'78 Big Block to 6.0 Swap

Discussion in 'High Tech Retrofits' started by Gene'78-LSX, Jul 6, 2015.

  1. Gene'78-LSX

    Gene'78-LSX Member

    Messages:
    54
    Likes Received:
    0
    Joined:
    May 31, 2015
    Location:
    New Braunfels, TX
    reedld:

    I love the T/A!! I can't weld good enough to trust myself on a fuel tank ant not allways worry that it will leak. About 12 years ago I had a second gen fuel tank flash (explode) on me while I was trying to melt the factory lead that holds in the vent tube so I could swap it over to my new tank. The flash burned my eyebrows and hair and melted my eye lashes together and gave me second degree burns on my face. The sending unit shot out of the tank and cut my leg before it rocketed to the roof. I had drained the tank rinsed and washed it out with a diesel powered steam cleaner pressure washer for about ten minutes and let it sit outside for three days before I started working on it. So welding or cutting on a tank is a no go my relatives would probably commit me....:screwup:

    Can I use the same accessories (alt, ac, ps,) with different brackets and water pump? or they not interchangeable?
     
  2. reedld

    reedld Veteran Member

    Messages:
    268
    Likes Received:
    5
    Joined:
    Aug 9, 2007
    Location:
    Painted Post NY
    ouch!
    I did the gas tank mod on a new tank-never even considered to mod a tank that had fuel in it. I've heard mixed reviews on the spectra tanks. lots of pump failures. I prefer the OEM fuel bucket for many reasons...GM engineered it that way..and works awesome. The tanks inc looks like a real nice setup with nobody unhappy from what I've read.

    I'm not sure about the bracket/accessory interchangeability...again, quick google search or hop onto LS1tech in the hybrid section- lots of LSx topics there. This site is one of the best for dealing with 2nd gen specific LS swap topics. Also, jump onto transamcountry.com...there is a guy who recently trimmed the factory truck intake and fit without hood mods. the truck intake is ugly but it does flow well-some say 7hp more than the ls1 intake. there are topics out there on how to "shave" it...looks real nice but I would be worried about leaks.

    The LS route is great but can be REAL pricey...do your research!

    off topic- just got back from a vacation out near you-canyon lake. My nephew graduated HS and I went down to visit.
     
  3. DFWJ

    DFWJ Veteran Member

    Messages:
    300
    Likes Received:
    0
    Joined:
    Aug 16, 2012
    Location:
    DFW
    In regards to the fuel pressure, if you build a new system, with new injectors, pump, ECU, all of that will be built around a 43-45psi rail pressure. You won't need to worry about it.

    You start to run in to some issues when you use a pump designed to hold X flow at 45psi and then try to run it at 60 psi to get the stock injectors to fire correctly being controlled by a factory ecu.

    I looked at going an LS in my Camaro project, but decided I could make more power with the BBC. I can build and tune my own efi system, so I went the the FAST XFI for this one.

    I still may do an LS swap in another project; I would look for a 6.0 w the 4l80e trans. The 80 is basically a th400 w/an OD.

    I would avoid the FAST Ez, the XFI is what you want. Or BigStuff3, or ... too many quality systems. several can control trans as well as engine now. So you may be able to simplify some wiring that way.

    US Shift makes a shift programmer for most of the modern OD trans that is super easy. This may be cheaper than getting an EFI ecu that controls trans.
     
  4. Gene'78-LSX

    Gene'78-LSX Member

    Messages:
    54
    Likes Received:
    0
    Joined:
    May 31, 2015
    Location:
    New Braunfels, TX
    Goodwrench1965:
    One of the main reasons I am swapping the engine is that i couldn't get the big block to run cool without A/C there was no way it would work with an A/C. It was an awesome engine ran great sounded incredible and was a hand full to drive with the 4-speed but the cooling issues were so bad that it was overheating in 40*F weather last winter that's when I gave up on it. It was a flat top engine 20 over KB pistons 10 in the hole beam polished & shot penned rods all balanced block was de greased pressure washed then boiled bored with torque plates the works it was done right as far as I knew 15yrs ago... I ran the engine as a commuter to college and back in my '76 chevy short bed while I was doing the body work on the Camaro back in 2000-2001 ish. I had a smaller hyd flat tappet cam and it would not overheat if you were moving but you could not sit in traffic for long it would start climbing. When I painted the Camaro I pulled the engine and painted it color match with the autobody paint (might have been a mistake) everyone says no but I think it might add to the cooling issues by not letting the block radiate the heat as well as engine paint (non clear-coat). The Camaro has a larger Solid lifter Crane cam F-290-2 500 int 256*@50 600exh 266*@50 it sounds nasty and pulls hard from about 3K up and It had zero flat spots from idle up but the heat is out of control! I have 2" primary longtube headers dumping into true dual 3" mandrel bent pipes 3" in and out flowmasters and 3" tail pipes over the axle out the back. I ran a new 4-core brass copper radiator with clutch fan and shroud also ran dual electric fans tried every type and heat range of t-stats from 190*-160* to no t-stat to a restrictor plate. I replaced the new cast iron water pump with an edelbrock high volume anti cavitation pump. I ran the redline water wetter I ran different mixtures of water and antifreeze I ran royal purple antifreeze. I purchased a new aluminum radiator with 2x 1" wide cores all aluminum welded no epoxy no lead no plastic etc. guaranteed to cool 700hp...I replaced the lower radiator hose with a reinforced hose that cannot suck flat. I got a MSD pro billet dist and 6al box and hot coil to make sure my timing and timing curve was spot on. I ran several different heat ranges cooler on the plugs due to the change to MSD etc. I was told it was to lean I needed to run larger jets. I played with the jetting to fatten it up even thought the plugs were nice and tan all it did was make it load up. I was running power valves in the mighty demon so It was happy with the smaller jets than the guys who blocked off their pv and only ran wot at the track. I used the gauge on my vacuum can to determine the idle vac and selected the appropriate pv etc. I put header wrap on the headers I tried the intake mod where you plumb coolant lines from the front of the intake to the rear water jackets to promote flow to the rear of the block....which is a joke by the way since the water comes from the front of the block around the cylinders to the rear of the block then up through the back of the head to the front of the head out into the intake out of the water neck and into the radiator. The coolant lines would only serve to bypass the cylinder head not cooling it and dump it back into the intake by the water neck and most likely make it run hotter. Tried blocking the water pump to intake by pass hose and only run a restrictor plate (no t-stat). Ran with auto trans ran with 4-speed I even ran the car down the highway without a hood! No dice :mad: After a ton of research and trying everything I could think of I ran into one last posibility....Apparently not all Mark IV big blocks are the same... Somewhere along the line GM changed the cooling system from series flow to parallel flow
    by adding coolant passages to between each cylinder to allow water to flow up from the bottom of the block beside each cylinder and then through the head and out to the radiator rather than having to go to the back of the block up to the back of the head across the head and out to the radiator. So the heads will interchange but if you use the parallel flow gaskets they will block off a large majority of the rear coolant passage on the back of the block due to the new design in to force water up between the cylinders and if you have the early Mark IV block like I do this will inevitably cause a cooling problem that cannot be corrected by any number of cooling tricks or tips. I thought wow this must be it I have finally found out why I have had so much trouble and have sent so much $$ trying everything and anything to cool this thing. So i decided to pull a cylinder head and accept the fact that a stupid gasket had been kicking my butt.. Well the Felpro gasket was the correct series flow gasket and I was once again out of ideas and at this point patience.....

    Well now you know how I ended up here...;)
     

    Attached Files:

  5. oldscamaro

    oldscamaro New Member

    Messages:
    20
    Likes Received:
    0
    Joined:
    Sep 19, 2014
    Location:
    Prince George, BC
    Wow that is crazy. I had a big block in my car before the ls swap. Did pretty good for heat. Ran a comp cams 282 duration at.006 and .561 lift. 10.8 to 1 compression. Iron oval port heads. 160 thermostat and water wetter. As long as the car was moving no problems. It did like to heat up idling though. Never to bad though. The clutch fan managed to keep it under control. The only reason to get rid of the water pump bypass is if you are running a restrictor instead of a thermostat other wise it will cause cavitation. Do you run a heater core or did you delete it?
     
  6. Gene'78-LSX

    Gene'78-LSX Member

    Messages:
    54
    Likes Received:
    0
    Joined:
    May 31, 2015
    Location:
    New Braunfels, TX
    I had a new heater core hooked up but it made the interior so hot it was impossible to enjoy the car even in shorts with the outside air vents open (factory non A/C car) you would sweat constantly after about 15 min of drive time. I installed a ball valve inline on the pressure side to prevent the hot water from flowing through the heater this helped keep the interior temps down but you would still roast. You would not dare drive it if it had been sitting in the sun somewhere. My Dad has an original '69 SS 396 Chevelle with factory A/C and it will stay right around 190-200 without A/C it is in the paint & body work stage so the A/C is there but not charged yet not sure what it will do. He said back in 1969 you could run it hard on the highway and then sit in traffic all day long with the A/C and it would never overheat....I wonder how much difference the old high octane leaded fuel made on keeping the temps down...?
     
  7. oldscamaro

    oldscamaro New Member

    Messages:
    20
    Likes Received:
    0
    Joined:
    Sep 19, 2014
    Location:
    Prince George, BC
    I was just thinking it might need the bypass do easy trees is to run a house from one port to the other instead of blocking them off. Have you gone to a serpentine belt setup or any thing. That may be spinning the water pump backwards. If so a reverse flow pump would help. Just throwing ideas at you hate to see a car down.
     
  8. FlatPat

    FlatPat New Member Lifetime Gold Member

    Messages:
    5
    Likes Received:
    0
    Joined:
    Mar 29, 2012
    Location:
    Austin, TX
    Grab a water pump from a 2010+ Camaro LS3 water pump. It will let you run the truck accessories with an LS1/6 style intake.

    Look on CL I see used LS6 intakes with rails/injectors on there fairly often. The stock LS rails (2001+) are what is called returnless (just mean they only have a feed line) which may be an easier fuel system for you to plumb/use. You would use the Corvette filter/regulator which you can mount close to the tank to run feed and return lines between the filter and tank. Then you only need one (feed) line from the filter to the rails. The Corvette filter/regulator is preset to 58 psi. The stock LS6 injectors flow 28.8 lbs @58psi and could get you close to your HP goal but you’ll probably be running 90+% duty cycle. A popular injector is the 30 lbs Ford SVO injectors, they flow 30 lbs @ 45psi so they are around 37 lbs @ 60psi. A 225lph @60psi pump will handle the power level you’re looking at so the 255lph will work just fine. If you are looking at force feeding the engine down the road you might as well get the 340lph and some 60 lbs injectors not that much more and will handle all the fuel you’ll probably ever use.

    With an LQ9 you can get to your HP goal with a better cam and headers pretty easily. Texas Speed as some appealing options for both.

    One thing to consider when looking at the FAST EZ EFI computer is it does not control transmissions. I would hold off until you do make the switch to the 6 speed. The LS computers are pretty powerful and a good tuner can control a lot using them.

    Not quite sure about mounts yet. I haven’t swapped to a 2nd gen yet (couple trucks, pretty easy) but it’s my plan when I get back from overseas next month. If you are later going to be switching to a 6 speed I would get engine mounts that allow you to adjust the motor back and forth this will help with lining up the shifter. From what I understand the truck oil pan will work on the 2nd gens but might sit a little too low if they car is low already. The f-body LS1 pan is the preferred pan. I think Holley makes a LS swap pan that is supposed to fit very nicely but is a little pricey.

    The LQ series with iron heads had the longer crank for running the 4l80e after which they then got the crank spacer for running the 4l80e. Your 2004 if it came from a Cadillac would have had a 4l65e behind it and the 4l60e from the 5.3 should bolt right up to it. If you drive fairly conservatively you might get the 4l60e to last behind a 500hp LQ9 for a while. Even if it’s just a place holder till you get a 6 speed I would probably slap a rebuilt kit in it, vette servos and a better converter or get a 4l80e.

    I am by no means an expert but I can at least relay what I’ve learned from doing these swaps. They are really not that hard to do. I've even rewired my own harnesses.
     
  9. Gene'78-LSX

    Gene'78-LSX Member

    Messages:
    54
    Likes Received:
    0
    Joined:
    May 31, 2015
    Location:
    New Braunfels, TX
    oldscamaro:

    I was running the stock type v-belt setup with stock ratios as far as I could tell. Dads '69 Chevelle has a vacuum operated shutoff valve on the pressure side from the factory so I just assumed it would be okay..? I ran it open and closed with little difference other than the interior temps climbing a lot faster and a little higher when open. After further investigation I did find what seems to be excess casting flash on the rear water jacket port (the main well for water flow from block to head) not sure if this would be enough to cause the problem....? I have attached pics...I also attached an image of another head off of a 90(s) 1 ton truck. My head is a 1968 oval port the truck is the small peanut port but it has huge water jackets.
     

    Attached Files:

  10. Gene'78-LSX

    Gene'78-LSX Member

    Messages:
    54
    Likes Received:
    0
    Joined:
    May 31, 2015
    Location:
    New Braunfels, TX
    FlatPat:

    Great info!! Thank you. I have decided to skip the ezefi and go with the XFI LS 2.0 I do want to do boost down the road if I can get everything else working properly. I like your idea of getting the larger pump now I wont over heat it with my low fuel requirements will I ? Do I need to get some sort of modulator controller to not kill it on the street? I figure as it is in the tank it should be okay I guess...? I believe I have to ditch the truck brackets because the A/C will hit the crossmember and the PS pump will hit the steering box...? I am thinking about going with the holley brackets and try to use the truck alt ps ac. I will look at the Camaro water pump if I go with the car style intake. I am going to see if I can get the truck intake to fit under the stock z28 hood.

    My first child is on the way :) so I have had several unexpected bills :eek: that have ate away at my project funds... so I have to wait a week or so before I can start ordering parts....

    Thank you for the advice this is my first try at EFI.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.