New engine build - 300hp tbi

Discussion in 'Engine Performance + Maintenance' started by Gramps, Jun 12, 2018.

  1. Gramps

    Gramps Newbie

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    With some careful planning we just woke the monster. TBI 350 I just finished building, took a 4bolt main block, roller cam and rockers, a set of eq heads(vortec chamber, tbi intake) hit the dyno and made 299.6 hp and 370 ft lbs of torque using the stock 350 tbi unit, with some modifications. Big block injectors, pod spacer, fuel pressure regulator/spring. Running 12psi of fuel pressure.

    I feel like a bunch of power was left on the table, the tbi unit seems to be the cork. At 4500 rpm it started pulling 1.5” of vacuum and by 5000 it was almost 2”. Wondering if I switched to the the big block throttle body unit if I would gain anything worthwhile or just wasting time. Aside from that it runs just awesome.

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  2. DerekTheGreat

    DerekTheGreat I'm Awesome

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    So its awesome around town and traffic conditions? Cool. How'd you tune it? Which cam exactly?
     
  3. 89GMCJOHN

    89GMCJOHN I'm Awesome

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    2nd that which cam did you use ? Nice torque numbers by the way ....I have read good things about those EQ vortecs - any issues you ran across with them ?
     
  4. Gramps

    Gramps Newbie

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    Won’t know how it is around town until it’s back in the truck - which will be after it’s done being painted. BUT seeing where the torque starts coming on strong it should be a ton of fun.

    It’s a comp cams roller, pulled 22” of vacuume at idle. Used the stock ecm, not chipped either. Tuned it with a little extra base timing, and bbc injectors. Modified the fuel pressure regulator to make it adjustable, and stock spring was too weak.

    If you are going to get the EQ heads, get them As BARE CASTINGS And take them to a good machine shop. I got them “loaded”. The valves were junk. Ate the guides up. The springs supplied were also very weak - even for use on a flat tappet cam. I ended up having tear the heads off after the first dyno session, $800 in machinework and parts to fix the damage and make them right. (They did reimburse me for $500 of that but if I wanted to spend $1500 on a set of heads they would have been AFR’s. So get them bare, and put your own quality valve train parts in them. The castings themselves are Ok.
     
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  5. 89GMCJOHN

    89GMCJOHN I'm Awesome

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    Cool tx
     
  6. DerekTheGreat

    DerekTheGreat I'm Awesome

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    Good info, thanks!
    You wouldn't have the part number or specs for that cam, would ya? Which spring did you put in the regulator?
     
  7. Schurkey

    Schurkey I'm Awesome

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    I bought a pair of the EQ Vortec/TBI hybrid cylinder heads, the 350 G version.

    The intake valve tips were uniformly higher than the exhaust valve tips. It's like they made zero attempt to get the valve tips even. The intake valve tips were taller, because they sank the intake valve into the chamber. Exactly the opposite of what you'd want--usually the exhaust valve is sunk a bit to reduce the loss of fuel/air out the exhaust valve on overlap

    I sent 'em back.

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    The two center exhaust valves, and the intakes on either side.
     
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  8. Gramps

    Gramps Newbie

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    That was another issue I had aswell, but had corrected.
    The spring in the regulator was custom - picked up several springs from the hardware store and figured out which worked the best and adjusted the spring height to get close and then fine tuned with the regulator “screw”
     
  9. L31MaxExpress

    L31MaxExpress I'm Awesome

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    I bought my Assault Racing heads as bare castings and built them. Basicall Dart Pro1 Platinum knock offs. Best thing to do with the chinese castings IMO because you can put better parts in them too. Machine work on them was practically perfect out of the box minus one chamber that had a very slight cutter mark in a place that would not hurt a thing.

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    Last edited: Jun 21, 2018
  10. arrg

    arrg I'm Awesome

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    Gramps, which intake manifold/intake manifold gasket did you use? I have the same heads and I've mocked up a couple different manifolds with them. None of the manifolds look like they'll seal the recommended Fel Pro 1255 gasket.
     

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