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What's going on with my engine

Discussion in 'The Garage' started by uglytruck, Jul 13, 2005.

  1. uglytruck

    uglytruck Registered Member

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    Recently I had a 383 engine built including boring to 060 over, roller cam (good torque) roller rockers, clevite77 bearings, hyperutectic pistons, etc... The problem I am having is an oil leak that is somewhere up in the bell housing area as the oil drips down mostly on the drivers side by the dust sheild and dripping onto the header. The oil is not coming from the rear main seal as the crank flange is totally dry. The leak gets much worse if I work the engine hard, Ie: Highway driving above 65, long steep grades, or when I am pulling the boat at speeds over 60 or up hills. The temp guage has never indicated above 200F and reads at 190-195 unless coasting down long grades. When engine is working hard oil pressure drops progressively from about 65psi to 45psi at about 2600rpm. I havn't been real impressed with the power output with this mill especially passing power as I thought I had built this engine to really be in it's power band above 2500rpm. I have chalked most of the lack of performance up to running 3.73s with 35" tires. The compression is 9.1 to 1 and does not ping on regular gas, however on occasion when I restart it does crank a little slow from timing being a little too advanced. :dunno:
     
  2. pornorob

    pornorob 1/2 ton status

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    a leak at the oil pressure sending unit :thinking: maybe????
     
  3. Mad-Dog

    Mad-Dog 1/2 ton status

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    There's a camshaft bore plug (freeze plug style) directly above the rear main seal......and the block also has threaded allen plugs that screw into the back of the block above and on each side of the rr mn seal.
    This is where the lifter vallley oil feed passage is.....
    If these plugs aren't sealed well they will leak.

    Having to run excessive ignition advance is a sign of poor combustion,
    due to combustion chamber size, design, valve-timing or weak ignition.
    The stock HEI (which is already lame) starts dropping serious power around 4500 rpm.

    Something aint meshing with your combination of parts, why don't you tell us everything about the motor.....cam specs, heads, intake, exhaust, carb, ignition, pistons, rods.....EVERYTHING...!
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Long shot, but my Vortecs were mis-tapped at the factory, and the accessory bolt holes in the heads would "bleed" if I didn't find that when I assembled the motor, and plugged them with bolts with thread sealant on them. It wouldn't have leaked MUCH, but it would have been more common at higher engine RPM's as oil gets slung about much more.

    Don't ask me how I know about oil leaks/RPM...something about leaving the hole on the front of the block that holds the fuel pump pushrod in place, off. :wink1:

    More likely to be plugs as mentioned, or the oil pressure sender.
     
  5. uglytruck

    uglytruck Registered Member

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    I replaced the the fittings that thread into the block and have verified no leaks there. It has tubing to an after market guage. Thanks for the reply.
     
  6. uglytruck

    uglytruck Registered Member

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    Thanks for the good info. mad dog. I am leaning towards just putting up with the way it is for now so I don't have to take it down during boating season and miss the upcoming blazerbash. However I will do a compression test and get a complete list of parts I put in that $ pit :mad: ,which I wouldn't mind a bit if it ran like it.
    Let me know if that isn't a good idea as I sure don't want any more problems with this engine, I've run out of time today I will continue tomarrow.
     
    Last edited: Jul 20, 2005
  7. Mad-Dog

    Mad-Dog 1/2 ton status

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    I'm not a advocate of running a engine with a oil leak, especially if it increases with rpm which is a great indication it's tied in with the high-pressure lubrication system.
    keep a eye on it bro.....hate to see ya break it. :bow:
     
  8. gambit420s

    gambit420s 1/2 ton status

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    it could be the rear intake manifold seal, i have a f**d van that was leaking there and even though i was staring right at it :doah: it took me a while to figure it out... the gaskets that are for the area suck big time and dont have enough surface to stay put, i remember seeing a gm tech post up here, bout a service memo that told them to throw the gaskets away and use rtv/silicone. thats what i do know and havent had a motor leak there yet, but check your oil pressure sending unit too its in the same area...
     
  9. uglytruck

    uglytruck Registered Member

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    Thanks gambit. It is sealed as you advocate and the oil is not anywhere on the outside of the bell housing area until it exits at the bottom.
     
  10. uglytruck

    uglytruck Registered Member

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    engine specs

    Here you go Mad dog this is every thing. 70's era 350 4bolt main block bored .060 over all work done by a reputable local machine shop, double roller time chain, 400 scat crank* (* means I can't read the p/n off the receipt because of water damage), I beam rods* same as for 350 engine, competition roller cam p/n124078 duration 252/258 lift .472/.480, hydraulic roller lifters p/n cca-885-16, roller tip rockers p/n sum141506 1.5to1, edl heads p/n edl60739 rpm aluminum 70cc chamber 170cc intake runner, wiend intake p/n8004 dual plane aluminum for qjet, edl qjet carburetor p/n edl1901 750 cfm, HEI from junkyard reworked with new parts and cap/rotor no performance parts though. All these parts should put some power to the pavement, right?
    With these hydraulic lifters do they need to be adjusted to exact specifications or is close good enough as I had to go back and loosen a couple of rockers that were adjusted too tight (acts just like a bad vacuum leak :mad:).
    What would you recommend for spark plugs as with being a different ignition and style plug wasn't exactly sure of an optimum plug to run.
    I have a very tight budget as I have already sunk a ton more $$ into this blazer than I planned on and sill have other things to do on this old truck.
     
  11. Mad-Dog

    Mad-Dog 1/2 ton status

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    (competition roller cam p/n124078 duration 252/258 lift .472/.480,
    Smooth idle, 600-4600 rpm powerband, good torque)
    That cam has 200/206 degrees dur. at .050" valve lift, that's slightly better than stock.....i don't know what your static CR is but the motor probably has excessively high cylinder pressures.
    Run a compression test when you get a chance and get back to me, I'm thinking they will be very close to 200psi.
    Definately the wrong cam for a 383 with roughly (i'm guessing here) 9:1 CR,
    If you can find the deck height, compressed gasket thickness and type of piston then we can figure the CR.
    hypothetically speaking.....with 70cc chambers, 5cc inverted dome (-5cc) piston, .035" deck height (unless the deck has been milled) and a .039" compressed gasket the static CR is 9.72:1.......need a lot more cam with this much compression.
    chances are the deck has been milled .010" bumping the CR to 9.93:1 (uh-oh), or flat-top pistons are in there bumping the CR to 10.46:1 (you're grounded young man).............see what were dealing with here...?
    Lets hope the pistons have a 12cc dish (-12) lowering the CR to 9.28:1, or better yet a 15cc dish rounding things off with a compatible 9.03:1 CR

    (edl rpm aluminum 70cc chamber 170cc intake runner)
    Those heads match well with the small cam, 190cc intake runners would be my smallest choice on a 383.

    (these parts should put some power to the pavement, right?)
    Yes.......at low rpm's

    (With these hydraulic lifters do they need to be adjusted to exact specifications or is close good enough)
    Adjust till zero lash then 1/2 turn more, it's best to adjust them with the engine not running.

    (What would you recommend for spark plugs as with being a different ignition and style plug wasn't exactly sure of an optimum plug to run)
    Whatever Edelbrock recommends, i couldn't find any plug info on em.

    (I have a very tight budget as I have already sunk a ton more $$ into this blazer than I planned on and sill have other things to do on this old truck.)
    I know the feeling UT, that combination of parts is why you're not impressed with the power and also why it seems lame above 2500, you're expecting a mid-upper powerband with a recipe that cooked up a stump puller.
    At the bare minimum i would change out the cam for the XR264HR which has
    212/218 at .050, 264/270 advertised, .487/.495" lift, 110 LSA, add some 1.6:1 rockers and stir for a corrected valve lift of .519/.528"
    That would give you the mid-range you're looking for without over-camming the 170cc intake runners.
     
  12. uglytruck

    uglytruck Registered Member

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    Mad dog,
    The machinist did all the math to come out a ratio of 9.1to1. I had stressed torque as being more important than HP. Although I am not sure what 450 lbs of torque should feel like as opposed to 450 HP. At full throttle I do have axel wrap issues in 1st and 2nd and sometimes 3rd gears, which I have no complaint with. I just need to get after the shackle flip and re-arch the springs with the addition of an overload spring should help if not fix that.

    I wanted an engine that I could putt around around on the trail w/o having to really spool it up to get up the hills. With my 3.73 gearing engine turns around 2800 rpm at 75mph so I don't need or wan't much more than that. I just want to be able to pull the 6% grades w/o needing to downshift when moderatly loaded down :D .

    I am toying with your cam change suggestion, although I remember my machinist saying that w/o out lengthened valves that they would bottom out w/ the 1.6to 1 rockers.

    I read your link to combustion theories and this has me wondering where that leaves me as far as ignition timing.
     
    Last edited: Jul 21, 2005
  13. Mad-Dog

    Mad-Dog 1/2 ton status

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    A 6% grade is pretty steep bro....I pull a 6% grade headed north outta Phoenix on I-17 just south of Flag, man i came up there 1 night and there was hundreds of Elk standing around.
    I am suffering the same spring-wrap issues and have decided to fabricate a parallel bar setup which is basically just the upper half of a 4-link, that will prevent the axle from twisting while still allowing the suspension to cycle thru it's range.
    UT i run thru Phoenix every 2 weeks, lemme know if ya need something delivered to ya from Cali, Florida or all points between.
    Anyway the 9:1 motor would be so much happier and stronger with more cam,
    I try not to hate myself for several high-dollar mistakes i've made while building "project scottsdale", like buying $880 Dart Iron Eagle 180's with 64cc chambers and 2.02/1.60's for the 350 then stroking it to 383cid with 10:1 CR :doah: , now i needed a set of Pro-Comp Engineering 195's in aluminum with 64cc chambers and 2.05 intakes for $850 :deal:
    Next mistake was a Comp 4x4 cam with 218/224 at .050" on a 111 LSA, great torque but the motor was not comfy at hiway speeds so in goes a XE274H with 230/236-274/286 on a 110 LSA :bow: rumble rumble rumble :yikes:
    And to top things off i got a set of Hooker Comp's not realizing they had 2.5" collectors and built a $300 exhaust sytem for em with balance pipe and 2.5" #40's.....it will get your attention.
    Now i'm replacing the Hookers with Hedman's (3" collectors) and running 3" pipe to the balance tube, that oughtta pump things up a tad :wink1:
    Installed a gear-drive, took it out 6 mos later.
    The list goes on n on n on n on........
    I guess it's best not to think about how much money (over $10K) we invest in our rides as it can really make ya sick to your stomach, but you only live once and ya gotta live for today bro.
    I'm a bit of a extremist and don't mind sacrificing a bit of this to gain a lot of that, do it like ya wanna UT and have fun with it...........catch ya later :bow:
     
    Last edited: Jul 21, 2005
  14. uglytruck

    uglytruck Registered Member

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    Mad-dog thanks for the good advice. Stepping the cam up sounds like the thing to do soon. I also look through the forums to see if I can hekp someone else avoid the :doah: if possible.
    I keep looking for different ideas on curing the axel wrap, I have seen a shock that rancho used to make but I don't remember what they call it or how effective it is. I would like to see your setup if possible.
     

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