Page 1 of 2 12 LastLast
Results 1 to 15 of 16

Thread: need help on my 350tbi

  1. #1
    Carb and Points!
    Join Date
    Oct 2014
    Posts
    6

    need help on my 350tbi

    I need help I have a 93 k1500 with 6in lift and 33s it has the bone stock 350tbi with a 5 speed I want it to have more get up I was thinking mild cam vortec heads and lifter and rollerrockers and tune I was wondering what I needed too make all this happen and what would be a good cam and what I need to put the vortec heads on it and I wanna use my tbi and where I would get a good tune its my daily driver so I dont wanna get to crazy any info if thankful

  2. #2
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    2,308
    Quote Originally Posted by 93 gmc_350tbi View Post
    I need help I have a 93 k1500 with 6in lift and 33s it has the bone stock 350tbi with a 5 speed I want it to have more get up I was thinking mild cam vortec heads and lifter and rollerrockers and tune I was wondering what I needed too make all this happen and what would be a good cam and what I need to put the vortec heads on it and I wanna use my tbi and where I would get a good tune its my daily driver so I dont wanna get to crazy any info if thankful
    Are you wanting more RPM or more low-midrange torque? If you have not already done so, I would look at regearing the truck first. All the power in the world will still feel lacking with the wrong gearing. I am guessING you currently have 3.42 gears with your 33" tall tires. Simply moving up to 4.10s would give you a noticeable performance increase. Once you get the engine back into the proper RPM operating range you can start to increase performance. Vortec heads really only make a big difference at higher rpms, above 4,500 rpm. You could change the cam, install long tube headers, 1.6:1 roller rockers and a good tune and really wake the truck up without converting to vortecs or buying a new intake manifold.

    I had a 8.75:1 1 ton GM Goodwrench 350 TBI that was rated at 190 HP and 300 TQ up to around 255 HP and 400 TQ (208 RWHP/324 RWTQ) without touching the long block. The only internal engine modification was a set of 1.6:1 full roller rockers. Stock short block, stock 810 casting swirl ports, and stock TBI cam. I had a cheap pair of Flowtech (Big Mistake) 1-1/2" primary shorty headers with 3" collectors, dumping into a 2.5 to 3" Y setup with a highflow 3" cat and a flowmaster 40 series single in/dual out muffler. My stock intake manifold was pitted badly around the water passages and I had to pickup an Edelbrock 3704 for smog compliance at the time. I bought a 1" oval center TBI spacer and put an ultimate TBI moded stock bore TBI on it. Used a stock air cleaner with a K&N filter and the base cut out for a hypertech powerbowl. I was running the 7747 ECM at the time and a slightly tweaked ASDU .BIN file. Timing table was almost stock with 6* added to the distributor base timing and the air/fuel ratio and VE tables calibrated to run around 12.4 @ 3,000 rpm and 13.2:1 @ 5,000 rpm @ WOT (No Ethanol back then). Total timing was about 28* BTDC at WOT.
    Last edited by Fast355; 10-29-2014 at 07:50 PM.

  3. #3
    Carb and Points!
    Join Date
    Oct 2014
    Posts
    6
    It has 3:73 gears long tube headers I forgot to mention but I heard that the tbi cast heads are poorly portted id like to get it up around 250hp but id like all around power and tourq but I dont want 8 mpg eaither I get about 15 mpg now with the 5 speed and 3:73s

  4. #4
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    1,022
    There are many different ways you can go. A Performer RPM intake with a TBI adapter plate can make a good intake combination. The above mentioned "Ultimate TBI Mods" give some good ideas on helping with intake air flow. http://www.thirdgen.org/ultimatetbi You can Google it as well for even more ideas and info.

    I'd think a camshaft kit like a Lunati 10120701K kit would go well towards increasing power. You need to confirm the heads and piston clearance would be good for that lift.

    2 big things required to use Vortec heads are the self-aligning rockers and the Vortec specific intake.

  5. #5
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    2,308
    Quote Originally Posted by 93 gmc_350tbi View Post
    It has 3:73 gears long tube headers I forgot to mention but I heard that the tbi cast heads are poorly portted id like to get it up around 250hp but id like all around power and tourq but I dont want 8 mpg eaither I get about 15 mpg now with the 5 speed and 3:73s
    Nothing wrong with TBI heads in your application, just don't expect 400 HP @ 6,000 rpm. 250-300 HP is not hard to get from a properly cammed, TBI head 350. With a mild cam like you would want in your truck a Vortec head will not offer any benifit until over 4,000, maybe as much as 4,500 rpm. When I had them on the same setup the TBI heads got better mileage than the Vortecs did.

  6. #6
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    2,308
    Quote Originally Posted by lionelhutz View Post
    There are many different ways you can go. A Performer RPM intake with a TBI adapter plate can make a good intake combination. The above mentioned "Ultimate TBI Mods" give some good ideas on helping with intake air flow. http://www.thirdgen.org/ultimatetbi You can Google it as well for even more ideas and info.

    I'd think a camshaft kit like a Lunati 10120701K kit would go well towards increasing power. You need to confirm the heads and piston clearance would be good for that lift.

    2 big things required to use Vortec heads are the self-aligning rockers and the Vortec specific intake.
    IMO that cam is wrong for a TBI head setup. The TBI heads really want and need a moderate duration, tight LSA, and really do not benifit from a split pattern. I would run this cam installed on a 106* ICL.

    http://www.summitracing.com/parts/lu...make/chevrolet

    If you rarely rev your engine over 4,500 rpm this cam would be even better. I would likely run a 1.6:1 roller rocker with this one.

    http://www.summitracing.com/parts/su...make/chevrolet

    I also feel this Comp Cam would do very nicely as well. Would be even better with 1.6:1 rockers.

    http://www.summitracing.com/parts/cca-12-205-2/overview/make/chevrolet

    The RPM intake is a GREAT match for TBI heads as far as port dimensions go but will need the 4 center bolts elongated and angled shims fabricated for proper intake bolt seating and sealing.
    Last edited by Fast355; 10-29-2014 at 08:38 PM.

  7. #7
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    2,308
    With long tubes, decent exhaust, performer RPM intake, ultimate TBI moded TBI, proper fueling and timing I feel the Lunati 260/260 would make about 260-280 HP in an otherwise stock TBI 350. It would pull well from just off-idle through 5,000 rpm with the bulk of the power from 1,500-4,000, right where you need it in a heavy truck.
    Last edited by Fast355; 10-29-2014 at 08:41 PM.

  8. #8
    Carb and Points!
    Join Date
    Oct 2014
    Posts
    6
    If I kept the tbi heads and when with that first cam tou mention should I get roller rockers and lifters and could I use 1.5 lift and what bout tunes what is there to tune on a tbi motor the computer is ancient would it run lean or rich without a tune if I could get aeound 250 go outta the tbi heads and without emptying my wallet id like that i just want a little more power

  9. #9
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    1,022
    That Lunati 06105 would make a great cam. I knew they had some other good choices.

    You'd use flat hydraulic lifters. You could use roller rockers if you wanted but not necessary. Make sure the valve springs match the new cam as well.

    Tuning is possible. moates.net is the place to go to. I believe an APU1 plus an adapter or ZIF socket would cover all the tuning you would need besides buying a wideband O2 sensor. I only did chip programming so hopefully others can add-in with better info on what they used.

  10. #10
    Carb and Points!
    Join Date
    Oct 2014
    Posts
    6
    Thanks I think im gunna go with the lunati cam and lifters and tune or chip

  11. #11
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    2,308
    Quote Originally Posted by lionelhutz View Post
    That Lunati 06105 would make a great cam. I knew they had some other good choices.

    You'd use flat hydraulic lifters. You could use roller rockers if you wanted but not necessary. Make sure the valve springs match the new cam as well.

    Tuning is possible. moates.net is the place to go to. I believe an APU1 plus an adapter or ZIF socket would cover all the tuning you would need besides buying a wideband O2 sensor. I only did chip programming so hopefully others can add-in with better info on what they used.
    I do not believe the cam you mentioned would run badly, I just feel the 06105 would be a better fit for the application. With only 40* of overlap the idle will still be very stable, despite the 110* LSA. Advanced 4* the intake close will be 56*ABDC which is fairly early and will trap good low-end cylinder pressure. If the engine is stock with 12cc dished pistons it is about 9.3:1 and the 06105 will bring the dynamic compression in at a pump gas friendly 7.85:1. The TBI heads do not need as much lift as alot of engines and do not benifit from anything over .450" in stock form. Keeping the lift mild means you can drop a set of Z/28 springs in and go with no retainer to seal clearance issues. The 06105 would not need to be used with 1.6s and 1.52s would probably work the best.

    Roller rockers would not be necessary, but can give a few HP even if they are the same ratio. The factory rockers vary anywhere between 1.42 and 1.46:1 and can even vary ratio during the sweep. A set of 1.5 or 1.52 rockers will deliver accurate lift and the roller tip and needle bearing fulcrum reduce friction. If you have a good set it is generally not a problem to run them 100K or more without problems.

  12. #12
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    2,308
    Quote Originally Posted by 93 gmc_350tbi View Post
    If I kept the tbi heads and when with that first cam tou mention should I get roller rockers and lifters and could I use 1.5 lift and what bout tunes what is there to tune on a tbi motor the computer is ancient would it run lean or rich without a tune if I could get aeound 250 go outta the tbi heads and without emptying my wallet id like that i just want a little more power
    With the stock ECM, timing, fuel pressure, and idle speed you will run a little rich at idle and lean under load.

    I would start by either buying or building an adjustable fuel pressure regulator and dialing in the fuel pressure to 14 psi. When you start the truck you should set the timing about 6* advanced with the timing wire disconnected. From there you will need to do some datalogging to see where the fuel trims and knock retard are showing. Chances are you will be a touch rich and it will have pretty decent manners. You may want to increase the idle slightly to 700-750 rpm as this will give a stronger vacuum signal. Most cammed setups also require the base idle/minimum air rate to be adjusted on the TBI. Generally on a mild cam like this one you can make the thing run quite well on the stock chip by manipulating the timing, fuel pressure, and minimum idle rate.

    Now here is where it gets fun...

    When you increase fuel pressure, you increase fuel delivery. Stock engines are borderline for WOT as they sit and airflow improvements mean more fuel demand.

    When you install a cam you will reduce the vacuum signal at idle, which will increase the fuel delivery.

    When you advance the timing you increase the vacuum signal and reduce the fuel.

    Opening the throttle plate helps draw the air/fuel mixture through the thorttle plates into the engine and alleviates the IAC vacuum leak.
    Last edited by Fast355; 10-29-2014 at 10:48 PM.

  13. #13
    Electronic Ignition!
    Join Date
    Aug 2014
    Posts
    15
    The Lingenfelter L98 single pattern 219 roller is actually a pretty decent cam. I had something very similar to it in a XFIRE using Trick Flow heads. Made 285rwhp @ 4700 rpm/347rwtq@3400rpm IIRC.

  14. #14
    Carb and Points!
    Join Date
    Oct 2014
    Posts
    6
    My plan was to get the adjustable fuel pressure and I has a msd ignition box I wanted to put on it too

  15. #15
    Fuel Injected!
    Join Date
    Sep 2012
    Location
    washington indiana
    Age
    69
    Posts
    884
    I would change the gear ratio first with them big tires, then start tunning and adding other idem's then you will see what you have acoplicet for your effert. a lower gear ratio an good tune may be all you wish from your truck, if not then add a lot of other things to help the horses and torque. your milage may even go up.

Similar Threads

  1. 350tbi sluggish and fuel guzzler
    By alkatyler in forum Introductions
    Replies: 21
    Last Post: 07-24-2014, 08:20 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •