351W - Max valve lift with TRW L2446 forged pistons

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351W - Max valve lift with TRW L2446 forged pistons

Post  jbozzelle on March 7th 2016, 5:24 pm

Guys

I'm putting back together a .040 over 351W with some L2446F40 pistons.  It's a used shortblock I picked up from Blake Cartwright a few years ago.  It was in my dad's car and ate the cam bearings (machine shop mentioned too much spring pressure).  It's got the older revision FRPP "X" head on it.  They have bolt down pedestal rockers, 1.94/1.54 valves, etc...

What are your thoughts on the max valve lift I can stuff in there?  Looking for it to be a good street car that can be bracket raced.  I've been looking at the Comp retrofit roller cams but not sure what I can fit for max valve lift.  Figured I'd ask if anyone has experience with this combo before I start buying cams and test fitting, etc...

Thoughts?

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  supervel45 on March 7th 2016, 6:32 pm

http://www.summitracing.com/parts/fms-m-6250-x303 Not sure on the valve lift but I always heard good words about the SVO cams and small blocks. I suspect it would have valve clearance with flattops?

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  jbozzelle on March 7th 2016, 8:29 pm

Can't use the FRPP "alphabet" cams since the block I have has different lifter bore heights. I need to use the retrofit rollers. Crane, Comp and Lunati all have some decent grinds. Just wish I knew how much lift I could stuff in there before I go buy a cam...

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  rmcomprandy on March 8th 2016, 12:44 am

jbozzelle wrote:Can't use the FRPP "alphabet" cams since the block I have has different lifter bore heights.  I need to use the retrofit rollers.  Crane, Comp and Lunati all have some decent grinds.  Just wish I knew how much lift I could stuff in there before I go buy a cam...

That's news to me ... ALL the production blocks, (roller or non-roller), can use the regular base circle size cams as long as the RETRO FIT, tie-bar lifters are used.

What are the valve diameters...?

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  jbozzelle on March 8th 2016, 8:31 am

1.94/1.54

Randy, I didn't know that. I now see the retrofit lifters in the catalogs.

I know the max lift I could run is all related to valve timing events but I figured someone may have some experience with a similar combo...

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  supervel45 on March 9th 2016, 8:33 am

Check your PM box.

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  jbozzelle on April 25th 2016, 1:58 pm

Anyone ran close to .600 lift with these pistons?

Also, what's the best way to check valve to piston clearance sine it's a hyd roller? Buy a single solid roller lifter with the same cup height and check it?

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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  gmsmkr on April 25th 2016, 2:09 pm

jbozzelle wrote:Anyone ran close to .600 lift with these pistons?

Also, what's the best way to check valve to piston clearance sine it's a hyd roller?  Buy a single solid roller lifter with the same cup height and check it?

With the Lifter deal I would buy 1 lifter just like what you got take it apart and stack washer's in it or a nut and bolt....

Lift I have run as much as 555 lift with those pistons at .015 below deck with a .042 gasket .... hope this helps
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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  DFI429 on April 25th 2016, 10:07 pm

jbozzelle wrote:Anyone ran close to .600 lift with these pistons?

Also, what's the best way to check valve to piston clearance sine it's a hyd roller?  Buy a single solid roller lifter with the same cup height and check it?

I took an old hyd roller lifter and had the plunger TIG'd in two spots to the lifter body.. works like a champ Cool
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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  dfree383 on April 26th 2016, 10:59 am

Use a pair of old solid roller lifters to check PV
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Re: 351W - Max valve lift with TRW L2446 forged pistons

Post  gt350hr on May 2nd 2016, 3:22 pm

The duration at .050 and lobe separation are the two critical pieces. Tight piston to valve typically occurs at 10* BTDC on exhaust closing and 10*s ATDC on intake opening. This is WAY below max lift and shows why total lift is relatively unimportant. Short duration , wide LSA cams like "letter" cams from Ford clear by a mile in most cases. Roll it over to 10 after and check P to V there.

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