[Amc-list] Big valve heads on 290/304

[Brien Tourville <hh7x@xxxxxxxxxxxxx>]

This is covered in depth over on the www.bulltear.com/forum 
- & you'll pull up solid recommendations.

There the  304 is noted for it's TURBOing potential - using
stock valve size 304 or stock valve size 360
heads notched bores - GM ECM - Bulltear modded Edelbrock manifold for EFi / Forged slugs / roller cam ?$

Normally aspirated , no one went with big valve heads on a 304
short block as a stock 360 would out pull the combo & returns were 
minimal.

I read the 370HP AMC 304 Small Block article.

Much of the thump comes from a roller cam kit set for lower RPM Torque and lots of matching high dollar pieces which if done to a 360 with your port massaged 360 heads , could 'unleash the hounds'.


As posted on BT - a Turbo 304 puts that cylinder wall thickness to good use keeping cool straights - rather than punching thick walls to thinned cylinder distortion - better to start with a 360
for displacement .


I totally understand building outside the box engines -
 370HP would bring on grins regardless - but a variable
boost 250 to 500HP Turbo
Street AMC would be scary..



T









From: "Greg Taylor" <amundaza@xxxxxxxxx>
 Big valve heads on 290/304


Hey guys,
We?re beginning the build-up of the stroker 304 and I have some questions
about running the 1970 291C heads on the smaller bore block. I?m boring the
304 out to 3.83? (0.080? over stock size of 3.75?). I picked up a set of
race-prepped 1970 360 heads with 2.02/1.60? SBC valves installed, because
they were a good deal. The heads are about done with a new valve job,
hardened seats on the exhaust and some new valves with undercut 5/16? stems.
The heads have had a mild port/polish done to them by NAMDRA?s head guy (don
?t recall his name ? he originally built the heads).

The spacing across the SBC valves measures in at 3.73? from outside of
intake to outside of exhaust valve. Does anyone know the relation of the
intake to the bore and the exhaust valve to the bore on a stock AMC? If one
is closer to the bore, which? Or if they are ?evenly spaced? it would leave
0.050? valve to bore clearance ? IF ? I run the 1970 360 heads on the 3.83?
bore block.

Performance AM Style calls for a 0.060-0.090? valve-to-bore clearance, when
running the bigger valve 1970 heads (2.02/1.625 stock) on the 290/304
blocks, and calls for notching the block for valve clearance. If this
becomes too much work for a street/offroad engine, I have a set of 1970 304
heads that I can put 1.94/1.50? SBC valves into. That would measure in at
3.63? across the valves and definitely clear the 3.83? bore 304 block.

Has anyone on the list run the big valve heads on the 290/304 or can point
me to someone who has? Herman Lewis? Atkins?

Thanks all for your feedback.

Sincerely,
Greg Taylor  :)  <><
Rochester Hills, MI

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