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Old 11-20-2009, 10:11 PM   #1
WIDESIDE72
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Best cam for Vortec in a K2500

I recently bought a 93 GMC 3/4 ton 4x4 with a blown 350. I swsapped a 97 Vortec into it, mainly because I already had the engine (used with 70k miles). My brother gave me an LT4 (not LT4 Hot, just LT4) cam that he bought for his 94 Impala SS but never installed. I installed this cam along with Comp Cams beehive springs, Crane 1.6 roller rockers, Crusader TBI to Vortec intake, custom chip, headers, bored TBI, etc.

Long story short, I spun three of five main bearings plling my travel trailer (only a 21 footer). I think I over revved it, as it didnt make mch power.

I now have a rebuilt 350 Vortec short block to put in it, and have to decide about going with the LT4 Cam, stock Vortec cam (L31?) or aftermarket... I ned a torque cam. THe LT4 cam didnt seem to have much torque, but I never drove the truck with the stock 350 TBI, so I have no bass for comparison...

Brian at TBIchips.com that sold me the custon chip said that the LT4 cam was the best torque cam ...???
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Old 11-20-2009, 10:27 PM   #2
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Re: Best cam for Vortec in a K2500

I don't remember the specs on the LT4 cam, but I really like the cam that GM used in the Ram Jet 350 and the HT383. It's the same cam but in the Ram Jet they used 1.6 rockers. I've had experience with this cam in a 355, flat tops, Vortec heads and 1.5 rockers and IMO it had good low to mid range torque. You can often times pick up this cam on ebay as new take outs for ~$80. I don't remember the entire part number for the cam but the last 4 digits are 7395
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Old 11-20-2009, 10:53 PM   #3
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Re: Best cam for Vortec in a K2500

I'd strongly consider a "4x4" type aftermarket hydraulic roller, something like the CompCams X4258HR.

LT4 (12551142) cam specs are .476/.480 w/1.6 rockers, 203/210 duration and 115 LCA. I would not consider that a "torque" cam.

Part Number for the cam referenced above is "14097395" - .431/.451 lift w/1.5 rockers, 196/206 duration and 109 LCA.

Last edited by Ticker; 11-20-2009 at 10:58 PM.
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Old 11-21-2009, 06:25 AM   #4
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Re: Best cam for Vortec in a K2500

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I'd strongly consider a "4x4" type aftermarket hydraulic roller, something like the CompCams X4258HR.

LT4 (12551142) cam specs are .476/.480 w/1.6 rockers, 203/210 duration and 115 LCA. I would not consider that a "torque" cam.

Part Number for the cam referenced above is "14097395" - .431/.451 lift w/1.5 rockers, 196/206 duration and 109 LCA.
That's kinda what I thought... I wanted to et some more input before sticking the LT4 cam into this rebuilt short block that I am putting in this weekend. I should have trusted my instinct that anything originally made for a Corvette wasn't right for a big 4x4 truck...I will look into another cam. Anyone looking for an LT4 cam with around 1k miles on it?
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Old 11-21-2009, 06:40 AM   #5
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Re: Best cam for Vortec in a K2500

I thought I double checked this before, but does anyone know if the TBI manual trans flywheel is the same a a Vortec manual trans flywheel?
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Old 11-21-2009, 07:11 AM   #6
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Re: Best cam for Vortec in a K2500

I get what I think is conflicting info. The '98 engine originally had an auto trans attached. When I swapped it, into the '93, I had the 93 flywheel resurfaced, installed a thrust bushin in the crank and installed all of it with a new clutch, throwout bearing and pressure plate for a 93 truck, since it still has the 93 NV4500 5 speed trans. it all seemed to work OK, and I never noticed any vibration or anything...When I got to the Autozone site and look up a flywheel for a 98 K2500 manual trans flywheel and a 93 K2500 manual trans flywheel, they are the same part #. When i go t O'Reilly's, I get two choices for each year, one of the two choices is the same part number for both, the other is not. The 98 listing mentions a NV3500, the 93 doesn't. They show to have both part numbers in stock, so I plan to call them to make sure they do and go take a look when they open. My brother is bringing the rebuilt short block and I am going to try and get it set in the truck while I have help.
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Old 11-21-2009, 07:12 AM   #7
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Re: Best cam for Vortec in a K2500

Advance Auto Parts shows two different part numbers for a 98 and a 93...hmmm
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Old 11-21-2009, 12:53 PM   #8
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Re: Best cam for Vortec in a K2500

OK.. after further investigation, it appears that the flywheels interchange. I am still up for anone's suggestions on cams, though. I am researching the Comp Cam mentioned above
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Old 11-21-2009, 08:52 PM   #9
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Re: Best cam for Vortec in a K2500

After some checking, I pulled the trigger on the Comp Cams X4258HR. Got it at Summit for $265. (Still an Ouch) At least I get 90 days no interest to pay for it on the Summit Speed card. Thanks to everyone for the advice. I saved a little by checking out my current roller lifters and plan to reuse them. I already have Comp Cams "beehive" springs in the vortec heads.
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Old 11-22-2009, 08:06 AM   #10
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Re: Best cam for Vortec in a K2500

Here's another good one: COMP Cams 08-408-8
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Old 11-22-2009, 09:08 AM   #11
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Re: Best cam for Vortec in a K2500

Quote:
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Here's another good one: COMP Cams 08-408-8
08-408-8 (part number) = XR258HR (grind number)
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Old 11-22-2009, 09:09 AM   #12
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Re: Best cam for Vortec in a K2500

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Originally Posted by WIDESIDE72 View Post
After some checking, I pulled the trigger on the Comp Cams X4258HR. Got it at Summit for $265. (Still an Ouch) At least I get 90 days no interest to pay for it on the Summit Speed card. Thanks to everyone for the advice. I saved a little by checking out my current roller lifters and plan to reuse them. I already have Comp Cams "beehive" springs in the vortec heads.
Cool; let us know how it goes! I've installed a few of these in otherwise stock trucks and the owners have been very happy. I'm 100% sure you'll like it better than the LT4 cam!
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Old 11-22-2009, 09:11 AM   #13
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Re: Best cam for Vortec in a K2500

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08-408-8 (part number) = XR258HR (grind number)
Doh. That is a good cam. Got great torque numbers in Desktop Dyno.
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Last edited by Sinister; 11-22-2009 at 09:11 AM.
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Old 11-22-2009, 06:35 PM   #14
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Re: Best cam for Vortec in a K2500

I believe that XR258HR is a retrofit roller. My engine is OEM roller...
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Old 11-22-2009, 06:43 PM   #15
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Re: Best cam for Vortec in a K2500

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I believe that XR258HR is a retrofit roller. My engine is OEM roller...
Nope; my bad for posting the grind # instead of P/N: retrofit is 12-408-8.

XTREME Energy™ 1987-1998 305-350 Originally Equipped With Hydraulic Roller Camshaft, Except LT1 and LT4.

http://www.compcams.com/Cam_Specs/Ca...?csid=185&sb=2

Last edited by Ticker; 11-22-2009 at 06:45 PM.
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Old 11-22-2009, 06:49 PM   #16
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Re: Best cam for Vortec in a K2500

I already have a set of Crane 1.6 full roller rockers on the engine now. I wonder if I should keep them or go back to 1.5 ratio...
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Old 11-22-2009, 06:51 PM   #17
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Re: Best cam for Vortec in a K2500

Keep the 1.6 as long as the total lift is within what your springs can handle.
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Old 11-22-2009, 10:18 PM   #18
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Re: Best cam for Vortec in a K2500

I believe that WIDESIDE72 bought the X4258HR pn. 08-409-8 which has different specs than the XR258HR pn. 08-408-8. I mention this since the different cam will net different max valve lift with the 1.6 rockers. This may be a factor when checking spring and retainer clearences.

http://www.compcams.com/Cam_Specs/Ca...?csid=197&sb=2


Quote:
Originally Posted by WIDESIDE72 View Post
After some checking, I pulled the trigger on the Comp Cams X4258HR. Got it at Summit for $265. (Still an Ouch) At least I get 90 days no interest to pay for it on the Summit Speed card. Thanks to everyone for the advice. I saved a little by checking out my current roller lifters and plan to reuse them. I already have Comp Cams "beehive" springs in the vortec heads.
Quote:
Originally Posted by Ticker View Post
Nope; my bad for posting the grind # instead of P/N: retrofit is 12-408-8.

XTREME Energy™ 1987-1998 305-350 Originally Equipped With Hydraulic Roller Camshaft, Except LT1 and LT4.

http://www.compcams.com/Cam_Specs/Ca...?csid=185&sb=2
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Old 11-23-2009, 09:27 AM   #19
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Re: Best cam for Vortec in a K2500

Quote:
Originally Posted by Captainfab View Post
I believe that WIDESIDE72 bought the X4258HR pn. 08-409-8 which has different specs than the XR258HR pn. 08-408-8. I mention this since the different cam will net different max valve lift with the 1.6 rockers. This may be a factor when checking spring and retainer clearences.

http://www.compcams.com/Cam_Specs/Ca...?csid=197&sb=2
I'm glad it's your day to watch me (re: other thread )

The 08-409-8 is the right pick as it has a bit more advance ground in to move the power peaks lower in the RPM range.

My complete bad here, guys - I just read and typed too quick and didn't double-check.
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Old 11-23-2009, 10:26 PM   #20
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Re: Best cam for Vortec in a K2500

I really wasn't tryin ta pick on ya......really.


Quote:
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I'm glad it's your day to watch me (re: other thread )

The 08-409-8 is the right pick as it has a bit more advance ground in to move the power peaks lower in the RPM range.

My complete bad here, guys - I just read and typed too quick and didn't double-check.
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Old 11-24-2009, 08:16 AM   #21
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Re: Best cam for Vortec in a K2500

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I really wasn't tryin ta pick on ya......really.
No worries at all - I'm glad you caught it!

Last edited by Ticker; 11-24-2009 at 08:23 AM.
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Old 11-25-2009, 06:21 AM   #22
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Re: Best cam for Vortec in a K2500

where do you get the crusader tbi to intake form?
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Old 11-25-2009, 10:09 AM   #23
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Re: Best cam for Vortec in a K2500

It was an EBAY buy from Mississippi... Originally a a marine app. No EGR. Scored it for $100 (!), I believe about a third of a GMPP intake. I was planning on this swap for a while was watchin feebay for it or comparable. "Even a blind hog can find an acorn once in a while."
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Old 12-03-2009, 06:08 PM   #24
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Re: Best cam for Vortec in a K2500

Got the Comp Cam from Summit the day before Thanksgiving,but was gone til Sunday after Thanksgiving. I got the cam slipped in, but work has stalled as all I have is a shade tree for cover. It's predicted to snow in Austin area and has been in the 40's all week during the day.
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Old 12-06-2009, 04:38 PM   #25
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Re: Best cam for Vortec in a K2500

...or to clean out all the junk I have accumulated in my barn. There was ICE outside this AM. It was actually colder last weekend, due to the wind. At least is was still this AM. I had to leave the motor hanging from the A-Frame, as my brother and I ran out of daylight last weekend, as I also had a Ford (Argh)tractor to work on while I had help. I wrapped plastic through the engine tilter/ lifter, then wrapped a tarp around the whole engine. I just had the pan on with a couple of bolts since the cam I bought hadn't come up yet. I pulled it to double check that I had tightend the oil pump bolt, and there was a big chunk of ice around the pump, from rain water that got in! I chipped it off before it occurred to me to take a pic. I got it cleaned up. Luckily since the cam wasn't in yet, the rockers and push rods weren't in either, so no valves were open to let water into the cylinders. My buddy and I got the engine set in and the engine well tarped for the night.
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