Big Block Bantam

bob w said:

sc5080, you are building to a sfi spec. Does that spec call for DOM when using mild steel for the cage?

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The SFI spec for 7.50 altered does not specifically call for DOM for the frame and cage construction so ERW will be allowed. Minimum wall thickness for round tubing is .118. For 6 point cage under 18" uprights minimum is 1 1/2" OD for the hoops and back braces and 1 3/8" OD for the shoulder hoop and upper frame rails. For 5 point cage under 18" or any cage over 18" uprights minimum is 1 5/8" OD for the hoops and back braces and 1 1/2" OD for the shoulder hoop and upper frame rails.

Nominal wall thickness for mild steel rectangular tubing is .058 with minimum 2" x 2".

I use the DOM because I believe it is more consistent wall thickness and easier to work with, especially if I am stepping the tubing - for example where my shoulder hoop joins the upper frame rails at the midplate. Also, I believe you have to be careful on how you bend the ERW so that it won't split the welded seam where DOM is more forgiving.

I don't have an SFI book on an 8.50 cert so I can't be certain what is required there but I suspect the cage rules will be the same.

Thanks for the information. The specs appear to be the same as the rule book shows for 10.00 and slower Altereds. I used the same requirements for the chassis/cage for my H--B dragster.

Nice looking gas tank for the hot rod and price was right. You may need a pair of them if you push that BBC to much on the way into town for lunch with the boys. [cl

More headaches with a little car. Couldn't find a good location for the battery. Finally, I settled on this location. Used a piece of 3" by 1 1/2" formed channel and put a square section in it to hold the battery. Made a hold down out of 1/2" angle iron. 3/8" threaded rod will be used to hold the top frame to the base, securing the battery.

Also made a mount for the Holley fuel pump. Mounted the gas tank to the rear crossmember. Welded a 2" dia. tube on the top of the gas tank for the fill tube. Waiting for a 2" 90 degree filler hose to finish the deal. A cap will be mounted next to the passenger side quarter window.

'Nuther view.
Having no luck getting 1 5/8" 10 gauge ERW for the roll cage. I have 1 1/4" structural pipe which is perfectly okay. Unfortunately, my tubing bender die doesn't fit the structural pipe. Yesterday I bit the bullet and ordered a die for only $300.

I know there's been discussion here regarding roll cage materials. The structural pipe I'm using is actually over spec. I perused the internet and on the Pirate 4 by 4 site I found many of the off-roaders prefer structural pipe.

You'll get no argument from me.
If I had a die, I would have sent it to you to use.

Tomorrow's project is to get the gas tank filler finished. got the 90 degree hose today

A friend gave me this billet cap and spud and I added the extension and made the retainer ring. It will be mounted behind the quarter window in line with the filler hose inside.

If you run that extension horizontally, you are going to hate filling with fuel. Run it at a 45 degree angle.

You make an excellent point, williej. I planned to pitch it a bit but I'll look at a location that provides more incline.

What type of breather set up are you going to run for the tank?

Will your alum interior sheet metal separate fuel tank from the driver area?

Kept the picture coming, lots of new ideas.[cl[cl

I made the A pillar and B pillar hoops. Got a nice tight fit in the upper corners.

Tom. I had to run a filler tube from the back of the roof down to the tank. NHRA won't like that. When drag racing I'll remove it and put a cap on the filler neck on the tank. All that, and the battery will be enclosed in aluminum panels. I've got an inverted flare fitting welded to the tank by the filler neck. I'll run a length of brake line up, over and down so if I happen to get upside down it won't leak.

Not much room to get in. I'm going to trim the front of the wheel well, extend the frame and move the B pillar hoop back to the body B pillar.

Not sure where the seat will wind up in this car but I assume the back of the seat will be behind the door opening. Don't forget that the rear roll bar hoop has to be behind your head (max 6").

"On full bodied car with driver in driving position, helmet must be in front of main hoop. Side bar must pass driver at a point midway between the shoulder and the elbow. All cage structures must have in their construction a cross bar for seat bracing and as the shoulder harness attachment point; cross bar must be installed no more than 4" below, and not above, the driver's shoulders or to side brace. " ~ from the 2015 IHRA rulebook

Yes, I'm planning on putting another hoop on top of the frame kick up, behind the B Pillar hoop. The seat back will butt up to the frame kick up so the driver's head will be forward of that hoop. It'll be sorta like a funny car cage for two.

Figured you had it covered but had to make sure.

Hey sc, I'm glad you're looking out for me.

Here's the hoop behind and narrower than the B pillar hoop. I made a couple quarter rounds out of the same tubing to tie them together at shoulder height. There will be a pair of top tubes too. Oh, I also moved the B pillar hoop back closer to the door post.

Made a cowl hoop today. Also bent these tubes that mount to the front of the frame and extend through the firewall and attach to the cowl hoop. I cut all the straight tubes a little long and notched one end.

Cage is looking real fine. Are you going to use a swing-out side bar to make it a little easyer to get in & out.

Thanks for posting all the cage pictures, helps use old dudes keep our idea bowl full. keep up the good work.[cl[cl