906 head capabilities?

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Csommers said:
Unfortunately I have no close ups on anything as it’s not at my house. Here’s what I have on had. All I know is that they are ProComp heads, ~84cc. We had measured the valves at one point but I can’t remember the size off the top of my head. COMP 924 springs (Valve Springs, Dual, 1.509 in. Outside Diameter, 347 lbs./in. Rate, 1.175 in. Coil Bind Height), Harland Sharp roller rockers .650 offset, 1.5 ratio and COMP Mag push rods 8.710”

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Yes those comp 924 springs are for a low lift hydraulic flat tappet cam. Never going to work with the cam you have. Better call the cam company and ask but your spring pressures need to be way higher than that
 
Csommers said:
I’ve been working on my Dart for far too long now and when it’s almost time to finish it I’m having engine problems. I believe most of the issue is these knock off procomp heads. On the last start up an unfortunate series of events led to a bent valve. Can I get away with running 906 heads? The only concern I have is with my cam. The block is a 400 stroked to a 470, zero deck and the cam card is below. Thanks!

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You better do some research and make sure what head you are running. Are they proComp or Speedmaster heads. Reason I ask is Speedmasters only big block head is an Edelbrock Victor copy with big offset rockers. You would not want to run those heads on that engine.
 
There’s only a few things it could be and it ain’t the springs. Unless someone shimmed the crap out of em and they’re in coil bind. Your retainers could be hitting the valve seals, or the rockers, the valves could be hitting the pistons, you could have junk pushrods that are pole vaulting. All can be fixed relatively easily but you’re going to have to dig in and start measuring and find what it is. Sticking some 906s on ain’t the answer.
 
9.82 on super stock springs with 906 heads many many years ago. Stock 3/8 valves. Imagine what’s capable now.

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pittsburghracer said:
You better do some research and make sure what head you are running. Are they proComp or Speedmaster heads. Reason I ask is Speedmasters only big block head is an Edelbrock Victor copy with big offset rockers. You would not want to run those heads on that engine.
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They are the ProComp heads which are Victor knock offs
 
TT5.9mag said:
There’s only a few things it could be and it ain’t the springs. Unless someone shimmed the crap out of em and they’re in coil bind. Your retainers could be hitting the valve seals, or the rockers, the valves could be hitting the pistons, you could have junk pushrods that are pole vaulting. All can be fixed relatively easily but you’re going to have to dig in and start measuring and find what it is. Sticking some 906s on ain’t the answer.
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You don't see an issue running a hydraulic flat tappet spring with a large solid roller?
 
pittsburghracer said:
You better do some research and make sure what head you are running. Are they proComp or Speedmaster heads. Reason I ask is Speedmasters only big block head is an Edelbrock Victor copy with big offset rockers. You would not want to run those heads on that engine.
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From the pic he posted, it’s got big offset intake rockers.
 
MOPARMAGA said:
You don't see an issue running a hydraulic flat tappet spring with a large solid roller?
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Oh I do but it ain’t causing contact between hard parts. He said it happened in a few starts.
 
TT5.9mag said:
Oh I do but it ain’t causing contact between hard parts. He said it happened in a few starts.
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Okay, yeah I agree but heavy valves bounce with weak spring pressures that could hit the piston on the way up and boink the rocker and bend pushrods
 
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I know not a lot about this engine. It was a buddy’s who used to race it. I was told it’s a 400 stroked to a 470. He swapped his whole setup and sold this short block to another guy who bought these heads but never ran the motor. I acquired it. My own stupidity, it’s not like a SBC or Import motors I’ve worked on. This is definitely more motor than I’ve handled and am now realizing the precision it needs. I know the pushrod tunnels have been clearanced in the heads. The heads have been off an I have never noticed any kind of contact on either the piston of valves until now when the spring and retainer came off the valve.
 
pittsburghracer said:
Get a set of 440source heads
Have them checked out
And send it!!!
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Man, that's choking the chicken. Big block Mopar intake ports are already tiny, closer to small block Chevy than any other brand big blocks and the op has a 470 cube. My trickflow 240s aren't even a good cross sectional area for my 470.
Smaller engines in production cars had bigger than max wedge ports and shoot even a mid 2000s ls6 in pick up trucks have a bigger port.
 
MOPARMAGA said:
Man, that's choking the chicken. Big block Mopar intake ports are already tiny, closer to small block Chevy than any other brand big blocks and the op has a 470 cube. My trickflow 240s aren't even a good cross sectional area for my 470.
Smaller engines in production cars had bigger than max wedge ports and shoot even a mid 2000s ls6 in pick up trucks have a bigger port.
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He is in so far over his head he’s lucky to see dinner on the table. Even if he by the Grace of God gets the engine right what transmission is he running, what rear gear, automatic??? What converter. So many unanswered questions and facts.
 
Csommers said:
I know not a lot about this engine. It was a buddy’s who used to race it. I was told it’s a 400 stroked to a 470. He swapped his whole setup and sold this short block to another guy who bought these heads but never ran the motor. I acquired it. My own stupidity, it’s not like a SBC or Import motors I’ve worked on. This is definitely more motor than I’ve handled and am now realizing the precision it needs. I know the pushrod tunnels have been clearanced in the heads. The heads have been off an I have never noticed any kind of contact on either the piston of valves until now when the spring and retainer came off the valve.
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What about the rest of the dart ? Trans , converter, gearing , weight ?
 
pittsburghracer said:
He is in so far over his head he’s lucky to see dinner on the table. Even if he by the Grace of God gets the engine right what transmission is he running, what rear gear, automatic??? What converter. So many unanswered questions and facts.
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Exactly, I just asked the same question lol
I'm getting junky cell coverage and didn't see you asked that
 
pittsburghracer said:
He is in so far over his head he’s lucky to see dinner on the table. Even if he by the Grace of God gets the engine right what transmission is he running, what rear gear, automatic??? What converter. So many unanswered questions and facts.
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Truth.

71 A833, 8.75 with 3.77s
 
Csommers said:
I know not a lot about this engine. It was a buddy’s who used to race it. I was told it’s a 400 stroked to a 470. He swapped his whole setup and sold this short block to another guy who bought these heads but never ran the motor. I acquired it. My own stupidity, it’s not like a SBC or Import motors I’ve worked on. This is definitely more motor than I’ve handled and am now realizing the precision it needs. I know the pushrod tunnels have been clearanced in the heads. The heads have been off an I have never noticed any kind of contact on either the piston of valves until now when the spring and retainer came off the valve.
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Did you find the keepers?
 
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