452 or 906's

I have a 400 I am building to the 400 to 450 range. Which heads would be a better investment, the 452 heads or the 906 heads with hardened valve seats for 80 bucks extra. I am ordering from Aeroheads. I have 902 heads currently. They said the 452's are the same design as the 906's but with hardened valve seats already is this true? Which would be a better investment for 400 - 450 h.p. I would do mild bowl porting also .. Thanx.

Put on the 452's,they already have the hardened seats and they are good cylinder heads. I have a set on my 440 Dart(not from Aerohead,we did ours) with the 2.14/1.81 valves and they work great.The big valves will help that 400 breathe real well,in fact I swapped my 906's with stock valves and slowed down 3 tenths,so the big valves do help,and they will fit the 400's bore without a notch for clearence.

[This message has been edited by Christopher (edited June 13, 1999).]

Christopher is right! I have the 452's from Aerohead and I love them! They woke that ol' 383 in my Duster right up. Definately get the 2.14/1.81 valves its not much more and its nice to have the extra for later. I also had mine milled 40 thousandths before I picked them up just to up the compression a tad and it was cheaper than taking them to a machine shop after I got them home.

My opinion of all this hype over hardened valve seats is a lot of hogwash! ( To a degree! ) I have 16 year old proof to back up this statement. So that I don't step outa line here I won't mention what these heads are on, OKay. They're not Mopar, I'll say that. They are '69 vintage heads and I've run them on the street using regular grade ( 87-89 ) octane and I haven't realized a problem. Now I don't run the car a lot of miles, maybe 2,000 a year during the summer. Also, for the past 7-8 years I've been using 4 ounces of Mystery oil to a tank of gas. I read this tip in a car magazine and decided to go with this little insuranc policy. The Mystery oil adds the lubricant ( they took the lead out of gasoline for environmental reasons )that saves the seats in non-hardened seat situations. I'm mentioning this so if anyone comes across a deal on a good set of heads, don't rule them out if they lack hardened seats. ( My '69 heads are the best factory heads for my application.) There is a workable way around it. I carry a small bottle containing the Mystery oil marked off @ 4 ounces in the trunk. If I have to tank up I just use it like any other additive. Dump it in before you fill 'er up, it mixes in as you fill the tank.
I would however be more apt to look for a set of heads w/ the hardened seats( or have them installed ) if I intended to drive the vehicle year round and put 15-20 thousand miles on it a year. In my case I drive for summer pleasure only.
Richard

Even with the additive being available I would still opt for the 452's the hardened seats may not be absolutely necessary but it doesn't hurt to be safe. In the long haul the hardened seats will pay off cause you can stop and put in any grade fuel you wish and not worry about having an additive(which will eventually cost more than $80 total anyway). I can't speak from personal experience about needing the hardened seats because I haven't ever had non-hardened seat heads, but from my point of view $80 was worth the piece of mind and I chose the Aerohead 452's.

Pick up the Jan. on up issues of Mopar Muscle Mag., they did a really great series of articles on the flow of bb Mopar heads in ported and unported form. They proved something that I have known for 15 years, that the 906 head is out flowed by the late"smog" heads intake port in mildly ported (MP templete) form. If this ride is going to see lots of street miles, go with hardened seats. I pretty much disagree with Richards reply. Yes, non hardened seats will last for years in a ride that sees limited use like his 2,000 mile a year cruiser. You will usually not see any valve seat degredation for about 50,000 miles unless you are lead footin it or put a heavy load on the engine a lot.....ie towing or pulling some long hills

Well....I'm gonna throw my hat in the ring on this.You don't HAVE to have hardened seats.The stuff they put in gasoline today is said to work.My 383 Road Runner ran on unleaded 93 with no valve seat recession.(I drove this car everyday to work)However I still think that if you have the heads(such as the 452's) use them.The hard seats will only help in the long run and it's cheap insurance.Now I will eventually put hard seats in my 906's on my Road Runner,but that will be after it's restored.I don't know what the gov't will take out of the gasoline next,so I opt for the hard seats.- My opinion that's all. Glad to see you back Richard.



[This message has been edited by Christopher (edited June 25, 1999).]

The 906's have a smaller chamber equalling more compression. Why not install hardened seat in the 906's if that's what you want. I have a pair of 906's with hardened seats on my tow vessile. I had heads without hardened seats and ended up cooking the exhaust valves out of them. I bought the engine used and cannot put the blame on the non hardend seats although that's where where I would point my finger

I have 346's. I want to buy the 452's from Aerohead. There around 600 bucks with valves, springs, retainers, and a valve job. The 906's would be 600 with soft seats, 680 with hard. If they flow the same I can go cheaper and dial in my compression ratio buy cutting the heads/block.
THANKS FOR THE HELP!

If you cut the 452's down to 80cc's,you'll be right where you need to be.this usually requires about a .040 cut.906's need to be cut too,to get them at 80cc's,just not as much.If they are both at 80cc's they are essentially THE SAME.