fresh built 4v slow crank when hot - Forums at Modded Mustangs
 
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post #1 of 15 Old June 22nd, 2019, 04:20 AM Thread Starter
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fresh built 4v slow crank when hot

Ok here is the story.

I put together a nice little 4v bullet to swap into my 04 gt.
Teksid block 20 over
JE 20 over pistons (total seal steel rings)
03 cobra crank
K1 forged rods
04 aviator C-heads
04 mach1 upper and lower intake
ford headgaskets

I yanked the 2v out of the car and put this 4v together for boost. installed it into the car along
with 2 Borg S366's and a cg fab twin kit. I filled the rings to the suggested gap by total seal, set my rod and mains on the low end of spec.

I moved the battery to the trunk and ran 1/0 welding cable directly to the starter and to the block for ground, also from frame to block ect.

I crank it up for the 1st time on megasquirt ms3x. She fires off and I proceed to run her through 3 heat cycles. Have 100+ psi cold oil pressure at startup idle (10w40 joe gibbs oil) and roughly 45-50 psi hot oil pressure at idle. Oil pressure shoots up when the rpm's are raised like it should ect.

Now to the problem. Once the car gets up to full operating temp(200f or so), if I shut it off and go to restart it, she will barely turn over with the starter(super tight even with breaker bar on crank bolt).

If I let it sit and cool off to 100f oil temp, she will crank and fire up no problem. I have no abnormal noises or sounds. Great oil pressure hot and cold.

I can shut it off say around 150-170f and she will crank and start, but it's slower(labored) then it should be, 200f and she is barely turning over 1 revolution a second.


Does anyone have any idea's/suggestions/tips/tricks ect? She runs and sounds great even at 200f coolant temp, so long as I don't shut her off. Doesn't seem to dragging/seizing (for lake of a better word) while running.
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post #2 of 15 Old June 22nd, 2019, 05:33 PM
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I think the first thing I would do is see what the torque required to spin the rotating assembly is, with the accessory belt off. Compare the values at hot and cold conditions. That will give you an idea of where to start, whether it's accessories, or the long block itself, and where to go from there.
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post #3 of 15 Old June 22nd, 2019, 10:15 PM Thread Starter
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Quote:
Originally Posted by WickedSnake00 View Post
I think the first thing I would do is see what the torque required to spin the rotating assembly is, with the accessory belt off. Compare the values at hot and cold conditions. That will give you an idea of where to start, whether it's accessories, or the long block itself, and where to go from there.
Thanks for the reply Wicked. I already know deep down it's likely in the short block (bearing clearances ect) but I just needed to hear it from someone else to bring myself to yank the engine back out and tear it down.

I'm not to proud to admit I used plasti gauge to "measure" clearances on the rods and mains, and even the plasti showed on the tight end (0.020 to 0.025) of spec. I should of broke down and bought a micrometer and dial bore gauge and done it the right way.

At the very least I should of ordered a 2nd set of bearings to get my clearances a tad looser, but was being a cheap ass and decided to skip out on the couple hundred $$ to get the right tools and another set of bearings. I was told being on the tight side of spec on the mains with the alum teksid block is okay, but i'm likely tighter than I realized when i put it together.

it's to the point now where it will crank slow even ice cold. So i'm pulling the plug, and pulling it all back apart before I spin a bearing and wreck a crank or rod.

I post up some pictures when I get it back out and apart

---------- Post added at 07:53 PM ---------- Previous post was at 07:47 PM ----------

forgot to add, I put a socket on the crank pulley and cold it seemed normal amount of force, and hot it was locked up.
Earlier I started it to back out of the shop to wash it (only ran 10 seconds), washed it and attempted to start up after washing car and it cranked over real slow maybe 2 revolutions and that was it. put a breaker bar on it again and she's as tight as a nun in church on Sunday.

---------- Post added at 08:15 PM ---------- Previous post was at 07:53 PM ----------

.0020 to .0025*
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post #4 of 15 Old June 22nd, 2019, 10:39 PM
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I'll have to check my paperwork on mine, and the book I have, but my machine shop specified things on the looser end for 5W-30 (as measured cold). Based on their experience it was necessary with the all aluminum motors when you run them hard.

There's no shame in using plastigauge, and it's perfectly acceptable. The question is where the binding is coming from, and its not necessarily from that. I even make it a habit to plastigauge engines that I've measured with dial bore gauges or had machined.

That said, don't blow it all apart just yet. Narrowing down if it's the engine or the starting system is only part of the battle. Now you need to identify where that friction is coming from. It's not just the shortblock; it's the heads as well. Pull the timing cover, check the timing system for any issues, then remove the chains and check the torque to spin the shortblock vs the torque to spin the cams. If the heads get too hot and out of true, the cams can bind something fierce, even if your shortblock is fine. But of course if the shortblock is still tight, well then it's coming apart anyway.
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post #5 of 15 Old June 22nd, 2019, 11:08 PM Thread Starter
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Yeah good idea. I'll yank the front cover and valve covers off, pull apart the timing set and spin her over with the cams out of the equation. The cams are 98 cobra cams, with new ford motorsports timing chains/tensioners/guides/sprockets ect, heck even new cam followers and lash adjusters.

The machinist checked over the heads originally and said they were flat and not cracked ect. Only needed 2 or 3 valve guides replaced and valves grinded to seal up.


I just looked at my notebook from the build and the rods were .0015", the mains were .0023", crank end play was .012".


Thanks for talking me off a cliff lol, it has been a LONG 2yr process getting this car built, and it finally moved under its own power today for the 1st time (backing out of garage to clean shop/wash car) only ran it 10 seconds but was nice.
Only to have this happen.
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post #6 of 15 Old June 23rd, 2019, 12:06 AM
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Ok I looked things up from a couple sources.

From this link http://www.mach1registry.com/Specs/Specs.htm:

Rod bearing clearance: 0.0010629-0.0027165 in (Note: for factory sintered rods)
Main bearing clearance: 0.00098-0.00177 in
Crank end play: 0.005118-0.011850 in

Per the Sean Hyland book:
Rod bearing clearance:0.002-0.003 in (aftermarket rods)
Main bearing clearance: 0.001-0.0018 in (aluminum), 0.0025-0.0035 in (iron)
Crank end play: 0.004-0.006 in

My specs:
Rod bearing clearance: 0.0022-0.0026 in (Manley H-beam)
Main bearing clearance: 0.0018-0.0024 in
Crank end play: 0.006 in

What PTW clearance and ring gap did you have?

I know your pain though. My build has been one disaster after the next. Nothing has been quite so painful as having to build and rebuild over and over again.
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post #7 of 15 Old June 23rd, 2019, 01:37 AM Thread Starter
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I'd have to dig up the spec sheet for my pistons, but i took the block and pistons to the machine shop together and handed him the spec sheet from JE for piston to wall. I didn't have the tools to verify his work on that.

I'm using AP steel rings. top ring .026" 2nd ring .028". gapped for hopefully 25-30lbs eventually.
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post #8 of 15 Old June 23rd, 2019, 05:58 PM
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What size main bearings did you use?

2002 GT Teksid TFS Heads Edelbrock Intake Twin PTE 6466 turbos TH400/UCC Converter Holley Dominator EFI
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post #9 of 15 Old June 23rd, 2019, 06:39 PM Thread Starter
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What size main bearings did you use?
The crank was turned .010/0.10 fresh when I bought it. Took it to my machine shop to be checked before assembly and they said it looked great/needed nothing. I ran a .010 over aluminum main bearing (standard clevite).

---------- Post added at 04:39 PM ---------- Previous post was at 04:38 PM ----------

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Originally Posted by 04TurboMustang View Post
The crank was turned .010/0.10 fresh when I bought it. Took it to my machine shop to be checked before assembly and they said it looked great/needed nothing. I ran a .010 over aluminum main bearing (standard clevite).
.010/.010*
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post #10 of 15 Old June 24th, 2019, 08:32 AM Thread Starter
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Well I found 2 rod bearings smoked on 1 and 5 (share the same journal) After further inspection, I see i somehow installed #5 rod backwards.. The chamfered side on the big end was facing the other rod instead of facing the crankshaft fillet.

All other bearings look brand new. Gonna have to find a new crank, possibly 2 rods.
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post #11 of 15 Old June 24th, 2019, 09:12 AM
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Well damn, that diagnosis was easy.

Interesting the rods were that direction sensitive. I remember looking at mine getting slightly nervous that there wasn't a big defined chamfer on just one side.
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post #12 of 15 Old June 24th, 2019, 12:12 PM Thread Starter
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Originally Posted by WickedSnake00 View Post
Well damn, that diagnosis was easy.

Interesting the rods were that direction sensitive. I remember looking at mine getting slightly nervous that there wasn't a big defined chamfer on just one side.
Must be a slight offset, because on the 1 rod that was backwards, if you looked at the wrist pin the small end of the rod was jammed all the way to one side against the piston and could only move a tiny bit on the pin. On all the others that are installed correctly, they sit dead center on the wrist pin and can float easily to either side.

The K1 rods have a very defined chamfer on 1 side of the big end.

Thanks for the help.

Also if you know of anyone with an 03/04 cobra crank, let me know.
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post #13 of 15 Old June 24th, 2019, 12:19 PM Thread Starter
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Do you think the 2 rods are savable? I dont see any damage on the big end bore, just the color from the heat on the outside.


The last pic is of another rod cap. All the rest of the rods and mains look good like this one.
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post #14 of 15 Old June 24th, 2019, 02:25 PM
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I would measure it and check if it went out of round, and if it didn't, then yes, they would work.

But on a max effort boosted engine with near zero miles? With that kind of discoloration I'd replace them for peace of mind.
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post #15 of 15 Old June 27th, 2019, 02:39 PM Thread Starter
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Does anyone know where I can find a used 03/04 cobra crank? Having trouble locating one. If I can find one in good shape for a decent price, I might jump on it instead of fixing this one.
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