L31 with LT1 241 cam?

Discussion in 'Engine Performance + Maintenance' started by trx125, Dec 5, 2018.

  1. trx125

    trx125 Newbie

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    I have a 98 L31 that I'm rebuilding. I'm boring .30 over with the stock lowers. Looking to run a lt1 241 cam from a camaro with 1.5 rockers, ls springs and retainers. I plan to run the stock intake and upgraded mpfi injection. Looking to add a few ponies, but not street racing. It's going on a 98 2d Tahoe 4wd. Will I need to get a tune done or will the stock pcm be ok and what if any upgrade do I need to do with the torque converter.
     
  2. L31MaxExpress

    L31MaxExpress I'm Awesome

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    It will run very well on the stock tuning but even a stock engine benefits from a good tune. I would go with 1.6 full roller rockers if you are changing the springs. Just be sure to drill out the pushrod holes to 1/2". Some people say the LT1 cam is not a great truck cam but I disagree. I have used it as well as the LT4 cam several times in L31s and it pulls noticeably better than the stock L31 cam or the L31 Marine cam. A good cheap converter upgrade is the 4.3 W S10 converter for the same year as your truck. It will stall around 2,600-2,800 rpm behind a F-car cammed L31.

    If you are going 0.030" over make sure to get a 1.56" compression height piston. I would also go with a flat top since it will give a slight compression boost. I would also go with a 0.016" compressed rubber embossed steel shim head gasket to get the quench as tight as possible. GM also offers a mls gasket that is 0.028" thick if the 0.016" gasket scares you.
     
    Last edited: Dec 5, 2018
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  3. trx125

    trx125 Newbie

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    Thanks for the info. I was going to stick with the 1.5 to keep from trimming the valve guides and messing with screw in studs, but 1.6 are still a possibility. I have flat top pistons and going with an arp stud kit for the heads and mains. I'll have to check out the .016 head gasket, cometic maybe? What about a double row timing chain set? I know slight strength advantage and but slightly more rotating mass, but seems to be a debate as to whether it will fit or not. I know I'll need an aftermarket cover with a crank sensor hole.
     
  4. L31MaxExpress

    L31MaxExpress I'm Awesome

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    Use the comp 787 retainers and the LS6 springs, no need to cut the guides. I have had the LT F-car cam and 1.6s on stock springs and retainers. I had .0530" retainer to valve seal clearance on multiple sets of Vortecs simply fully seating the seals. Ran them thousands of miles with no ill effects too.

    Felpro .016 rubber gasket has worked well for me. Current setup has the GM 0.028" MLS gasket because I have aluminum heads on it.

    I run the GMPP single roller chain on my 350 with .578" lift on a 215/224 @ .050 comp custom grind cam and double springs. Has not given me issues with the occasional 6,200+ rpm shift and 6,000 rpm shifts everytime it is driven. I also run a big block oil pump. My CMR has not changed at all in 20K miles. I datalog the CMR angle everytime I change up the tune on mine. It stays a consistant 0.2 to 0* every run even at WOT high rpm. I do have an aluminum base distributer for cam signal reference only and it is correctly shimmed. I have not had the engine cover off mine in 8 months and about 20K. Since the engine has been together I have changed the oil once, the engine filter 4x and cleaned the K&N once. I run an Amsoil bypass filter. The oil looks like new at 10K, Blackstone testing shows it could go 20K but Mobil One 0w40 is fairly cheap. My bypass filter gets changed yearly and its not cheap but it is worth having like new oil forever in the engine. I think alot of the good oil testing results are the Total Seal gapless street rings that keep blowby to an absolute minimum.
     
    Last edited: Dec 5, 2018
  5. trx125

    trx125 Newbie

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    Comp 1.6 rocker set from summit?
     
  6. trx125

    trx125 Newbie

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    I'll have the heads at the machine shop next week, I might as well go ahead and have him cut the bosses down and install the screw in rocker studs.
     
  7. L31MaxExpress

    L31MaxExpress I'm Awesome

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    I built Assault Racing 200cc Aluminum heads for $800 for mine that flow 265 cfm @ .550" lift. Engine runs very strong with them. The ports are a little larger than I wpild have liked but it still comes on ALOT sooner than a LS in the torque department.
     
  8. c1500deathtrap

    c1500deathtrap I'm Awesome

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    Drill the pushrod holes to 1/2" ? Do you mean the oiling holes in the pushrod? The pushrod itself is less than half of an inch in diameter..... And i would wager that with that low of a lift cam the push in rocker studs are okay. At least they are on my setup, but more stable is more better so if they're already at the shop i don't see why not.
     
  9. L31MaxExpress

    L31MaxExpress I'm Awesome

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    I am talking about the hole in the cylinder head where the pushrod comes through. When you go to a higher ratio rocker the pushrod moves in closer to the rocker stud. The pushrod can then possibly bind in the pushrod hole. Drilling it larger is an easy fix or quick and cheap insurance from broken or bent pushrods..
     
  10. c1500deathtrap

    c1500deathtrap I'm Awesome

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    Okay, just checking it wasn't clear to me from the post. To me it sounded like you wanted to drill the pushrod.
     

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