Crank end play, destroyed converter, 408 nightmare

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1974scamp

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Hi guys,

long story, built the 408 about 2 years ago, was my first engine and i did a lot of mistakes, always had some problems with it, ran really hot all the time, had really high oil pressure (up to 100psi), and then suddenly my new converter (hughes 2500stall) was completely destroyed, the 2 impeller had contact.
I thought it was just a bad product and got a new one from summit, but there was so much metal in the trans oil, so i took the 904 out (just the trans), paid a guy 900€ to clean it up, he said he replaced a few bearings but generally nothing wrong with the trans just cleaned it.
Put it back in with the new converter and it worked but when i shifted 2nd to 3rd gear it was slipping so i took out engine + trans 2 weeks ago cause i needed to overlook the engine anyway.
Gave the trans to the guy again, he said he will check it again.
Just before i removed heads and oil pan (cause i want to install a thicker head gasket to get my compression from 11.6 down to 10.5, and got a new milodon oil pan, used the stock 360 pan with a windage tray till now) and i noticed a massive crank end play, the thrust bearing looks worn out (probably hard to see in the pics) on the back side of the engine have not pulled the crank till now.

What can be the reason for all this? Did the end play destroyed the converter or did the damaged converter caused the end play?

Also the fel pro head gaskets have been deformed when took off the heads.
And there was a lot of metal in the pan there are 3 magnets in there.

Thanks for your help!
Laurin

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If that figure is correct, end play is not the problem. I'm no expert, I've heard of "converter ballooning?"
 
If you took out the thrust bearing on the transmission side, most likely you didn't get the converter seated all the way into the transmission before you bolted it up. It doesn't take much to kill a thrust bearing. That's most likely what did that damage.

Now, you need to figure out why you are killing it with detonation and why it runs hot.
 
how many miles on this engine build? that's a lot of metal debris in the pan. I'm not totally sure, but looks like the crank thrust cheek is beginning to turn color like it may have been heating up. Is there an interference between edges of bearings and crank fillets/ no fillets.
Were you doing a lot of holding the engine at high revs and holding it against the brakes?
a brand new trans slipping on 2 to 3 shift is not very encouraging, unless you just had poorly adjusted kick down linkage.
 
And the camshaft specs, please.

Very likely detonation for the head gasket as said.

What thicker head gasket are you going to use?
 
Thanks for the answers, these are the engine specs till now:

1976 360 block 0.30 over
Scat cast steel crank
Scat I-beam rods
+5cc flattop pistons
windage tray
stock oil pan and pickup
Melling HV oil pump
summit double remote oil filter with stock oil filter plate
Rapom alu heads 2.02 intake 1.60 exhaust valves 65cc
Comp hydraulic flattapped xe274 cam
Edelbrock air-gap intake
about 10.6 to 1 compression
Hughes 2500 stall converter
TF-904 reverse full manual valve body
8 3/4 with 3.23 to 1
Car is 1974 Plymouth Scamp

wanted to install
-the new cometic head gasket (.086 thick) to bring the compression down to about 10.5
-change to the comp xe275HL cam with comp double 995-16 valve springs
-install the milodon 30940 pan with new pickup and remove the windage tray
-replace the stock oil filter plate with the canton one
-install the moly coated fuel pump extensioner
-install a timing chain tensioner
 
If you took out the thrust bearing on the transmission side, most likely you didn't get the converter seated all the way into the transmission before you bolted it up. It doesn't take much to kill a thrust bearing. That's most likely what did that damage.

Now, you need to figure out why you are killing it with detonation and why it runs hot.

could always push the converter forward and backward before i bolted it to the flexplate

how many miles on this engine build? that's a lot of metal debris in the pan. I'm not totally sure, but looks like the crank thrust cheek is beginning to turn color like it may have been heating up. Is there an interference between edges of bearings and crank fillets/ no fillets.
Were you doing a lot of holding the engine at high revs and holding it against the brakes?
a brand new trans slipping on 2 to 3 shift is not very encouraging, unless you just had poorly adjusted kick down linkage.

yes it definitely have been heating up there the crank has coloured all the way round

engine must have maybe about 500miles

No big burnouts or so and now kickdown due to the full manual valve body
 
I asked on the head gasket because of the finer surface finish that should be used on heads and block with the Cometics. Just be aware of that.

That thickness increase ought to get the SCR down about 0.8 or 0.9 points. But any quench effect you had will be lost; the dimensions are not given to know how much quench gap there was.
 
What pin boss diameter do the pistons call for? Did you use a wider LA rod on a magnum pin boss width piston?
I would think the convertor wasn't in at first.
 
are these wedge closed chamber heads? how many cc's now?
if so going to that thick gasket will remove your quench and be counteproductive
I'd look at opening the chambers and/or D Dishing the pistons (is that +4 mean more cc's in the piston (i.e. add 4 cc to the volume ) or 4cc dome (take away 4ccs)?
piston guys use both terminologies
x2 on checking the surface finish (heads and block)for cometic gaskets
mopar does not have a generous crank thrust but I think this is a result not a cause
most likely not getting the converter seated in all the way
when you have it apart with thrust bearing installed chamfer the parting lines to the rear from the bearing oil groove use a bearing scraper or whatever- it's not fussy
you can also drill through the thrust into the oil passage .040 ish through the block 1/16 through th bearing and make a little oil pocker
when thrusting all the oil wants to go out the front
and do a complete cleaning- all the plugs out and brush brush brush
 
are these wedge closed chamber heads? how many cc's now?
if so going to that thick gasket will remove your quench and be counteproductive
I'd look at opening the chambers and/or D Dishing the pistons (is that +4 mean more cc's in the piston (i.e. add 4 cc to the volume ) or 4cc dome (take away 4ccs)?
piston guys use both terminologies
x2 on checking the surface finish (heads and block)for cometic gaskets
mopar does not have a generous crank thrust but I think this is a result not a cause
most likely not getting the converter seated in all the way
when you have it apart with thrust bearing installed chamfer the parting lines to the rear from the bearing oil groove use a bearing scraper or whatever- it's not fussy
you can also drill through the thrust into the oil passage .040 ish through the block 1/16 through th bearing and make a little oil pocker
when thrusting all the oil wants to go out the front
and do a complete cleaning- all the plugs out and brush brush brush
I would add that you could make sure the crank is totally free spinning. when you test fit the crank into the block, hand-spin the crank in the block with only the end (upper)main inserts (#1 & #5), lightly oiled, and run a dial indicator on the other crank main journals to make sure the crank is straight. If OK, install end main caps and torque to spec. Take note of crank spinning drag. Reinstall crank on all the main bearings with caps installed, torqued, and again hand-spin the crank, comparing to earlier hand-spin feel. if there is substantial increase in drag, you need to investigate the reason and the source of added friction.
If you have another oem crank, I would double and triple check all the dimensions of the distances between journals and the flex plate surface, to make sure the stroker crank was machined properly.
 
“Rapom alu heads 2.02 intake 1.60 exhaust valves 65cc”

What is a rapom aluminum head ?

At first you said reduce compression from 11.6 to 10.5. Later you said 10.6 to 10.5

What’s the orignal compression?

I see you are in Austria. What is the octane of the gas you run? Is European octane rating calculated 100% the same as US ?

Looking at 65cc and 4cc domed flattop piston in a 4” stroker makes me think you have way to much compression. But I don’t know how your gas compares.

I run your same cam with 9.7:1 measured cc’d compression. And with 91 octane it’s on the edge of pinging.

The advertised compression of motors in the 60’s did not actually measure that high. So running real 11:1 now is a lot different than running fake 11:1 back in the day with 100 octane gas
 
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we don't know if that's a 4 cc domed piston
more likely the KB style nomenclature where +4cc means add 4cc to the chamber volume when doing your calcs
but I do not know
If you have done a compression test please post the reaults
 
“Rapom alu heads 2.02 intake 1.60 exhaust valves 65cc”

What is a rapom aluminum head ?

At first you said reduce compression from 11.6 to 10.5. Later you said 10.6 to 10.5

What’s the orignal compression?

I see you are in Austria. What is the octane of the gas you run? Is European octane rating calculated 100% the same as US ?

Looking at 65cc and 4cc domed flattop piston in a 4” stroker makes me think you have way to much compression. But I don’t know how your gas compares.

I run your same cam with 9.7:1 measured cc’d compression. And with 91 octane it’s on the edge of pinging.

The advertised compression of motors in the 60’s did not actually measure that high. So running real 11:1 now is a lot different than running fake 11:1 back in the day with 100 octane gas


Ok seems neither of the compression was right, this is what i calculated now

The heads are from german moparshop they say they are compareable to the edelbrock rpm but better quality here some pics

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“Rapom alu heads 2.02 intake 1.60 exhaust valves 65cc”

What is a rapom aluminum head ?

At first you said reduce compression from 11.6 to 10.5. Later you said 10.6 to 10.5

What’s the orignal compression?

I see you are in Austria. What is the octane of the gas you run? Is European octane rating calculated 100% the same as US ?

Looking at 65cc and 4cc domed flattop piston in a 4” stroker makes me think you have way to much compression. But I don’t know how your gas compares.

I run your same cam with 9.7:1 measured cc’d compression. And with 91 octane it’s on the edge of pinging.

The advertised compression of motors in the 60’s did not actually measure that high. So running real 11:1 now is a lot different than running fake 11:1 back in the day with 100 octane gas


till now I filled it always with 98RON, this must be 93Pump in the US

wanted to change to the thicker cometic gasket that i can use 95RON (91Pump US) without worries also thought this could be also a reason why it ran so hot

this is my calculation with the new head gasket, but also just read on summit site that you shouldnt have a bigger quench than 0.060, the new cometic head gasket is 0.086 thick

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we don't know if that's a 4 cc domed piston
more likely the KB style nomenclature where +4cc means add 4cc to the chamber volume when doing your calcs
but I do not know
If you have done a compression test please post the reaults

Thats the stroker kit
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Pistons are Icon flat top with 2 valve reliefs +5cc
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All the CR numbers make sense... ran them this AM and they all hang together with the latest info from the OP.

98 RON (research octane number) is indeed about the same as 93 octane in the US, which is the average of RON and MON (motor octane number), and gives usually about 5 points numerical lower results.

IMHO, 10.5 on 91 US octane (the 95 RON in Europe) may be marginal. But I also think the final SCR may be lower... the OP has not told ups if the deck of the engine block was cut to reach true zero deck for the pistons. With a nominal 360 block, these pistons are around .010-012" in the hole. So actual SCR with the .086 thick head gaskets may be more like 10.1-10.2.

Additionally, most of Austria is at or above 1000' altitude, and much higher in much of the country. That is going to lower the operating compression ratio. From direct experience, going from sea level (where I think autoxcuda lives) to 1000' altitude WILL make a very definite improvement in detonation resistance.

OP, you may want to increase the head gasket bore hole to 4.10 or 4.12. The gasket cylinder bore holes do not always perfectly register (align) with the block holes so some extra opening size is wise.
 
OK 4cc's is valve notch in piston not dome
thanks NM
I would strongly suggest you do not use a thick gasket to lower your compression
most likely it will ping worse and be more susceptible to bad gas and timing
work on your distributor curve
open up the chambers say 5 cc there are those on this forum who can tell you how to do it and even pick up some flow
back in the day we'd put the head on the bare block and flip it upside down and scribe around the bore (using some dykem or dye to see the scribe
do not take the chamber out to the gasket
you could also retard the cam to straight up
NM can tell you how much difference that would make (do we know what cam?)
all good questions 1974 scamp
 
[QUOTE="nm9stheham, post: 1972489334, member: 331881”]
....
Additionally, most of Austria is at or above 1000' altitude, and much higher in much of the country. That is going to lower the operating compression ratio. From direct experience, going from sea level (where I think autoxcuda lives) to 1000' altitude WILL make a very definite improvement in detonation resistance.....[/QUOTE]

Actually I’m in a suburb valley of Los Angeles at 768’ elevation. To get out of the valley one direction I go over a mountain pass at 1500’. That’s where I got light pinging in hot weather. Just did slight timing chance and other small things to fix.

But that’s with 9.7:1 compression, 416 stroker, edelbrock heads, quench, and a comp 274-S cam very close to original poster’s cam.
 
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I shift my magnum down going over the ridge route, or "Baker grade" I have excellent cooling (73 New Yorker 4 core radiator) but can't use the DC computer without octane booster
 
Check the progressive fire-ring failure pattern on that headgasket from a almost no distortion on #6 to maximum at #2. And #8 matching #4..... and all failures on the intake side. I think that means something.
I can't really see detonation on the piston tops, soooooooooo

As for heat, I would check the piston clearance, and ring-gaps. I had to take my engine apart and machine-hone it out another 3/10s, plus open the top gaps up a tad, which solved my heating issues. I run it at 205*F now.
I had a pair of .028 gaskets do what yours did, at 11.3 Scr on my 367, but with a 292/292/108 cam. The cylinder pressure with aluminums was about 180psi. I redid the decks a lil rougher, and installed FelPro .039s, with no more trouble. That was in 2001 or 2002;IIRC.lol. Mine were still sealing but it was close.
 
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