hi

that just happened to my car last weekend .

not sure what the cause was ?

same motor been together sence 1986

maybe fuel pump ?

only have stock breathers / vale covers .

replaced dist cap , cleaned carb, replaced valley pan car runs but not like it should ! vac and idle not steady like it was before backfire .

The breather locks were bent and it is very loose/wiggly now in the tower. So it’s possible if it was just a push in it might of done that, but the pressure did have to make it through the cover baffle first too. First thing in the path is that valley pan and it’s got a lot of surface area, but I really have No idea haha.

That’s the odd thing I thought I’d see some lack of performance after, but it’s still a ball of fire. Did you compression test it?

hi

have not did comp test yet .

gona do all the easy stuff first ecu, dist change out ect as heders will be blocking some plug acces .


happened on race day 2 time runs at 109 mph, eliminations 1 st round big backfire with smoke out all sides of hood and filled driver compartment then suddenly takes off and runs 108 mph ?

3/4 sec. off my dial ?

now not running normal and exhaust not sounding right ???

I always opened the slits in the breathers all the way to 90° on my dual 4bbl 383. Never had a valley pan grow into a hill pan.

Yeah I think I’m just gonna open up the breather/baffles and run it. From what I hear I may have been somewhat lucky, though I do think I want to limit my Revs going forward haha. Does anyone know of a Rev Limiter set up that works with the orange box and OEM style Mopar Distributer? It definitely winds to quick for me to mechanically regulate with the 4.10 rear she’s got.

There's a cpuple companies that make an ignition box with a rev limiter built in.

FBO is one, Rev-n-nator is another.

If it has cast pistons I would be looking for broken ring lands on the pistons.

Do you know if the Rev N Nator is still being made? It says out of stock on the site unfortunately. The issue with the FBO is that it doesn’t have the ability to limit lower than 5200 RPM. Does anyone know if the “Pertronix 600 Digital Rev Limiter” would work inline with the orange box?

On your deal having excessive crankcase pressure I would do a leak down test also now to see if it is possibly ring seal, especially after doing a good compression test
Crankcase pressure ( a lot of it) is the only thing that will cause that to happen, invert the intake valley pan

A Crankcase Evacuation System before the mufflers will do that also ! LOL

A long time ago (high school actually) I installed a new set of valve covers on my car. The valve covers did not have breathers and I didn't think anything of it since that was how they came. The valley pan looked like a microwave popcorn bag after driving the car.

Engines build a fair amount of pressure in the crankcase, even if the rings are in good shape. It is fairly common to see engines push the dipstick out or push breathers off at WOT.

My 1963 Plymouth 415 HP M.W. with 25,000 miles on the original pistons would push one or both stock breather caps off on almost every run, I ended up having them safety wire on so I didn't lose them after several times of having them fall onto the track during a run

AKA as a crankcase pressure system with mufflers on

Hey every bit of change is useful to me with this issue haha. Thanks everyone for you help with this! Unfortunately there’s no access to air at the unit it’s at so it’s gonna be difficult to perform a leak down on her, and on top of that it’s not Insured/reg’d since it’s been sitting for over a year thinking I had a blown engine. Wouldn’t the grade A compression readings indicate good ring sealing?

Also she’s running single chamber Super 10 Flowmasters, do you think a Crankcase Evac to the header extensions would still build too much pressure? Those are barely even mufflers haha.

Why would you want a limit lower than that?

Any rev limiter that says it will work with an inductive ignition will work. MSD 8728 is an example but a bit pricey. There should be others still available. Just don't get one that is made for any kind of CD ignition.

I’d have it set to 4000ish RPM as a right foot limiter during break in process haha. Its all to easy to go light years past that just cruising with the low rear it has in it. Going 65mph on the highway on my way to work it would be spinning 3500 RPM, one accidental down shift from partial throttle kickdown and it would scream immediately. I know this current engine is already broken in, but in the worse case of something failing I want to not worry about the next one.