289+ gt40 valves

Would gt40 valves fit in a 289/260 head? and if so how do i go about doing this? Iam thinking of doing some 289 heads on my 306 and i would like a little bigger valve ,but not the 1.6 exh valves. I hear people doing this mod alot and i would like to know what cutting is done to the head?

Yes, they will fit. Your machinist should know exactly what to do. First, they replace the valve guides so that the seat and bowl cutters will have a proper concentric alignment. Then they hog out the bowl area (valve pocket) under the valve with a big cutter as there is little sense to use bigger valves with the same old size just under the valve. Then they establish the new seat with a light cut. Additional cuts are made to form a multi-angle on each side of the seat cut for better flow. At this point the machinist should stop and return them to you, as the bowl cutter will leave small steps or angles that need blending into the remainder of the bowl (port roof) and the port floor radius.

Once that (and any other work accessed through the valve pocket) is finished, the machinist makes the final seat cut, usually with a 1° interference for better sealing and additional angle cuts if not done previously. The reason the final cuts are done last, it that a tiny slip when blending can nick the seat, ruining the valve job and requiring more cutting to repair, sinking the valve lower and stealing some of that new flow capability. Hope that helps.

David

EDIT: BTW - if you're spending the time and money, why not just use C9, D0 or GT heads? Less work for the same or better results.

Yea thats what i figured it would be alot of work =$$ into 289 heads. Might just go with gt40ps or windsor jrs some times d00e's turn up for sale,but its rare. Anything to dump these sorry e6's

FYI - C9OE and D0OE 351 heads are the same. D0OE heads were used up through 1974 and are often found on family car engines like station wagons and stuff most 'yard pickers overlook. I've found several sets that way for cheap $. Since a careful search for aftermarket heads can bring new sets for under $600, you may want to get pricing for the machine work and figure your time and porting costs. You may find it's actually cost-competitive and less hassle to go the aftermarket route and likely getting better flow to boot.

Do you have c6 or e6?

Labor costs are so high now that it is not cost feasable to have even a stock rebuild done . I had a quote done on a set of heads for a boal hog and install bigger valves . just the labor was over $800.00 less the parts .

Originally Posted by MY TWO STANGS

Labor costs are so high now that it is not cost feasable to have even a stock rebuild done . I had a quote done on a set of heads for a boal hog and install bigger valves . just the labor was over $800.00 less the parts .

Not for stock rebuild - maybe with some port matching and blending, I could see that. My local machine shop does guides, bowl hogging, oversize seats with 3-angle and your parts for $310. Was $260 until just recently. Add a mild port and blend job and you're at $800 in a flash. That's why I'm almost all aftermarket now. I just grabbed another set of complete Twisted Wedge heads for $650 shipped and a set of loaded Victor Jr. 2.05" 70cc blower heads for $890. Both sets new. Hard to beat that kind of competition in anybody's book.

David