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TBI engine experts!!! Rebuild questions!!

Discussion in 'The Garage' started by yeild2me, Jan 18, 2004.

  1. yeild2me

    yeild2me 1/2 ton status

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    Well, the ole mill is going to the machine shop to get rebuilt in the morning. It was running fine, but with close to 200000 on the ole ticker, I figured its about time.

    Anyway, I am going to keep it simple with a standard bore, valve job etc. I do want to put a slightly larger cam in though, and was wantin to hear some suggestions.

    Truck specs....

    Headers, 2.5" dual exhaust with flomasters, rebuilt 700r-4, 456's with 44's....

    I want a cam that will be computer friendly..

    As usual lots of low end torque!!!!

    Rob
     
  2. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Save the money that you would have spent on the cam and have that engine rebored and buy new pistons. With 200,000 miles there's no way those cylinders are still round and not tapered.

    Having a good ring seal goes a long way towards having good torque for a long time. It's the difference between a hack job of a motor that goes 20-30000 miles and a good one that goes 100000+
     
  3. yeild2me

    yeild2me 1/2 ton status

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    I guess I should have clearified a little!!

    I am not taken it to get a lot of machine work done, but if it needs it, then it will get it. With all the talk of cams lately, I figured I could up it from the OEM grind to get a little more power. I do agree, just having it "freshened up" will help tons.

    Rob
     
  4. SUBFAN

    SUBFAN 1/2 ton status

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    I would look into converting that block to roller cam. Fill out a reccomendation card on comp cams websight. Having the right block makes the switch to a roller cam much cheaper.

    Check into going the 383 route too. not that much more than just redoing the 350.
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I'll 2nd the 383 thing. If/when I ever do a motor it's definitely going to get stroked.

    I don't think the roller cam is really worth it for a DD rig though. It just costs too much to really benefit you. You're going to make more power and get better MPG, but by the time you pay for the retrofit, you can buy lots of gasoline. /forums/images/graemlins/thumb.gif
     
  6. SUBFAN

    SUBFAN 1/2 ton status

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    The biggest cost is the retrofit lifters. The TBI blocks can use factory lifters for 1/2 the price. Granted a 'spider' will need to be installed, and this set up is not recommended for high rpm useage.

    If a person wanted to, they could even pick up the lifters and the spider from a j-yard and use them, making the cost of a roller cam that much more feasible. (Do not forget to upgrade the valve springs, whichever route you choose.)
     
  7. jjlaughner

    jjlaughner 3/4 ton status

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    ok lets get some specs!

    Cam - who's part number
    #'s for telling the machine shop how you want the block setup for roller cam and are the 100lb valves springs going to work with what cams? And in that case if I spend $200 for a 'head job' /forums/images/graemlins/grin.gif (I'm sure that number is conservative for a 3angle valve grind, mill, magna flux, seals, and springs). Should I just drop another $200 and get what heads (performance heads ready to bolts on) to use with the roller cam setup....

    /forums/images/graemlins/ears.gif MORE INFO /forums/images/graemlins/ears.gif

    I know I have 93 block that needs a new crank and bearings... everything else is like whats said above ^ it ran great it just needs cleaned up!
     
  8. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    [ QUOTE ]
    I'll 2nd the 383 thing. If/when I ever do a motor it's definitely going to get stroked.

    [/ QUOTE ]
    Can the standard ECU cope with a 383. I've heard that you need to be careful with cam choice (ie.mild) as the computer throws it's toys out of the pram with a big cam. Can the computer compensate for the fuelling on a 383?? /forums/images/graemlins/confused.gif
     
  9. yeild2me

    yeild2me 1/2 ton status

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    Thats what I was thinking on the 383... I wouldnt mind doing it, but by time you add in the price of the work/parts for the 383 then dealing with the computer..........I hate PIA problems!!!

    What about some nice aftermarket ignition systems??? I may just replace my OEM with all new.

    Rob
     
  10. SUBFAN

    SUBFAN 1/2 ton status

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    In a mild application, I bekieve it would....
     
  11. SUBFAN

    SUBFAN 1/2 ton status

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    For the price of the aftermarket ignition stuff, you could have the 383 and a chip....
     
  12. SUBFAN

    SUBFAN 1/2 ton status

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    I sent him several links via messenger last night, I will have to look those up and get them put on here....
     
  13. jeffro

    jeffro 1/2 ton status

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    The TBI system will not support a radical cam profile. An "RV" or towing profile will do you good. Roller cam will not work with a stroker kit due to the clearance issues. personally I'd go the standard rebuild route and stick an RV cam in it and get another 200,000 miles on your clock. If it wasn't good enough you would have changed it by now.

    Also IMHO 2.5 duals is too fat for TBI. 2.25 will do you fine. You will need to muster up as much low end torque as you can to start the 44s on 4.56s and fat exhaust will hurt more than it will help.

    Jeff
     
  14. fad2blk99

    fad2blk99 1/2 ton status

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    I'm all ears on this post too...
    I want to stay with my fuel injection, but I also want more power. I haven't herd anything good from people getting the custom burned chips, and that's way too much money to not have any sort of garuntee.
    I like the 383, or even better a 400, w/ the votrec heads /forums/images/graemlins/tongue.gif. I just wnat to see someone make it work on a TBI setup.
    Until then, I'm just planning on a .030" over bore, a 4x4/RV cam, and an adjustable fuel pressure regulator for the TBI.
     
  15. wayne

    wayne 3/4 ton status

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    Rob, since this is a trail only rig and light weight to boot just go with a stock rebuild like you plan and get the Edelbrock TBI stuff to pump it up a little. I don't see the need to spend a ton of money to make power in something used to crawl. Start adding roller cams, stroker kits, yada, yada, yada and you wind up with a $4000 engine to go 5 mph. Heck if ya want to spend that kind of money just drop a TBI 454 in it.
     
  16. Thunder

    Thunder 3/4 ton status

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    Yeah I agree with Wayne on this too. A 383 will cost a lot of money to make work with TBI. If your rig were a DD maby it would be worth it. But for a trail rig it is overkill unless you have deep pockets and nothing better to spend money on.
    For the trail. Keep it Simple.
    I would just build the engine you have. Stick a mild torque building idle -4500 rpm computer grind cam like a Crane or Comp cam. I think a regular non roller hydraulic cam is your best bet.
    Edelbrock or Weiland TBI manifold.
    Keep the ign stock with maby a MSD coil for a little hotter spark.
    That should set you up with a nice reliable 260+ hp trail engine that builds good torque.


    The 454 aint a bad idea either. The wireing harness for TBI is the same for 350 and 454. All you need is a 454 chip and an adapter wire for the IAC. The rest plugs right in
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    To say that the 454 isn't a bad idea but the 383 is too much work/expense is absolutely ridiculous. If you're buying a new rotating assembly anyway, the 383 adds nothing to the cost of parts except the balancer and flywheel, and adds everything to the build.

    I think that as long as a small cam and decent heads were used, one could get by with a 383 simply by bumping up fuel pressure and a custom chip, I think.

    The main advantage of the 383 in this application is more lowering the powerband than raising it. The fact that you get MORE torque is just a fringe benefit. The fact that you pick up tons of torque right at idle is what is so great about that build.

    I agree though, if its just a trail machine, I don't know if I'd spend any money at all on the motor. In fact, I'd consider running the bottle brush down the cylinders, throwing rings/bearings/gaskets in it and calling it done.

    Making the stroker work with EFI could potentially get interesting if you go to wild though, so be careful with that one. It's just too tempting when you're already building a bad ass motor to go overboard.
     
  18. Derf00

    Derf00 1/2 ton status

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    [ QUOTE ]
    Roller cam will not work with a stroker kit due to the clearance issues.

    [/ QUOTE ] /forums/images/graemlins/confused.gif

    My stroker is running a LT1 roller cam, Edlebrock MPFI, Vortec heads.
     
  19. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    Well, choose your camshaft very wisely.

    I'd do a lot of research and call up Comp Cams to see what they have to say.

    I, personally, am a favorite of the XE262H in its various forms. But, I like to go fast. I like to pretend my truck is a racecar. I run #12-238-2 in my 305. I don't think it'll work well with a stock TBI fuel injection system. I know some people that run the #12-262-4 cam in their L98s (TPI), but that's a different injection system. The biggest difference is the lobe separation between the two cams. Here is a link to the dyno sheet on the XE262H in a 355 with Dart heads.


    The entire Chevy section of Comp Cam's catalog.
     
  20. yeild2me

    yeild2me 1/2 ton status

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    Thanks guys for all the suggestions.....I dropped it off this morning, and told the guys at the machine shop....standard rebuild, and asked for a little hotter cam. Those guys totally understood the TBI nightmares that can arise with worng cams and told me they were going to put the next hottest cam from stock (R/V). They have built lots of these motors for local guys and everybody loves the results...

    Again, thanks for all the ideas!!!!

    Rob
     

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