Man! Sorry to see this Dave! Def need a blow-off on those manifolds. Glad u had the fire system

The big issue with these manifolds is the flat or depressed areas at the front and back corners(left to right).If you pump fuel from the accelerator pumps before starting or have a float or needle valve issue the raw fuel puddles in these areas and the slightest kick back or backfire ignites the fuel and fumes causing a hard explosion.If you look in the manifold you will see the blackened area where the fuel/fumes ignited.
Indy has an insert(epoxy) that helps but fuel can get behind and under it,it also kills the volume of the intake which makes this intake work so well on large cubic inch engines.We maximize the volume buy welding in small angled ramps at these areas.We also install the Wilson or similar valves for extra insurance.

I decided to go to the Track with my son and leave the problems sit a few days. I'll pull the heads today to check for any pieces that might have made it inside of the ports. Now that I think about it spinning the motor with ignition off probably contributed. Bob, do you have any pictures of the pieces you weld in? I like Rat Patrols blow off valve. Anybody know where to get that style valve/plate? It has a MSD 7al2 box w/crank trigger at 32 degrees. I'll check the carbs as well. In fact as long as the steering linkage off to remove the headers Ill pop the pan for a bearing check as well.
Doug

Man, really sorry 2 c this after all of the beautifull and hard work you put into your car and hopefully you`ll be back up and running soon enuff............

Yep yep that sucks

You are taking it better than I would, I would still be pouting about that intake blowing up

Good luck getting it fixed and going again. still cant wait to see the car

Doug when that happen to us we put longer bolts in and was racing in an hour. I know you want to make sure things are all right but remember it blew out not suck in so everything went out. You will probably not find anything in the heads .

Pulled the heads,found no shrapnel. My theory was if an intake was open the pressure could have sent a piece down the hole. As long as the steering linkage and diaper were off I pulled the pan and checked the rod bearings. I'll put the heads back on tomorrow. Has anyone back fired one of these after the blow off valve install? I can see why it popped the top. Only had 3 threads of engagement of the lid bolts. Total carnage. Melted 2 temp sensor wires,1 vacuum line, 1 accelerator pump(there plastic on Eddelbrocks,throttle cable, fill the fire bottle, distributor rotor (Intake knocked the distributor cap off), very lucky.

I have backfired mine after I had the Bob George made blow off valves on and they worked. I have also seen guys with the Wilson valves backfire and they also work well. And yes the top bolts are short and I replaced all of mine with longer ones. Indy always told me there was no issue with these intakes but said the short bolts are a safeguard in case it did happen The epoxy inserts from Indy also help with the puddling of fuel and I did install them too. If you want I can get a pic of what they look like intsalled.

Just seems like with the big plenum volume backfires will happen and even more so when cold starting. I knew there was always a chance on start up but my 2nd blowup was while driving through the pits so that was different.

Russ