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Old 04-27-2013, 04:50 AM
gearheadslife's Avatar
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vortec 350 #12530283 & ramjet 350

Hi..
between these two the long block is the same with the only changes (it looks like) to the cam and rockers,,
my silly question is does anyone know if they did any machining to the ramjet to use that cam and 1.6 rockers??
the wallace racing caculator comes up with .475 lift on the exhaust side( with 1.6 rockers, cam is .451 with factory 1.52)
vortecs can take .480 is that a tad tight or is that fine.. did gm use different springs?? ( normally use the springs/etc to match cam i.e. comp 292 bought comp springs for that cam..
all my pontiacs the machine shop set up the springs installed height/etc) so I'm not sure just how close to that .480 lift is ok.. in a 5000-5500 red line engine)


I'm thinking no.. but the ramjet listing has me wondering..

the crate engine cam is
Roller Camshaft-




Specs-
  • Intake Lift- .414"
  • Exhaust Lift-.428"
  • Intake Duration @.050"- 191
  • Exhaust Duration @ .050-196
  • Lobe Centerline-111
the ramjet 350 and ht383 crate engine cam is..
This hydraulic roller design is used on the 383 truck and Ramjet 350.
The duration at lash point in degrees (intake/exhaust) is 288/308; duration at .050" tappet lift (intake/exhaust) is 196/206 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 431/451. Valve lash is zero/zero and lobe centerline is 109 degrees.
This camshaft is a great upgrade for 1996-2000 Chevy/GMC trucks equipped with the L31 Vortec 350 Engine. This cam is great for additional bottom end torque. If installed in one of these trucks, a custom computer re-program is needed.

^^^ that listing is with 1.5 rockers,, but is used in the ht383 and ramjet efi 350 both with vortec heads..

the 1.6 rockers bring the exhaust side to .475
coil bind and pushrod to head casting issues is what I'm askin about..

the ramjet gm listing list the exhaust at .481 lift no idea how they are coming up with that.. maybe my math(or wallace racings) is off..


thanks for any insite.. my bigblocks gonna have to wait (yet again) so this sounds like just the ticket for a tad over 300hp and cheap..
all said and done 2200.oo

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Last edited by gearheadslife; 04-27-2013 at 04:55 AM.
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Old 04-27-2013, 09:27 AM
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The L30/L31 camshaft is 0.412/0.428" with the stock 1.5:1 rockers.

0.412 /1.5 =0.274666667 lobe lift, multiply obe lift by 1.6 rocker ratio of 1.6 gets you 0.439466667 of 0.439" lift using a 1.6:1 rocker


Exhaust
0.428 /1.5=0.285333333 lobe lift , now x by 1.6 = 0.456533333 or 0.457" lift


Now for the Ramjet/HT383/Marine camshaft with 0.431"/0.451"
Intake
Go 0.431" / 1.5 =0.287333333 lobe lift, multiplly by 1.6 rocker = 0.459733333
or 0.460"

Exhaust
go 0.451 / 2 =0.300666667 lobe lift
then multiply your lobe lift by 1.6 and it gives you 0.481066667 or 0.481" lift


Just remember that you divide whatever the valvelift is by the rocker ratio gets you lobe lift, then you can recalculate by multiplying lobe lift by the new rocker ratio. Its really simple math.

Now for your question.
Do you really think GM would do machine work for JUST the heads on a Ramjet 350 engine? Doubtful.
Either the Ramjet 350's really dont run the 1.6:1 rockers, or the Vortec heads can take a little more lift that every thinks they can.

peace
Hog
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Old 04-27-2013, 09:40 AM
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I wouldnt go through teh hassle of swapping out that Ramjet 350 cam for the stock truck cam.

there are plenty of other cams that will do much better.

The Hotcam will get you over 300 rwhp.
From this setup, same longblock you are buying, Ramjet intake, LT4 Hotcam/headers/tune



And here is what it made


LT4 hotcam has 218º/228º lift of 0.525"/0.525" on a 112ºLSA with 1.6:1 rockers
or 218º/228º lift of 0.492"/0.492" 112ºLSA with 1.5:1 rockers

It all depends on what you plan to do with the truck, but for teh same money, you could have almost 400hp.

There is also the 1996 LT4 Vette Prodduction cam with 203º/210º 0.476/490" on a 115ºLSA with 1.6:1 rockers or 0.446"/0.450".

Just a thought.

For more lift all you have to do is buy a set of LS6 or nowdays LS9 matched valvesprings form Lingenfelter for $65, buy a set of 787-16 retainers from Comp Cams for $40 and be able to lift to 0.550" without issue on stock Vortec heads.
Just another thought.

The PCM tuning is the key in the end/

peace
Hog
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Old 04-27-2013, 09:57 AM
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thanks.. I'll look into the different cam/springs..
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Old 04-27-2013, 10:02 AM
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Lingenfelter "Matched" LS9 springs
GM LS9 Valve Springs Matched Sets - Lingenfelter Performance

787-16 retainers for use with above or any Beehive spring
http://www.summitracing.com/parts/cca-787-16

peace
Hog
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Old 04-28-2013, 10:26 AM
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2-3 years ago when I set up my vortec heads, I made a thread about ls6 springs. There where a number of questions that I could not answer for other people. When I checked the spring height, and contact point to umbrella seal. It was fine for the performer cam with at least .470" with clearance to spare.

People wanted to know if it had enough clearance for other cams, like the 268xe. I had already bolted them on my truck. There was no way I could be sure. I did take pictures to put in my journal, but they were taken at points of completion.

Good to know this has been verified as safe for bigger cams.

Here is a picture of the ls6 springs on the vortec 906 heads.

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Old 11-21-2014, 08:20 PM
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I know this is an older post Hogg, but can you indeed just use these springs and retainers on a set of vortec heads and then be able to use the GM hot cam?

i'm wanting to put on a set of vortec heads on my 92 Camaro with L98 350 but evidentally the stock vortec springs are only good for around .450 or so lift and the hot cam with 1.6 rockers are .525

thanks


Quote:
Originally Posted by Hogg View Post
Lingenfelter "Matched" LS9 springs
GM LS9 Valve Springs Matched Sets - Lingenfelter Performance

787-16 retainers for use with above or any Beehive spring
http://www.summitracing.com/parts/cca-787-16

peace
Hog
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Old 11-24-2014, 11:25 AM
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Yes, guys have measured enough clearance for 0.550" lift.

Here is some pics of the Vernier measureing.
GM Performance :: View topic - LT4 Hotcam in L31

peace
Hog
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