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Discussion Starter #1
I was pulling my heads of my 70 Malibu's 350 and found that they both had different casting numbers. The drivers side had head # 3947041 and the passenger side had #3970126. Is this ok to have two different heads on the same motor? What are the differnces in these heads? I looked up the numbers in Mortec.com but they just said one was a high HP 64cc head the other was just your standard 350/327 head with no further info. I'm wondering if this is the root of all my engine problems. Btw, if anyone cares the casting number on the block is 3970010.
TIA!

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Bob
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According to my book the 041 castings are probably the original ones for your motor lists for 68-70 350 /300 HP with 64 CC chambers. The 126 Casting lists for a 327 but with the 1.94/1.5 valves like the 041's have. The 327/350 had 2.02/1.6 valves. I don't have chamber info for the 126 heads.
Your Block casting is a 2 bolt block from 69-79.
I can't tell if those heads are significantly different. I would suspect greatly different chamber size would make the motor run strange. The book also lists the larger spark plugs for the 327 heads. Sounds like one head got munched some time ago.

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Frank W
Gen X Member#22 (MA)
73 Malibu Coupe
http://hometown.aol.com/folingo/myhomepage/auto.html
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I have had several sets of the 041 heads but I don't remember having any of the 126 heads so I can't help you much there. You can measure what size chamber and valves they have and if they are the same it shouldn't be a problem. Some chevy heads are nearly identical to each other. If you have the 300 horse motor, I'll bet it's a 4 bolt main. The 010 blocks came in either version but all 3 69 and 70 300 horse motors I had came with 4 bolts..........GT
 

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Mixing heads is ok as long as the chamber size is the same and valve size is the same with no big difference in runner size.I do this sometimes on my "poor boy" motors to help get rid of 307 heads (on the drivers side). Both of the heads you mentioned will have "soft" seats and unless hard seats have been installed you will have to do it. Sounds like it's time for a set of sportsmans.
The 010 block could be 2-bolt/4-bolt it also could be a "heavy duty" truck block and if you are really lucky it could have nodular main caps. Check it out very closely as the last two mentioned are very rare and desireable. I have traded a built short block for a nodular block as circle trackers go bannans for 'em.
Harley
 

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Discussion Starter #5
Any particular way I can tell what exactly I have here, or is that only determined after ripping her down?
I guess for now I'll just call her Frankenmotor!


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Bob
Email: [email protected]
My Chevelle: members.aol.com/rdcnh/70index.html
Team Chevelle Gold Member #169
New England Chevelle & El Camino Assoc. #085
 

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Not for sure,There are three possable size intake valves,two sizes possable exaust valves and at least two chamber sizes. But I wonder if one of those fancy dynomonters that the shop mechanics have can tell?
Harley
 
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