Junkyard 5.9L Magnum + Edelbrock LA heads build

[MopaR&D]

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Except the 400 4speed crank is forged where the 360 is not.

Were there even that many made though? And I don't think they kept it forged for very long into the 70s as the power went down.

So what rings should I look at? I'm guessing i'll have to file-fit them myself or do they come pre-gapped in different sizes? Is there a gap spec for factory Magnum pistons when adding light boost?

Also i'm guessing when I remove the crank to replace the bearings the rear main seal will be "disturbed" and i'll need to install a new one?

 

[Jadaharabi]

Were there even that many made though? And I don't think they kept it forged for very long into the 70s as the power went down.

So what rings should I look at? I'm guessing i'll have to file-fit them myself or do they come pre-gapped in different sizes? Is there a gap spec for factory Magnum pistons when adding light boost?

Also i'm guessing when I remove the crank to replace the bearings the rear main seal will be "disturbed" and i'll need to install a new one?

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In response to the 400 forged crank they made them in to the late 70 at least.
I have one if your wanting one I'll sale it to you.
1978 400 crank question.

As for the rings you can get them pre gapped or file fit.

 

[rumblefish360]

So what rings should I look at?

I'm guessing i'll have to file-fit them myself or do they come pre-gapped in different sizes?

Is there a gap spec for factory Magnum pistons when adding light boost?

Also i'm guessing when I remove the crank to replace the bearings the rear main seal will be "disturbed" and i'll need to install a new one?

Q1
Moly faced is all I ever needed. The break in right quick.

Q-2&3
You can get them pre gapped. A file fit would be needed for a specific piston and clearances, like, KB requires a specific gap that may not be a OOTB part. Supercharged/turbo/NO2 require specific gaps as well.
So what are you doing? What do you plan to end up with?
What material are your pistons?

Q4
At this state of the game, adding boost, I would replace and remachine everything for the intended application. Ether you take the JY engine and just run with it or rebuild it stronger and tighter for a much more sound foundation.

 

[nm9stheham]

So what rings should I look at? I'm guessing i'll have to file-fit them myself or do they come pre-gapped in different sizes? Is there a gap spec for factory Magnum pistons when adding light boost?

Also i'm guessing when I remove the crank to replace the bearings the rear main seal will be "disturbed" and i'll need to install a new one?

Moly top rings for me all the way. It just makes life easier for little added $$.

Normal ring sets will come pre-gapped for the bore size for which they are specified (standard, .020"-over, etc.) If the bores are worn, the gap is going to be on the large side, so it's hard to say where you will end up with those bores and standard rings. (Stating the obvious!) Not sure if this is your question but I never put rings in any engine without checking the gap of each & every ring (even if they come out of the box with an in-spec gap and I don't apply the file to any of them).

Here's one of many pieces of info on ring gaps that you can find:
Everything You Need to Know About Ring Gap!

It seems foolish to me to not change the rear seal.....it be worn some already.

What is your planned level of 'light boost', in inches?

 

[dusted]

I have found that if the jy engine has some miles on it the ring gap will be sufficient for small boost 4-6 psi, just run a good headgasket -felpro or cometic but I’m not sure of your budget or goal.
The stock headbolts should be good also, there 1/2” but since you already have ARPs then use them. I waiting on the Pre magnum (91) in the Truck to have an issue so I can start on my 360 magnum for it. So far I’ve broken everything but the engine!

 

[MopaR&D]

The boost would be more to make up for the lower local air density than anything; I wouldn't try more than 10 psi gauge pressure above ambient which is more like 7 psi boost at sea level. It's not something in my build plans but it would be nice to have that option if i'm looking for extra power later on; it would help give me a leg up on all the turbo 4 and 6-banger cars around here which aren't really affected by the high altitude.

I'll start looking at ring kits with moly compression rings, any particular brands of choice? I'm willing to pay for something a bit higher quality, I want long-term high-mileage compression and reliability. I hate reading stories about re-ringed engines having tons of blowby. I suppose I can hit up my machinist for those parts too he'll definitely know what's good.

 

[nm9stheham]

At your build price level, I would go with any quality ring: Hastings, Sealed Power, Mahle. I just looked on RockAuto and saw both Moly top rings, and interestingly, an Enginetech set that says it has a ductile iron top ring.... ductile iron is supposedly good for higher heat use. (I just hope that description is accurate, as the price is low! When I have question on a part from a site like RockAuto, I take the PN to the MFR's website and research it.)

I have used standard replacement Hastings and Sealed Power moly top ring sets in my 2.6L Mitsubishi turbo rally car engine, running 8.2 true SCR and 14-15 boost, and they worked fine. But, I always re-bored and had a good hone job on them.....

This may not be wlecomed input....Your results will have more to do with the bore conditions than the ring itself. If you really want to guarantee longevity, then a re-bore is almost a given. You can borrow a good bore gauge and run it up and down for taper, and then vertical and sideways for out-of-roundness, and see what you have. It's clear from your 2nd pic that you do have some level of bore wear; the cross-hatching is all gone on a couple of places so I'd expect some of both taper and out-of-roundness. The former can kill rings pretty fast, and the latter hurts the seal. IMHO, a good, straight bore is the foundation of a good engine.

 

[MopaR&D]

While I agree a full bottom-end rebuild would be ideal it's just not in the cards; the whole reason I went with a JY Magnum block was so I wouldn't have to go through all that. If installing new rings means I need to have the cylinders bored I'm just going to leave it alone. Adding boost is not a priority, it's something I *might* add later knowing I *might* break something.

If I'm going to spend any money on block machining I'll just find a 360 LA block, then I wouldn't have to deal with the rocker oiling issue.

 

[Abodybomber]

While I agree a full bottom-end rebuild would be ideal it's just not in the cards; the whole reason I went with a JY Magnum block was so I wouldn't have to go through all that. If installing new rings means I need to have the cylinders bored I'm just going to leave it alone. Adding boost is not a priority, it's something I *might* add later knowing I *might* break something.

If I'm going to spend any money on block machining I'll just find a 360 LA block, then I wouldn't have to deal with the rocker oiling issue.

Khalid ,ignorance these guys.... You blow a a 800 dollar short block ..
I know you ,Khalid ,Be conservative on your tune ,Be very cautious .....

 

[Abodybomber]

Go get it ,Khalid ....

 

[dusted]

While I agree a full bottom-end rebuild would be ideal it's just not in the cards; the whole reason I went with a JY Magnum block was so I wouldn't have to go through all that. If installing new rings means I need to have the cylinders bored I'm just going to leave it alone. Adding boost is not a priority, it's something I *might* add later knowing I *might* break something.

If I'm going to spend any money on block machining I'll just find a 360 LA block, then I wouldn't have to deal with the rocker oiling issue.

Just roll with what you have, at the minimum I would at least install a new oil pump. I wouldn't be afraid to run those bearings also.

 

[rumblefish360]

To the casual eye, it is missed when your just walking by. For most every car guy, it would take 5 seconds or less to realize there not stock if you look.

 

[nm9stheham]

No need to re-bore with new rings. Just hone. I get what you are doing 100%. My point was not to discourage you, but to dispell the idea that new rings would fix bore issues. It was all about that word 'longevity'....

 

[MopaR&D]

No need to re-bore with new rings. Just hone. I get what you are doing 100%. My point was not to discourage you, but to dispell the idea that new rings would fix bore issues. It was all about that word 'longevity'....

I hear you, all valid concerns. Well in that case I'd be concerned about getting the correct crosshatch pattern, I don't want to ruin my cylinders if they're already in say, 90% good shape? And stripping the block and hauling to my machinist sounds like a pain just to get a hone. HOWEVER... my machinist (actually it's a team of 2) is a badass and can probably take one glance at my block and tell me how it looks and if it needs anything. These guys are used to building 1500-hp BBC drag engines and crazy giant-turbo LS monsters so I trust them for a moderate street SBM build.

 

[MopaR&D]

To the casual eye, it is missed when your just walking by. For most every car guy, it would take 5 seconds or less to realize there not stock if you look.
View attachment 1715236215

I'm going to guess you might have posted that in the wrong thread? LOL.. I noticed what looks like one of those fire core distributors, is that your engine? Are those dizzys any good?

 

[rumblefish360]

I'm going to guess you might have posted that in the wrong thread? LOL.. I noticed what looks like one of those fire core distributors, is that your engine? Are those dizzys any good?

Maybe so. Wrong picture/wrong thread... just getting up after a long double shift... ugh!

Someone mentioned painting aftermarket heads to hide them?

The distributor is from Pace Performance and it is a direct copy of the MSD ready to run but with a slight difference of 1’metal part vs. the MSD plastic part.
Speak with Jonny Pace about it. Works fine, I still need to get into it for best performance.

 

[nm9stheham]

I hear you, all valid concerns. Well in that case I'd be concerned about getting the correct crosshatch pattern, I don't want to ruin my cylinders if they're already in say, 90% good shape? And stripping the block and hauling to my machinist sounds like a pain just to get a hone. HOWEVER... my machinist (actually it's a team of 2) is a badass and can probably take one glance at my block and tell me how it looks and if it needs anything. These guys are used to building 1500-hp BBC drag engines and crazy giant-turbo LS monsters so I trust them for a moderate street SBM build.

And they probably have a nice bore gauge that they can set to 4.000" and know in a minute of running it up and down the bores what you have...

I've done the no-bore thing before a coupla times....when in college, workgin part-time, racing, and limited on $$, on bores probably worn considerably more than yours, and the results were pretty poor/irregular cylinder sealing. I just don't feel anymore that it is any real cost savings long term.

 

[dusted]

With the low tension rings on engines these days, I bet the bore is with in spec unless it was overheated.

 

[MopaR&D]

Good news (well, not for my bank account LOL), major machining has been completed on the Edelbrocks and Jim at Racer Brown has finished up my cam. I decided I'm going to just leave the short block alone; if I get the engine together and it burns a bunch of oil and has no compression well then sh*t, I'll get an LA 360 block and machine that. I highly doubt that would be the case though as my old 318 did that and it had all the tell-tale signs of worn bores. This block has no ridges at all at the tops of the cylinders, I can't feel any difference and certainly can't catch a nail on it.

It's harder to tell from the pics but the spots in the cylinders where the honing finish is worn away coincides with where the head bolt holes are. Just goes to show that having your cylinders honed with a torque plate installed actually does make a difference. Chrysler engineers actually figured out that problem and redesigned the head bolt holes on the Gen 3 Hemis btw.

@rumblefish360 I totally forgot lol my mistake, I did mention painting my aluminum heads... you are right from that pic I wasn't able to tell it had non-factory heads, very nice

 

[rumblefish360]

Thanks for the mention because I thought I was going crazy. I thought I read that. Most casual lookers miss it. Most who stop to take it in catches it.

 

[nm9stheham]

It's harder to tell from the pics but the spots in the cylinders where the honing finish is worn away coincides with where the head bolt holes are. Just goes to show that having your cylinders honed with a torque plate installed actually does make a difference. Chrysler engineers actually figured out that problem and redesigned the head bolt holes on the Gen 3 Hemis btw.

Yep that is what I would think too. Maybe now they are 'pre-worn' to be round LOL.

FWIW... I've had certain 4 banger blocks distort .003-.004" in the #4 cylinder by just putting in the top bellhousing bolts and torquing them lightly....!

Can you give a bit more detail on the head bolt hole changes on the GenIII ?

 

[MopaR&D]

Yep that is what I would think too. Maybe now they are 'pre-worn' to be round LOL.

FWIW... I've had certain 4 banger blocks distort .003-.004" in the #4 cylinder by just putting in the top bellhousing bolts and torquing them lightly....!

Can you give a bit more detail on the head bolt hole changes on the GenIII ?

Yeah it makes me want to make sure my torque wrench is accurate before putting the heads on, I know the head studs will probably put different loads on the cylinders but I don't think I'll be taking this thing another 50k miles to make a difference.

I read about the G3 Hemi head bolts in an SAE article about new manufacturing methods used for the engine, the authors didn't go into much detail but engineers basically found the head bolts could be made shorter and somehow pull the clamping load more from around the cylinder than the cylinder itself. I have a 5.7 short block on a stand in my garage I should take a look...

 

[nm9stheham]

Yeah it makes me want to make sure my torque wrench is accurate before putting the heads on, I know the head studs will probably put different loads on the cylinders but I don't think I'll be taking this thing another 50k miles to make a difference.

I read about the G3 Hemi head bolts in an SAE article about new manufacturing methods used for the engine, the authors didn't go into much detail but engineers basically found the head bolts could be made shorter and somehow pull the clamping load more from around the cylinder than the cylinder itself. I have a 5.7 short block on a stand in my garage I should take a look...

If you are using ARP studs, their lube, torque numbers, and procedures, the clamping force is gonna be something like 50-70% higher. That force all comes from the block at the threaded end. So, yes, it may be different; it all depends on how the material twists/distorts to hold varying loads. In the case of that 4 banger block distortion, I did not find any increase in distortion beyond 25 ft-lbs or so on the top bellhousing bolts... so it's possible you won't have any significant change. The only way to know is to assemble the heads on without a piston in a hole, and flip it over and measure the bore at the top once all is torqued.

OK on the other bolts....if you ever run across more info, I'd like to know; tnx.

 

[MopaR&D]

Got my cam in the mail! Along with some cool retro stickers... check out the specs on the card, pretty interesting.

Heads are also done, the shop really did me a giant favor and fully ported those Edelbrocks to the tune of 290 cfm on the intakes, basically FOR FREE... they still need to drill the holes for oiling the rockers but I will post pics as soon as I get them back. Seriously good people at work there, I felt like I won the lottery when I saw those ports.

 

[Abodybomber]

Nice cam,great airflow!