Doing a Ford Racing 347?

[Canuk40]

Hi Guys,

If you're moving up from a stock 302 or built 302 with stock dimension heads (at the exhaust ports) to a Ford Racing 347 crate motor with the GTZ heads there are modifications to be made to the stock CAV headers.

The GTZ heads have raised ports and are 7/16 of an inch wider at the exhaust flange than stock dimension 302 heads. The solution was to make a spacer plate for our 302 dummy engine (so we didn't have to work on the customer motor) put the flanges in the same position as the GTZ heads and start cutting up the headers.

Although the port opening on the flage is correct, the bolt holes are inverted relative to the stock heads. We could have flipped the cut off old flanges, however the best way was to spring for the new flanges. Now were tooled to make them in .250 stainless for future conversions.

As you can see, there's no way the headers could be bent or forced into the collectors and the stock flanges were obscuring the top of the exhaust port. That'll cost a lot of ponies.

If your headers were supplied for a Getrag spec 302 and your going to ZF you will have to either splice and reweld your collectors at the muffler to fix the downward angle or do it all at once when fixing the tube lengths and angles for the raised port heads.

After cutting off 8 flanges, slicing the tubes into 17 peices, making up slices of stainless tubing and test jigging on the dummy motor we had it beat and ready to tig up.

It was a bit scary at first as these are not cheap parts to begin with and the stainless is really tough compared to mild steel, however once it was all done the results were worth it. We also picked up some additional clearance for the Weber Heat Sheild and Valve Covers making the whole setup better.

We can do this for you if you're faint of heart

Cheers

[David Briggs]

Looks like too much work! Ford sells a 347 shortblock, minus the cam, for about $3,000. It has a forged crank, rods and pistons, in a new sportsman block(beefed up 5.0 block), add your choice of hydraulic roller cam and a set of AFR 185's and you can use the exhaust that comes with the car.

[Canuk40]

Hi Dave,

You're right about too much work, we weren't that far off making new headers

Also about going a 347 shortblock really speaks to the choices you have to make and how it all fits together.

Just wondering if there's a source of stainless headers for raised port heads like the Ford Racing GTZ heads? How's the CFM on the AFR 185s compared to the GTZ?

Cheers

[Jac Mac]

Ian,
One way you could overcome this problem with one set of headers to cover both options would be to enlarge the header flange to cover both port options, then with standard heads also supply a spacer port plate to make up for the effective width difference.
So on a 'normal' 302 you would use --headers plus spacers.
On a 347 with the above raised port heads-- headers only.

You would then have to ensure clearance in the collector area for both options, but this would allow you to have one set of exhausts only-- of course as soon as you do that some turkey will wander in with a set of 'Yates' heads.

Jac Mac

[Canuk40]

Hi Jac,

Great idea, I've seen adaptor flanges used to correct port shapes on regular 4 into 1 type headers. We had to accomodate the extra width in this setup but you're absolutely right, with a set of spacers, these pipes could be fitted to a stock 302.

Also seems like these modified headers would fit a 351 with stock SB Ford heads...

Another good point on the Yates heads, so many combinations are possible, different manufacturers, the GW heads and on and on. Maybe I should get into the header business

Cheers