.030 5.9 magnum

-
O

ok93zj

Active Member
Joined
Jul 25, 2013
Messages
32
Reaction score
0
Location
vinita, ok
I finally got the heads off the 5.9 so I can get them checked before I put a cam and intake on it. Well it turns out it has already been rebuilt and bored .030 over and you can still kinda see hone marks in the piston wall so it's a pretty fresh rebuild,so my questions are:

1- how can I tell if they are flat top pistons vs stock style dished without pulling a pistion.

2-if the heads are good, I'm going to put hughes engine spring and retainers on it. should I go ahead and get a cam from there to? Either way what size cam should I get?

Info on the car '74 Duster full sheet metal, plan on putting a 8.8 with 3.73's under the rear, what ever size converter I need.
I'm still un decided on tire size since I can't find 14'' tires anywhere, and I love my 14'' western wheel mags.
I've heard these engine can do 12's with the right setup and that would be awesome. I'm wanting to build this as a real hot street car.

I'm trying to match everything to the cam, so any help would be appreciated. This is my first engine build so go easy on me.
 
If they are flat tops they will have a flat top. If they are dish pistons they will have a dish. First is a flat top, second is a dish. Kinda self explanatory, really.
 

Attachments

  • FLAT TOP.jpg
    14.4 KB · Views: 618
  • DISH.jpg
    13.3 KB · Views: 624
I guess when I read that they came stock with dished pistons I was thinking more concave not like what you have pictured.. :banghead:

That being said I have flat top pistons.. sweet.
 
I run that same cam in my 360....I didn't get to drive it much before I left stateside....Strong runner and a good choppy idle...
 
Peep this:

http://www.forabodiesonly.com/mopar/showthread.php?t=57501

The people that responded all run the KB107 and talk about 425HP/TQ with a mild cam, high dynamic compression ratio running on 89.

It's the way I'm headed as well.

Here have a calculator:

http://www.wallaceracing.com/dynamic-cr.php

Plug in the cam Intake Valve Closed @ .050 and have at it!


PS: did you already order those heads? The 1.92 RHS-X bare heads are pretty easy to put together with stock valves, Hughes 1110 springs and 2.2 K car retainers. Might shave a few bucks. Just a thought. :D
 
No I haven't ordered anything yet. I'm just getting the list of stuff I want to put in the motor. So I have a goal and a budget.

Reading the thread makes me want to go check to see how far down in the hole my pistons are. Hopefully they are not to far down in there. I don't know what rebuild kit they used. Or what the compression ratio should be now.
 
Ok so I checked to see how far down the pistons were in the hole and I came up with .085 that seems way low.
I was using feeler gauges and a 6" straight edge.
Is there a better way to check this?
 
Say I wanted to replace my pistons with some kieth blacks. What p/n should I get?
Also would I be able to just hone the cylinders out a little to get rid of the glaze?
 
I have a question, and before I start let me just say that I'm not trying to come off as rude or anything. There's no way of knowing your experience level, so, I've got to ask. How exactly did you come to the conclusion about the motor being already .030" over? Did you measure or possibly see a stamp on the piston that said it was 4.030"? The reason I'm asking is because if you're just going by the fact that you can still see the crosshatch marks in the bores, then that is not an accurate assessment. It's not uncommon to see an 100k+ mile magnum with good very visible crosshatching, a testimate to modern fuel injection, low tension piston rings, better machining processes, etc.

As for running 12's you should be able to hit that goal fairly easily. Myself as well as a few others (LXGuy comes to mind) have run 11's with some very basic builds. My best 1/4 mile combo was a stock 5.9 magnum (cracked heads and all) with a baby rv cam, an Edelbrock Air-Gap intake, Holley 850dp (a little overkill), and block hugger headers (which, lets be honest here, don't really count when compared to longtubes) ran a best of 11.87 @ 112. I know I know, different car, I've got an aero as well as a weight advantage, but LXGuy (check out http://www.magnumswap.com to check out his car) has run both quicker and faster than me with a combo not much more radical. I think just a bigger cam, some EQ (Iron Ram) heads, a well sorted drivetrain, and presto, easy 11's.

The point is that it looks like you're jumping in deep (bottom-end work is not cheap) to build a motor to run a number that is easily attainable with a simple bolt-on magnum. I'm not trying to talk you out of anything, but just kind of putting things in perspective. It looks like you've got a good plan with the rear-end swap. What trans are you planning to use? Also, whatever you do, DON'T SKIMP ON THE CONVERTER. It can make or break your combo.
 
The pistons have .030 stamped on top of them.. I have the heads off going to be pilling the pan this weekend.. this motor does not have over 50k on it. And if it does not by much. It got rebuilt and drove for a couple years and then swapped for a diesel. It was in a 95 dodge 2500..

As for tranny I plan on using the 904 that I have but rebuilt with a shift kit added.. the converter will be based on cam/motor build..

Like I said earlier I measured the piston to deck gap and came up with .085 which from what I read would put me in the 7 to 1 cr and I want more like 9.5 to 1 or 10 to 1. That's why the stock heads are going away and I was asking about pistons..

I don't know much about motors.. this is my first build and I want to do it right the first time. But I try to research as much as I can.
 
I'm wondering if maybe your rebuild was done with a set of .030 360 flat top "LA" pistons and not Magnums and maybe a lower compression part? Factory Magnum pistons look like these on the top.

Checking piston to block clearance.
[ame="http://www.youtube.com/watch?v=0VsjaY4PBMg"]Checking piston to block deck clearance.MP4 - YouTube[/ame]
 

Attachments

  • stock-magnum-piston.jpg
    8.6 KB · Views: 445
ok93zj said:
See that's what I'm thinking too.. every piston I looked up for the magnum had valve releifs in them and these do not.

View attachment 1714643540

That is number 3 piston.
Click to expand...
I did the same research before posting. Couldn't find a flat, flat top for a Magnum. Are you certain your engine is a Magnum and not an older LA block?

I suppose you could always get some new pistons. The KB107s mentioned before are popular. Speed Pro has some inexpensive ones as well that I've heard are close to factory piston weight and don't necessarily require you to balance the rotating assembly. On my 5.9 Magnum I was lucky enough to just require a little honing to clean it up. I re-ringed the factory pistons and put in new main and rod bearings and bolted it back together.
 
Yeah its a magnum. It has a balanced flex plate with tone ring. Everything on it is magnum except for the pistons apparently.

Kb107 with the heads list above should net the ration I want right?
I'm going to go ahead and pull a piston to make sure everything else is okay I.e rods, bearings, crank..

Also with the kb's would I have to balance my crank?
 
You will need to balance with the 107's
 
View attachment ForumRunner_20130801_225357.jpg

Top piston is stock out of a 89 block 318
bottom is what I pulled out of the magnum today.

The numbers inside are 8290 or B290. I can't find anything for either.

Either way I'm getting the 107's to get my cr up. I'll deglaze the bores and have my new pistons balanced to my crank..

Anyone want some LA block 360 .030 over pistons? Lol
 
Badger B290 pistons 1.576" CH. Flattops w no valve reliefs

Kb 107 has a 1.67 CH.......these will be .100 higher in the bore...
 
I have been thinking and looking at my piston choices for this build. Based on what 70aarcuda found or knew the kb107's will be .1 higher in the hole than what is currently in (badger b209's) which are .085 in the hole which puts the kb's at .015 above the deck. right? And I will have to use a really thick gasket to make sure the valves dont hit and so I will have enough quench.

now if I put kb 362's (ch-1.645) in I will be .016 in the hole and could use a thin gasket to get quench where I need it and I won't have to worry to much about valves hitting at high revs.(i have a buddy with a 383 stroker that didn't have enough clearance and reved it to much and bent a valve and messed a piston)

Am I doing the math right or am I way off and over-thinking stuff?
 
I have KB 107 in my 94 mag and they are flush with the deck.
 
You must log in or register to reply here.
-

Back
Top