May 21, 2012

LSx (LM7) Low Mount Alternator DIY

Parts needed. Note this will delete your power steering pump and a/c and add more HP. Plus it will remove that nasty looking truck alternator bracket.

  1. Fbody Alternator Part #12563327. $20+shipping.
  2. Ribbed Pulley - Gates Part #38008 = $20 O Reilly
  3. Gates Belt – K060547 – $20 O Reilly
  4. 2 Long Bolts for alternator bracket (M10 x 1.5 140MM long). I ordered mine from Grainger for $10 and received 5 of them.
  5. 1 Shorter M10x1.5 about 50mm for ribbed pulley
  6. A 1/4 – 3/8 washer. You might have to drill out the center. Depending on what you get. This acts as a spacer on the back side of the ribbed pulley.
  7. 10mm x 1.5 Tap
  8. 11/32 drill bit
  9. 3/4 in spacer to space the alternator off the block to line up with the water pump and crank pulley. You will also need some type of straight edge to make sure you get it right.

Look at this HIDEOUS truck mount for the alternator. Talk about the MILE high club.


Tap your block here. I screwed in the lower bolt to the fbody alternator bracket and used a pencil to mark dead center on where the new hole needs to be threaded.

photo 2

Then I drilled the hole a little over an inch deep with a 11/32 drill bit.

photo 4

Now we need to tap it. Use some tapping oil or watch a YouTube video if your not sure how to do this. Make sure you drill it straight and tap it straight otherwise your screwed and you really only have one shot at this.

photo 5

Tapping the threads is the scary part. Error on using lots of oil and pulling out (lolz) and cleaning it after each turn.

I ended up cutting my 3/4 in spacers using the ones on the original truck bracket. One was exactly 3/4 the other I had to grind down a bit.

photo 1

Use your 1/4 – 3/8 spacer on the back side of your ribbed pulley. This should be enough to line it up with your crank pulley. Check with flat edge. Make sure to go from the first rib on the pulley and not the front. When lining it up.

Here is the end result.

photo 8

It looks 1000X better.

photo 7

I hope this helps you out. Any feedback is appreciated.

Jan 22, 2012

Megasquirt 3 Wiring Help LM7 / LS1 / LS

Well its been a while since I posted last. I’m going to make it a priority to post more frequently now that things are speeding back up on the project. I’ve been making steady progress but just had things slow down a lot when it came to getting the motor running on the Megasquirt 3 and assembling the Megasquirt 3.

Here are some links that should help you wire up a LM7 (LS 5.3L) or LS series motor to a MS3 with MS3X (Megasquirt 3 with Expansion for sequential fuel injection).

Step 1) Decide which manual is correct for your engine (24x reluctor engine or 58x reluctor engine)

Misc Info on LS engines very helpful site

Step 2) Run all the correct wires to your engine. If you buy the DIYAutoTune harness it comes with the wires pre labeled def worth the ~$160 bucks.

Step 3) When it comes to wiring up your ignition if you want to use the parent (7 or 8pin I forget plug) for cleanness it connects to all 4 ignition coils. There are one of these parent plugs (on top of the valve cover) on each side of the motor and each one runs to 4 ignition coils.  Look at this diagram for help in wiring those up.

I cant remember of the top of the head which ones I had to use.

Even Ignition Coil Diagram:


Odd Ignition Coil Diagram


That should get you going in the right direction. Here is a pic of my motor fully wired up on the stand. It’s got a fuel pump and is pretty much ready to start.


My next post will talk about how I built a little Arduino (microcontroller) that controls relays over bluetooth. This will allow me to remove start the engine and control relays from a bluetooth device like a phone or tablet. Thanks!