Re: 906 & 346 heads
[Re: dodgepu360]
#1655423
08/05/14 08:56 PM
08/05/14 08:56 PM
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Joined: Sep 2004
Posts: 6,906 IL, Aurora
ademon
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IL, Aurora
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Quote:
I was looking over the heads that came with my RR (the engine was apart when I bought it) and noticed the heads are mismatched one is a 906 and the other a 346. What are the differences between these heads? I had never heard of the 346 before. Can you mix these? Should I look for both and run which ever I find first or just look for a 906?
that will run fine mismatched the 346 should have hardened seats. If it bothers you look for the correct 906 head
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Re: 906 & 346 heads
[Re: dodgepu360]
#1655424
08/05/14 09:03 PM
08/05/14 09:03 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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The 346 is the head that came after the 906. It is functionally equivalent. Same combustion chamber Same cc Same intake and exhaust flanges. Same flow Slightly different intake port configuration, if one was porting Neither one has induction hardened valve seats (It is possible that a 1973 model year 346 head could have induction hardened exhaust seats.)
What you do depends entirely onyour budget, your wish to restore and your vehicle year.
If you are a restorer, you want to find a head which matches the year. The 906 was a 1968 to 1970 head. The 346 was a 1971 - 1973 head. You can look up Chrysler casting numbers online.
If you have the budget and don't wish to restore, there are much better heads out there, the 440Source Stealth and the Edelbrock E-street are the two lowest priced worthwhile heads.
If you have any notion about the stock iron heads for high performance, give it up. It'll cost more to have them ported and rebuilt than it'll cost to buy the above aluminum heads.
Before you put a nickel into either head, get a firm written quote from the shop, then check your options.
If you "just want an iron head so I can drive the car" then look for a set of 452s, the latest bigblock castings that have induction hardened valve seats and have the same lousy flow and combustion chamber as any of the 1968-and-up bigblock heads.
R.
PS: I have edited the content to correct the model years. I hate to be inaccurate.
The reality is, these heads are satisfactory in four aspects: 1. They cover the cylinders. 2. They connect to the intake and exhaust manifolds. 3. They position the sparkplugs. 4. They hold the valves and springs.
They fail in that they flow only marginally better than a stock 340 head, and they have a lousy open combustion chamber that aggravates detonation and requires a lot of ignition lead to get to best power.
Last edited by dogdays; 08/06/14 07:13 PM.
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Re: 906 & 346 heads
[Re: dodgepu360]
#1655426
08/05/14 10:12 PM
08/05/14 10:12 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Lincoln Nebraska
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they are nearly identical & you will not notice any difference tho it does go against the grain to have an identical pair of parts on an engine but they ain't the same. If you want to read up on em access Dulcichs' Mopar Muscle porting articles which impressed me as the final word on porting iron BB heads. As said I would not sink any serious money into them. iron is heavy/likely need milled to be flat (decks and intake face)/open chambers give no quench potential/452's can be cracked/early ones (915/906) need a flow bench/experience to properly port em & I would stay with OE valve sizes on early ones/use the MP templates. If I was to invest in em I would find a pair of crack free 452's and go with 2.14/1.81 valves & unshroud the chamber (valve) ends and cut the MP templates larger out of the laminated sheet. Always always always practice porting on a junk head bufore starting on a good set. With the good alum heads available and how much it will cost to do the iron ones I would pass unless they are ready to go & even then I would just port with the MP templates on the stock valves (if you can still get them) (alot of gain to be had).
live every 24 hour block of time like it's your last day on earth
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Re: 906 & 346 heads
[Re: Cab_Burge]
#1655428
08/06/14 01:33 AM
08/06/14 01:33 AM
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Joined: Dec 2008
Posts: 2,782 USA
JoesMopar
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Quote:
I believe that the 346 head was first used in the 1971 production motors As already pointed out, no noticeable differences in performance though
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Re: 906 & 346 heads
[Re: JoesMopar]
#1655430
08/06/14 02:02 AM
08/06/14 02:02 AM
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Joined: Jan 2003
Posts: 6,591 Canton, Ohio
Sport440
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Quote:
Quote:
I believe that the 346 head was first used in the 1971 production motors As already pointed out, no noticeable differences in performance though
Yep, the most difference is in the intake port design. But stock they will perform exactly the same. With the valve covers on nobody will know the difference. Both heads are good, IMO
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Re: 906 & 346 heads
[Re: dogdays]
#1655431
08/06/14 01:36 PM
08/06/14 01:36 PM
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Joined: Apr 2005
Posts: 15,134 Kelowna, B.C. Canada
DPelletier
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I Live Here
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Quote:
If you are a restorer, you want to find a head which matches the year. The 906 was a 1968 head, maybe 1969. The 346 was a 1970 head. R.
906's were used in 1970
Dave
1970 Super Bee 440 Six Pack
1974 'Cuda
2008 Ram 3500 Diesel
2006 Ram 3500 Diesel
2004.5 Ram 2500 Diesel
2003 Ram 3500 Diesel
2006 Durango Limited
[url] http://1970superbee.piczo.com [/url]
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