jimmyjeep
How hard is it to find a set of 291 heads? Am I asking for the rediculous, or are they out there? I know my 401 would like to have a set for its birthday! lol
73hornut
There not the end all be all heads anymore.They were the best when pistons were limited, but there are lots of pistons available now. I would stay with the ones you have, and go with a smaller dished piston. Something like these.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&tc=photo&item=7951670537&category=33623
tufcj
They're not that hard to find. I have a set on my 77 CJ and a set on my 69 AMX, I also have a spare set (not for sale). I see them pop up on ebay quite regularly. Be prepared to pay about $300-350 for a set of bare 291 heads.
The 58cc heads actually only lose you about 1/2 point in compression. The 71-73 heads (993 casting I believe) flow better with less work because they're cast with less shrouding around the valves, and they also have the Chevy style rockers.
I agree with going to a better piston, and staying with the later head. Money spent will probably be equal. When I built the Jeep engine, nothing else was available. On the AMX I used good forged pistons, and wanted the additional compression, but it will be seldom street driven.
Also, The 291 heads have a 1.62" exhaust valve, the later heads are 1.68". I had the 1.68 valves put in my AMX heads.
Bob
tufcj
KEV
:idea: I have a set off a 70 304, I know they are small valve but they are small chamber also.
jimmyjeep
Thanks guys, Im sold on the better pistons, but this brings up a couple of interesting questions. (1) Do they make a higher compression piston for a std. bore? Those on ebay and all the others I have found are all based a +.030 or better piston. (2) I have read and heard more opinions on what to call the limit on a 401 bore job, than I can shake a stick at! I read in Car Craft, this month that .030 is the limit. Then why do they sell .040 pistons? I also read that 401's are not compression sensitive, so you can go a little higher without disaster following you around. How about someone weighing in and putting us straight on these questions. Thanks Gang. :t:
73hornut
Look under Mad dog racing on ebay. I've seen std. My 401 is 60 over with no problems, but I would'nt bore it if you don't have to.
ol' school power
How far you can go beyond .030" on a 401 depends on the individual block.
FActory max on a 401 is .022". The blocks are thinwall casting and 35 year old technology so no guarantee on core shift.
I'm running a .040" over block with 10.7c/r and have to run a radiator big enough to cool a nuclear reactor.
jimmyjeep
:shock: oooh! Now thats setting the record straight! Thanks from all us cooks, ol' school!
