Lots of performance parts on my LA 360 - let's build my Magnum / Stroker

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ATW

ATW

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My goal is a to have a 408 Magnum Stroker with EFI - I'd love to hear everyone's thoughts on what I currently have and what can be transferred to this new engine. This will be a 98% street car. I'm trying to bridge the gap and come with a realistic budget but it makes it interesting since I have a fair amount of transfer friendly parts.

Builder engine: - 2002 360 Magnum - M1 Dual Plane Intake (Magnum)

Current engine: - 1976 360 LA - M1 Intake - HEI Distributor - EQ Heads
Current trans - A500 with 9.5" 3200 stall converter
Current rear: - 8.75 (742) with 3.91 gear (245/45/18 tire)

Wishlist: Scat stroker kit - EFI

  • Previous owner installed a set of 2.02/1.62 EQ heads on the LA Engine drilled for LA intakes. I assume these will transfer without issue.
  • Previous owner had a custom Comp roller cam ground on an LA blank - specs are: 224/230 .050" and .513 lift I/E on 110 LSA - ground for 1.6 rockers. Would this be good fit for the 408 Magnum? Any issue that anyone can foresee?
  • With the roller cam, he also opted for a set of retrofit Hughes LA roller lifters ($$) - can these be used in the Magnum with the EQ heads? Or would I be better off using the OE lifters here?
  • I have a pair of M1 intakes - I'd obviously use the LA style with the EQ heads - is this an adequate intake for my plan or would I further benefit from a RPM Air Gap or other suggestion?
  • Current engine has a Coyes index timing chain - will this transfer to Magnum?
If you need any other details to clarify anything - I'll report back. Bare with me as I'm a bit green to this process - thanks.
 
The first question is there something wrong with your current LA that you need to change it for some reason. It sounds like it has a good solid build, and the Magnum block is not going to gain you anything. The one good thing about the Magnum block is it is set up to run a hydraulic roller, and your LA already is set up that way. Your LA heads will not work on that era of Magnum without some work to the oiling system for the shaft mounted rockers of the LA. The Magnum oils through the push rods for the stud mounted rockers, where the LA oils through a passage in the block and head to the shafts. You can run a oil line from the oils sender hole and T if off through the back of the heads, or there a couple of other ways to route the oil. Personally, if you LA block is still usable, I would do what machine you need to, and throw the stroker kit in. You will end up trying to make your Magnum into an LA, and you already have one without the hassle.
 
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The LA is pretty tired in my opinion and the pistons are .088 in the hole.. and the fact that I already have the Magnum on the engine stand helps!

Also, the EQ heads on my current LA are just drilled for an LA intake bolt pattern--they are Magnum heads with stud mounted rockers. So there should be no issue with oiling.
 
The EQ heads will bolt right on to the Magnum block. Retaining the Magnum rocker arm arrangement is no problem, but you'll have to check pushrod length no matter which lifter setup you run, since Magnum blocks have a slightly shorter deck height.
You say you want EFI but you mention dual plane M1 intake. Should we assume this means one of the throttle body setups like Holley Sniper, not a full factory Magnum style EFI?
Post a picture of both M1 intakes you have, so everyone knows for sure what your options are.
If you keep the same camshaft, you may be leaving a lot on the table, in terms of performance. You'd basically be running the same overall setup with more cubic inches, and a little better driveability from the EFI.
 
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Correct; I'm aiming for an aftermarket EFI solution- sniper, fitech, etc..

I was hoping to reuse the camshaft if it made sense to but I'm not against purchasing one better suited for the build since I'm already ahead with a lot of the other components.

Bobzilla said:
The EQ heads will bolt right on to the Magnum block. Retaining the Magnum rocker arm arrangement is no problem, but you'll have to check pushrod length no matter which lifter setup you run, since Magnum blocks have a slightly shorter deck height.
You say you want EFI but you mention dual plane M1 intake. Should we assume this means one of the throttle body setups like Holley Sniper, not a full factory Magnum style EFI?
Post a picture of both M1 intakes you have, so everyone knows for sure what your options are.
If you keep the same camshaft, you may be leaving a lot on the table, in terms of performance. You'd basically be running the same overall setup with more cubic inches, and a little better driveability from the EFI.
Click to expand...
 
ATW said:
My goal is a to have a 408 Magnum Stroker with EFI - I'd love to hear everyone's thoughts on what I currently have and what can be transferred to this new engine. This will be a 98% street car. I'm trying to bridge the gap and come with a realistic budget but it makes it interesting since I have a fair amount of transfer friendly parts.
Click to expand...

This sounds like fun!
Builder engine: - 2002 360 Magnum - M1 Dual Plane Intake (Magnum)

Current engine: - 1976 360 LA - M1 Intake - HEI Distributor - EQ Heads
Current trans - A500 with 9.5" 3200 stall converter
Current rear: - 8.75 (742) with 3.91 gear (245/45/18 tire)

Wishlist: Scat stroker kit - EFI
Click to expand...
Well you certainly have some good parts to start with. As asked above, pictures of the intakes please. Are both M1’s are dual plane?
You have a lot of stall for the camshaft below. I run a similar one in the wife’s car. It is a great driver with good power. It’s not setting the house on fire, but it makes the car run really well.

  • Previous owner installed a set of 2.02/1.62 EQ heads on the LA Engine drilled for LA intakes. I assume these will transfer without issue.
  • Previous owner had a custom Comp roller cam ground on an LA blank - specs are: 224/230 .050" and .513 lift I/E on 110 LSA - ground for 1.6 rockers. Would this be good fit for the 408 Magnum? Any issue that anyone can foresee?
  • With the roller cam, he also opted for a set of retrofit Hughes LA roller lifters ($$) - can these be used in the Magnum with the EQ heads? Or would I be better off using the OE lifters here?
  • I have a pair of M1 intakes - I'd obviously use the LA style with the EQ heads - is this an adequate intake for my plan or would I further benefit from a RPM Air Gap or other suggestion?
  • Current engine has a Coyes index timing chain - will this transfer to Magnum?
If you need any other details to clarify anything - I'll report back. Bare with me as I'm a bit green to this process - thanks.
Click to expand...
1: There should be no issues with the head transfer as mentioned above.
2: The cam is small for a 408. It will make a LOT of torque. Be an absolute driver. Depending on the head capabilities, a stock head could make an easy 360 hp.
3: The Hughesengines roller lifters are probably much lighter and worth the use. There’s nothing wrong with them or the heavier LA lifters.
4: The RPM is a better bet. The M1 single plane would loose a bit of torque against the RPM below the 3500 rpm area. This rpm spot is give or take a few hundred.
5: The timing chain will swap.
 
Get a cam specific to your heads, gearing, and larger engine size. With a 4" crank, I think I'd go with the single plane intake if using fuel injection. You are going to have a lot more low rpm torque than you currently have and the FI will compensate on the lower end better than a carb can. I doubt you'd miss it and you may get a benefit on the upper rpm side.
If the heads are stock, now is the time to get them ported and maximize flow. That 408 should be able to use all the air those EQ heads can flow, plus some. Figure all that out before you determine the cam though.
 
Oh, dang, I dropped that fact of throttle body FI.
Changing my vote to a single plane.
 
run the cam you have to get a baseline
not that hard to change once you see how much bigger you want to go, if you do
get the transgo kit for that tranny and upgrade the cooler lines to half inch and a cooler with half inch in and out
weak spot is the thrust washers and they need all the cool oil they can get
ask me how I know
lifter weight is no big deal- it's weight on the valve side- beehive springs and retainers save a bunch
if you have head flows or can estimate from others run your numbers past Mike Jones for one of his inverse radius grinds
 
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