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Old 03-06-2014, 08:17 PM
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nx284h lets talk cam and springs

hello guys i'm going to try this one more time. im hoping that this thread stays on track. im building a 454 which i found out that is bore 40 over. my selection is the nx284h this is going to be on my daily driver which i only drive about 6 to 8 miles per day. so not much driving! the motor is going to be topped with 049 heads stock replacing my peanut port. i have weiand intake i have a 750 vs that ill up grade if necessary. dished pistons with fly cuts. and possibly putting in some roller rockers 1.5. this is in my 90 ss Silverado just looking for fun truck combo.

would i be able to use stock springs?

would the combo work well till i have the time and money for a blower ??

thought about putting a 100 150 shot just for a once in a while.

will this combo get me good hp?

3000 stall will be no problem...

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Old 03-07-2014, 12:36 AM
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1. pretty sure that's a small block cam

2. big block rocker arm ratio is 1.7, not 1.5

3. youre gonna want to use the springs recommended for the cam. that's a big hydraulic ft cam

4. better make sure you have the compression to support a big cam
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Old 03-07-2014, 03:59 AM
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Quote:
Originally Posted by clwhoops44 View Post
1. pretty sure that's a small block cam

2. big block rocker arm ratio is 1.7, not 1.5

3. youre gonna want to use the springs recommended for the cam. that's a big hydraulic ft cam

4. better make sure you have the compression to support a big cam
http://www.summitracing.com/parts/cc...68-4/overview/

I'm sorry i was looking at that small block rockers. what i meant to say is ill just go with the stock rocker size. but roller 8.5:1 compression i know it might slow me down now but shine with the blower. i was thinking on milling the heads 20 thousands just to bump it up just a bit so it would be be better while off the blower.

there is the link it dose not specify what springs to go with. i see these motors come already with a double spring that why im asking they might be ok..

would u happen to know what springs i should up grade to. i ordered the cam already. and i really didn't want to wait till get here to see the cam card to then order the springs it would take for ever to finish...
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Old 03-07-2014, 04:32 AM
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11-568-4 - Nitrous HP™ Hydraulic Flat Tappet Camshafts
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Old 03-07-2014, 05:31 AM
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thanks!!! i have been on the site a million time and hadn't seen this
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Old 03-07-2014, 09:22 AM
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how long are you planning to wait on this blower upgrade?

that engine is going to be a total PIG with 8.5 compression and a cam that big. its all about intake valve closing point. the engine cant build compression until the valve is fully seated. this is called your DCR (dynamic compression ratio)
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Old 03-07-2014, 09:26 AM
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using a dcr calculator off of google, i find your DCR to be just 5.7:1.

youre looking for somewhere between 7.5 and 8.5:1

i think you seriously need to reconsider this.
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Old 03-07-2014, 10:01 AM
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using a dcr calculator off of google, i find your DCR to be just 5.7:1.

youre looking for somewhere between 7.5 and 8.5:1

i think you seriously need to reconsider this.
this is the type of guidance i needed! i was originally going with a ex260h i believe. but sense i mention blower the whole thing changed. they stated steering ome different. then i thought about the nx268h nx274h nx284h sense they are good for blown engines. and me being me i went with the biggest cam for my app...
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Old 03-07-2014, 10:37 AM
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Trying to build a motor to run as naturally aspirated while having an eye on running a blower later just creates a motor that won't work at either of those tasks. The parts chosen to work with no blower won't work with a blower and vice versa. Also, the chances that a big block Chevy will work well with a flat tappet camshaft are slim and none. Use a roller cam or you'll be doing the whole mess over again when one or three lobes eat up the bottoms of the lifters, particularly with the springs you'll have to use with a cam like the one you linked. Bad juju homey, start over.
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Old 03-07-2014, 10:39 AM
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Your looking at NITROUS cams they have a different profile then a Blower cam!! Boost and Nitrous are too different engine builds. Nitrous is not boost!!! Its a cold spray and oxygen adder when used on a N.A. engine! On a boosted engine it will compliment the boost and cool the hot blower air charge especially on a Roots blower that's case gets really hot from the pressure it produces and transfers the heat to the air going into your cylinders!!

Check out BDS cams (blower drive service) or other Blower services cams look at their cams pick the one you want and then match the profile to a Comp cam or other that is much cheaper!

To bring up your engines compression a little till you get your blower go to a really thin head gasket and when you get your blower go to a thicker head gasket! Get 2 sets of blower pulleys one for high boost at the track and one for lower street boost!

Jester
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Old 03-07-2014, 10:53 AM
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im with ya Jester, but comp does list the cam as a blower/nitrous cam.

to the op, i think you need to consider the total cost of a blower set up. are you ready to spend 2 3 4 thousand dollars or more?

if not, use the cam you have, spend a grand on aftermarket heads with smaller chambers, and hang on tight.

should make good power, just not with 8.5 compression
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Old 03-07-2014, 10:54 AM
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Flat tappet and roller opinions are very controversialLOL

My opinion is: There is a place for flat tappet cams and a line drawn when to go to a roller and that is when high valve spring pressures make it unfeasible to use the flat tappet, or there is so much lift that the flat tappet lifter will cause trouble (digs into) the lobe profile! The extra reciprocating wght. of roller lifters and the slack inherently built into them: in some builds make a flat tappet a better choice to lighten the reciprocating wght. of the valve train, there are good points in favor of both and I judge which one to use carefully, but if you don't know how to break in a flat tappet cam I guess you may not like the flat tappet cam yourself. No arguments needed about cam choices aimed at me!! Its just my opinion! from years of building engines with both styles of cams!!

I was using racing roller cams in the '60 s on my Mopars they are no new innovation!
Some people think its a new thing because they have been introduced over the recent years in more and more American model cars that's all!!


Jester
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Old 03-07-2014, 10:54 AM
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Quote:
Originally Posted by techinspector1 View Post
Trying to build a motor to run as naturally aspirated while having an eye on running a blower later just creates a motor that won't work at either of those tasks. The parts chosen to work with no blower won't work with a blower and vice versa. Also, the chances that a big block Chevy will work well with a flat tappet camshaft are slim and none. Use a roller cam or you'll be doing the whole mess over again when one or three lobes eat up the bottoms of the lifters, particularly with the springs you'll have to use with a cam like the one you linked. Bad juju homey, start over.
dam! i should have known better. im going to have a talk with this guy and see if i can stop the order on that cam. and then get back on here and have a chat with u guys again

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Your looking at NITROUS cams they have a different profile then a Blower cam!! Boost and Nitrous are too different engine builds. Nitrous is not boost!!! Its a cold spray and oxygen adder when used on a N.A. engine! On a boosted engine it will compliment the boost and cool the hot blower air charge especially on a Roots blower that's case gets really hot from the pressure it produces and transfers the heat to the air going into your cylinders!!

Check out BDS cams (blower drive service) or other Blower services cams look at their cams pick the one you want and then match the profile to a Comp cam or other that is much cheaper!

To bring up your engines compression a little till you get your blower go to a really thin head gasket and when you get your blower go to a thicker head gasket! Get 2 sets of blower pulleys one for high boost at the track and one for lower street boost!

Jester
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Old 03-07-2014, 10:56 AM
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Quote:
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To bring up your engines compression a little till you get your blower go to a really thin head gasket and when you get your blower go to a thicker head gasket! Get 2 sets of blower pulleys one for high boost at the track and one for lower street boost!
Jester
The difference in head gasket thicknesses and the volumes they represent will not have enough range to make much of a difference. Head gaskets are for sealing the cylinder head to the cylinder block, not for adjusting the static compression ratio. You do that with piston crown configuration, piston deck height and chamber volume.
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Old 03-07-2014, 11:09 AM
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Yes its listed as both but the profile with a roots blower is wrong!!! And the RPM range is way off power should start right off Idle not at almost 3000 rpm! and peek RPM should be about 5500 to 6000! It might be fine for a centrifugal supercharger (that is a belt driven turbo) or a turbo set up that produce power at higher RPMs but completely wrong for a roots type that can produce great power in the low RPM range!


Nitrous HP Hydraulic Flat Tappet Camshaft NX284H
Lift: .575"/.595"
Duration: 284/305
Lobe Separation Angle: 113
RPM Range: 2800-6800

Jester
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