Rod Bearings ???

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Rod Bearings ???

Post  HELI-ARC on August 6th 2013, 2:34 pm

Looking for some input on why I keep loosing #3 rod bearing?

We have had 3 different engines now that have hammered out only #3 rod bearing and everything else is in awesome shape.

The first engine:
72-74 block, std bore. 429 crank, scj rods with factory forged scj pistons
DOVE heads, solid lift cam, ran motor to 7000 rpm, 15-40 rotella oil std volume pump.
38 degrees total advanced, locked out dizzy. approx. 110 octane fuel. approx. 8-10 hrs hammered upper rod bearing on number 3 only.

second engine
72-74 block .030 over, 460 crank, truck rods with forged pistons
DOVE heads, solid lift cam, ran motor to 6500 rpm, 20-50 Castrol oil HV oil pump.
38 degrees total advance, locked out dizzy, 110 fuel. approx. 4 hrs, hammered upper rod bearing on number 3 only.

third engine
72-74 block .030 over 429 crank, truck rods with cast pistons
d3ve heads, solid lift cam, ran motor to 6000 rpm, 20-50 Valvoline vr1 oil HV oil pump
38 degrees total advance, locked out dizzy, 50/50 110 fuel and premium again number 3 rod bearing.

Now all were three different blocks and cranks. The only common part was the heads on the first two motor which are still fine. We do not have a valve train problem.
All three had a 30 psi low pressure led light which never came on and was tested too work. All the motors were checked for timing mark alignment to TDC when built.
All three where .0025 to .003 on rods and .003 on mains. First and second motor had 3/4 groove mains, third motor had full groove mains. Rod bearing have been Summit in house brand on first one, Clevite on second, unknown on third as we purchased the motor done. These are all used for Sand Drag use 6-8 second pass, Deep rear sump pans, 9 to 10 quarts of oil with brand name zdp additive for the cam to live. Also running 1" dia pickup tube assembly per Paul @ Hi Flow.

After all of this does anyone have an idea on how I can use up number 3 and have every other bearing in great shape??? Is it possible to detonate just one cylinder with the firing order these thing have? Or is it an issue with number 3 main and wiping #3 rod dry????

Thanks in advance for your time Cool 

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Re: Rod Bearings ???

Post  Lem Evans on August 6th 2013, 3:03 pm

What causes hammering is generally detonation or pre-ignition.

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Re: Rod Bearings ???

Post  BradB on August 6th 2013, 5:18 pm

Out of curiousity, what heads are they?

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Re: Rod Bearings ???

Post  BradB on August 6th 2013, 5:21 pm

Nevermind, I see where the heads are listed.

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Re: Rod Bearings ???

Post  HELI-ARC on August 6th 2013, 5:57 pm

Lem
so what I was hoping all your experience would tell me is how I can detonate or pre ignite just one cylinder and have no sign of this what so ever on the other 7 cylinders. I in no way clam to be an expert tuner, but we ran a 466 with 175hp of nos on cast pistons for over 10 years with zero problems and no have 3 motors in a row that have the exact same issue. Open to any thought or theories.
Thanks

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Re: Rod Bearings ???

Post  Dave C. on August 6th 2013, 6:41 pm

Same ignition system on them all?

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Re: Rod Bearings ???

Post  Lem Evans on August 6th 2013, 6:48 pm

Got any pictures of the bearings?

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Re: Rod Bearings ???

Post  rmcomprandy on August 6th 2013, 6:54 pm

I would guess that the number 3 cylinder, (for some reason or another), needs less ignition advance or there is an intake manifold or fuel delivery problem.
Just because a certain amount of ignition timing advance gives the best power does not mean that 1 or a couple cylinders aren't happy with that amount.

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Re: Rod Bearings ???

Post  Lem Evans on August 6th 2013, 6:56 pm

38* sounds on the high side to me.

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Re: Rod Bearings ???

Post  Dave C. on August 6th 2013, 7:02 pm

x2

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Re: Rod Bearings ???

Post  kim on August 6th 2013, 7:23 pm

possibly getting inductive ignition from either a spark arc in cap, or from a parallel or crossing wire. So cylinder is firing at way more timing than all the others.

Same cap? Same wires? Same wire loom.... 38 t

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Re: Rod Bearings ???

Post  cool40 on August 6th 2013, 8:18 pm

What fuel?
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Re: Rod Bearings ???

Post  maverick on August 6th 2013, 9:12 pm

Same intake manifold?
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Re: Rod Bearings ???

Post  HELI-ARC on August 6th 2013, 9:26 pm

First and second motor were in the same truck with a MSD 6AL box, stock dizzy locked out, accel coil.
Third motor was in a different truck with a MSD 6AL box, MSD dizzy locked out, blaster coil.
Now all three motors had the same set of Ford Racing plug wires......... A common factor I did overlook!

The first motor was a victor jr intake with a 4150 carb, second motor was the same intake converted to a 4500 and light porting. Third motor had an out of the box weiand stealth intake.

I will have my son help me get pictures of the bearings on here tomorrow. The first motor chucked the rods out, second and third we caught and have all the pieces to inspect.

Now this does come to mind. First two motors showed no issues at all. Third motor did have an intermittent miss on the passengers side at an idle, but instantly went away and ran great beyond that and again it was a random miss that would come and go.

I listed the fuel for each motor at the top.

As for the 38 degrees, we ran that on our 466 with nos and did not pull timing. It was together for years. Now we did have the base timing at approx 28-30 degrees.

So its sounding to me like its getting hammered at low rpm with dizzy locked, or I have an issue with the wires that were on all three engines?

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Re: Rod Bearings ???

Post  HELI-ARC on August 6th 2013, 9:33 pm

And not to be offensive on the timing issue, what do you guys consider a good number?

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Re: Rod Bearings ???

Post  Dave C. on August 6th 2013, 9:56 pm

 32-34 IS GOOD.

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Re: Rod Bearings ???

Post  cool40 on August 6th 2013, 11:11 pm

i've ran 40+ but have always found problems.cap walk,bearings,broke rings,and cracked block. too much timing will hurt parts. Suspect 
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Re: Rod Bearings ???

Post  rmcomprandy on August 6th 2013, 11:56 pm

I have run several engines on the dyno with iron D0VE heads with a dish, reverse dome, flat-top or mini-dome piston and never needed more than 35 degrees total ignition timing to make peak power below 7,000 RPM; and those engines were accelerating 300 RPM per second, not like being in high gear straining for more.
I just finished a 501 puller D3VE headed engine with a very large dome piston having almost 14/1 compression ratio and going past 36 degrees of timing lost power. Same accel rate.

Lower gears will want the same or near the timing seen on the dyno but, high gear will want SLIGHTLY less.

Of course, if you don't make any cylinder pressure and little power then you can run whatever total amount of ignition timing the engine will accept without consequence ... regardless of power output.

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Re: Rod Bearings ???

Post  bbf-falcon on August 7th 2013, 10:24 am

38* is way too much imo w/Dove's. Mine always liked 32---36.From FT's to Domes.

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Re: Rod Bearings ???

Post  HorsinAround on August 7th 2013, 11:20 am

bbf-falcon wrote:38* is way too much imo w/Dove's. Mine always liked 32---36.From FT's to Domes.

Yea, I was thinking the same thing when I read the post, but figured others more knowledgeable then myself would chime in. My puller motors liked 32-34 deg. best. Also, when I read the OP, I saw where the timing advance and fuel was common to all three motors. I would bring the timing down to 32-34 and maybe look at trying 112 fuel.

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Re: Rod Bearings ???

Post  Paul Kane on August 7th 2013, 12:15 pm

There is no dead-set timing rule with the factory iron heads and it depends on the build combo, application, rpm range, where the power is needed, etc. In the majority of hot rodder cases, yes, the preferred numbers noted in this thread might be the ballpark. On the other hand I have a special purpose engine out there that runs best at 42* BTDC and is a dog at 36* BTDC and is completely useless at the "standard" 32-34.  It really depends on overall needs.

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Re: Rod Bearings ???

Post  kim on August 7th 2013, 12:19 pm

Paul,. How long is the cam in that special purpose engine?

I agree, all things are never equal. Hell, unless I have at least 30 degrees initial in mine, it wont even start. But peak power still comes at 32 on alcohol and 34 on gasoline.

That is at almost 18-1 static compression with aluminum heads.

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Re: Rod Bearings ???

Post  HELI-ARC on August 7th 2013, 4:56 pm

So while I am getting pictures of the bearing, which the top half is hammered from pre ignition or timing. Has any one ever seen a cross fire condition with these or any wires? Is there a cool way to test for this? As I would like to sort this out on the next build. Just a note when the third motor was running at an idle I did check all the plug boots on the pass side and up the wires bare handed trying to find my intermittent miss and did not get shocked any where. Also like every other motor out there the wires are just draped over the valve cover (trick flow tall cast alum).
Thanks for the input to date Smile

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Re: Rod Bearings ???

Post  Lem Evans on August 7th 2013, 6:52 pm

HELI-ARC wrote:So while I am getting pictures of the bearing, which the top half is hammered from pre ignition or timing. Has any one ever seen a cross fire condition with these or any wires? Is there a cool way to test for this? As I would like to sort this out on the next build. Just a note when the third motor was running at an idle I did check all the plug boots on the pass side and up the wires bare handed trying to find my intermittent miss and did not get shocked any where. Also like every other motor out there the wires are just draped over the valve cover (trick flow tall cast alum).
Thanks for the input to date Smile

Here is the Hillbilly way to check the plug wires for 'leaks'. Wait untill the sun goes down...raise the hood...put a little heat in the engine...Put the engine on the trans. or foot brake and see if you have 'light show'.

It is my opinion that your combination has more ign. timing than it wants. Could be that the timing being locked is making it worse.

What do you have for a spark plug?


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Re: Rod Bearings ???

Post  69F100 on August 7th 2013, 7:51 pm



Here is the Hillbilly way to check the plug wires for 'leaks'. Wait untill the sun goes down...raise the hood...put a little heat in the engine...Put the engine on the trans. or foot brake and see if you have 'light show'.

It is my opinion that your combination has more ign. timing than it wants. Could be that the timing being locked is making it worse.

What do you have for a spark plug?

  [/quote

Not only the hillbilly but also the redneck way too check plug wires or just grab them 1 by 1 and run your hand up and down them if it bites you you want to do the after dark test.
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