Re: [Amc-list] 304 head swap (Big Valve Heads on small bore block)

[Greg Taylor <amundaza@xxxxxxxxx>]

Bruce,
Just curious, when you installed the 2.02/1.625" heads on the 290/304 bore, did you have to notch BOTH intake and exhaust sides of the bore for clearance?  I'm considering having the intakes redone for a 1.94" and leaving the 1.60" exhaust valve, if they clear OK.  Your thoughts ????

Sincerely, 
Greg Taylor :) <>< 
Rochester Hills, MI
1989 Jeep Grand Wagoneer "TRMN8R2"

And the testimony is this, that God has given us eternal life, and this life is in His Son. He who has the Son has the life; he who does not have the Son of God does not have the life. - 1 John 5:11-12


--- On Thu, 10/16/08, Bruce Hevner <scramblr@xxxxxxxxxxx> wrote:

From: Bruce Hevner <scramblr@xxxxxxxxxxx>
Subject: [Amc-list] 304 head swap
To: amc-list@xxxxxxxxxxxx
Date: Thursday, October 16, 2008, 9:42 AM

 I have done the 290 head swap both ways.
I had a Javelin which had the 343 in it. Since it was a daily driver I
didn't want it out of commission while I modified the heads for
"stock"
class racing. I bought a set of new castings from the local AMC dealer and
modified them in my spare time so I could just swap heads and keep the car
on the road.
I did a 3 angle valve job, a little "blending" in the bowls, cc'd
and milled
them to the minimum and a set of stouter valve springs. It definitely helped
the performance but not by a lot.
  Anyway that left me with the OE stock heads. A friend of mine had a 290
AMX and wanted to see how much a "big valve" head swap would help.
While the
heads are a bolt on replacement I still needed to notch the cylinders AND
the piston notches. I did this IN THE CAR by greasing the gap around the
piston at TDC and then using a die grinder to notch the pistons and edge of
the block till I had .060 (using clay) at all points. As you might imagine
this took a LOT of time!! The results were mixed. It absolutely KILLED his
bottom end power and response but did help power after about 3000 RPM. I
couldn't say what the difference was since this was "back in the
day" before
gTechPro and dynos were so readily available. I would say it probably was
faster overall, just can't say by how much.
 Then later on I wanted to do some more work on the Javelin heads (which
were on the car) so I decided to temporarily use the 290 heads. While it DID
increase the mileage and low RPM response by a good bit. It KILLED power
above 3000 and I was BARELY able to make it to the shift point of 4500 RPM
(automatic with a shift kit).
 So if I were giving advice to YOU (not knowing the rest of the specs on
your build) I would STRONGLY advise you against the big valve heads UNLESS,,
you have a 4 speed trans and a decent gear (3:70).
I do NOT think you would be happy using that combination in a heavy car with
an automatic and 2:70 rear end!!
REMEMBER,,, it's the RIGHT COMBINATION that wins the race!!!

But HEY,,, that's just ME!!
Bruce Hevner
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