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Thread: Flat tappet cam and Vortec heads

  1. #1
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    Flat tappet cam and Vortec heads

    So I scored a set of 906 heads at work. I'm looking for a recommendation(or 2) on good flat tappet cams. This is in my 1990 1500 Stepside bed, 5.7L 7747. Currently has the 3.08 gearset but soon to be installing the gu6 3.42's. I have a couple of Comps in mind although I can't find the cards for them at the moment. Anywho, what have you used? What did you think? Thanks,

    Buddrow
    If it don't fit force it, if it don't force fit f&%@ it!

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    Quote Originally Posted by buddrow View Post
    So I scored a set of 906 heads at work. I'm looking for a recommendation(or 2) on good flat tappet cams. This is in my 1990 1500 Stepside bed, 5.7L 7747. Currently has the 3.08 gearset but soon to be installing the gu6 3.42's. I have a couple of Comps in mind although I can't find the cards for them at the moment. Anywho, what have you used? What did you think? Thanks,

    Buddrow
    What are your other plans for the engine. What intake manifold, TBI unit, exhaust, converter stall speed.

    I myself would run something around 212-218 on the intake and 218-224 on the exhaust, but I like running long tube headers, decent exhaust, around 2.600-2,800 rpm stall speed and like power from 1,500-5,500 rpm. I also don't mind a little rougher idle.

    Case in point I am building a L30 to go into a 1997 Astro van tomorrow. I have a Lunati flat tappet high efficiency 268 cam, new flat tappet lifters from a GM 330 HP 350 HO I put a LT4 Hot Cam in for someone I know, and the set of matching pushrods and timing set. The Astro has factory hydroboost so I am not really overly concerned about idle vacuum. I can tune the Vortec PCM or swap in an 0411 if I need. The van has a factory high stall in the 4L60E that will stall about 2,500 rpm behind the 305 and 3.42s. I will let you know how it runs when I am finished. The Astro van with a 4.3 is only 4,197 curb weight and the V8 swap only adds about 100 lbs. Weighing in at about 4,600 lbs with me in the seat it should run out pretty good from a stop. I have a L31 short block on the stand too, but feel the added low-end grunt would be a waste of time with an open differential plus the 305.

    The Lunati High Efficiency cam specs

    268/268 @ .006
    218/218 @ .050
    .457/.457 lift
    110* LSA
    106* ICL

    On a 350 I would probably go with the newer Lunati Voodoo series with a split pattern grind. I run single pattern cams in 305s or in TBI head engines and have found they work well in both. Generally speaking your single pattern cams make more grunt in the low-midrange than the split pattern cams and only give up a few HP above 4,500 rpm to a single pattern grind.

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    Looking at one of the edlebrocks. I like the rpm's and have had good success with them so I figure they are a good bet. :-D I have a couple of big block throttle bodies to put on it( only one at a time of course) and a set of long tubes out 2.5" true duals. As for stall, depends on the cam but would like to stay within the range you stated.

    Future plans include an upgrade to a 7427 and multi-port but thats a ways away.

    Definitely let me know how that engine feels. I'm looking for low-midrange gusto and decent street manners. Thanks for the info.

    Buddrow
    If it don't fit force it, if it don't force fit f&%@ it!

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    Quote Originally Posted by buddrow View Post
    Looking at one of the edlebrocks. I like the rpm's and have had good success with them so I figure they are a good bet. :-D I have a couple of big block throttle bodies to put on it( only one at a time of course) and a set of long tubes out 2.5" true duals. As for stall, depends on the cam but would like to stay within the range you stated.

    Future plans include an upgrade to a 7427 and multi-port but thats a ways away.

    Definitely let me know how that engine feels. I'm looking for low-midrange gusto and decent street manners. Thanks for the info.

    Buddrow
    The cam is definately part of this build. It has been installed in the L30 and as soon as I get the pistons installed I may break out the degree wheel just to check its positioning. I fell behind on this build waiting for the correct ring set. Apparantly GM re-invented the wheel and created 305s with two different depths of oil control ring lands in the piston. A deep .200" or shallow .170". I had the commonly available, cheaper .200 set. Had to order the .170 from out of state and they are a $55.00 ring set.



    Desktop dyno is predicting ~280 hp through cast iron manifolds and a shade over 300 hp with long tubes. Through the manifolds HP peak is 5,000 and with long tubes 5,500. The torque peaks show to both be at 3,500 with 310 ft/lbs for manifolds and 340 ft/lbs for headers. I have a set of Hooker Super Comps for a 2nd gen Camaro that looks like it will fit tye Astro perfectly and I may test fit them

    The Vortec crank reluctor still fits fine on an older chain, just can't use a double roller.

    Last edited by Fast355; 04-27-2015 at 11:11 PM.

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    Apparantly GM re-invented the wheel and created 305s with two different depths of oil control ring lands in the piston. A deep .200" or shallow .170". I had the commonly available, cheaper .200 set. Had to order the .170 from out of state and they are a $55.00 ring set.
    Ran into the same issue a couple of years ago when refreshing some 5.7s here. Some w/ deep grooves, some w/o.

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    Quote Originally Posted by 1project2many View Post
    Ran into the same issue a couple of years ago when refreshing some 5.7s here. Some w/ deep grooves, some w/o.
    Seems like once GM got something right they would leave it alone.

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    Haven't run into the oil ring issue but I spend more time building transmissions than engines these days. I like your solo cup holder btw. :-) Im running the stock non-Vortec block so no reluctor issues, just running the heads. I was kinda bummed, pulled the donor engine out of the express van due to broken block on outside starter bolt hole, pulled the pan because a customer wanted a pair of rods/pistons, only to find it to be a 4bolt main block. Depressing to say the least lol. But I scored the heads so thats an improvement over the swirl ports. Anywho, I really just wanted to know what cams guys were running with these heads.

    Buddrow
    If it don't fit force it, if it don't force fit f&%@ it!

  8. #8
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    Quote Originally Posted by buddrow View Post
    Haven't run into the oil ring issue but I spend more time building transmissions than engines these days. I like your solo cup holder btw. :-) Im running the stock non-Vortec block so no reluctor issues, just running the heads. I was kinda bummed, pulled the donor engine out of the express van due to broken block on outside starter bolt hole, pulled the pan because a customer wanted a pair of rods/pistons, only to find it to be a 4bolt main block. Depressing to say the least lol. But I scored the heads so thats an improvement over the swirl ports. Anywho, I really just wanted to know what cams guys were running with these heads.

    Buddrow
    That is a cup of 80w90 that I put the bearings before I do the final install on them. I drop them all in place first, then plastigauge them, then put

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