My current spring loaded blow off valve won’t clear the new carbs. So I’m thinking of just bolting a thin piece of metal between the frame of the old plate and the intake. Beer can seems awfully thin. Any suggestions. It’s a oval not quite 2 square inches.
Doug

Definitely want it to be significantly weaker than the manifold, but having seen your car, you have a good enough grasp of engineering concepts to figure that out. The obvious solution is to drink twice as much beer, and use two cans if you believe one is too light.

Doug, Honestly a beer can is probably to thick, most engineered burst reliefs are very thin and ussually weakened in the center, if you wanted to you could test them fairly easily with a 2 to 3 inch piece of pipe with some fab work on one end, and a cap screwed on the other. One of the respected engine builders on here mentioned, on a thread a bit back, using plastic bolts to bolt the Indy intakes we use together with plastic bolts, I checked and the bolts are easy to come by and really very reasonable, I haven't ordered any yet but I do plan on getting some for my car, I think they might work? Opinion? You can buy those in several grades rated by pressure.

The problem I see with the plastic bolt solution is plastic tensile strength is very temp dependent, meaning your protection level might vary widely. There are engineered low profile alum burst panels available. I used a spring loaded burst valve on my TR. I think your intention is a smart idea.

what about aluminium supercharger/blower bolts ? They are designed to shear on a large back fire .

Tex

How about adapting something like these ?

Score a big "X" in the center.

It currently has a spring loaded blow off. It's mounted between the carbs. Now going to 4150 style carbs mounted sideways. So the blow off springs hit the linkage. 3 choices. #1 fab a burst panel to cover the existing hole. #2 fab a cover to plug the hole and run nothing. #3 plug the hole purchase a second valve and mount one on each side of the intake.
Doug

I would tig weld up the existing hole and then put one on each side like Russ has - those spring loaded wilson valves are the best choice - very forgiving and ready to go after they pop - no replacing a burst plate

Measured the thickness of a beer can .005". Thinking about the pulses in the intake that it may work harden and fracture. Didnt really want to cut and weld on the intake. So this is what I came up with. Ditch the springs holding down the plate. In their place 5/16" nylon bolts. Thinned the heads to .175" Also drilled a .250" hole .125 deep in the head of each bolt. Made a spare pair of bolts. I'll add a small lanyard to tether the plate if pops.
Doug

I don't like rupture diaphragms for a number of reasons. What I've seen in my short and uneventful life is that if you have an unstable process, you will pop the diaphragms repeatedly. What then happens is the user uses progressively thicker and thicker diaphragms until you lose any protection you have. The only time I ever used rupture diaphragms was in conjunction with a relief valve when zero leakage was necessary or as protection as a last resort.

Rupture diaphragms are not precision devices like a spring loaded relief. I've seen test results on identical rupture discs and the simple ones without a cutting bar failed in a range,not at the same pressure. Have you got a picture of your current arrangement? There have to be other options.

To be honest it hasn't back fired on start up for 7 years. Once the starting process was figured out it's been fine. No boost, no spray. I could plug the hole and mount it on the side.
Doug

I think you have chosen the best solution. BTW I think you will be in for a new PB soon

This latest solution, can it possibly lock the throttle linkage when the nylon bolts fracture and keep fuel entering the motor?

I like it - Real curious to see how it will run with the bigger carbs - Those sure are pretty

Here's an old thread.

Crossram Burst Plate

The Wilson offering is along the lines of what I was thinking. May still be too tall for your application, about 1 1/4" high.