360 mystery breakdown

[MopaR&D]

I had a feeling this was going to happen at some point; been running this 360 on the edge of detonation for so long it was bound to fail somehow. I'm at the point now where it's back in my garage and I've confirmed that it has a rod knock on #8 cylinder by doing the plug-wire pull test while it's running. I'm willing to bet one of the rod bolts failed because being the newbie I was back when I built this thing, I bought ARP rod bolts without knowing that the rods needed to be resized so I just reused the old factory ones

So I think I'm gonna at least pull the intake and heads with the engine in the car and then probably drop the pan to take a look in the crankcase before I pull the short block. My conundrum is that I used factory rods and crank but had them balanced with my KB 107 pistons. I would like to reuse as many parts as possible and put it back together without spending more than necessary, I guess that depends on the condition of everything else inside... I wouldn't be surprised if my pistons were chipped from all the pinging although it ran great and had little to no blowby with very little oil consumption.

It's probably safe to assume though that I should at least prepare for a full teardown...?

 

[dukeboy440]

I had a feeling this was going to happen at some point; been running this 360 on the edge of detonation for so long it was bound to fail somehow. I'm at the point now where it's back in my garage and I've confirmed that it has a rod knock on #8 cylinder by doing the plug-wire pull test while it's running. I'm willing to bet one of the rod bolts failed because being the newbie I was back when I built this thing, I bought ARP rod bolts without knowing that the rods needed to be resized so I just reused the old factory ones

So I think I'm gonna at least pull the intake and heads with the engine in the car and then probably drop the pan to take a look in the crankcase before I pull the short block. My conundrum is that I used factory rods and crank but had them balanced with my KB 107 pistons. I would like to reuse as many parts as possible and put it back together without spending more than necessary, I guess that depends on the condition of everything else inside... I wouldn't be surprised if my pistons were chipped from all the pinging although it ran great and had little to no blowby with very little oil consumption.

It's probably safe to assume though that I should at least prepare for a full teardown...?

If you had detonation, your pistons are probably done for. Wouldn't be surprised if they look like someone hit them with a ball peen hammer. Could get lucky though, I'd just plan on a complete rebuild

 

[K.O. SWINGER]

you wont now till you open it up sounds can be very deceiving.I would do just like you are suggesting pull the top end apart and start looking. there is a good possibility its something in the top end, lets hope!

 

[Killer6]

What happened & to which cylinder(s) when the head gasket blew?

 

[Marcohotrod]

when rod bolts are replaced the large end may be out of spec, and may not, if you did not have them checked the bolts do not fail, the size or roundness of the rod might be off. if the blown head gasket was leaking water into a cylinder, that can blow a rod bearing. rebuild it with like weight parts and it will not need a rebalance

 

[MOPAROFFICIAL]

I had a feeling this was going to happen at some point; been running this 360 on the edge of detonation for so long it was bound to fail somehow. I'm at the point now where it's back in my garage and I've confirmed that it has a rod knock on #8 cylinder by doing the plug-wire pull test while it's running. I'm willing to bet one of the rod bolts failed because being the newbie I was back when I built this thing, I bought ARP rod bolts without knowing that the rods needed to be resized so I just reused the old factory ones

So I think I'm gonna at least pull the intake and heads with the engine in the car and then probably drop the pan to take a look in the crankcase before I pull the short block. My conundrum is that I used factory rods and crank but had them balanced with my KB 107 pistons. I would like to reuse as many parts as possible and put it back together without spending more than necessary, I guess that depends on the condition of everything else inside... I wouldn't be surprised if my pistons were chipped from all the pinging although it ran great and had little to no blowby with very little oil consumption.

It's probably safe to assume though that I should at least prepare for a full teardown...?

What was the quench distance again?
When I was young, this friend of mine told me the same about hammering in the arp bolts and it more than likely being fime to run as is...every single one bulged the rod into its bore like .025 and I said to hell with that.....don't ever screw up by chincing with rods or it'll bite you.

 

[brian6pac]

I don't understand what every one is talking about?? He blew a head gasket and the cylinder filled up with coolant and it hydrauliced a piston, you can't compress liquid, and bent a rod then it wiped out the rod bearing and now it knocks. End of story.

 

[MopaR&D]

Just to clarify I did NOT replace the rod bolts, I realized that in order to use them properly required machining the rods so I decided to use the FACTORY rod bolts that were in the engine when I got it, which was in long block form with an already .060" overbore so it's safe to assume it had been disassembled at least once or twice...

Quench distance worked out to be around .042-.045", again I didn't take the time to measure each piston individually on each side. The block had also been decked previously but I doubt it was square decked. I suppose now would be the time to find out if I can get the proper tools.

 

[MopaR&D]

I don't understand what every one is talking about?? He blew a head gasket and the cylinder filled up with coolant and it hydrauliced a piston, you can't compress liquid, and bent a rod then it wiped out the rod bearing and now it knocks. End of story.

That makes the most sense, the oil filled with coolant FAST almost immediately so it very well could have burst into a cooling passage.

****.

 

[Pascamp]

I don't understand what every one is talking about?? He blew a head gasket and the cylinder filled up with coolant and it hydrauliced a piston, you can't compress liquid, and bent a rod then it wiped out the rod bearing and now it knocks. End of story.

That's what I thought too before I even clicked on the post.

 

[brian6pac]

None of this matters the rod is under compression the bolts have nothing to do with it. The coolant got into the combustion chamber and the piston hit it that is what happens when you blow a head gasket.

 

[jos51700]

None of this matters the rod is under compression the bolts have nothing to do with it. The coolant got into the combustion chamber and the piston hit it that is what happens when you blow a head gasket.

While I do agree with this, I also feel that ARP bolts in a properly resized rod could possibly offer a little more forgiveness if a light hydrolock impacted a bearing insert.

 

[MopaR&D]

While I do agree with this, I also feel that ARP bolts in a properly resized rod could possibly offer a little more forgiveness if a light hydrolock impacted a bearing insert.

Even if that was true I'm definitely not going to try to find out again lol. I'm gonna pray for now that the crank is OK and I can get away with just replacing that rod, bearings, maybe pistons, and maybe I'll go ahead and get the rods resized now since I still have those ARP bolts NIB.

Also I definitely won't be putting it back together with the same camshaft, I know that was part of the issue all along; too little overlap for the cubes and compression = high cylinder pressure + shitty pump gas = POP!

 

[yellow rose]

Even if that was true I'm definitely not going to try to find out again lol. I'm gonna pray for now that the crank is OK and I can get away with just replacing that rod, bearings, maybe pistons, and maybe I'll go ahead and get the rods resized now since I still have those ARP bolts NIB.

Also I definitely won't be putting it back together with the same camshaft, I know that was part of the issue all along; too little overlap for the cubes and compression = high cylinder pressure + shitty pump gas = POP!

The good news is it sounds like you have learned some things from the process.

Education, real education, costs an assload.

 

[MopaR&D]

The good news is it sounds like you have learned some things from the process.

Education, real education, costs an assload.

Lol true, what sucks is I learned a lot of these things soon after the engine was assembled and running and I didn't think it was serious enough to at the very least change out the cam way back then. And get a cold-air intake. And stop trying to be a cheap-*** and run mid-grade gas when it should have had 100% premium always, at least

 

[MOPAROFFICIAL]

Lol true, what sucks is I learned a lot of these things soon after the engine was assembled and running and I didn't think it was serious enough to at the very least change out the cam way back then. And get a cold-air intake. And stop trying to be a cheap-*** and run mid-grade gas when it should have had 100% premium always, at least

Cold dense air, hmmm..
The first post if not read a few times sounded like you hammered bolts into it without a re size, then blew the head gasket...lol.
What head gaskets did you use?
What was the cranking compression?
What was the total timing?

 

[MOPAROFFICIAL]

The good news is it sounds like you have learned some things from the process.

Education, real education, costs an assload.

So does ignorance, you don't keep running it while its rattling like that, and if raged edge builds are your aim....you better damn well know how to tune for that octane and have a good ear.

 

[MopaR&D]

So does ignorance, you don't keep running it while its rattling like that, and if raged edge builds are your aim....you better damn well know how to tune for that octane and have a good ear.

I did spend a lot of time playing with the ignition timing, seemed like every year or so I was backing it down a degree or two more than the previous year even running the same grade from the same station (I know still varies). Last I had it was 32* total all in at just under 3000 RPM. Head gaskets were Fel-Pro 1008s. Cranking compression was 170-180 psi on all cylinders taken just this past summer, pretty substantial for 5000' above sea level I think.

Looking at head gaskets now, same situation it was 7 years ago... if I want the ideal quench with a .030-.035" compressed height I gotta pay 2x as much for Cometics. Fel-Pros only come in .039" and .028" which I think would be pushing it (would it?). It's all speculation anyway heck I'll probably want new pistons.

 

[yellow rose]

So does ignorance, you don't keep running it while its rattling like that, and if raged edge builds are your aim....you better damn well know how to tune for that octane and have a good ear.

This is true.

You have to be willing to tune every part of everything...timing, carb, plugs and how each affect each other.

 

[AJ/FormS]

Your engine sounds a lot like my367.It is 4.04 x 3.58, KB107s .005 out of the hole, .034 quench with a .039 gasket. 10.9Scr. Fresh cold air, and 205*F minimum running temperature. I have run three different cams in this with the ICA running 70*,61*, and now 64 or 66*. All on fat-boy bushed factory318 rods, with ARP bolts, and resized.
I run that FelPro1008 gasket. It's on it's third install. Good stuff. I also run ARP headbolts, lubed and IIRC somewhat over-torqued, on account of I was lazy and didn't want to go back and retorque it. I think I threw in 5 extra pounds.With Aluminum heads and with full timing and a modest timing curve I run 87E10. I've got over 100,000 miles on this engine now.I have had cylinder pressure as high as 185, but currently run 175. I am at 900ft
I tried the thin Orange gaskets when the pistons were a tic under the deck, but they were coming out by the end of the summer. I caught it just in time. I'm not sure where I purchased the Thin Orange ones; maybe Mopar? It mightabin the P4120094,IDK. In any case, I cannot recommend that Orange one.

I think she woulda survived with all-in at 3400 where I run mine. Plus I have a kink in my curve. I run 14* initial, 28* at 2800 and then it slows down to 32 at 3400. More timing didn't knock, but it didn't make her any faster either, so 32 it is. And 22* in the VCan, for 50* at 2800 for cruising. I have a manual transmission.

To run that high a cylinder pressure at 5000 ft takes a very early intake closing angle, or a very small total chamber volume.I know how mine ran with a 270/280/110 cam, at 900 ft. It was T-N-T. I bet yours is too. What stall and gear were you running? Iron heads?

 

[MOPAROFFICIAL]

I did spend a lot of time playing with the ignition timing, seemed like every year or so I was backing it down a degree or two more than the previous year even running the same grade from the same station (I know still varies). Last I had it was 32* total all in at just under 3000 RPM. Head gaskets were Fel-Pro 1008s. Cranking compression was 170-180 psi on all cylinders taken just this past summer, pretty substantial for 5000' above sea level I think.

Looking at head gaskets now, same situation it was 7 years ago... if I want the ideal quench with a .030-.035" compressed height I gotta pay 2x as much for Cometics. Fel-Pros only come in .039" and .028" which I think would be pushing it (would it?). It's all speculation anyway heck I'll probably want new pistons.

In your case...you shouldn't need more than 30 degrees of timing "on premium". You only need as much adv as the octane can resist the cyl pressure or the pressure will light it for you. The gasket pushing into a water jacket sux, half the time or more when they go do to detonation/pinging they push toward the valley and you avoid the water.
I use 8553 head gaskets, 185 cranking, quench domes with j heads and BPR5EY plugs. 28 total timing by 2200rpm on 91 w/4 spd. If I run anymore timing then go down the freeway and at 65 cruise decide to stomp on it....it will rattle and you bet your *** the second it did I lifted out and was back in the shop checking plugs and taking timing out 2 degrees at a time. Pistons are a nice golden color, pretty clean with light film on them. The pistons mirror the chambers ....remember that when tuning.
Your cyl pressures are wide spread @ 170-180...you could have been better with a tighter quench...but really you ran too much power timing.imo

 

[AJ/FormS]

Also I definitely won't be putting it back together with the same camshaft, I know that was part of the issue all along; too little overlap for the cubes and compression = high cylinder pressure + shitty pump gas = POP!

Too little overlap is not the cause.
Too much Dcr is perhaps the first nail in the coffin, but the 32* at 3000 was the second ,a thin headgasket would have been the third, and not enough octane was the final. For you it is/was a combination factors, probably lead by lack of knowledge.1008s should have been successful; that they were not is a testament to the very high cylinder pressures that detonation can produce.
You don't need the Q to be that small. Do not sacrifice durability for Q. Just don't run Q between .050 and .080; I have read that this can actually create problems(no experience). Anywhere in the range of .035 to .045 should be fine, rather,it has been fine for me.
I did a quick check on what it would take to make 175 psi at 5000 ft and I came up with; Scr of 11.3,Dcr of 8.6/psi of 176.
8.6 is too much for iron heads and 87 as you have found out. It should have been a real ripper with sufficient octane.
I ran nearly this exact pressure a few years ago but with aluminum Eddies, on 87 no problem. I did it with a 270* cam and an ICA of 61*and a Q of about .025.and at 900ft. So you have all the ingredients. The recipe is good. This engine was crazy torquey, an awesome streeter.
With the .060 overbore, your cubes comes to 370.78 to make 11.3Scr, the total chamber volume needs to be about 73.74cc. With .042Q and a 1008 gasket,your pistons would need to be about .003 in the holes;which is .64c the gasket is 8.9cc and the KB107s are advertised with 5cc eyebrows. So far we are up to 14.54cc. Then 73.74 less 14.54 leaves 59.2 cc in the heads. That's pretty small. But that is what you need at 5000 ft.
There is certainly room in your Dcr for a bigger cam. If my calculations are close, the 55*ICA is a pretty small cam.I redid the calcs with a 64* ICA and with the same 11.3Scr, the Dcr comes in at 8.03/161psi. This will burn 91 for sure under full load,full timing. I think it might even be happy on 89 with a slightly delayed all-in. And it will be happy on 87 for day to day cruising, and for hiway.
So the 64* ICA is almost a magic number for you.
To get it, the math works out to a 276*/110 cam in at 106. Many other combinations are possible, but it just so happens that all the cam companies have something on the shelf like this. It is a very popular cam. It will not work with a stock TC, and it will not like less than 3.55s with an automatic.
Of course all my math is based on the very meager info spread out in all your posts,lol, so you know the old saying;"garbage in/garbage out".
Your results with different math will vary, WILL.

 

[JBurch]

If you haven't yet; do pull the heads off to get a look at what happened. I'd be interested in good pics of the gaskets and the crown's of the pistons.

Hypers don't like detonation, though strong, they are brittle, at the very least the piston hanging on the rod with the bad bearing is toast. If the others check out ok, get one replacement, and one rod, put it back together.

 

[Killer6]

I don't understand what every one is talking about?? He blew a head gasket and the cylinder filled up with coolant and it hydrauliced a piston, you can't compress liquid, and bent a rod then it wiped out the rod bearing and now it knocks. End of story.

This was the nature of My question w/o leading the witness............If cyl #8 was blown and full when He pulled the head the bearing got hammered & the rod got tweaked.
If your balancer is marked every 90deg. check the accuracy of TDC for that crank throw on #7&#8, if not get a degree wheel & do it, what was going on when the gasket blew?
If it hit hard enuff under load now is the time to get it right, check everything...................

 

[MopaR&D]

The thing that's strange is I actually thought I had the timing nailed down; after I cut a hole in my hood and attached a scoop I can't remember hearing it ping much at all really. I had also backed the timing down a hair and even richened up the carb a tad when the weather started getting cold.

When the head gasket blew it was pretty cold outside (15*F) and I was going down the highway at 3000 RPM just under 80 MPH; I stepped on the gas and got into the secondaries for a bit of "fun" and to pass a line of cars going super slow, once I let off I realized something wasn't right and once I pulled off the road and popped a valve cover it was obvious (inside of valve cover was coated in what looked like vanilla milkshake). Like I said I hadn't heard any AUDIBLE pinging for a long time but I know that doesn't mean it wasn't happening.

AJ I have talked to you before a couple times about my engine (been a bit though), it's a 1975 360 LA block with factory crank and rods, KB 107s, and factory iron Magnum heads. When I built the engine I cc'd the heads and calculated the true static compression to be 10.42:1. The cam I used that I think was way too small was the Lunati Voodoo 256/262 adv. duration (213/220* @ .050"), especially with the 1.6 Magnum rockers I think the cylinder fill was just too much at too low of RPMs. Peak torque on this thing felt like it was 2800-3000 RPM and it liked to be shifted barely past 5000 RPM.