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  1. #1
    Carb and Points!
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    "New" guy

    Good evening gentlemen, registered here a while ago, mostly to see pics of others builds and what not. Lurked ... old (current) engine is a stock 95 TBI with Vortec heads, beehive springs, stock 350 TBI with "free mods" and the stock flat tappet TBI cam. I find myself currently at the tail end of building a new engine. 6 inch rod 355, 2vr flat top pistons, Vortec heads with LS6 beehive springs again. Currently have an LT4 Hot Cam and Holley 670 TBI in my possession, was told by a tuner there is no way this will work in my application, 3.90 gear 4door 2WD Tahoe. Too heavy, will need too many RPMs, etc. I'm fine with another cam, the Lunati 20080660 was the one suggested. The Hot Cam was for another project that never happened. I didn't want to get another TBI unit or cam if someone can help me make this work and it will make power where I need it. I'm going to be doing a lot of reading over the next few weeks. I have TunerPro (think that was the name of the software) on my old notebook, did some data logging and looking with an ALDL cable, never burned a chip but I see that's far cheaper and easier now. Any thoughts? Am I crazy? Am I screwed? Do I need new parts? What's that smell?

  2. #2
    Fuel Injected!
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    Quote Originally Posted by retorq View Post
    Good evening gentlemen, registered here a while ago, mostly to see pics of others builds and what not. Lurked ... old (current) engine is a stock 95 TBI with Vortec heads, beehive springs, stock 350 TBI with "free mods" and the stock flat tappet TBI cam. I find myself currently at the tail end of building a new engine. 6 inch rod 355, 2vr flat top pistons, Vortec heads with LS6 beehive springs again. Currently have an LT4 Hot Cam and Holley 670 TBI in my possession, was told by a tuner there is no way this will work in my application, 3.90 gear 4door 2WD Tahoe. Too heavy, will need too many RPMs, etc. I'm fine with another cam, the Lunati 20080660 was the one suggested. The Hot Cam was for another project that never happened. I didn't want to get another TBI unit or cam if someone can help me make this work and it will make power where I need it. I'm going to be doing a lot of reading over the next few weeks. I have TunerPro (think that was the name of the software) on my old notebook, did some data logging and looking with an ALDL cable, never burned a chip but I see that's far cheaper and easier now. Any thoughts? Am I crazy? Am I screwed? Do I need new parts? What's that smell?
    I have a Lunati version of the Hotcam in my Express van with 1.6 rockers. It pulls the van around with ease and pulls strong to 5,800 with the GM L31 Marine intake. Stock B82 GM 4L80E torque converter stalls about 2,300 rpm and I have 4.56 gears and 29" tall tires. It pulls my 6,000 lbs Jayco travel trailer down the highway at 65-70 mph in overdrive at about 2,600-2,800 rpm with no issues. About to swap the intake for an Edelbrock proflow with a 90mm forward facing LS throttle body and put my Etec 170s back on after I had them surfaced(warped them when I overheated it a while back). I put down 290 rwhp @ 5,800 and 330 rwtq @ 4,000 with more than 300 rwtq @ 2,500 on a Mustang dyno that is super stingy. The Lunati Hotam with 4.56s pulls better in OD than the Marine cam did with 3.73s in 3rd. The tiny 196/206 marine cam only put down 230 @ 4,400 rwhp and 304 rwtq@ 3,400. When I hit a hill the thing only downshifts to 3rd vs 2nd before and I run up the same hill turning about 800 rpm less at the same speed. In the 3,500+ range the Hotcam has ALOT more TQ than the Marine cam.
    Last edited by Fast355; 04-19-2017 at 06:19 PM.

  3. #3
    Carb and Points!
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    Quote Originally Posted by Fast355 View Post
    I have a Lunati version of the Hotcam in my Express van with 1.6 rockers. It pulls the van around with ease and pulls strong to 5,800 with the GM L31 Marine intake. Stock B82 GM 4L80E torque converter stalls about 2,300 rpm and I have 4.56 gears and 29" tall tires. It pulls my 6,000 lbs Jayco travel trailer down the highway at 65-70 mph in overdrive at about 2,600-2,800 rpm with no issues. About to swap the intake for an Edelbrock proflow with a 90mm forward facing LS throttle body and put my Etec 170s back on after I had them surfaced(warped them when I overheated it a while back). I put down 290 rwhp @ 5,800 and 330 rwtq @ 4,000 with more than 300 rwtq @ 2,500 on a Mustang dyno that is super stingy. The Lunati Hotam with 4.56s pulls better in OD than the Marine cam did with 3.73s in 3rd. The tiny 196/206 marine cam only put down 230 @ 4,400 rwhp and 304 rwtq@ 3,400. When I hit a hill the thing only downshifts to 3rd vs 2nd before and I run up the same hill turning about 800 rpm less at the same speed. In the 3,500+ range the Hotcam has ALOT more TQ than the Marine cam.
    That is certainly promising information!

  4. #4
    Fuel Injected!
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    Quote Originally Posted by retorq View Post
    That is certainly promising information!

    My buddy ran one in a Vortec head 350 tbi in a 1995 C1500 that was lifted on 32" tall tires. Had a 4L80E that came from a 6.5 diesel. Even with the stock 1,000 rpm diesel stall speed and 3.73s it ran well. Had an edelbrock victor jr 2bbl intake on it as well. It lagged a little on a WOT hit from a stop but it would run 0-60 in 1st gear. Once it got a little rpm built up it pulled HARD. He ran the MAF TBI 4L60E ECU code that Adam over on Thirdgen.org wrote.
    Last edited by Fast355; 04-20-2017 at 12:34 PM.

  5. #5
    Electronic Ignition! Queencityspeed's Avatar
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    I've done a lot of builds similar to yours but with carbs on them. I cant see why it wouldn't work great in a Tahoe with a Holley TBI on it. I think it would like a slightly higher stall. ( like the S-10 converter) I've never tuned a Holley TBI so keep us informed. I have one coming up soon.

  6. #6
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    When presented with high lift / shorter duration or low lift / longer duration for EFI, a good general rule is to pick lift if possible. The cam recommended by the tuner may not be all that different from the HOT cam. It's got less lift and slightly more duration. The difference in ICL (1 degree) could disappear in manufacturing. The HOT cam has fairly mild ramps and I'm betting the Lunati version is the same. I'd have no problem running the HOT cam.

    And I think your tuner would choke if told I'm using a 302 with a smaller cam in a Suburban. My truck has 3.42's and it tows a trailer. I originally built the engine with an LT4 stock cam for an S10 Blazer but changed to the Marine cam before the engine was installed. Short stroke engines tend to like smaller cams.

    The HOT cam has little overlap and makes strong and steady vacuum. In a heavy truck with an automatic it will prefer a looser converter. If you're in an area with lots of hills you might tune for faster unlock of TCC on the highway and let the converter work for you. You might also tune for 4 -> 3 downshifts at lower throttle angle.

    Put the biggest dang cooler you can on that transmission. The trans will be expected to shift and in some cases a looser converter generates more heat.

    Do your prep work on that Holley TBI. I don't know how old it is but you need to be sure you have it in good shape before tuning begins. Understand what injectors are installed, make sure the throttles close properly, and make sure the IAC works.

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