Valve springs for magnum heads

[AdamR]

I need a set of valve springs for magnum heads and a XE274H cam. .513/523" lift with the 1.6 rockers

Will the R/T or 6062 spring work ? Will I need new retainers. Comp recommends the 995-16s but they wont work with these heads.

 

[dgc333]

I just went through this with my magnum heads.

When I talked to the Comp Rep he told me that they didn't have any springs for the magnum heads at this time. He did tell me that the magnum R/T springs were suitable (apparently they are familiar with the spring) for the XE268H cam I planned to use.

When I was talking with him and asked about why Comp recomended a single spring with damper for the 268 cam but a double spring for the 274 I was told that there testing indicated that the additional lift and ramp speeds of the 274 required the extra spring rate to ensure the lifters would track the lobe and not result in valve float.

Doesn't really answer your question but the R/T spring is right at it's limit with .525 lift. I would be hesitant about using it with the XE274 cam if you plan on running the engine in the upper rpm range.

The P4876062 spring will work for sure but will require you to have the seats machined on the head. This spring is enough larger in diameter that will hit the edge of the machined seat area.

Also, don't forget with either of these springs the stock retainers won't work. They are too small in diameter to locate the spring and actualy almost fall through (they do with the recomend LA spring, don't ask!). Comp (or Crane that I could tell) doesn't have retainers that work with the 8mm valve stem. A cheaper alternative to purchasing them from Mopar Performance is mopar 2.2/2.5 retainers with the stock magnum locks (the 2.2 locks are single and 4 groove and have a different grove shape). I made a junk yard run for mine and they looked at me like I was nuts when I put a handful on the counter and they said no charge.

If you don't want the extra expense of maching seats and have not purchased the XE274H cam (or can exchange it) I would recomend using the XE268H with the R/T springs. I have never heard a bad word about it and has been used in several build ups in the mopar rags with great results.

 

[AdamR]

Thanks.

I already have the cam and its well matched to the rest of the car. If the 6062 springs require cutting I may aswell have the seats cut to use LA springs.

I was told about the 2.2 retainers.

I also hear that CompCams has a Beehve spring that works. They are almost $200 and require $175 set of Titanium retainers.

Another option I was told is GM LS1 springs.

I'll keep digging around.

The nice thing about the Magums is that you can run Chevy Roller rockers. Wonder if a Chevy Stud girdle would work too?

 

[dgc333]

If you decide to go with LA springs the 2.2 retainers won't work either. The LA spring is even larger again over the 6062 spring.

You have confirmed the Chevy roller rocker? I had never heard that not even on the truck boards where a lot of mods are being done to the magnum engine.

What do you plan to use for a manifold? I just picked up one of the Cross-Wind manifolds for my engine.

 

[AdamR]

Any clue on what retainers I'll need then ?

Yes the Chevy rocker arm thing is true. I checked a few catalogs and the Magnum rockers have the same part # as the Chevy's. They have to be for 3/8" studs though not the 7/16s.

You'll also need screw in studs and new guid plates.
Im going to start to put together a list od parts that will work on these heads. info on them is hard to come buy.

 

[AdamR]

Almost forgot, For the intake I'll either redrill the heads and run my LD340 or go with the Professional Products air gap.

I looked at the M1 single plane and the Eddy Magnum airgap but Im not paying $300 for an intake.

 

[dgc333]

The retainer thing is tricky. It has to be large enough to support the spring, it's has to have the proper lip on the bottom to fit into the spring and keep it centered and has to have locks available that are compatable with the grooves on the valve stem while postioning the retainer for the correct installed height for the spring.

I am quite sure there are retainers that will work with LA springs on a magnum head but the experts at Comp Cams couldn't tell me. I looked at the Manley catalog and all the variations they had made my head swim and with out having the pieces in front of me to try and verify I was not willing to make the investment to try.

I have both a set of 360LA heads and the magnum heads sitting on the bench. The LA heads need a valve job, the magnums are low mileage off a bottom end warranty claim my son brought home from the dealership he works at. I knew I would need push rods and the mopar ones are relatively cheap from Mancini. I also purchased Comp LA springs for the XE268 cam. It was when I started trying to assemble things I realized the LA springs were too big and I didn't have retainers that would work. I assumed when I got the R/T springs they would be the beehive style like the stockers. When they weren't I was about to give up and use the LA heads when I learned that 2.2 retainers were the same as the mopar performance ones they sell for the R/T springs.

My cost for the M1 magnum intakes was about $230 through my son but these are relatively old designs and I was much more interested in the Air Gap. When I noticed that the Cross-Winds are going for around $140 on eBay the scotch blood in me said that's the way to go.

 

[AdamR]

I found this. Lots of info.
http://www.geocities.com/coronetranger/index2.htm

I also heard Hughes Engines has springs and retainers for the 8mm valves but the springs require seat work.

The Beehive springs require cutting to run a spring cup so al said and done your talking almost $600 to use them. Not worth it.