GM Inside - Ford Inside - Ford Ranger - Jeep - American Muscle

Support FSC and see no ads! - Click Here
Results 1 to 20 of 20

L29 Questions.

This is a discussion on L29 Questions. within the Performance forums, part of the General Discussion category; Hey guys its BEEN a while since ive been on here! I am going to start tearing into my daily ...

  1. #1
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    L29 Questions.


    Support FSC and see no ads! - Click Here
    Hey guys its BEEN a while since ive been on here!

    I am going to start tearing into my daily driver, and I need a few questions answered hopefully there are few BBC guys that can help out. Im doing all these mods to be more competitive in the stock truck pulling class at local fairgrounds, I am tired of being out pulled by mid 90s ford 460s! and to gains some mileage out of the truck. (I know this is not really possible but one can hope) Oh truck specs: 98, 4x4, xcab, shtbed, L29, 4L80E with 3.73's

    My Plans are:

    *0411 ECM
    *EFI live tune
    *long tubes
    *no cats
    *4" exhaust
    *cold air intake
    *Port match the lower intake to the cyl head ( I read this really helps)

    so my questions for the BBC guys with L29s:

    What shape are the ports on the stock heads?
    Does the lower intake port matching really help?
    What else can i do to gain power/economy (without pulling the cam)
    Thanks for any help or opinions.

    Joe

    Note: I refuse to change to tbi
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  2. #2
    Registered User 454cid's Avatar
    Join Date
    Mar 2003
    Location
    West Michigan
    Age
    41
    Posts
    4,643

    Re: L29 Questions.

    I have a stock engine.......... the stock air cleaner setup is a cold air intake. The ports on the stock heads are small oval.

    I don't understand the TBI statement...... why would you switch to TBI from MPFI?
    454cid
    1999 K3500 RCLB

  3. #3
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    Quote Originally Posted by 454cid View Post
    I have a stock engine.......... the stock air cleaner setup is a cold air intake. The ports on the stock heads are small oval.

    I don't understand the TBI statement...... why would you switch to TBI from MPFI?
    From what k&n says an new air intake is good for over 20 horsepower.

    http://www.knfilters.com/dynocharts/57-3016_dyno.pdf

    From what Ive read the L29 head are about as good as the TBI swirl port heads! and thos were junk. Ive read that you can make them better but you need to spend a bunch of time machining and grinding the intake bowls and the Combustion chamber. (it makes no sense to me GM usually has great head design)

    and sorry about the TBI statement I posted this exact question on another site, TBI is a running joke on that site.
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  4. #4
    Registered User 454cid's Avatar
    Join Date
    Mar 2003
    Location
    West Michigan
    Age
    41
    Posts
    4,643

    Re: L29 Questions.

    Quote Originally Posted by BowtieWarrior View Post
    From what k&n says an new air intake is good for over 20 horsepower.
    They're also trying to sell you something. I'd never pay all the money they want for all that plastic.

    From what Ive read the L29 head are about as good as the TBI swirl port heads! and thos were junk. Ive read that you can make them better but you need to spend a bunch of time machining and grinding the intake bowls and the Combustion chamber. (it makes no sense to me GM usually has great head design)
    I think they're probably better than the Gen V TBI heads, but they're also built for torque so they don't flow as much as some of the early MkIV heads, or aftermarket. I've read lots of posts by "experts" that don't really seem to know what a L29/GenVI engine is though, so I doubt the accuracy of a lot of what I read whenever I've looked for information on those heads. I've also seen that the TBI heads are listed as covering some of the Vortec years on some of the casting number charts. I don't know if that's a mistake or not, since I didn't think Gen V heads would bolt onto a Gen VI block correctly. It could be a source of confusion, Though.
    454cid
    1999 K3500 RCLB

  5. #5
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    Quote Originally Posted by 454cid View Post
    They're also trying to sell you something. I'd never pay all the money they want for all that plastic.



    I think they're probably better than the Gen V TBI heads, but they're also built for torque so they don't flow as much as some of the early MkIV heads, or aftermarket. I've read lots of posts by "experts" that don't really seem to know what a L29/GenVI engine is though, so I doubt the accuracy of a lot of what I read whenever I've looked for information on those heads. I've also seen that the TBI heads are listed as covering some of the Vortec years on some of the casting number charts. I don't know if that's a mistake or not, since I didn't think Gen V heads would bolt onto a Gen VI block correctly. It could be a source of confusion, Though.
    yes, I agree on the plastic thats why I am going to make my own.

    and yes, yes, yes, the stuff on the net makes it very hard to pick out the real from the fake the good from the bad. thats is why im asking on this site there are many more BBC guys on this site and i feel if I get a lot of repitition I can make a decent judgement.

    as I stated in my original post, I am trying to be more competitive in the "stock" truck pulling class, If i cannot do this someone affordable then I am not going to mod my BBC beyond the 0411. its really my daily driver and my tow rig so I don't need to spend any money on Go fast stuff for it I've got plenty of money/time wrapped up in my L31 truck.
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  6. #6
    Registered User 454cid's Avatar
    Join Date
    Mar 2003
    Location
    West Michigan
    Age
    41
    Posts
    4,643

    Re: L29 Questions.

    Have you seen this thread? Reading the whole thing is like a full time job...... http://www.fullsizechevy.com/forum/g...ec-owners.html
    454cid
    1999 K3500 RCLB

  7. #7
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    Quote Originally Posted by 454cid View Post
    Have you seen this thread? Reading the whole thing is like a full time job...... http://www.fullsizechevy.com/forum/g...ec-owners.html
    yeah, that thread IMO has some great info but is so misleading and "dirty" it needs to cleaned out it has so much irrelevant info in it.
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  8. #8
    Registered User 454cid's Avatar
    Join Date
    Mar 2003
    Location
    West Michigan
    Age
    41
    Posts
    4,643

    Re: L29 Questions.

    Quote Originally Posted by BowtieWarrior View Post
    yeah, that thread IMO has some great info but is so misleading and "dirty" it needs to cleaned out it has so much irrelevant info in it.
    A 454 sub-forum was requested, but apparently the board administration doesn't want to do it, so the one thread gets filled up with everything. Some stuff is chit chat, and some stuff is more about the truck that the 454 is installed in. Even if it's not about the engine it's nice to be able to ask guys something that you know they know what you're talking about.
    Last edited by 454cid; 08-29-2011 at 10:23 AM.
    454cid
    1999 K3500 RCLB

  9. #9
    Registered User Busted Knuckles's Avatar
    Join Date
    Oct 2006
    Location
    Texas
    Posts
    1,160

    Re: L29 Questions.

    Email me at 81vette4speed@suddenlink.net, I'll send some pics of the mod I made to the top half of the clamshell intake. There's a significant restriction where the ports split. Port matching of the lower intake will help.
    L29 heads have almost the same port size as 781/049 castings, they're large ovals. The swirl ramp is somewhat restrictive as is the vane in the chamber, it shrouds the valves badly. If the rules allow it, I'd find some closed chamber 396 heads (702 castings) and have those reworked, you'll pick up 30+ hp.
    You'll probably want bigger injectors, factory is about 19lbs IIRC.
    4" exhaust is too big if it's duals.
    Stroke it and spray it!

  10. #10
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    Quote Originally Posted by Busted Knuckles View Post
    Email me at 81vette4speed@suddenlink.net, I'll send some pics of the mod I made to the top half of the clamshell intake. There's a significant restriction where the ports split. Port matching of the lower intake will help.
    L29 heads have almost the same port size as 781/049 castings, they're large ovals. The swirl ramp is somewhat restrictive as is the vane in the chamber, it shrouds the valves badly. If the rules allow it, I'd find some closed chamber 396 heads (702 castings) and have those reworked, you'll pick up 30+ hp.
    You'll probably want bigger injectors, factory is about 19lbs IIRC.
    4" exhaust is too big if it's duals.
    Stroke it and spray it!
    Busted,
    Thanks for the info I very interested in seeing the pictures of your modifications. Right now I am for sure doing all sorts of information gathering so I can do this work next spring after the snow comes and goes.

    Ive been trying to find out if old BBC heads will bolt on to a L29 block and intake, you mentioned 702 are you referring to the late 90s Kodiak/top kick 6.0 liter heads? (ive seen these trucks with a BBC in them that was not a 7.4 ) Or are you talking about the old 70s 396 heads?

    My plan is to run dual 3 pipes off the long tubes into a single 4 that I got off a 454 powered school bus.

    I always thought the injectors on the BBC were 24# if they are 19# then I for sure need new ones.

    Does anyone know if I can remove the existing FPR and upgrade to an aeromotive FPR?

    I would love to build it out to stroker, but the problem is the heads what is the point of more cubes on junk heads/intake.

    And all my buddies say NO2 as well but I would need to build a very sneaky system to pass tech inspection.
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  11. #11
    Registered User Busted Knuckles's Avatar
    Join Date
    Oct 2006
    Location
    Texas
    Posts
    1,160

    Re: L29 Questions.

    702's are late 60's closed chamber 396 heads. If you can find someone who knows what they're doing, the chambers can be opened up around the valves to significantly improve airflow. Chevy didn't screw with the bolt pattern on the big block stuff, they'll bolt up, use the Gen 6 gaskets.
    All my research showed the injectors at 19lbs, I had folks recommend 29lb injectors for my stroker.

  12. #12
    Registered User 454cid's Avatar
    Join Date
    Mar 2003
    Location
    West Michigan
    Age
    41
    Posts
    4,643

    Re: L29 Questions.

    Quote Originally Posted by Busted Knuckles View Post
    ..........Chevy didn't screw with the bolt pattern on the big block stuff, they'll bolt up, use the Gen 6 gaskets.
    The bolt pattern wasn't what I was thinking of in my post. The coolant passages can be an issue...... Gen V especially, but I don't know what might need to be done to use MKIV heads on a Gen VI....... the coolant is series on one and parallel on the other. I think the Gen VI is parallel. I'd love to try Gen VII heads, but GM did mess with the bolt pattern (due to coolant passages being changed again) on the 8.1L.
    454cid
    1999 K3500 RCLB

  13. #13
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    From what I have read there is a difference in the L29 heads and intake from the 60-70s heads, coolant flow actually makes sense. I think if I choose to change heads Im going to go to the a Bowtie steel head that will work with the L29 intake manifold, and appear stock but as for now Im more concerned with the amount of machine work that the intake needs it honestly doesnt make sense GM would make it this way.
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  14. #14
    Registered User 454cid's Avatar
    Join Date
    Mar 2003
    Location
    West Michigan
    Age
    41
    Posts
    4,643

    Re: L29 Questions.

    Quote Originally Posted by BowtieWarrior View Post
    From what I have read there is a difference in the L29 heads and intake from the 60-70’s heads, coolant flow actually makes sense. I think if I choose to change heads I’m going to go to the a Bowtie steel head that will work with the L29 intake manifold, and appear “stock” but as for now I’m more concerned with the amount of machine work that the intake “needs” it honestly doesn’t make sense GM would make it this way.
    They're cast iron, not steel.
    454cid
    1999 K3500 RCLB

  15. #15
    bikes cars trucks women vic_V8's Avatar
    Join Date
    Jan 2004
    Location
    Dixon IL
    Age
    31
    Posts
    3,769

    Re: L29 Questions.

    this is a 1/2 ton truck right? so you still have the 10 bolt rear and the IFS front that you can't add a traction aid too? When I pulled my old 91 the front diff was the biggest down fall
    Selling a front Chevy Dana 60, 5.38s welded, $1000 never run, PM for more
    1992 K2500 6.5 Turbo Diesel/4L80e/4.10s (sas with Dana 60 just sitting around waiting for a rainy day)
    '84 K10, 6" Tuff Country, now 1 ton frame swap and Cummins swap have begun
    Veteran of Afghanistan (Army SGT)

  16. #16
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    Quote Originally Posted by vic_V8 View Post
    this is a 1/2 ton truck right? so you still have the 10 bolt rear and the IFS front that you can't add a traction aid too? When I pulled my old 91 the front diff was the biggest down fall


    No, its a 3/4 ton truck 8 lug with 14 bolt FF rear. and yes stock class I cannot add any traction bars front or rear.
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  17. #17
    bikes cars trucks women vic_V8's Avatar
    Join Date
    Jan 2004
    Location
    Dixon IL
    Age
    31
    Posts
    3,769

    Re: L29 Questions.

    got you, I meant traction aid as in a Locker. Are you in Lombard IL? I have a SAS kit sitting around I just haven't pulled the trigger, I'll have a 4.10 front laying around for cheap when I do. I will also have a set of 4.10s for a 14FF also laying around.
    Selling a front Chevy Dana 60, 5.38s welded, $1000 never run, PM for more
    1992 K2500 6.5 Turbo Diesel/4L80e/4.10s (sas with Dana 60 just sitting around waiting for a rainy day)
    '84 K10, 6" Tuff Country, now 1 ton frame swap and Cummins swap have begun
    Veteran of Afghanistan (Army SGT)

  18. #18
    bikes cars trucks women vic_V8's Avatar
    Join Date
    Jan 2004
    Location
    Dixon IL
    Age
    31
    Posts
    3,769

    Re: L29 Questions.

    also, I misunderstood and though you were swapping in a BBC, hence I was worried about it being a 1/2 ton
    Selling a front Chevy Dana 60, 5.38s welded, $1000 never run, PM for more
    1992 K2500 6.5 Turbo Diesel/4L80e/4.10s (sas with Dana 60 just sitting around waiting for a rainy day)
    '84 K10, 6" Tuff Country, now 1 ton frame swap and Cummins swap have begun
    Veteran of Afghanistan (Army SGT)

  19. #19
    Wheres the mud BowtieWarrior's Avatar
    Join Date
    Jan 2007
    Location
    Lombard
    Age
    29
    Posts
    157

    Re: L29 Questions.

    Quote Originally Posted by vic_V8 View Post
    got you, I meant traction aid as in a Locker. Are you in Lombard IL? I have a SAS kit sitting around I just haven't pulled the trigger, I'll have a 4.10 front laying around for cheap when I do. I will also have a set of 4.10s for a 14FF also laying around.
    I've contemplated going to 4.10, but I really don't want to gear it any higher because I do alot of highway driving. I honestly was considering going down to a 3.42 for hwy driving. I will keep it in mind tho thank you.

    Yes I live in IL, I actually just sold my 89K5 to someone that lives in Dixon. I used to store it in eldena I have a buddy that lives there.

    yeah, sorry about the confusion I have a 1/2 ton L31 truck and a 3/4 ton BBC truck.

    Joe
    1996 RegCab 2WD, 3/6 drop, L31 heavily modded! 1998 EXCab 4X4 L29 bone Stock! (pulling truck)

  20. #20
    bikes cars trucks women vic_V8's Avatar
    Join Date
    Jan 2004
    Location
    Dixon IL
    Age
    31
    Posts
    3,769

    Re: L29 Questions.

    small world, I also lived in Eldena, and my buddy still lives there.
    Selling a front Chevy Dana 60, 5.38s welded, $1000 never run, PM for more
    1992 K2500 6.5 Turbo Diesel/4L80e/4.10s (sas with Dana 60 just sitting around waiting for a rainy day)
    '84 K10, 6" Tuff Country, now 1 ton frame swap and Cummins swap have begun
    Veteran of Afghanistan (Army SGT)

 

 

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •