360 magnum. 1 piston lower in cylinder??

-
What did the engine come out of? Splashing through a big puddle and inhaling water will/ can bend a rod/ hydro lock an engine also! Any history of this being possible, or nobody's gona say anyway.
 
Like I said. My local machine shops are backed up for weeks otherwise I would take it to one but if I can do it accurately myself I will.
 
JoePole1 said:
Like I said. My local machine shops are backed up for weeks otherwise I would take it to one but if I can do it accurately myself I will.
Click to expand...
I think you will be fine, wouldnt worry about the crank, the rod was the weak link as you see.
 
JoePole1 said:
Does anyone know of an accurate way to check the crank for straightness besides what I have already done? I don't have access to a lathe but I suppose I could rig up some sort of jig and dial indicator. Maybe a straight edge across the length of the crank at the journals? Remember.....previous owner said he heard the engine running fine before it was pulled but I only have his word.
Click to expand...

You can make V blocks out of wood and set it up on the main journals and measure it with a dial indicator.
 
Thanks Rusty. I layed the crank back in the block with #1 and #5 bearings installed. I then measured #2 and #4 journal runout with my dial indicator. Got zero so I will call it good to go.
 
That's a good check IMHO.
Youcould get some twist but I'd guess that would likely cause some bit of runout too.
 
Hey ham.....I believe you mentioned before but the factory magnum slugs weigh the same as the H116CP's so no balance needed. Going with STD bore, small valve EQ heads and .028 head gasket. Should give me around 10.1:1. Sound good?
 
dusted said:
I bet it would show up on a scan tool. My Solus shows misfire data, even though it doesn't feel like a miss or skip. You probably wouldn't have noticed.
Click to expand...
It would if the ecm has misfire data. Would be nice to scan a running engine before its pulled.
 
JoePole1 said:
Does anyone know of an accurate way to check the crank for straightness besides what I have already done? I don't have access to a lathe but I suppose I could rig up some sort of jig and dial indicator. Maybe a straight edge across the length of the crank at the journals? Remember.....previous owner said he heard the engine running fine before it was pulled but I only have his word.
Click to expand...
Look at the main bearings for wear on one side or the other. Ssssprobably straight.
 
#3 main bearing shows the most wear but nothing i would call excessive for the mileage. Rod bearings look normal as well.
See post 81.
 
Last edited:
JoePole1 said:
Hey ham.....I believe you mentioned before but the factory magnum slugs weigh the same as the H116CP's so no balance needed. Going with STD bore, small valve EQ heads and .028 head gasket. Should give me around 10.1:1. Sound good?
Click to expand...
Hey Hoe,
Mmmmm .... H116CP is the same as the 360 LA....
H116CP: Pin 154 gr & Piston 567 gr = 721 gr total (from FME Catalog)
My 360 LA info: Pin 154 gr & Piston 576 gr = 730 gr total

My 360 Magnum info: Pin 135 gr & Piston 469 gr = 604 gr total
KB107: Pin 118 gr & Piston 492 gr = 610 gr total
H655CP stock Magnum replacement piston: Pin 128 & piston 488 = 628 gr total (Weighed by 70aarcuda; see here: Magnum slug weight vs...

Maybe you were thinking of the KB107's? Or maybe I made a misstatement?
 
Thanks ham. No worries. Was probably my misunderstanding. At the time I was bouncing back and forth between my LA and magnum for build. Now I am committed to the Magnum and looking for a STD bore high compression piston giving me around 10:1 with EQ heads.
 
Well the KB 107's would be the closest. Weight is close enough to be within factory balance tolerance, and with the flat top and the compression height and a .039" head gasket, with 62 cc Magnum head combustion chambers and a .039" thick head gasket will be around 10.6 SCR; with a .050" thick head gasket, it'll be around 10.3 SCR. (Those pistons will stick out a few thousandths from a Magnum block...)

Now if you are using the EQ's IIRC the chambers are 62 cc's and so you are in the same CR range.
 
Thanks again ham. You are correct with the EQ's. I am also using the.28 head gaskets so I will calculate for that.

Dude... I am shooting for around 400HP/400TQ so forged is not necessary but will check them out. Are you running these in a Magnum without rebalance?
 
Sounds as if that motor was put together on a Monday morning or Friday afternoon and the technician just threw in the wrong connecting rod and never noticed the difference.
 
I saw that. Just wondering how the engine held up over time. From what I have been able to find for the 5.9 Magnums STD bore is...

Stock: 470 +154 = 624 or 469 + 136 =604
ICON IC741: 530 + 118 = 648
KB107: 524 + 132 = 656

Any idea what is acceptable without balance? +/- 10%?
 
Last edited:
Stock SBM has reportedly ranged +/-20 (or maybe even +/-30 grams) around nominal. I have weighed just a couple of sets to compare to nominal and found as much as 15 grams off with just that limited sampling.

The ring pack for the KB's or ICON's may be different than stock so that enters into the picture, and IIRC that is part of the equation for IMM to do the no-re-balance 360 build linked in post #92. It would be worth reading that to see.

BTW, glad you got the right numbers for the KB107's. You're doing your home work!

The ICON's are the same for eyebrow volume and compression height as the KB107's so would give the same numbers for SCR. BTW, I see a recent post saying .028" head gaskets..... With either the KB107's or the ICON's sticking a few thousandths above the stock Magnum deck, you don't want that thin of a head gasket. The piston-to-head clearance will then be in the .025" range + or - and that is too tight. So go with at least the .039" head gasket thickness.

Do you have a cam selection yet? That is the DCR (dynamic compression ratio) can be calc'd. With the 10+ SCR range you look to be heading for, you need to look at DCR in some detail. Too high of a DCR will lead to detonation, and your altitude is not high, so no relief from the altitude in that department.
 
I did re-read that article. Yeah.....028" Head gasket may be pushing it. In fact I am a little concerned with the CR in the 10.5 range especially with iron heads. May be looking at .050" h.g. instead. I want to run this on 91 octane. I was under the impression that they were down in the cylinder. Oops. Really stinks to be limited on choices for Magnum pistons and really don't want to spend $650 on forged ICONS especially at my horsepower level.
I removed one of my pistons from the rod the other day and will weigh it tomorrow. If I go with KB107's maybe I can remove some metal from under the piston head to get within 20 grams of stock.
Another option is to play around with pin weight but good luck getting that info. Not too worried about the rings. They should be close to the same weight.
No cam selected yet but will be checking with Comp, Lunati and grinders for suggestions. That will be happening soon. May ask here as well. Thanks again.
 
Last edited:
KB has some lighter pins, pn R73 IIRC, at something like 110 grams. I forget the length, may be 2.75" long instead of 3.00". I have one at home for another project that I can weigh and measure but it will be a few days. And Manley has some.

More than 5 grams from the piston may be some work. I'm gonna take 40-50 grams off of piston but that is with cutting the crown down .070", plus cutting eyebrows and some more.

I personally would lower the SCR unless the cam is large enough. I've run 10.3 and 8.3 DCR as daily driver on 93 octane. At least you will have quench to help.
 
Thanks ham. Don't worry about weighing that pin. I think I need to make a better piston choice to get me closer to 10:1. I'd rather not be running that high with my
iron EQ's.
 
Or grind out the chambers some. 66 cc's with ICON 742's and a .050" head hgasket getsd you at 9.4- 9.5.

KB362's drop you to 9.1-9.2 with .039" thick head gaskets.
 
Don't skimp on pins, you really don't want one failing on you.
Buy the best/strongest pin you can get and make "lightest"secondary
 
You must log in or register to reply here.
-

Back
Top