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-   -   rebuilding a chevy 350 with votec heads (http://www.hotrodders.com/forum/rebuilding-chevy-350-votec-heads-208797.html)

kennyhammond 11-15-2011 08:42 PM

rebuilding a chevy 350 with votec heads
 
ok i have a chevy 350 motor is out of a 2008 chevy 3/5 what are a couple things i can do to male some good torque money is tight so the cheaper the better and it is going into a 81 chevy c10 t350 transmission and 2.72 gears just a truck to drive to workand have some fun with (hince why i am not dropping alot of money in it)

VARS_85MONTE 11-25-2011 12:40 PM

There are plenty of ways to do a nice budget upgrade. But what exactly are u looking for?

Here are a couple ways to get some budget HP/tq.

U have a great start with the roller block. You could buy an aluminum intake manifold, get your heads done to accept a higher lift cam, buy a nice 210-220 @50 roller for torque, some nice roller tip rocker arms. Full length long tube headers with at least 1 5/8 primaries.
With simple upgrades like this u could have a nice little motor and not much money spent.

techinspector1 11-25-2011 01:34 PM

Quote:

Originally Posted by kennyhammond
money is tight so the cheaper the better and it is going into a 81 chevy c10 t350 transmission and 2.72 gears just a truck to drive to workand have some fun with

If you're going to keep the 2.72 gear, then you will need to go easy on the cam, very easy. Going easy on the cam means going easy on the static compression ratio. I believe these motors were somewhere between 8.5:1 and 9.0:1, so will not tolerate a lot of cam. The stocker is probably the best cam you could use, particularly with the tall rear gear. Surfing around on the web will reveal that the stock cam was probably in the area of
192 intake/197 exhaust degrees duration at 0.050" tappet lift and 0.404"/0.414" valve lift.

This chart will tell you the range of cam duration to use with the static compression ratio of your motor.
http://www.crankshaftcoalition.com/w..._compatibility

Bottom line, I'd leave the motor stock until you decide to upgrade the rear gear to a performance number and change pistons to raise the static compression ratio so it will support more cam.

kennyhammond 12-11-2011 03:39 AM

Sorry just looked and I missed spelled some words in my post..... first all its a 98 block out of. 3/4 ton..... don't know if that matters

BigEd36 12-11-2011 10:27 AM

Quote:

Originally Posted by kennyhammond
Sorry just looked and I missed spelled some words in my post..... first all its a 98 block out of. 3/4 ton..... don't know if that matters

Kenny, here's the specs for a 3/4 ton Vortec engine from the Pace Performance website:
Quote:

1986-2000 style block - (No mechanical Fuel Pump Provision)
Nodular Iron Crankshaft
Powdered Metal Connecting Rods
Hypereutectic Pistons
9.4:1 Compression Ratio
Roller Camshaft-
Specs-
Intake Lift- .414"
Exhaust Lift-.428"
Intake Duration @.050"-191
Exhaust Duration @ .050-196
Lobe Centerline-111
Vortec Cylinder Heads- 64cc,1.94" intake,1.50" exhaust
These specs are pretty much what techinspector1 quoted so your typo didn't really change anything. The Vortec engines are pretty well spec'd for torque as they come from the factory, and even in stock form will be a big step ahead of any SBC that Chevy put in an '81 C10. One thing to remember is that the Vortec heads are limited to .475" lift in factory form so cam choices are limited unless you have the heads modified for increased lift. But there are still cams that would be an upgrade. Howard's #180225-12 .450/.465 lift, 260/266 advertised duration, 207/213 @ .050" duration, *112 lobe spacing from their "Max Factory" line of cams would be a step up from stock, and should work with the stock Vortec heads. Use a dual plane manifold along the lines of an Edelbrock Performer, your choice of 600-650 cfm carb, and 1 5/8" headers like VARS_85MONTE recommended.

kennyhammond 12-11-2011 12:36 PM

OK thanks a lot...... realy appreciate the help....just hat I was wanting to know... am just making the motor to drive the truck to work and wanted somethen that would be good on the freeway..and still be able to break the tires over to make the son smile....thanks for the help guys

kennyhammond 12-11-2011 12:52 PM

Is that can going to be to much for what I am looking for....? Seems like the durations are high... just wardering

BigEd36 12-11-2011 08:20 PM

Howards gives the description for that cam as "Great daily usage, smooth idle, great fuel economy." The rpm range given is 800-4200 rpm, so it will pull right from idle. The cam and compression ratio chart that techinspecter1 linked to shows that 9.25:1 needs 208 degrees at .050", 9.5:1 needs 212 degrees. Your 9.4:1 falls between them so 208-212 degrees. The Howards is 207 degrees at .050" so it's pretty close. Hopefully techinspecter1 will chime back in on this. GM usually uses pretty long and gentle ramps so I suspect the Howards cam may be shorter on total duration (which will give more torque) even tho it's bigger at .050".

Another cam that would work well is GM #14097395. This is the cam used in the 383HT (383 High Torque) and 350 Ram Jet crate engines. It's $177.12 at Pace Performance Here's the description from the Pace Parts website:

Quote:

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.
The 383HT I notice this GM cam uses 288* advertised for a 196* @ .050", that gives 92* for the ramps. If they used the same rate of ramps for the stock cam it would make the total duration approx. 283* for 191* @ .050". This reinforces my suspicion that the stock cam probably has more total duration than the Howards cam, even tho the Howards cam has more at .050". "More area under the curve" to put it in the language that the cam companies use to advertise their cams.

I believe either of these cams would be a worthwhile upgrade to your Vortec 350.

kennyhammond 12-12-2011 03:24 AM

Thank you fir sharing all you knowledge

kennyhammond 12-13-2011 08:43 AM

For the last and final question ...will either of the cams have any rumble or notice to them....its not a deal breaker for me just like to have a little rumble ....if not its fine just curious

BigEd36 12-13-2011 03:56 PM

I don't believe you'll have any choppiness to the idle, especially with the GM cam as the duration is shorter then the stock 350 300HP cam. The Howards cam has duration and LSA specs that are very close to the Summit K1102 flat tappet cam. I've found this YouTube video of a 355 with the K1102 cam idling. Actually, I like the exhaust note of this Camaro, has a nice rumble.

kennyhammond 12-13-2011 04:03 PM

Yeah not much rumble at all...... but its fine..a set of long tubes a d some flowmaster 44's. It will be OK..... if you have to choose witch can would you take.... I am sorry just don't know the pros a Con,s of either ...thansk for all your help...

BigEd36 12-13-2011 05:22 PM

Between the two cams (the Howards and the GM) I would go with the Howards cam. I haven't been able to find the advertised duration for the stock Vortec cam, but going by the degrees on the ramps on the GM cam, I believe the Howards cam probably has smaller advertised duration even tho it has more at .050" lift, so I think it will give more low end torque and still give more topend too. If you were of a mind to change to a hydraulic flat tappet I would have to give serious consideration to the Summit K1103. It's Summit's version of the grind that GMPP uses in the 350HO 330HP crate engine with Vortec heads (which for practical purposes is your Vortec engine with a flat tappet cam). It has mild street manners (idles well with plenty of vacuum for power brakes), has a noticeable choppy idle, and pulls well.

Here's a Chevy with the K1103 cam.

kennyhammond 12-13-2011 05:35 PM

Yeah since it isn't going to be a everyday driver I thaught about a flat tappet.....but still can't get much lift or anything with the stock vortecs ..... still a toss uplol

kennyhammond 12-13-2011 05:56 PM

That k1103 can sounds about as far as I wana go with mine.... it don't need that much lump to it but sounds nice


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