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  #1  
Old 01-28-2000, 05:00 AM
larry phillips larry phillips is offline
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i have two sets of heads to work with 906s and 452s ive got the porting templates from mp im using the old 509 mp cam and m1 single plane with headers and want a 10-1 c/r does anyone have an opinion of with heads to use ?
thanks bigl
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  #2  
Old 01-28-2000, 05:14 AM
Chris A Chris A is offline
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Both heads have the same basic design but the 452's aren't as old and have the hardened valve seats already installed. I would just use the 452's if you are runing on unleaded.
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  #3  
Old 01-28-2000, 07:09 AM
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ehostler ehostler is offline
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From my understanding, if you enlargen the vavle seats, on the 452's, you are still going to need hardend valve seats installed. This is because you have machined away all of the factory hardening.

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'96 Dodge Ram 1500 SLT CC 360 4X4
'68 Charger 383-4
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Old 01-28-2000, 07:21 AM
DartGT66 DartGT66 is offline
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I think that's true, but I didn't notice anyone talking about bigger valves?
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  #5  
Old 01-28-2000, 04:38 PM
Dart Dart is offline
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The 452's are the way to go, they are cast from higher nickel content metal (making them stronger) and are flame hardened, they also have hardened valve seats.
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  #6  
Old 01-28-2000, 05:30 PM
bemiller bemiller is offline
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One of my ford buddies found me a set of 452 heads when he was at the junkyard. They were in the trunk of an old beater and free. They are covered in completely covered in rust and the valves are pretty well froze. Can these heads be saved? Also, one of the valve guides or spring perches whatever there called is chipped, where someone may have tryed taking out a valve. I would think bronze valve guides would fix that and most of the spring perch is milled away for double springs anyway. I have the MP porting template and before I spend hours grinding away want to know if worth it.

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  #7  
Old 01-28-2000, 06:25 PM
ChristianCuda ChristianCuda is offline
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The 452 heads are better if you port them. As stock the 906's are better. The broken guides wont matter once new guides have been installed. Make sure with anything you do to install new valave springs. These old heads have springs that are 20-30 years old and worn out.

Peace
Christian
68 Cuda
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  #8  
Old 01-28-2000, 06:35 PM
Richard Reardon Richard Reardon is offline
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I think the chip issue is a "non-issue!" You should be able to use this head wo/ any problem, maybe only having to replace that particular guide if you deam it necessary.
As for the rust business, I'm hoping Christopher can elaborate on this issue. I know he's told me to use "muratic acid" on cylinder walls that have become rusted, before honing or boring the cylinders. I'm not sure exactly that the acid does, hence I hope Chris sees this post. He also said to start with a 50/50 mix of the acid and water and increase the acid ratio as needed. This acid is available @ drug stores I think. Be careful, as this acid is nasty stuff. Protect yourself in relation to the handling proceedures on the container. I would think that what you need is a rust disolver, that you could put on and let it sit for a period of time to "eat" the rust away. Whether or not this muratic acid does this or not, I don't know. Ask the druggist.
As for the 906 vs the 452 heads, most will go w/ the later 452s only because they have the hardened exhaust seats. I keep telling people how to get around this so called problem of not having these hardened seats, but I guess it isn't general knowledge yet! Use 4 ounces of Marvel Mystery oil to 16 gallons of gasoline. This will provide the lubricant the lead in gas use to do. I've done this since 1983 and all is well. Therefore, the 906s can be used. I've got a pair of 906s and they are going on my 413 this spring.

Richard
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  #9  
Old 01-28-2000, 06:59 PM
MopART@hm MopART@hm is offline
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Take the heads to an engine shop and let them put them in their furnace or whatever it's called. Most engine shops have converted to theis process insted ao using solvents and such. So if your engine shop can do this, they'll come out looking like new.
Just toss the valves and springs if they are that bad.

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  #10  
Old 01-28-2000, 08:35 PM
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Christopher Christopher is offline
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I do use muratic acid on very rusty junkyard parts that are cast iron.I start with a 50/50 mix and rinse after the rust is gone.It doesn't hurt the core metal at all.I learned this trick from John Labbous who runs the "Loose Caboose" Mopars.As far as the heads,I like the 452's.I'd look at the valve guide boss(the part where the actual guide is pressed into)if it's cracked,it will need to be repaired as this supports the guide.I have my guides machined at the top for spring and retainer clearance,and I use the PC valve guide seals,on both intake and exhaust.Some guys don't use exhaust seals,but then the exhaust will get a bit "smokey" on a drag car.I'm not sure on losing the hardness of the valve seats when grinding for larger valves.They are induction hardened at the factory,so I don't think you lose all of the hardness.I've been a proponent of using 452's because of the hardened exhaust seats,but with the gas today being rich in MTBE additives,this stops valve seat recession.You'll have to mill the 452's to get the compression up as they have a 86cc chamber.I like getting mine down to 80cc's.
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  #11  
Old 01-28-2000, 09:32 PM
ChristianCuda ChristianCuda is offline
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As far as the 906 vs 346 or 452 the reason why I state to use the 346 or 452 heads has nothing to do with hardness. It has to do with porting. When ported the 346 and 452 flow better due to a hump right before the intake on the 906 and 516 heads and this hump can not be ground down because it will run into the water jacket. The 346 and 452 and later heads due not have this hump and in such flow better but only when the heads are ported. Note this is only for Big Block heads. Small block heads are a different story.

Christian

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68 'Cuda 383
Working on adding EFI

[This message has been edited by ChristianCuda (edited January 28, 2000).]
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