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Javelin_GT View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Javelin_GT Quote  Post ReplyReply Direct Link To This Post Topic: Engine Build Opinions
    Posted: Jun/21/2018 at 6:29am
This engine is going into my rally AMX build. For hill climbs and road course. Power band 3000-7000.
Right now it’s at the machine shop.

Block: 343
Crank: Steel 343 3.28 stroke
Rods: 6.200 Carrillo
Pistons: Forged flat tops
CR: 12:1
Heads: 291s with good valves and some port work
Intake: Torker
Carb: Modified 4150 750cfm
Cam: Solid Lifter

Big question is about the cam. Anyone care to comment on how it will work with the combo? This was the grind recommended by Howard’s.



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jcisworthy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jcisworthy Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2018 at 6:45am
Cam will work with your rpm range. 

The heads will hurt the combo some. Probalby not movine a lot of air with what you described and the CSA is probalby on the small side for turning the rpm you want. The engine will go to 7K but it will do it a lot better and make more power with more cylinder head on it. 
Specializing in dyno services, engine building, and cylinder head porting

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Javelin_GT Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2018 at 6:47am
What if I sent with Indy SR heads?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jcisworthy Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2018 at 8:50am
Edelbrock with some work or full port on the 291's is probalby best for that CID

Specializing in dyno services, engine building, and cylinder head porting

rbjracing.com
Phone Number 518-915-3203
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jpnjim View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2018 at 4:48pm
Closest lobes to those that I could find in the Howards Lobe List are:


Tight lash mechanical (.016" lash):

Intake lobe:
AF250343  293 @seat  278@.020"  250@.050" .343" lift  .549"w/1.6 rockers
AF250360  293 @seat  278@.020"  250@.050" .360" lift  .576"w/1.6 rockers


Exhaust lobe:
AF256343  299 @seat  284@.020"  256@.050" .343" lift  .549"w/1.6 rockers
AF256367  299 @seat  284@.020"  256@.050" .367" lift  .587"w/1.6 rockers

^ lifts are close, but different (one each with slightly lower, and higher than the .350"/.560" of your lobes).


The "Tight Lash Mechanical" lobes aren't listed as AMC/Mopar or Ford specific lobes to take advantage of the wider lifter,
 but the numbers that they supply are very similar to Howards Ford Mechanical lobes, just with much less lift:

Ford Mechanical Flat Lobes (.875" lifters) .018" lash:
FF2503861A  advertised/seat not given  278@.020" 250@.050" 167@.200" .386" lift .618"w/1.6

FF2563940A  advertised/seat not given  284@.020" 256@.050" 173@.200" .394" lift .630"w/1.6



If those tight lash mechanical lobes are what's being used (maybe in a AF250350 & AF25350 not shown in my catalog),
 They look like great fast acting lobes when you're not looking for .600+ lift.

As far as the 250 & 256 durations for your application,
 I'm in over my head when it comes to spec'ing race engines.
 
I'm guessing this is strictly a race engine from the application, and compression ratio.

Are you planning on race gas?
Are you drilling the block for later 1/2" bolts?

Just curious,
 I like 343 builds Smile


Edited by jpnjim - Jun/21/2018 at 4:51pm
71 P-code 4spd Javelin/AMX
some Jeeps and some Fords
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2018 at 4:56pm
One more thing,
 when I ordered my Howards Cam I got it from Competition Products,
 they occupy the same building as Howards, and it came in a ridiculously fast turn around time.

They also had the best price.

I had called Competition, and ordered it right through them.

Mine was Hydrolic,
 but here's their custom solid 319992 for $169.00



I checked my cam and it was spot on. Big smile
71 P-code 4spd Javelin/AMX
some Jeeps and some Fords
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1982AMCConcord Quote  Post ReplyReply Direct Link To This Post Posted: Jun/22/2018 at 7:56pm
Howard's will also grind anything you want in house for like $150 I think... If I remember correctly... A custom grind was very reasonable.
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