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Technical New Engine lacks power SBC in the Studebaker-RESOLVED

Discussion in 'The Hokey Ass Message Board' started by vtx1800, May 20, 2020.

  1. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    Here's the background.
    SBC 350, heads cleaned up, rings, .030 over pistons and bearings (one piece rear main seal)
    Howard flat tappet hydraulic cam LS 111 .450 lift part number 110931-11 very mild
    Petronix III distributor 34 degrees total lead
    Edelbrock 600 CFM carb
    Edelbrock performer manifold (early model modified to fit later heads)
    Block hugger headers with glass packs, it's loud.
    Compression is 175-180 on all cylinders.

    When I first fired the engine it lit off almost immediately and we ran at about 2000 rpm for about 20 minutes, I had help putting water in, filling the new 700 R 4 with fluids etc. It seem to run fine sitting in the driveway.

    About a month later when I got license and insurance on the car I took it out on the hiway and it's a pooch. will hardly run over 2000 RPM wide open. I thought it might be the Petronix, I used a Petronix II initially and had upgraded to a Petronix III for my 38 Chevy and had it left over. I swapped out the distributors and it made no difference (Note....yes I did have the correct coils for each distributor). The Petronix II is back in the 38 and I can see no difference.

    The carburetor came off of the 38 Chevy and had operated just fine. Yes....the throttleblades do open all the way. (even though it acts like they aren't) I double checked the timing and its OK, the motor will rev till about 4500 then starts missing.

    I suspect I have either not properly set the cam/crank sprocket or I have a flat cam:(

    Chime in, I'd like to not have to pull this engine apart seems almost inevitable.

  2. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,912

    dirty old man
    Member Emeritus

    My suspicions match yours.
    loudbang likes this.
  3. theboss20
    Joined: Dec 30, 2018
    Posts: 265


    Was the cam new or a regrind? Did you use assembly lube on the cam? Are you sure you got the correct cam?

    Sent from my iPad using Tapatalk
    loudbang likes this.
  4. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 2,192

    from Brooks Ky

    Have you checked the float level to make sure it isn't starving for gas ? Perhaps some dried up residue in the float bowl.
    It should be easy to do a vacuum check and remove the valve covers to check valve action by the cam.
    loudbang likes this.

  5. Are you still at 180 cranking compression?
    Try any vacuum gauge diagnostics ?
    We had a cam go flat on break in last year. Not fun.
  6. Did you have one of those timing chain sets with 192 sets of marks for advance and retard?
  7. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    And I thought I included everything:)
    I didn't include that the first fuel pump was low on pressure (I thought) so I went to a higher pressure unit (electric), every time I'd take the top off the carb there was plenty of gas in the float chamber.

    Compression was the last thing that I checked.

    Note also that I put the plug wire set on my 38 and it worked fine.

    Vacuum, low....note on the gauge indicated late timing....that made me wonder about the cam.

    Yes, brand new Howard cam and I used their assembly lube. Is it correct cam?? well I hope so.

    The timing chain set was a "one position" install, to add a bit of humor?? when I built the engine for the 38 I used a Cloyes timing chain set with multiple possible timing (advance retard etc) and didn't get it right. I WAS VERY careful when I assembled the timing gear this time. I tried carbs, intakes, ignition changes (and lots of money) trying to find out why it wouldn't run. I felt really stupid.

    I am wishing now I would have sprung for the roller cam version now.
    loudbang likes this.
  8. If the cam has a few lobes gone flat, it’s easy to see by measuring the distance the valves are moving or really not moving.
    Usually they are perfectly adjusted then for some unknown and unthinkable reason they get loose uhhhhh because the lifters are getting smaller too.

    Ok having the rockets too tight will cause you tuning fits too
    dirty old man likes this.
  9. Still might ha
  10. Gotgas
    Joined: Jul 22, 2004
    Posts: 6,998

    from DFW USA

    Funny question, but is there something plugging up your exhaust?
    dirty old man and partssaloon like this.
  11. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    As loud as it is, I don't think so. I fabbed all the pipe, interesting thought though. I guess the first thing I will do is start checking lift on the cam. And the engine has no leaks.....yet.
  12. jaracer
    Joined: Oct 4, 2008
    Posts: 1,313


    If you have 175-180 compression on all cylinders, I don't see how it could be a flat cam or cam timing. Could your timing mark on the damper be wrong? You said it will barely run over 2000 rpm wide open, then you said it is begins missing at about 4500 rpm. Which is correct? Could you have a massive vacuum leak? Like someone else said, a restricted exhaust will cause low vacuum as you rev it up.
  13. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    I'll clarify, driving down the road, abut 2000 RPM is about all it will do, sitting in the drive with no load, it will run up to about 4500 rpm before it starts missing. The timing mark (damper cover? I don't have the right name) is indexed on the crank key. I am fairly sure that I looked inside the block hugger headers to insure there was no obstruction and the rest of the exhaust it basically straight pipe with two glass packs (that I ran on my 38 for a short time) It doesn't cost much to use an endoscope and pull the exhaust down and recheck does it? Thanks for your comments.
  14. There’s a few different combinations of timing covers and dampers. They all fit fine and swap around with ease but the wrong combination can show you ignition timing marks that are really really far off. Basically you need to verify the marks with a piston stop test and that’s the only way you’ll know the timing light isn’t telling you stories.

    You can make your own marks too.
  15. KenC
    Joined: Sep 14, 2006
    Posts: 668


    Revving to 4500 with no load before it misses versus 2K under load sure sounds like ignition to me. Weak spark not lighting off under compression. Not timing, just not hot enough. Coil?
    Tri-power37 likes this.
  16. Phil1934
    Joined: Jun 24, 2001
    Posts: 2,717


    Chevy has had 3? different timing pointers. I would crank in 10* more timing before I tore into it.
  17. Mr48chev
    Joined: Dec 28, 2007
    Posts: 30,188


    Most of those later model small blocks have the timing mark on the damper (and on the timing cover) straight up at 12 O'clock and you have to shoot the timing light down behind the water pump (long pump) to set the timing if you don't have it hooked to a scope with a probe. Bolt one of those little chrome timing tabs to the side because it no longer has the accessories hanging off it and you can't set the timing right and throw in a short water pump because you need the clearance and you just made yourself a mess.
    The above comment from putting a 78 350 in my 71 GMC and using a short water pump as came on the 71 so I could run the 71 power steering and alternator brackets. I could never get it timed right until I changed pumps and could see down behind the pump.

    Post #14 by 31Vicky with a hemi saying that you need to bring #1 up on a confirmed TDC and verify the timing marks is the best suggestion and what you need to do first. Then if that is all on the up and up and where you think it should be go to plan 2.
  18. Budget36
    Joined: Nov 29, 2014
    Posts: 7,544


    I saw mention of a higher pressure fuel pump and a Edelbrock carb. Could you be flooding the engine?
  19. Road Angels
    Joined: Mar 2, 2015
    Posts: 134

    Road Angels

    I had some thing similar..on a customers car years ago...newly rebuilt 350...guy replaced every thing...would not rev as it should every thing checked out...except the valve spring tension was way off I could easily push the springs down with my thumb..they where just bouncing off the seats...shimmed them and every thing was was really weird the way the engine ran
    vtx1800 and Desoto291Hemi like this.
  20. jaracer
    Joined: Oct 4, 2008
    Posts: 1,313


    That's beginning to sound like an ignition problem. Although I might try timing it with a vacuum gauge. With the engine idling and a vacuum gauge installed, advance the timing until you achieve the highest steady vacuum. Then back the timing down to drop the vacuum about 1" of mercury. That should get you pretty close.

    I did have a coil make me chase my tail. I had a 88 or 89 Bronco I took on a trade deal. Sometimes it would break up like it was running out of fuel. Backing out would smooth the engine out, but trying to accelerate any would shut it down again. Then it quit and wouldn't restart. Got it home and started checking things including the ignition on a scope. I was sure it was a fuel problem so I pulled injectors, checked sensors, checked fuel delivery and didn't really find anything. I had so much apart that I put it all back together to start over. To my amazement, it started right up and ran fine. I hardly got it out of the garage before it died again. A guy I worked with said he had a Ford with a similar problem and it turned out to be a weak coil. Bought a new coil, but before I installed it I hooked it to an old Sun coil tester and checked the new against the old. The old coil put out a little over 12K volts. The new one was off the top of the 30K scale. The old coil was capable of just enough voltage to make it run okay at times, but not under any load.
    wandi harry likes this.
  21. Could you please change the title from
    Engine Lacks Power - Studebaker
    over to the more realistic
    Engine-Lacks -Power-Chevy ?

    Thanks :)

  22. studebaker46
    Joined: Nov 14, 2007
    Posts: 688


    first thing I would do is get a known good chevy dist. and try that. use an HEI since they are easy to hook up. petronix does not always play nice. Tom
  23. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,794


    First..............PULL A VALVE COVER and confirm the cam ain't flat!!:mad:
    It takes hardly ANY time and answers a BUNCH of questions!o_O
    I'll keep my fangerz crossed fer yee!
  24. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,235

    from Quincy, IL

    Sure looks like your ‘fangerz’ were crossed while you were typing.....:confused:
    Blues4U and 31Vicky with a hemi like this.
  25. Warpspeed
    Joined: Nov 4, 2008
    Posts: 532


    Already been mentioned, but......

    Have you checked the exhaust back pressure ?
    Might be a constipated cat, collapsed muffler, or a crushed pipe.
    Last edited: May 26, 2020
  26. vtx1800
    Joined: Oct 4, 2009
    Posts: 1,378


    Note.....I have swapped one ignition system (a Petronix II w/coil for a Petronix III with correct coil) for another, both work fine in my 38 Chevy. With a little luck I will get the car out tomorrow and play with the advance (to maximize vacuum) and see if that has a positive affect (or is it effect?)

    Exhaust....block hugger headers dumping into basically two six foot straight pipes and then into a pair of Stainless Steel glasspacks that I ran on the 38 Chevy for awhile (didn't like the sound). I can't imagine that the headers are plugged but I am going to drop the exhaust and use an endoscope to insure they are open.

    I have not pulled the valve covers yet and I need to double check to see if the timing marks are correct (I think my neighbor has a plug welded up to do that so I don't have too, he needs to get out of the house too)

    Fuel pump.....I started with a 1.5 - 4 psi pump, thought it might not be enough and was starving the engine, went to the 4-7 PSI pump with no change in engine performance.

    I edited the title @dare-to-be-different , anyone that has a wheel standing lark has to be listened too:) Right color too!!

    I've been sidetracked with the disassembly and repair of two trunk lids (using the inner panel from a Hawk trunk because it has the hinge mounts that are not totally rusted away) and the outer of the 53 trunk because it looks better.
    craig b blue and dana barlow like this.
  27. Penetrator
    Joined: Aug 25, 2011
    Posts: 514

    from SK CAN

    Where is the pump located? In my experiences, electric pumps make good pushers, but don't pull worth a shit...
  28. scrappybunch
    Joined: Nov 16, 2011
    Posts: 359

    from nj

    Vacuum gauge will show a lot of information, KISS. Vacuum-Diagnostics-min.jpg
  29. indyjps
    Joined: Feb 21, 2007
    Posts: 4,533


    Whats the ballast resistor, or resistor wire situation in a Studebaker? Asking because Ive been fooled in the past by this same thing.

    Found this on a Studebaker board, I dont know what year your car is, verify that you actually have 12V where you think, or if its stepped down somewhere.

  30. Okay guys I'm posting this for two reasons. When I first read the headline at this thread I instantly thought of my absolute most favorite songwriter and singer Warren Zevon. I don't know if you guys are aware have him but his music is absolutely the best cruising music you can have. This is actually the only one where he sings about any kind of car. I hope you guys can enjoy and appreciate his talents.

    No offense to Mr. Vtx1800
    alfin32 and vtx1800 like this.

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