Has anyone ported a set of 289/302 stock heads? I've got an extra pair sitting around and thought I'd give it a try. Is there a template I can buy or a guide that shows pics I can look at??? (I don't want buy a new set of aluminum heads but heard that some mild work to stock heads can wake them up - especially on the exhaust port side).

I'd probably have them re-conditionedwith avalve job / springs too.

 

yup they are great i also got larger valves and a bowl blend i did the port myself and had the head shop clen it up i didn't get wild cause i didn;t wanna junk the heads i just did one really clean as best i could then i got some playdough and pushed it in there and let it harden and i went over alll the rest and when the playdough fit right i stopped the head shop charged me $4.50 to cut the larger valves it cost me $385 all together with those to things plus a valve job and milling the mating surface flat and that was with new valves lemme tell you they are very nice

 

unless theyre 289 hi-po I wouldnt bother. Years ago I sent out a set of 289 hi-po's to TFS and had em ported and milled .060. Those heads ROCKED!!! But we went too far with the milling and the heads wound up warping really bad. Had to junk em.
-P.

 

What about a set of the 5.0 GT40P cast iron heads - there is a set here locally that has everything but the rockers onthem for $300.

 

Not a bad deal, definitly get teh exhaust side ported out. Maybe mill em about .030 thatll bump your compression really nicely. Only draw back youll HAVE to run premium.
-P.

 

What is the difference from the GT40P and non-P heads?

 

the angle of the spark plug mainlyull need compatible headers with the gt40p with the gt40 stock manifolds or standard header will be fine

the gt40/gt40p are the best 289/302/351w head from the factory even out performing the fabled 69-70 351w heads

but basically a 289 head ported out will flow just a tad bit more maybe thana gt40/p head if that much

 

there is no point in getting your heads ported if the intake and exhaust dose not match it. make sure that if you do port the heads the make the port on the intake and exhaust

 

If you really want to try it, get a quality die grinder and carbide bits at the very least. This is a rough sketch of a port and what you will find in there.

What the people who port heads have found is the short turn radius likes to be apporximately the same radius as the valve, maybe just a little smaller but smooth and with an obvious curvature. Filling the floor with epoxy is the best way to achieve that gentle rounded curve. Dont flatten it and dont take too much metal from the area. You will find water there quite soon if you remove a bunch of metal.

There is flow to be found by raising the roof rather than dropping the floor or making the port wider. You dont want to go so far as to hit the spring seat or find a water passage, but raising it and contouring it so its smooth with no obstructions will yeild the best flow.

You can remove a little from the throat behind the valve, air likes to flow faster through a coke bottle shape (venturi) more than it does down a hallway. Some pinch right there is a good thing. be very carefull not to hit the seats with the cutter, you will really mess things up if you do. The only fix for a gouge in the seat is a new seat. you cant replace metal there, only take it away. Valves recessed into the head dont flow as well as valves at the end of the port.

The valve guide is already tapered, but what you want is a gradual slope to divert air around the valve stem, you want an airfoil shape and you dont want to drop the length the guide bulge goes into the port. If you have ever seen an old propeller driven airplane, where the wings attach there is an area called a fillet, you want that smooth transition from one axis to another. you dont want to cut it out completely, as that creates an adverse turbulence in the port, swirl and some turbulence is okay but not to the extent a valve stem protrudes from a flat port roof.

leave the intakes rather rough finshed, carbs are wetflow and the fuel seems to stay in suspension with the air better if there is some roughness to the port walls. Not bumpy, just not mirror smooth.

the exhuast ports do need help, remember about the short turn in them as well, its very important to either leave it alone or make it smooth with a very gradual roundness with the same radius as the valve. usually its best to leave it alone. You can open the exhuast ports to fit the header gasket, and open them all the way down the port, walls and roof only, dont drop the floor. Lowering the floor only creates a dead space and hurts velocity. Dont put any sharp bumps or attempts at swirl, as it doesnt take much to create the effect and the exhuast doesnt need it.

The same profile can be added to the guide bulge in the exhuast port, smooth transitions, nothing abrupt. Think jet fighter more than Mustang front end.

Try a junk set of heads first, go ahead and find the water passages and if you know someone with a flow bench , you can test a few ideas. if you flow bench, then you just gotta wing it and hope you didnt make things worse by grinding.

Cast iron creates dust and a large pile of chips, be careful use a respirator and eye protection. It takes more time than you think to open a port from front to bottom, and a dremel tool isnt going to cut it. you will wear out your hands and two dremels before you get anywhere usefull in one port.

There are electric and pneumatic die grinders, one with a long thin snout works best so it will fit down the port.

Good luck.


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So the P heads need a particular header? I was going to go with a set of Doug's tri-y's so if that's the case then I'll port my own stock heads a bit, match the ports (intake/exhaust) and that should do it. Any difference between the 289 or 302 heads (I know there shouldn't be but just in case...)

What is the ballpark compression ratio for the stock heads anyway? If I get them decked or milled by ten or twenty thou what would the compression be close to? (Stock 1965 289 short block)

I've got two sets of heads to choose from. 1966 289 heads or 1972 302 heads.