Thread: 72elk

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Please read through this tutorial on the L31 Chevy heads.
http://www.crankshaftcoalition.com/w..._cylinder_head
Write down questions that you have and ask them at the end. These are what I would advise for someone looking for a bolt-on hp increase where you don't want to do a lot of work. Make the seller agree in writing that you can excnange the heads or get your money back if you magnaflux them and find them cracked. Get the stock self-guiding rocker arms with the heads. You will not need the pushrods, they are shorter than conventional Gen I pushrods because the L31 used a roller cam. You can use either self-guiding rockers with no guide plates or you can use conventional rockers with guide plates. You cannot use self-guiding rockers with guide plates. I would use a cam with up to 0.500" lift or just a little more (these heads will stop increasing flow at about 0.500" valve lift) by taking the retainers to a machine shop or a friend who has a surface grinder or Blanchard grinder and having them machine 0.080" off the bottoms of them. This is called a "ghetto grind" and will allow clearance between the bottom of the retainer and the top of the valve guide oil seal at full lift when using a cam with more lift. I would also drill and pin the studs. The article says that it is a stop-gap measure. Baloney. It's a permanent fix for preventing studs from pulling out of the heads. Mr. Gasket makes a kit to do it.
https://www.summitracing.com/parts/mrg-806g

I would not use an Avenger carburetor. Use an Edelbrock 650 AVS or AVS2 on an Edelbrock 7116 manifold. Install 1 5/8" full length headers with an H or X pipe installed immediately after the collectors. Build the motor 9.5:1 static compression ratio with a zero deck and 0.039" to 0.041" head gasket. Use a cam not to exceed 216 degrees duration @0.050" tappet lift with max lift around 0.500". This will make a very streetable 370-390 horsepower, depending on your tuning abilities.

Read through this thread to understand zero decking.....
http://www.hotrodders.com/forum/zero...ck-184870.html
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Great article. Thanks for the info, I think I finally have a plan to follow. It's always tricky getting money out of my wife but that's good because otherwise I'd be broke. I currently have a 1948 Plymouth that I'm going to sell but it needs a new carburator. So, my wife agreed that I need to buy a new one and put it on my ElmCamino swapping its carburator to the Plymouth. I've also convinced her that if I'm going to all that work that I might as well get a new performer rpm manifold at the same time (per your earlier recommendation).
With the current info you offered I like the idea of going with the vortec heads. In doing an internet search I found a new pair for $680 from Machine Shop Pros who say they have been in business for 40 years and offer a 7 year warranty. The heads come with new guides, new stem seals and 3 way valve job. I know that they would still need some work to meet all of your recommendations but I was wondering if you think this is a fair price and would get me going in the right direction. Have you ever heard of them? Their web site, machineshoppros.com, doesn't address the vortec heads but there is a pretty good description in the eBay ad. Again, I do appreciate all the info you gave me and would value your opinion on this. At this time I will go ahead and buy the carb but wait in the manifold until I get heads.

If I get vortec heads, are their exhaust ports different than those with stock heads? If so how do I get headers to fit my 1972 el Camino with vortec heads?