Author Topic: 350 build w/ vortec heads needing opinons  (Read 16296 times)

Offline 87scottsdale

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350 build w/ vortec heads needing opinons
« on: July 12, 2013, 03:56:21 PM »
Ok guys. I want to start my own thread even though the topic is talked to death. There are a ton of arm chair quarterbacks and so much miss-information out there.

I will be starting with a 350 TBI block. Not sure of year yet around 9.8-10.1 depending on what cc head I use

GMPP TBI intake or Edlebrock RPM airgap

Trans is 700r4 (No other option) Will not swap to 3 speed

I am hoping it will already have provisions to make it a full roller motor

I will be using Vortec cylinder heads. I have not decided if I want to use a summit modified version or get them GMPP

I am looking for a comp 4x4 cam  (Not sure which one)as this is a 4000lb 1/2 truck with 4" lift and 35's

The rear gear I am using is 4.56

I have really no Highways around here. Mostly long pulling hills and rolling terrain.

It will go offroad. Nothing extreme,but off pavement

My brother is trying to talk me into going carb. I know carbs can do very well with MPG as long as they are setup right. However I am getting the complete 350 TBI so I would already have an upgraded TBI with the injectors I fell i would need to make around 320WHP and as close to 400Tq as possible.

What would be involved with getting the TBI up and running perfectly (No dyno close) I have worked with tuning programs before such as turbo edit,crome etc.



Help me out with some real world experience.

Offline 74 C-10 Shorty

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Re: 350 build w/ vortec heads needing opinons
« Reply #1 on: July 12, 2013, 06:13:18 PM »
I got a stock Vortec 350 and 700R in mine has an AirGap with an Edde 600, gets good mileage but it's a torqueless wonder but then again I'm not a small block person either,lol, can't wait to put the big block in..

Offline 87scottsdale

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Re: 350 build w/ vortec heads needing opinons
« Reply #2 on: July 12, 2013, 07:25:54 PM »
I got a stock Vortec 350 and 700R in mine has an AirGap with an Edde 600, gets good mileage but it's a torqueless wonder but then again I'm not a small block person either,lol, can't wait to put the big block in..

I honestly wouldn't mind a big block,but picking up a complete running(Has a tick,probably rod or main bearing) TBI 350 for $75 bucks.

I need torque specifically for 4x4. I know I can make good WHP numbers and have the torque to match. I have been in the Honda game for a long time now building High HP NA and Turbo cars.

I have forgotten all about SBC and BBC. I grew up on SBC and BBC and even built a couple 383's and 454's,but left the life behind to stuff my brain on 4 bangers. Dollar to HP ratio just isnt the same. I bought this 87 305 tbi to get back into something you dont have to have 5k in to make big power.

Offline rich weyand

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Re: 350 build w/ vortec heads needing opinons
« Reply #3 on: July 12, 2013, 07:35:17 PM »
Four bits from me:

1) If you use the air-gap manifold, you must use a thermostatic air cleaner (i.e. stock) that can pull heat off the exhaust manifold/headers to get the carb warmed up.  The process of vaporizing gasoline requires the heat of vaporization.  This is why gasoline spilled on your hands feels cold as it evaporates.  This has the effect of refrigerating the carb or throttle body, hindering carburetion and resulting in poor gas mileage and performance.  ANY induction system will benefit from a thermostatic air cleaner, but the air-gap manifold requires it, so if you want to go the two-chrome-pie-plates, exposed-element setup, don't use an air-gap manifold so the carb can get some heat from the intake manifold.

2) You will always get more precise mixture from fuel injection, of whatever type.  Carburetion is by nature an approximation.  That approximation has to err to the rich side, because if it errs to the lean side, the fire goes out.  Those two things taken together mean that you will always get better performance and gas mileage -- other things being equal and both set up properly -- from fuel injection than from carburetion.  I chose carburetion because that's more date-appropriate to the truck and I like to tinker, but if you want the best performance, other things being equal, go fuel injection.

3) You race horsepower, but you drive torque.  Unless you are circle-track racing and can keep the engine high in the rpm band all the time, you want torque over horsepower, and torque peaking at lower rpms.  Lots of high-hp muscle cars got embarrassed by the Buick GSX back in the day, because though it had only 360 hp, it had 510 ftlb of torque at only 2800 rpm.  Several good cams for torque.  I used the Comp 12-300-4.  You can compare the Comp cams at their camquest.com dyno simulator.  Google my last name and 12-300-4 and you'll find several threads here and elsewhere about my selection process and some other cam choices depending on your trade-offs.

4) To properly set up the fuel injection or carburetion, the best bet is to get an air/fuel ratio meter.  Yeah, it's $240, but you are spending a lot of money already and poor carburetion will keep you from getting the most out of it.  I recommend the NGK unit over cheaper items.  I've used it a lot, and it will keep you from convincing yourself that you are set up right when you are not.  http://www.amazon.com/NGK-Powerdex-Air-Fuel-Ratio-Monitor/dp/B0018MUNTM
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline 87scottsdale

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Re: 350 build w/ vortec heads needing opinons
« Reply #4 on: July 12, 2013, 08:29:49 PM »
Four bits from me:

1) If you use the air-gap manifold, you must use a thermostatic air cleaner (i.e. stock) that can pull heat off the exhaust manifold/headers to get the carb warmed up.  The process of vaporizing gasoline requires the heat of vaporization.  This is why gasoline spilled on your hands feels cold as it evaporates.  This has the effect of refrigerating the carb or throttle body, hindering carburetion and resulting in poor gas mileage and performance.  ANY induction system will benefit from a thermostatic air cleaner, but the air-gap manifold requires it, so if you want to go the two-chrome-pie-plates, exposed-element setup, don't use an air-gap manifold so the carb can get some heat from the intake manifold.

2) You will always get more precise mixture from fuel injection, of whatever type.  Carburetion is by nature an approximation.  That approximation has to err to the rich side, because if it errs to the lean side, the fire goes out.  Those two things taken together mean that you will always get better performance and gas mileage -- other things being equal and both set up properly -- from fuel injection than from carburetion.  I chose carburetion because that's more date-appropriate to the truck and I like to tinker, but if you want the best performance, other things being equal, go fuel injection.

3) You race horsepower, but you drive torque.  Unless you are circle-track racing and can keep the engine high in the rpm band all the time, you want torque over horsepower, and torque peaking at lower rpms.  Lots of high-hp muscle cars got embarrassed by the Buick GSX back in the day, because though it had only 360 hp, it had 510 ftlb of torque at only 2800 rpm.  Several good cams for torque.  I used the Comp 12-300-4.  You can compare the Comp cams at their camquest.com dyno simulator.  Google my last name and 12-300-4 and you'll find several threads here and elsewhere about my selection process and some other cam choices depending on your trade-offs.

4) To properly set up the fuel injection or carburetion, the best bet is to get an air/fuel ratio meter.  Yeah, it's $240, but you are spending a lot of money already and poor carburetion will keep you from getting the most out of it.  I recommend the NGK unit over cheaper items.  I've used it a lot, and it will keep you from convincing yourself that you are set up right when you are not.  http://www.amazon.com/NGK-Powerdex-Air-Fuel-Ratio-Monitor/dp/B0018MUNTM

I am already using Long tube header so that eliminates the use of exhaust to heat the air cleaner.

2. I am looking for torque and not HP,but there is no reason I can not achieve 320WHP with gobs of torque.

3. I have always used AEM widebands. I will not however be buying another,because of cost and the plethora of builds people have done over the years should fairly have setups narrowed to to what needs to be run.

4. Like I say cam choice is up in the air. I want to stick with something with .450 lift or less and a 4x4 cam simply based off what a stock vortec head lift can handle unless I end up getting a modified vartec style head.

I really appreciate your input. Like I say I need re schooled!!

Offline 74 C-10 Shorty

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Re: 350 build w/ vortec heads needing opinons
« Reply #5 on: July 12, 2013, 09:23:25 PM »
I honestly wouldn't mind a big block,but picking up a complete running(Has a tick,probably rod or main bearing) TBI 350 for $75 bucks.
Can't go wrong with that I guess.. :D

Offline 87scottsdale

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Re: 350 build w/ vortec heads needing opinons
« Reply #6 on: July 12, 2013, 10:28:15 PM »
I honestly wouldn't mind a big block,but picking up a complete running(Has a tick,probably rod or main bearing) TBI 350 for $75 bucks.
Can't go wrong with that I guess.. :D

Free 99 would be better,but its already out. I have a 454 95 GMC dump truck but I would have to pull the motor. Makes more since for a build when someone else has already done the work :P

Offline rich weyand

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Re: 350 build w/ vortec heads needing opinons
« Reply #7 on: July 12, 2013, 11:15:46 PM »

I am already using Long tube header so that eliminates the use of exhaust to heat the air cleaner.

2. I am looking for torque and not HP,but there is no reason I can not achieve 320WHP with gobs of torque.

I have long tube headers on mine and scavenge heat off the headers.  I used a down-curve stainless steel tailpipe extension, had a shop machine the downcurve off and machine three half-inch slots across it, then mounted it to a header pipe with band clamps.  I cut the original heat riser pipe into pieces and used those and pieces of a flexible tail-pipe repair piece to build up a new heat riser pipe.  See this pic: http://users.rcn.com/weyand/smalls/dsc03924small.jpg and this one: http://users.rcn.com/weyand/smalls/dsc03925small.jpg.  I also routed the snorkel to the radiator bulkhead for cold air induction when the carb heat kicks off.  I have put a chrome lid on the stock air cleaner since these pics were taken ($20), and the whole setup looks pretty cool and works great.

Agreed that you can get lots of horsepower while making tons of torque, given your choices.  Not sure about 320 hp at the wheels.  Your cam choice is limited with the Vortec heads unless you machine down the valve guide bosses to clearance them for higher lift cams.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline Irish_Alley

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Re: 350 build w/ vortec heads needing opinons
« Reply #8 on: July 12, 2013, 11:28:07 PM »
TBI heads arent true vortecs, TBIs where in 87-95 the real ones where under the hoods in 96-02 L31 and these where TPI. only under one hood that i know of that has the true votec heads and tbi setup and it was a 96 g30. i have heard of problems when using tbi vortec heads with a carb its only power robbing flow between the intake and heads think aftermarket intakes do flow better. im only putting this out there so when you buy heads you just dont go with tbi heads and think you got the real deal.
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline 87scottsdale

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Re: 350 build w/ vortec heads needing opinons
« Reply #9 on: July 12, 2013, 11:59:10 PM »
TBI heads arent true vortecs, TBIs where in 87-95 the real ones where under the hoods in 96-02 L31 and these where TPI. only under one hood that i know of that has the true votec heads and tbi setup and it was a 96 g30. i have heard of problems when using tbi vortec heads with a carb its only power robbing flow between the intake and heads think aftermarket intakes do flow better. im only putting this out there so when you buy heads you just dont go with tbi heads and think you got the real deal.

I will be looking for "906" or the "062" casting If i find OE heads. If I end up going with the summit iron version they already accept the higher lift cam and have 67cc chambers instead of 64cc. There are so many Vortec option heads out now it's hard to decide which to go with.

Offline Irish_Alley

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Re: 350 build w/ vortec heads needing opinons
« Reply #10 on: July 13, 2013, 12:14:08 AM »
good deal. just when i saw tbi i thought you were using tbi vortec heads
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline 87scottsdale

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Re: 350 build w/ vortec heads needing opinons
« Reply #11 on: July 13, 2013, 10:14:37 AM »
good deal. just when i saw tbi i thought you were using tbi vortec heads

No sir. If I am going to put energy into a build I don't want to use an inferior design.

Offline Irish_Alley

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Re: 350 build w/ vortec heads needing opinons
« Reply #12 on: July 13, 2013, 11:19:28 PM »
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline ehjorten

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Re: 350 build w/ vortec heads needing opinons
« Reply #13 on: July 15, 2013, 09:19:00 AM »
A real good source for inexpensive Vortec heads is Partiot if you go the aftermarket route.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline 87scottsdale

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Re: 350 build w/ vortec heads needing opinons
« Reply #14 on: July 15, 2013, 10:37:18 AM »
A real good source for inexpensive Vortec heads is Partiot if you go the aftermarket route.

Are those going to be somewhere in the neighborhood of performance as the edlebrock E-tech and the scoogin-dicky pieces? I have heard of patriot,but have never had any experience or anyone that I know to run them.

Are these the ones?

http://www.jegs.com/i/ProMaxx-Performance/723/2151/10002/-1