoice and make sure you got what you wanted.

 

I started with a pair GT40 heads for $106. I cleaned up my heads with hot water & oven cleaner & the valves on a bench wire wheel.

I took then to my shop & had them make the call on what I needed as far as guides &/or replacement valves. (Needed neither.)

Got a single pass on the surface of the heads and light touch up of the valves & seats (single angle cut to match stock 45*) I think I payed $200. They tanked & bead blasted them too.

I bought a Trick Flow stock spring upgrade kit for Ford iron heads (intake & exhaust are different heights). $170? Crane cams makes a similar kit but without valve seals for slightly more money. Another company named Alex something also sells a kit. (somebody has a link)

I got the Crane pedestal rockers for about $260.

Lapped in the valves to the seats & I did the assembly myself with a screw type compressor that I've had for years. (slow but steady)

Little bit of port matching on the exhaust side, bowl smoothing under the seat.

 

Thanks for the replies and advice guys, really appreciate it. I'll talk to the shop after they've had a chance to look them over and then make a determination on which way to go. I can get the heads for $100, so I'm going to set my max budget number at $1000. Should be able to make them like brand new for that.

 

It's a crap shoot really. When you get up to 1K, you're pushing your financial return.(VS buying a complete aftermarket set of aluminum heads w/adjustable rockers)

I'm chasing push rod length which will mean an additional $100+ plus over what I spent on the first set + incidentals.

 

What exactly caused the stock push rod length to change?

 

Decking the block, changing head gasket thickness, or decking the heads all work to make you need shorter push rods. The pedestal mount rockers can be shimmed upward for small adjustments to lifter preload (if preload is excessive). If the valves & valve seats were ground, but the valve stem wasn't also ground, that can throw things off as well. If you need longer pushrods you must replace them, but shorter can be shimmed if it's close. The Crane rockers should help keep things as near to stock as possible. I don't know about other rockers.

 

Milling the head, decking the block. Just changing the head, or even a different head gasket. None of my prior parts would come close.

(.020-.030 space between the tip of the stock rocker tip & valve tip)

Buy a push rod checker. Trick flow has them for about $15, Crane makes a better one for about twice as much.

Here's some tech:

COMP Cams® - Pushrods

 

I lucked out. Different block that was decked 0.007, decked/milled GT40P heads (unknown how much they were decked), slightly thicker head gasket at 0.047", and I only had to shim one or two rockers just a hair. Rocker bolts hit torque spec between 1/3 to 2/3 turn past zero lash for just the right amount of lifter preload.

 

Is there any way to tell if a head has been previously milled? And if so, how much it was milled?

 

Is this the correct Crane checker for our push rod length? https://www.amazon.com/Crane-Cams-99...e+Cams+99726-2

 

Looking up a 5.0 roller cam engine for 85 & up (in that catalog) yields a stock push rod length of 6.248 inches.

I'd go to summit & enter push rod length checker & look for one that goes from 6-to 7 inches & get that one.