Wow, 61 409 heads

[models916]

Somebody must be looking for these!


http://cgi.ebay.com/ebaymotors/Chevy-409-CI-Engine-Heads-Impala-SS-Chevelle-Nova_W0QQitemZ4598416232QQcategoryZ34202QQrdZ1QQcm dZViewItem

[real61ss]

Actually, these are not 409 heads, they are hi performance 348 heads.

[models916]

What makes them 348 and not 409? I was just going by the casting numbers on our home page. Thanks

[real61ss]

Models 916
The 1147 heads were used on 1960 and 61 348 hi performance motors. In 1961, a new head was introduced, it was the 3795586 head and was used on the new 409 motor that came out in 1961.
The 1147 head has the W shape and will work on a 409 but to my knowledge, they were never installed by the factory on a 409 motor.
Hope this explains what I meant when I said they were 348 heads.

[CDNpontiac409guy]

Tommy... you would know best:? ...
It's my understanding that the only physical difference between the hi perf "1147" 348 head and the 61 409 head, is that the 409 head was machined to accept 3/8" pushrods:dunno
Other than that, they are identical in construction, flow, ect:dunno
Yes ?
No ?

[real61ss]

Aubrey,
The answer to your question is yes, well I think so. The only reason that I responded to the original question was I wanted to point out that if you're trying to assemble a correct 61 409 motor, 1147 heads are not what you should be looking for. You need 586 heads.
I was thinking about you last week, we were having pretty cold weather here for the time of year but I bet it's really cold up there.:)

[MK IISS]

The 586 head, in the 409 application, was also machined for a larger diameter valve spring than the 348/305, 348/340 & 348/350.

[CDNpontiac409guy]

AHAH !

Thanks Richard...

I take it then that the new "big" valve spring was similar to the soon-to-be-released "690" large port head ?
That would make sense

[RCE1962]

Capacity for similar flow as 690's. Can the 1147's be manipulated...machined for push rods, valves and...aftermarket springs that would be compatible with performance? :dunno

:scratch

[models916]

Depends on what you are going to do. 690 heads are superior race heads. I personally don't like the big gear they need to respond well on a street driven car. My 64 Impala convt. seemed to need 4:56 to run with the fast street pack. The smaller heads in the same heavy car runs as well with 4:11, and seat of the pants is better to a point (around 6,000 rpm). Valves are valves, same for springs.

[RCE1962]

Maybe these heads are the ones to go after since they would provide good street performance and maybe not as pricey as the 690's?

RCE1962

[Tic's60]

Not exactly apples for apples but in the 396 - 454 heads the square port is way over kill on the street (kinda like the 690 to some) and the standard hi perf are rather snappy. BBC breath in pretty good stock wise but getting rid of the gasses is where they suck. Real bad in some cases. That's why headers wake up a BBC so easily since they scavage better.
Just another point of view