Valve springs and cam

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Rapid Randy Baker
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Postby Rapid Randy Baker » Tue Jun 27, 2006 10:21 pm

One of the major reason cams are getting bigger is because now a days a 500 inch motor is a baby. Darn near small block cubic inch. It takes a large amount of lift and duration to adequately fill the cylinders. The 2nd reason for so many large cams is that you can buy for 2-3,000 bucks what were experimental 10-12,000 dollar pro-stock heads 5-8 years ago. :shock:

There are way too many variables and we don't know enough about your combination, and what your goals are to suggest anything more than the choices you have presented. It is like Gator and Vic said. Cyl pressure, compression ratio, gearing, converter, clutch, weight, rpm range play an important roll in what will work the best.

With your mentioned rpm range, I probably would tend to look at the smaller cam also, until you said the duration was the same. That tells me the cam guy listened to your specs, and has in mind filling the cylinders with the added lift at the same duration. Do some more research on valve springs. You just might find that the triple spring is a much better choice for valve control and harmonics than your dual spring. Just my opinion, with it and 2-bucks you can still buy a candy bar anywhere in this town. :lol:
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SLICK VIC
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Postby SLICK VIC » Tue Jun 27, 2006 10:41 pm

I WAS JUST IMPLYING THAT IF YOU HAD THE BOX STOCK
DART 225 HEADS THEY ARE DIFFERENT FROM THE CNC
VERSIONS, $1900 AS APOSE TO $2600 FOR THE CNC HEADS
AND ABOUT 15 HP DIFF AND AND THE CALCULATED CFM AT A
DESIGNATED LIFT, I AM GOING WITH .800 LIFT @294-296 DUR.
I WILL BE TURNING AROUND 7500 RPM THREW THE TRAPS.
225 AND 325 IS THE CUBIC FEET PER MINIUTE THE INTAKE
RUNNERS WILL FLOW AIR AT A GIVIN .LIFT
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gary b
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cam choices

Postby gary b » Wed Jun 28, 2006 5:56 am

the old dragster had a 505 and the combo worked well with a few flaws.. ran 10 to 1 with 871 high helix 20 lb boost 800 lift 230dur 110 separation 1.8 rockers, rev kit, kmotion 1000 springs, swedged push rods my biggest problem with this set up was repair went thru a lot of push rods and lifters. listen to mnt man and the others bigger is not always better gary b

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Billy Mac
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Postby Billy Mac » Thu Jun 29, 2006 2:19 pm

in that ^^ case...my lil' ol' 708-714 roller should work fine :roll:
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greenracing
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Postby greenracing » Thu Jun 29, 2006 3:19 pm

I'm a believer in high spring pressure. I usually run about 300lbs in mine regardless of what the cam wants. Of course you need the rest of the hardware that will hold up to the pressure. We started running high seat pressure on Newberry and Veney's suggestion when we ran the Newberry hemi in the truck. You take the heads off after 20 or 30 runs and the seats still looked like new - with low pressure we were always redoing the seats.

If you're not going to run over 7500, that should help. We tended to run our 496ci at close to 9000. And that was in a pulling truck so you were looking at close to 10 seconds at that RPM - tended to be a lot harder on valve train than the drag car.

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Buffjhsn
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well we got it back together

Postby Buffjhsn » Mon Jul 10, 2006 4:59 pm

we went to the track on Saturday. we got two passes before my father got sick and was out of contention for the day. the car went 9.220 the first pass. he changed the shift point from 7200-6800 and the car went 9.30. it spun off the line 3 hundeths so i guess it would have went a 9.27.

we put new valve springs on it. put on Manley nex-tek with 350 lbs on the seat after making like 6 phone calls to different companies. we also changed the cam and ran the clay smith. put it in with 1.7 rockers on both the intake and exhaust to make the lift .773/.773 and duration 286/286.

at least it didn't slow the car down any :shock: i guess that's a plus huh? this was in 90* air with track temp about 125 throughout the day.

oh yeah my dad is feeling better, i guess he got the flu bug that's going around. just thought i would fill you all in since i haven't posted anything for a while. still looking for about 2 tenths so if anyone has any suggestions I'm all ears!

Corey
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Leon
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Postby Leon » Mon Jul 10, 2006 6:47 pm

Methanol.

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Buffjhsn
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Postby Buffjhsn » Mon Jul 10, 2006 7:00 pm

Methanol.
lol i knew someone was gonna say that! we have no alky experience or alky carbs though. we tried it once, but since the car would hardly run on gas, it fell completly on it's face on alky. we have the fuel system for it. the cell is in the front, magna fuel pump, big enough line, etc.
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Leon
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Postby Leon » Mon Jul 10, 2006 7:52 pm

Actually its pretty simple to run and besides, it means no overheating and minimal water in block without circulation. And all this bs about milkin the oil is frm a too rich idle anyway as if its rich on the run, it will just blow out the pipe.


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