Help with my first engine build (5.9 Magnum)

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ValleyRat

ValleyRat

Well-Known Member
Joined
Feb 23, 2022
Messages
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Location
Palmer, AK
Application:
1967 Barracuda Coupe
4 speed manual

Starting Point:
Stock 360 Magnum (141k miles)

Plan:
-Dingle Hone Cylinders
-Re-ring Kit (Federal Mogul 205-6378-000)
-Professional Products 4 bbl aluminum intake
-Carb 4bbl (I haven't decided yet)
-Cam Upgrade (COMP Cams 20-746-9) Advertised Duration 265/273, Lift .506/.506
-Upgrade Valve Springs (Mopar Performance P5249464 - 1.418 in. Outside Diameter, 1.640 in. Installed Height)
-Headers (I haven't decided yet)

Questions:
1) With this sort of cam application, do I need to upgrade my valve keepers?

2) Would a fresh set of stock roller lifter hold up, or would they need to be upgraded as well?

3) Any other miscellaneous advice would be warmly welcomed. This is my first motor build of any sort, so I am learning as I go. Thank you!

* I am aware with this sort of swap, there are some small things to look out for: Rear sump oil pan, rear sump oil pump, timing cover swap for mechanical fuel pump, engine mounts won't line up perfectly.

Again, thanks for all your comments!
 
On used magnums the heads are prone to cracking. It is more common on the Magnum Heads. The reason is because Dodge went to a thinner casting in the cylinder heads from the factory. LA heads off any of your small blocks will have the same problem just not as common but, almost. They like to crack between the intake & exhaust valves.

Not trying to piss in your cornflakes or saying you need to buy need heads but just something to be wary of.
 
If your heads are cracked then look into a set of Edelbrock heads for the Magnum.

You can use regular LA heads IF you get oil through pushrods and rockers that use oil through pushrods. There available from Comp (Pro Magnum rockers in 1.5 ratio only) Hughes engines, PRW and then the more expensive TD or Jesel brands.

Spring keeper & retainers need upgrading when you start to make a good amount of power. As in a lot off power. Think along the lines of 10.5-1 & better with cam durations @.050 of greater than 250

Stock Hyd roller tappets are OK, a little heavy. But fine for use. Your cam is tiny and OK to use the OE roller tappet without an issue.
 
Slant Six Bumblebee said:
On used magnums the heads are prone to cracking. It is more common on the Magnum Heads. The reason is because Dodge went to a thinner casting in the cylinder heads from the factory. LA heads off any of your small blocks will have the same problem just not as common but, almost. They like to crack between the intake & exhaust valves.

Not trying to piss in your cornflakes or saying you need to buy need heads but just something to be wary of.
Click to expand...
Not at all, I'm glad you mentioned that, I just pulled the heads yesterday. I will look them over carefully and check for cracking between the valve seats!
 
rumblefish360 said:
If your heads are cracked then look into a set of Edelbrock heads for the Magnum.

You can use regular LA heads IF you get oil through pushrods and rockers that use oil through pushrods. There available from Comp (Pro Magnum rockers in 1.5 ratio only) Hughes engines, PRW and then the more expensive TD or Jesel brands.

Spring keeper & retainers need upgrading when you start to make a good amount of power. As in a lot off power. Think along the lines of 10.5-1 & better with cam durations @.050 of greater than 250

Stock Hyd roller tappets are OK, a little heavy. But fine for use. Your cam is tiny and OK to use the OE roller tappet without an issue.
Click to expand...

That's great information. I 've been told that the stock Magnum cams are very whimpy, but wasn't sure when I would have to start worrying about upgrading keepers and retainers with my choice of new cam. Its nice to know that I'll be able to use stock components (aside from valve springs).
 
Your cam pick is close to mine. I sent my stock 5.9 Magnum cam to Oregon Cam Grinding for his #1280 regrind.
.215/.223 @ .050
.517/.539 lift w/1.6 rockers.
110 Lobe Separation
Edelbrock 2.02 heads

I used my original lifters.

Runs great!
 
ValleyRat said:
That's great information. I 've been told that the stock Magnum cams are very whimpy, but wasn't sure when I would have to start worrying about upgrading keepers and retainers with my choice of new cam. Its nice to know that I'll be able to use stock components (aside from valve springs).
Click to expand...
The OE roller cam will fall on its face right about 4500. Mine does at least. Great power until then. Don’t go crazy on the lift as the head flows only so good so far. Max lift area for the stock head should not really exceed .500. There really is no point. Just increase the cams duration to for your axle ratio and plan.
 
66fyssh said:
Your cam pick is close to mine. I sent my stock 5.9 Magnum cam to Oregon Cam Grinding for his #1280 regrind.
.215/.223 @ .050
.517/.539 lift w/1.6 rockers.
110 Lobe Separation
Edelbrock 2.02 heads

I used my original lifters.

Runs great!
Click to expand...
Any work in the heads bowl area? Or anything else?
 
ValleyRat said:
Not at all, I'm glad you mentioned that, I just pulled the heads yesterday. I will look them over carefully and check for cracking between the valve seats!
Click to expand...
Let us know what you find
 
Get a set of rod and main bearings also. And check the cam bearings. The magnums had detonation issues because of the valley plate on the stock efi intake manifolds and ate oil which caused them to detonate. 3 of the 7 I’ve disassembled also needed cam bearings. Your keepers just need to match your new springs and retainers. Buy accordingly. The stock magnum lifters will be absolutely fine with your cam and intended use, no reason to spend money on new anything. Clean and reuse the stock ones.
 
Depending on what front timing cover/accessory drive you go with, the PP Crosswind intake may have interference issues with later model AC compressors. And they’re known for core shift. Check the intake out carefully.
 
rumblefish360 said:
Any work in the heads bowl area? Or anything else?
Click to expand...

I was considering doing some mild porting to my cast iron heads. Just polishing the ports smooth, not removing much material. I'd be a little nervous to go hog wild on them my first time attempting anything like that. Aluminum heads are the plan down the road, for now I'm going to work with what I have.
 
TT5.9mag said:
Depending on what front timing cover/accessory drive you go with, the PP Crosswind intake may have interference issues with later model AC compressors. And they’re known for core shift. Check the intake out carefully.
Click to expand...

Thanks for the heads up, Ill be sure to look over that carefully when I get it disassembled further. Is Plastigauge a accurate way for checking main bearing clearances?
 
ValleyRat said:
I was considering doing some mild porting to my cast iron heads. Just polishing the ports smooth, not removing much material. I'd be a little nervous to go hog wild on them my first time attempting anything like that. Aluminum heads are the plan down the road, for now I'm going to work with what I have.
Click to expand...
To actually smooth down the ports and polish is a power looser. Don’t do it.
66fyssh said:
No porting at all, just OOTB. Air Gap and a 650 AVS with Doug's headers. 8.75 with 3:55's.
Click to expand...
I just installed a 750 AFB on mine. I have Hooker 1-3/4 headers into a 2-1/2 exhaust. Also like yourself, an AG, 3.55’s rolling 245/60/15’s. Will be installing a 2500 converter in the 727 soon. Still mulling over a cam, but the shortages…. Ugh! Smallest cam I have on my shelf is a 230@050 and a 236@050. Which I’ll probably do the latter (236) with Rhodes lifters on the intake inky and drop the duration some. Might work OK.
 
rumblefish360 said:
Still mulling over a cam, but the shortages…. Ugh! Smallest cam I have on my shelf is a 230@050 and a 236@050. Which I’ll probably do the latter (236) with Rhodes lifters on the intake inky and drop the duration some. Might work OK.
Click to expand...

Sounds like a good combo with the 1.5 rockers. I had a Edelbrock 750 but couldn't get the thing tuned...I didn't want it to beat me but I gave in and went with the 650.

When i bought the engine, i tore it down and had a machine shop hone, new rings and cam, rod, and main bearings. Then I did the rest myself.

Just got back from taking the long way to and from the store. Its such a pleasure to drive.

@ValleyRat keep us posted!!
 
ValleyRat said:
Thanks for the heads up, Ill be sure to look over that carefully when I get it disassembled further. Is Plastigauge a accurate way for checking main bearing clearances?
Click to expand...
Plastigauge is just fine for the do it yourselfer for a quick check. Is it the most accurate? Absolutely not. But in your position it’ll give you a good idea. Your eyes will tell you a lot about a used bearing. You’ll likely see copper on the top half of the rod bearings. If you do replace em.
 
66fyssh said:
Sounds like a good combo with the 1.5 rockers. I had a Edelbrock 750 but couldn't get the thing tuned...I didn't want it to beat me but I gave in and went with the 650.
Click to expand...

No no, stock Magnum heads, 1.6 ratio.
With the 1.6, on the [email protected] LA Hyd cam above, the lift toes to .539, IIRC. Or something like that. I’ll have to find the card. It’s an old Crane grind on a 108, single pattern.
 
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