My 383 took a dump today, #3 piston crapped out at 5500 RPM, it has been to 6300 with no complaints, i thought it was a rod till i tore it down later. I was making 450ish flywheel HP. Too much for hypers? Busted the block and heads, what you guys think?

This was in the intake...

 

Looks like it dropped a valve. I've been running hyper pistons in my 383 for 5 years. It's seen 7200 quite a few times. I shifted at 6800 for one whole season. But I don't spray it. My 2800 lb car runs 6.70s in the 1/8. The engine also has a CAT cast crank. Going to pull it tomorrow for a freshen before the season starts. What kind of valves were you running?

 

I was told hypers can handle 500hp or so as long as you keep it under 6500 rpms. But some ppl have ran more than that and abit higher rpms

 

My first guess is a dropped valve also.

Running a 2 step can put a lot of stress on cast or hypereutectic pistons also.

The key to making a high revving survive is lightweight parts. Hypereutectic pistons are better than cast but are heavy compared to forged pistons. Making sure everything is balanced can make them last longer but it's still a lot of weight being thrown around inside the cylinders.

 

Well, the assy was ballanced, the valve was broken, as you can see. The retainer and lock is perfetct on the spring. Theese heads have seen 7000+ RPM on another engine. Would the valve tip still be connected to the valve spring?

 

Dropping a valve doesn't mean physically dropping the entire valve into the cylinder. Breaking the head off so it falls into the cylinder causing damage is still considered dropping a valve.

 

what kind of heads/valves are those? patriot heads had a problem with valves breaking and dropping like yours a couple years back so they started putting ferrea valves in their heads.

 

Too much spring pressure will pop off the valve head. Those cheaper ss valves on the market are not designed for very much pressure. Almost all of the valves on ebay won't handle over 160 or 170lbs seat pressure. I asked alot of the vendors selling on ebay, what seat pressure their valves would handle. Most of them didn't have a clue. I'm going to be running 240lbs seat pressure on my next build, so I wound up going with ferrea valves that would handle the task. They cost a lot more, but what does an engine cost?

 

OK, thanks Stephen, fellas. Guess that is what happened. They are 1970 over the counter GM "Turbo" heads. They are really good since they are full ported and polished, i have heard from some folks i can have the head fixed. If so i would be happy if the price is right, they were a bad *** set of old schoolers that have plenty of wins under their belt. I have no idea what valves they are bit the springs are good for 650 lift, i was pushing 550. Still sucks, i hope my roller cam is ok.

 

personally, i would dump those heads and buy some aftermarket aluminum heads at this point.

 

Well, if it is a cheap fix i will keep them, they are exceptional for what they are. Aluminum is fine when you have the $$$, i only had 1000$ in this engine, i didnt know the valves were stock. Id spend over 1000$ in good aluminum castings ya know...cannot do it yet. The 408 will have dart pro 1 aluminums

 

well, my thoughts are that if you wind up having to dump $400 into getting these old turbo heads back into shape, youd be better off saving up another $500 and getting some GOOD heads already assembled with new valves. and much lighter, too.
or, how about some vortecs? i would think your looking at a good bit of money once you get that head welded/fixed, all new ferrea valves, and valve job.

 

Trust me, theese kill vortec heads, they arent just a set of cammel humps. I will wheel and deal to get them fixed if possible, just as the rest of the motor it will be scraped together.

 

DUMP them and I highly doubt they "kill" vortecs. where's your flow sheet? I haven't seen any ported GM factory castings outflow out of the box vortecs by any reasonable amount at all.

 

No sir, not out of the box by any means, they have been extensivly ported and polished. They were not available stock on ANY car, they were over the counter thru GM way back when.

 

don't care that they are extensively ported and polished, show me a flow sheet, otherwise for all you know, the head cfm could still be poorer than stock vortecs.

 

Thats true, a flow sheet is important to have.

Your heads make the power so its best to know what they are capable of, and spend the most money on the heads to run the best times. Great heads and small cam will outrun a big cam and crappy heads motor all day long

 

if those heads still have the stock valves in them, i would not call them extensively worked.
besides, even if they are worked to the hilt, they still arent all that impressive. there is only so much you can do with those things.

 

As for the Horsepower rating, When I broke my blower motor years ago
I threw in the block from my 87, which I had installed hyper pistons, and
10:1 compression with 7 lbs of boost - mind you running stock rods.
It was just to play, plus alot of street beating,
before yanking the engine out to start my BBC build.
not caring if it broke, car was pushing over 620 at flywheel and spinning to 7000 with out
a problem.. Made about 20 passes with the car
P.S. been trying to sell that block still - has never been abused!

 

Well, after porting and polishing several heads and researching what im doing, you cna see the intake runners of theese and compair to vortecs and others, they are great, bigger runners and simply a great deal of a larger port. They went 7500 RPM on a 406. I know what your saying but i have never seen a set of vortecs that would allow a 400 cube motor to rev tha high and make power, i allways see them fall off at 6000 on that many cubes, make hell of allot of torque though. Aftermarket vortrcs with the larger ports are dissapointing for the price too. Dont get me wrong, i love my vortecs too but theese werent a stock set of heads ya know. The only down side might have been that there was no heart shaped combustion chamber.

 

Well, the head is junk, that is what the machine shop said anyways. Said it would be better off to machine a new block since i am making power too. Go figgure...

 

I'd invest in a good set of aftermarket heads (iron or alum.) they will flow a ton better than any factory cast head and made of alot thicker material ! I'm a machinest and see alot of people dump a good amount of money into "double hump" and other older casting to make then flow/work better. SBC parts are cheap now days (try building a BBC and you will almost wish you would have stayed SB lol .. I mean you can get a set of alum. Brodix heads out of there IK series for under $1500 for a pair! where as alot of good BBC run almost that and if not more for ONE) but I say save the cash for some good heads ... you will be happier later!

 

Trust me, as i tell oters, theese heads were good. They were not a set of castings off ANY production car. So many folks think they are junk *** camels or 041s and things of that nature. Theese heads are a tragic loss as they are rare. One is still good but even if i found another casting the port and polish work that would have to be done to match it wouldnt be worth it. I had 0$ in them, that is the best part. The funny thing is i have folks say "Find some cammels..." They have no idea that vortecs blow them junks away.

The shitty part is that they arent stock valves in my heads, thats what i am not understanding why i dropped one, guess **** happens eh fellas?


Ither way, i found a set of Pro 1 aluminum 230ccs for 700$ used Too bad i dont have 700$

 

I pulled my engine down over the week end, for pm. The pistons has 5 seasons on them. Cleaned everthing up and check for cracks ect. The pistons look the same as they did 2 1/2 years ago. Rings were only wore about .0015. Deglazed the block, and putem back in. New bearings and gaskets, painted it. Putting it back in tomorrow night. This will be a spare engine by mid May anyways. I like the Dart castings, but the usally need quite a bit of work too. Going to try a set of Pro Comps on my 406. The ones I have look like a decent set. I have done some port work on them, so we'll see how they work.

 

Great, i have seen them so let me know how they work and i wondered how they did, the numbers they claim to flow were not impressive but i really want somone to tell me what they think.

 

The set I bought is 210cc. I have a set of ported Dart 200cc on my 383. I also have a set of Dart 215s as cast. When comparing the 210s and the 215s, I haven't measured them yet, but they do look very similar. The Darts intake port was a little more uniform, but we always trim to gasket and intake we are using anyways. The Darts ports were roughfer. I spent very little time doing the bowl work on the Pro Comps. The spark plug angle is differant on the Pro Comps, is angled more toward the center of the piston and lower, closer to the piston. Milling much off of them will be impossible, as the plug may come in contact with the piston. Don't know if lighting the fire high or low will make much of a differance. Guess we'll find out. My buddy just had an engine built, his engine builder used afr heads with the light weight valve train. His cam has a couple degrees more duration and about .030 more lift than the one I picked out to use for my build. His car is 100lbs lighter than mine, but I have less frontal area. Going to be an interesting summer.

 

"Going to try a set of Pro Comps on my 406. The ones I have look like a decent set."

A Little FYI....

These heads have serious quality issues. Make sure you bolt them on and check the valve train geometry before touching them. A friend of mine had a set and the tips of his rockers were at the very edge of the vlalve stem and ready to the fall onto the retainer. The problem was due to poor machining. The rocker bosses were off about .100 towards the intake side. There was no fix ( I.E longer pushrods, different rockers, etc.) So be careful....

 

Hmm, i did see on Ebay somone selling pro comp castings and stated "Defective machining". Same thing, was talking about the valves being off. that is wierd.

 

Mine appear to be ok. I stuck some valves and studs in them today. They measure the same as my Darts. Must have got lucky.