71 delta88guy

I've found that the 1 single issue with headers and an x pipe kit is that the trans crossmember humps and the header outlets are not centered. So that a bend in the pipe is needed to get from the headers past the crossmember. So, I'm going to ditch the super heavy crossmember and fab up a much lighter,centered to the header outlets crossmember. 2 birds one stone.

joe_padavano

You DO realize that the "super heavy" crossmember is designed that way for a reason, right?

71 delta88guy

Um, no. A tubular steel,boxed steel,aluminum crossmember will suffice.

joe_padavano

Which is it, steel or aluminum? Aluminum has one third the stiffness of steel, so it will deflect more under vibration loading. It will also be subject to fatigue fractures far more quickly.

71 delta88guy

Really? No mention of the tubular or boxed steel units? How about the 4 bolts holding it TO the frame. C'mon man.

joe_padavano

Don't confuse stiffness with strength. That's like confusing horsepower and torque, or ET and top speed. The bolts holding the crossmember to the frame have exactly zero effect on bending stiffness of the crossmember.

Can you design a tubular crossmember with equal stiffness and less weight? Of course you can. Given that your car is well over 4500 lbs, is saving a couple of pounds on the crossmember the highest priority for weight savings?

Olds64

I have headers and an x pipe on my 71 98. They clear the stock cross member fine. You aren't using 4" sewer pipes or anything, are you? What headers do you have?

71 delta88guy

Hooker supercomps, for the headers. They exit too wide for a straight shot at the humps on the crossmember, as do hooker comps, as do hedmans. Used all three on this car with different engines.All big blocks. I was figuring on losing more than a few pounds on the crossmember. I hope to use aluminum. Just as wide and as light as I can.

Kennybill

If I recall, isn't your car a convertible? I remember you had a 1971 Royale convertible, i bought some trim pieces (the "gills")for the front fenders off you. I've got "no name" generic headers with torque tube on my 1971. Are you going to get the Ford 9 inch rear housing?

71 delta88guy

I sold all my 71 stuff after I found a 74 with 40k on it. I LOVE the 71's. I would KILL to own a 71 with 40k on it.Granted Iwould still hot rod the **** out of it but MAN what a run ride it would be. Doing the same to the 74. Engine is done. 468, rocket racing heads, 5 main girdle, 11.5:1 compression, 630 lift 245 duration @.050 cam, all roller. Fun car. With quick performance making a ford 9 inch for our cars, the sky is now the limit. LET'S TEST THAT SHALL WE ?