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Race Hemi Piston to Valve Clearance #1718396 12/31/14 12:05 PM 12/31/14 12:05 PM
Joined: Oct 2005 Posts: 290 Manitoba, Canada liteweight OP enthusiast
liteweight OP enthusiast Joined: Oct 2005 Posts: 290 Manitoba, Canada	Need concensus on mininum piston to valve clearance on my 489 Hemi 7500 RPM MAX probably won't see over 7,200 Steel block Steel heads Crower Crank & rods DLI rockers Manton pushrods .700" lift roller (to be determined exact numbers) I am also getting conflicting information from cam manufacturers on spring pressures for a cam of this approximate lift. Installed @ 2.00" anywhere from 600 lbs to 700 lbs thanx liteweight Last edited by liteweight; 12/31/14 12:10 PM. 68 Hurst LO Hemi Dart 70 hemicuda 4 spd. R code owned since 76 70 GTX 4 spd. 21,000 orig. miles 55 Ford F100 chopped,slammed,bagged & supercharged 96 Ram 2500 4X4 Twin turbo'd Cummins 550hp 1200 ft. lbs tow vehicle

Re: Race Hemi Piston to Valve Clearance [Re: liteweight] #1718397 12/31/14 01:43 PM 12/31/14 01:43 PM
Joined: May 2004 Posts: 12,388 Taxes & Virus's R-US, NY Dragula I Live Here
Dragula I Live Here Joined: May 2004 Posts: 12,388 Taxes & Virus's R-US, NY	Call Ray Barton, his standard .680 lift cam he sells is in hundreds of engines. And you have to remember at that rpm, the valve will not exactly ride the lobe, there is definitely a grey area at that rpm. You will run a box with a limiter correct? '70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft) https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car) https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car) https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9) '66 Barracuda AWB Stretched nose Blown 440 Car in build stage '71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph https://www.youtube.com/watch?v=Znuo3jMUXTk

Re: Race Hemi Piston to Valve Clearance [Re: liteweight] #1718398 12/31/14 03:50 PM 12/31/14 03:50 PM
Joined: Jan 2003 Posts: 6,392 nielsville, minn. Q quickd100 master
quickd100 master Q Joined: Jan 2003 Posts: 6,392 nielsville, minn.	Quote: Need concensus on mininum piston to valve clearance on my 489 Hemi 7500 RPM MAX probably won't see over 7,200 Steel block Steel heads Crower Crank & rods DLI rockers Manton pushrods .700" lift roller (to be determined exact numbers) I am also getting conflicting information from cam manufacturers on spring pressures for a cam of this approximate lift. Installed @ 2.00" anywhere from 600 lbs to 700 lbs thanx liteweight Daryl, I've been running a Bullet solid roller, .767/.676, 288/292@.050 on a 113 center. Piston to valve clearance is .108 at zero lash on the intake and .106@ zero lash on the exhaust. Spring pressure is about 740lbs. over the nose I've got 4 years on it so far with one broken pushrod cup. The motor has seen 7200rpm a couple times, the valve train is stable to about 7800. Most of the time I shift it below 6500.Dave

Re: Race Hemi Piston to Valve Clearance [Re: quickd100] #1718399 12/31/14 05:36 PM 12/31/14 05:36 PM
Joined: Oct 2005 Posts: 290 Manitoba, Canada liteweight OP enthusiast
liteweight OP enthusiast Joined: Oct 2005 Posts: 290 Manitoba, Canada	Thanx for the responses I am running the MSD Grid box & controller. My current cam is a Crower solid roller: Int 266/ Exh 279. @.050. Delivered lift at valve: Int..706"/ Exh. .692" 0 lash,. Valve spring pressures : installed @ 2.00" 240. On nose 570. current piston valve @ 0 lash Int. .081/ Exh..097" here's the deal. This motor lays down flat after 6100 RPM. Confirmed on a chassis dyno. It's peak HP is 600 @ wheel 760 (calculated)@ flywheel. The motor itself is a 12.7-1, 4.280 bore, & 4.25 stroke. Cylinder heads are ported iron street hemi. Int. 398cfm @ .700" 402cfm @ .800"/ Exh. 288cfm @ .600" & flat lines with more lift. Induction that was installed on the motor @ the time is a factory uncut mag. X Ram. with a couple reworked 4235 & 4236 holleys on top. They flow 897cfm each dry. i fiqured this motor should pull well over 7,000 RPM & have somewhere between 825-850 hp. I fiqured the intake was the "choke" on the motor so I've picked up a couple others. One is a heavily modified Mag. X Ram done by Dean Nicopolis from Ramchargers fame, The other is a old Hogan square port sheet metal X Ram. I've heard Bullet has been putting out some good numbers on their profiles, so they were contacted. he says the original intake is fine, but the camshaft can be improved on. with the above numbers I don't have alot of piston/valve clearance left here. my spring pressures are low? Is it really worth putting another cam in this thing? What's your thoughts on intakes? liteweight 8379597-492HemiSpring2013042_zps3ab937b9.jpg (129 downloads) Last edited by liteweight; 12/31/14 05:37 PM. 68 Hurst LO Hemi Dart 70 hemicuda 4 spd. R code owned since 76 70 GTX 4 spd. 21,000 orig. miles 55 Ford F100 chopped,slammed,bagged & supercharged 96 Ram 2500 4X4 Twin turbo'd Cummins 550hp 1200 ft. lbs tow vehicle

Re: Race Hemi Piston to Valve Clearance [Re: liteweight] #1718400 12/31/14 05:40 PM 12/31/14 05:40 PM
Joined: Oct 2005 Posts: 290 Manitoba, Canada liteweight OP enthusiast
liteweight OP enthusiast Joined: Oct 2005 Posts: 290 Manitoba, Canada	Nicopolis modified Mag X Ram 8379600-$_575.jpg (115 downloads) 68 Hurst LO Hemi Dart 70 hemicuda 4 spd. R code owned since 76 70 GTX 4 spd. 21,000 orig. miles 55 Ford F100 chopped,slammed,bagged & supercharged 96 Ram 2500 4X4 Twin turbo'd Cummins 550hp 1200 ft. lbs tow vehicle

Re: Race Hemi Piston to Valve Clearance [Re: liteweight] #1718401 12/31/14 07:50 PM 12/31/14 07:50 PM
Joined: Jan 2003 Posts: 1,938 Sonora CA Mopar_Rich top fuel
Mopar_Rich top fuel Joined: Jan 2003 Posts: 1,938 Sonora CA	500+ lbs over the nose is too weak for a HEMI with those long pushrods and heavy rocker arms.

Re: Race Hemi Piston to Valve Clearance [Re: Mopar_Rich] #1718402 01/01/15 05:20 AM 01/01/15 05:20 AM
Joined: Sep 2005 Posts: 621 Deep DEEP SOUTH LAD 524 mopar
LAD 524 mopar Joined: Sep 2005 Posts: 621 Deep DEEP SOUTH	Quote: 500+ lbs over the nose is too weak for a HEMI with those long pushrods and heavy rocker arms. Im with Rich; Im no guru, but everything I've read/researched for roller cams in Hemis indicate that with your cam you'd need more than 500lbs - more like at least around 600-620lbs+ or so open. Not enough is just as bad if not worse than too much pressure; esp with the heavy valvetrain/pushrods etc.

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