Conference vmsnet::car$note:carbuffs

    Can anyone recommend a good engine shop that could handle diagnosis up
    through repair or swap if need be?  This would be for the GMA or even
    out to Worcester or Fitchburg.  Indications are that I have ring
    problems (maybe valves too) on my 305 Chevy.
    
    You can e-mail negative recommendations if you feel more comfortable. 
    Any help would be appreciated.
    
    Tony

I know a guy that runs a small shop in Nashua, did my truck, great work.

send me mail is you expand your search..

    Typically, does the end crank bolt that holds the harmonic balancer
    turn "off" opposite the direction the engine turns? I've got one that's
    really frozen on and I want to make sure I'm turning it in the right
    direction. Also, is an impact wrench suitable for removing this bolt or
    could the hammering action of the gun cause internal problems?
    
    Ross

    
>>Typically, does the end crank bolt that holds the harmonic balancer
>>turn "off" opposite the direction the engine turns?
    
    Yes.  But let the engine unscrew the bolt by itself.
    
    Put a long breaker-bar on the bolt and lay the handle on the ground.
    Go and crank the engine with the starter. The bolt will unscrew.
    No doubt about. Done this a zillion times.
    
    -john

I didn't know third brake lights had harmonic balancers!  Live and learn!

				Steve

    Yeah Steve, evidently I'm more than a little lost today! I thought I
    was in the general engine note. 
    John, that's an interesting method I wouldn't have thought of. A short
    hit on the starter will do it?
    
    Ross

>>>Typically, does the end crank bolt that holds the harmonic balancer
>>>turn "off" opposite the direction the engine turns?
    
>    Yes.  But let the engine unscrew the bolt by itself.
    
>    Put a long breaker-bar on the bolt and lay the handle on the ground.
>    Go and crank the engine with the starter. The bolt will unscrew.
>    No doubt about. Done this a zillion times.

be sure to put the handle on the correct side.  
otherwise it will smash into whatever it can find.

    And make sure the coil wire is diconnected so it doesn't start on you
    as well.

    
>>And make sure the coil wire is diconnected so it doesn't start on you
>>as well.
    
    Whats the problem?  Don't you realize just how much faster the bolt
    will unscrew if the engine starts?  (^/
    
    -john

    Cars that have a computerized ECU (engine control unit) usually require
    disconnecting the ECU harness. Some manufacturers caution that
    disconnecting the coil alone can cause damage to the ECU.
    
    
    JBS 

    I piclked up a GMC 270 cid this past weekend that had recently been
    rebuilt and bored .030" over. In attempting to start it last night, it
    was very tight and did not want to turn over easily even w/o the plugs.
    After I rebuilt the starter which helped a little, when it did start 
    (I had put some oil in the cyls) it made a screeching noise. After I
    had gotten a good fuel supply to it so I could run it longer the noise
    stopped. It had oil pressure (judged from the rockers) and seemed to
    run well after running a while. After running for a while it would
    start normally on 12v as opposed to 24v (double) that was necessary
    initially.
    
    I will set it up with a radiator tonight (I hope) and run it longer.
    
    
    Opinions, guesses? What does a spun bearing sound like if anything?
    
    Steve
    

Geez Steve,

Sounds like the rebuiler did not put vaseline on the cylinder walls when he
assembled the engine. You probably just did a high speed ring seating ;^) before
you got the oil pressure up.

Just keep an ear on it and check the filter when you change the oil after 300
miles for debris.

roger.

    I did not take any precautions like with a just rebuilt engine as I was
    told that it had been run since rebuilding and the engine oil did not
    look brand new. Maybe the cylinders were rusty from sitting...
    
    Steve

    I'm rebuilding my cavalier engine.  I had a machine shop do all the
    machining.  I had to have the engine bored and I had to have the
    crank turned.  I bought parts BASED ON WHAT THE MACHINE SHOP TOLD
    ME.  In otherwords, I haven't really doublechecked the shop.
    
    My question is about using plastigage.  Do I need to do this step,
    for example, my crank was turned .001.  And my bearings are .001.
    So, can I stick this thing together, or should I use plastigage to
    check everything before I assemble the thing?
    
    MadMike

    I ran the motor for about 10 minutes last night. It seems to run well
    w/o any sign of burning oil or unnatural noises. It got up to temp and
    ran 30 psi oil pressure at idle and 40+ at higher RPMs.
    
    I think I did alright with the purchase.
    
    Steve

   <<< Note 274.299 by VMSNET::M_MACIOLEK "Four54 Camaro/Only way to fly" >>>
                       -< Do I need to use plastigage ? >-

	RE: -2

      	I would. Plasigauge is "CHEAP", it takes an hour or so to do,
    and is worth the peace of mind.

      	Unless of course, you want to get it back together, have a
    tight clearance, drive 20 miles, and launch a rod.

        Voice of experience speaking here...trust me.



      Steve

    <<< Note 274.299 by VMSNET::M_MACIOLEK "Four54 Camaro/Only way to fly">>>
                           -< Do I need to use plastigage ? >-
    
    Some years ago, a friend of mine once rebuilt a Studebaker engine using
    NOS factory main bearings.  Being pressed for time, he skipped the
    plastigage step.
    
    Thirty years before, someone had packed the wrong size bearings in the
    box.  Ever try to find a Studebaker crankshaft?
    
    I'd check it...
    
    Karl

    Do the plastiguage.. 
    
    I was helping a friend reassemble a Ford 289 boat motor once, under the
    same situation (machine shop did the work, and got the correct parts
    for reassembly).
    
    The crank was supposedly .010 under, and the bearings were .010 under
    to match.
    
    The crank turned out to be .030 under. The plastigage didn't even
    squish.
    
    ...tom

From my own experiance I have learned to check absolutly everything. I built a
351W once, and let the shop order the piston kit. Even after I told the guy I
had a tall block 351 he ordered the shorter version pistons. Deck height ended
up somewhere in the .050 to .070 range. I had to have the block decked to bring
the compression up from the 7.5:1 that it would have been had I not checked to a
more reasonable 9.5:1 after decking. I won't even go into the horror show story
I have just been through trying to get pistons for the Kawi I've been building.
Anyway, measure everything. Double check every last detail. Then and only then
do you know what you've got...

				Brian...

    Me too. Thrust bearings that didn't fit exactly right after
    line boring the block and I tried to squeak by...oops.

    Enough said... I'll check it.  I'm doing too much.  Way too much
    all at once.  I'm supposed to be focusing on the cavalier.  In
    a month I'll have a LS-7 in the Z and probably have the crankshaft
    installed in the cavaliers block.  
    
    Time to sell more blood.
    MadMike 

    
        2 days ago a friend and I got finished installing a rebuilt SBC
    in his vette. Previous to vehicle installation it spent time on the
    dyno getting the jetting and timing adjusted.
        Its got a problem, In first gear at full throttle it lays down
    between 5-6K rpm then continues pulling right to 10k.
        2nd gear is not as bad but its still there. When it happens in 1st
    is akin to a third foot stabbing the brake pedal for 2 full seconds
    and then letting go. In third and 4th the problem don't exist.
    We even drove it down the highway in 2nd gear for 3 miles with the
    engine turning 8k rpm looking for a fuel delivery problem.
    This is a very high dollar nascar spec built engine and my friend is
    broke and naturally the dyno guy claimes he can fix it with a "few more
    hours on the dyno" NO.  So we gotta figure this out.
    ANy strange ideas?
    
    -john

    Getting jetting down via seat of the pants is difficult but it can be
    done.  I recommend the following:
    
    o identify the various parts of the fuel an ignition systems that
      engine operation at various rpms such as jetting or fuel injection
      setting, fuel delivery rates, and ignition curves.  At this point
      items like cam degree setting, carb lift, intake flow, etc do not
      have to be considered because you will not be changing them (during
      this round of testing).
    o make a graph of these control curves in relation to rpm
    o to do "seat of the pants" tuning you must keep a record of you starting
      point and a description of the performance for each combination
    o make a change to a control system curve related to the rpm of
      problem, only one system at a time, record change
    o do "seat of pants" testing and record associated performance
    o evaluate results, if needed try another combination
    
    Eventually a pattern will arrise and you will be able to find the best
    setting for each rpm.  If you can keep the number of things you change
    small then the number of combinations you must evaluate will also be
    small which will allow you find you solution quicker.
    
    A downside of highly developed engines you can get into uncompatable
    mixture of parts for streetable performance throughout the entire rpm
    range.  An example here is that a NACAR engine would rarely be used
    between 5/6K rpm and but even if it was a slight problem at this rpm
    point could be an acceptable tradeoff for better high rpm performance.
    
    Hopefully you will find that the only the jetting or ignition is off
    and a small adjustment will fix you 5/6K rpm problem.
    
    Rob

    
        To answer some questions that came via mail...
    It has dual 600's with vacuum secondaries. .5" fuel line off of a 600
    GPH pump. The ignition is a Crane 300+ digital off a flying magnet
    trigger on the damper.
         We are currently looking at the power valves and figuring a way to
    attach "on road" test equipment to look at things underway......
    
    -john

    
    
    	You lost me right after "The ignition is a.." :*)
    
    

    600 what's?  Holleys?  Model #?
    Where was the engine dynoed?  Altitude & conditions.
    Where is the engine now?  (Mountains of Colorado?)
    Do you have the dyno data &/or graphs?  What did the guy do in order
    to set it up?
    
    The thing pulls hard in all gears all rpm, except in 1st and 2nd where it
    lays down for 1000 rpm (from 5-6K)?  Is that the situation?
    
    Initially, I'm thinking you have a float problem.  You're sucking the
    bowls dry... 
    
    MadMike
    PS.  Got any TH-400's you don't need?

    ... and as far as "on car" stuff... I'd get one of them o2
    sensors you weld into your header.  See what that thing reports.
    Obviously, you'll probably be big time lean when the thing is laying
    down.  This should help you quickly narrow down what is happening.
    
    MadMike

    More float evidence.
    The dyno is bolted to the floor.  (stationary)
    When the engine is in the chassis and the car is doing its thing
    you tend to get fuel pick up problems or other things related to
    G forces.  
    
    Check it out.  Fire the car up and wind it up by hand... slow... can you
    get through 5 - 6 without croaking?  
    
    MadMike

>>Check it out.  Fire the car up and wind it up by hand... slow... can yo    
>>get through 5 - 6 without croaking?
    
    6 acceleration runs were made on the dyno against a 3200 LB. flywheel.
    No problems existed. Jetting was perfect except for a slightly rich
    idle according to the sensors they had hooked up. My friend could not
    afford any more time or money to fix the last remaining 1% of the
    tuning issues. I talked to Ted at lunchtime....he's got he carbs apart
    to look at the power valves. Let ya know tomorrow.
    
    -john

    } >>get through 5 - 6 without croaking?
    
    5 - 6000 rpm...

I had a SBC with a Q-jet that would lay down at 3K rpm. A weaker secondary
spring fixed it. The secondaries wern't opening up fast enough and I would get
a lean spot at 3K.


				Brian...

>        2 days ago a friend and I got finished installing a rebuilt 
SBC
>    in his vette. Previous to vehicle installation it spent time on 
the
>    dyno getting the jetting and timing adjusted.
>        Its got a problem, In first gear at full throttle it lays 
down
>    between 5-6K rpm then continues pulling right to 10k.
>        2nd gear is not as bad but its still there. When it happens 
in 1st
>    is akin to a third foot stabbing the brake pedal for 2 full 
seconds
>    and then letting go. In third and 4th the problem don't exist.
>    We even drove it down the highway in 2nd gear for 3 miles with 
the
>    engine turning 8k rpm looking for a fuel delivery problem.


So it's a fuel delivery problem, and it's "G" related. At 5-6k rpm, 
you're probably at or near the torque peak, so it's pulling like a 
son-of-a-gun in first gear - and it *has* been pulling for awhile, 
and has been using a ton of fuel for that duration.

I'd try punching it from 4.5-5K rpm to see if it exhibits the exact 
same condition, as a check. There's a reasonable chance that the 
condition will be reduced or eliminated. If that's so, then we know 
we have a marginal problem of fuel delivery that needs just a little 
tuning. If the condition is unchanged, then if it isn't fuel 
pickup problems in the secondaries (see fourth bullet, below), it's a 
little more serious (maybe involving parts changes), but it's still a 
G-related fuel delivery problem.

The obvious checks are:

- Fuel is being pulled away from the tank pickup from G forces. Try 
it with a tippy-top full tank.

- Check voltage to the fuel pump.

- Make sure fuel filters are clean.

- Fuel is being pulled away from the secondary jets or metering 
plates due to G forces.  A) Install (or tighten) those extender rods 
you can get that give you a fuel pickup point at the back of the 
bowl, and/or B) Raise the float settings.

Make sure you don't have extender rods in the primary bowls :-)

- There's a chance that this is a marginal fuel delivery problem, 
complicated by vibration in the chassis/motor mounts. Install two 
gaskets sandwiched with copious quantities of somebody's gask-a-cinch 
goop under the carbs, for vibration insulation.

- electric pump mounted too far forward from the tank. Electric pumps 
are great pushers, but lousy pullers. High Gs may cause a problem if 
this is so. Move the electric pump so that it's pretty much making 
love to the tank, with minimal fuel line footage that is aligned 
front-to-back between tank and pump. As a backup and after you've 
eliminated every other option, install an in-tank pump of reasonably 
high capacity to feed the gonzo pump you've already got. The in-tank 
pump would be pumping into zero pressure, so it's actual fuel 
delivery capacity might be double (or more) what its rating 
indicates. Therefore it wouldn't have to match the capacity of the 
pump that's in there already.

That's all I can think of at the moment, but you and your friend 
surely get the drift, and will look at other related things if 
necessary.

Good luck,

Bruce    

    Actually, wouldn't the electric fuel pump then be better behind the
    tank as G forces would help supply it with gas then starve it for gas?
    
    Steve

>    Actually, wouldn't the electric fuel pump then be better behind 
the
>    tank as G forces would help supply it with gas then starve it 
for gas?

Yessir. Shoulda said that. Thanks.

As a by the way, -john, if you've gotta have a problem, this is a 
helluva terrific problem to actually have. :-)

Bruce 

    
        Both power valves in each carburetor were damaged. We replaced
    them.
    We went for a ride; 3 Perfect acceleration runs and the problem came
    back. The power valves were damaged again. Neither of us could detect
    any popping or backfire, probably because the engine is mechanically
    noisy and the exhaust is on the hairy edge of just being legal.
    Compression test...#6 has only 40 PSI. We pulled the valve cover, and
    the inner spring on the intake valve for #6 is broken. Thats all we did
    last night. He's gonna pull the head this morning and let me know
    the internal condition.
    
    -john

    
        The head is off....heres what he found. The intake roller rocker
    has dry needle bearings, he found a piece of flash covering the oil
    feed hole in the pushrod socket. The piston and valve got to know
    eachother and the valve is bent but the guide has no damage but will
    get replaced anyway. The piston gotta come out too. The broken spring
    and the dry rocker probably have nothing in common other than
    coincidence. Hell...its only money!
    
    -john

    If he wasn't totally broke before, he is now. I thought you said
    this was a professionally build engine?
    
    

    
>>        If he wasn't totally broke before, he is now. I thought you said
>>        this was a professionally build engine?
    
        It was....Regardless of who you get an engine from wether it be
    Ed Pink, Keith Black, Ed Berger....etc.  You get no warranty.
    You are buying the builders reputation. $hit happens. and there was a
    ton of oil being fed to all the rockers when we were messing with the 
    Hot lash valve adjustment. The heads on this engine, due to the
    extensive flow bench work are in the 4k price range. One of us, when
    assembling the engine could have missed a piece of flash and the damn
    thing probably came out of hiding under vibration. It may have even
    been in the used dry sump oil pump thats on this engine.  He said the
    piece was tiny and he flecked it off with just his fingernail.
    So the car will sit around for a few weeks untill his next commission
    check....he'll live.
    
    -john

Well, I'm scratching my head on how a power valve can have that kind 
of an effect on engine performance. I can clearly see how a bent 
intake can trash a power valve, but I'm at a loss thereafter.

Have we got any power valve experts in the group?

Bruce

    
>>Have we got any power valve experts in the group?
    
    Yes...ME.
    
    Power valves are sized according to Atmospheric pressure, total engine
    intake (air capacity) at peak torque. and the transition time of the
    opening of the secondaries in relation to engine at various throttle
    openings. I've been playing with Holly carbs for 30 years.
         The engine had a simple lean condition when it should have been
    feeding off the secondaries. Damage to the power valve diaphrams caused
    the secondaries to open too late=flat spot. This engine moves more air
    past its 8 throttle plates than most BBC's do.  This engine makes its
    peak torque at 6800 rpm and its peak HP of 619 at 8600 rpm.
         I asked for advice based on the fact that I thought I was getting
    stupid....It ran fine on the dyno then it was bolted in the car and has
    an immediate problem the first time a foot was put in the throttle.
    Everybody that said it was a lean condition was correct. Its just a
    matter of finding out what? where to look? why?
    The Why? is gonna cost some big bucks to fix. Well....maybe not that
    big, but a couple 300 anyway.
    
    -john

    
    Oops...and one more thing to mention. The power valves in each carb are
    not identical. The front carb is rated 1" of mercury lower than the
    rear carb. Its a neat trick I learned years ago to prevent a bog on
    dual carb setups caused by an over-rich condition when both carbs dump
    the secondaries at the same time.
        It was written up in a book someplace by some mumbiltifizz famous
    engine builder, but I forgot who it was.
    
    -john

>    Oops...and one more thing to mention. The power valves in each 
carb are
>    not identical. The front carb is rated 1" of mercury lower than 
the
>    rear carb. Its a neat trick I learned years ago to prevent a bog 
on
>    dual carb setups caused by an over-rich condition when both 
carbs dump
>    the secondaries at the same time.

Very cool.

But hey, guy. As long as you're in a sharing mood, why would that 
5-6k bog condition go away in third and fourth? I would've thought it 
would be prolonged and really noticeable in the higher gears if it 
were power valves acting up. I ruled them out for that reason.

???

Bruce

>>were power valves acting up. I reled them out for that reason.
    
    Because in the higher gears, the engine revs *slower* the timing of
    the secondaries is not so critical. Even running on 7 cylinders this
    vette was lifting the front end through first gear and hitting 10K
    rpm in less than 3 seconds. It revs quicker than some motorcycle engines
    do. Think about that duration of time and the critical timing of the
    secondary fuel system.....Thats why the owner knew it was necessary to
    get it on the dyno before it ever saw street operation. An incredible
    amount of stuff was sorted out while it was bolted to the shop floor.
    
        While My buddy Ted's motor was on the dyno, the tech pointed out to
    him a 620 cube mountain motor that was going to be installed in a older
    Ford LTD. The dyno testing was already done on that engine and it was
    making 1150 HP. I'm glad I grew out of this stuff years ago...Its nuts!
    My ol'lady woulda sent me packin....
    
    -john

>    Because in the higher gears, the engine revs *slower* the timing 
of
>    the secondaries is not so critical. Even running on 7 cylinders 
this
>    vette was lifting the front end through first gear and hitting 
10K
>    rpm in less than 3 seconds. It revs quicker than some motorcycle 
engines
>    do. Think about that duration of time and the critical timing of 
the
>    secondary fuel system.....

Gotcha. I wasn't actually thinking at all about how, uh-h-h, 
*chiropractic* this car would be with the loud pedal down.

Thanks,

Bruce