427 rebuild

**Joe L.** · February 21, 2003, 08:34 PM

Re: 427 rebuild

Mike-----

No, you're not dreaming; what you suggest can be accomplished rather easily.

First of all, the original pistons for your application were GM #3888327, left side, and GM #3888328, right side. These pistons were conventional cast pistons and were long-ago discontinued by GM. The camshaft was GM #3883986 which was also discontinued a long time ago. However, I believe that it's available in reproduction.

To build the engine that you describe and desire, I suggest doing as follows:

1) Use Keith Black hypereutectic pistons. These pistons are considerably stronger than the pistons originally used in your engine and are, in fact, nearly as strong as forged. Hypereutectic cast are used in virtually all modern, high performance engines, including the LT5 (ZR1), LT1 (92-97), LS1, LS6, Dodge Viper 500 cid/500 hp V-10, and many others. For your application, use KB-360 pistons. These will yield a compression ratio of about 9.4:1 with the gaskets recommended below. This compression ratio will ensure that you can run the engine on pump gas, but mid grade or premium MAY be rquired;

2) Use head gaskets Fel-Pro 1017-1

3) Use retro-fit roller hydraulic camshaft. I suggest one of the following:

Crane 139721----also use Crane lifters, valve springs, special push rods and retainers recommended for use with this camshaft

Speed-Pro/Federal-Mogul CS-1072R----also use Speed-Pro lifters #HT2207RA and Speed-Pro VS1581 valve springs, and special length push-rods (note: this will be the most economical of the hydraulic roller set-ups) It's available as a complete kit under KS-1072R;

Competition Cams camshaft kit #K11-410-8

4) Use re-sized stock rods with ARP rod bolts. If you wish/want to invest in new rods, use set GM #12496661. These are 7/16" bolt rods and can be purchased new for about $350/set;

5) Use stock carburetion and inlet manifold

**Tom H.** · February 21, 2003, 08:41 PM

Re: 427 rebuild

Joe- How about a similar prescription for a 327SHP-Please, Thanks in advance. ( How's that for a hook )

**Michael S.** · February 21, 2003, 09:29 PM

Re: 427 rebuild

Thanks Joe,

Just exactly what I needed.

Have a great day.

Mike

**Joe L.** · February 21, 2003, 10:11 PM

Re: 427 rebuild

Tom------

Are you talking about an L-79 with the idle characteristics and maximum RPM limits as specified in Mike's requirements or are you talking about something like a "modernized" L-79 with idle and max RPM similar to the original?

**Tom H.** · February 21, 2003, 10:13 PM

Re: 427 rebuild

More specifically the SHP 365/375 327's. Sorry- & thanks again

**Joe L.** · February 21, 2003, 10:22 PM

Re: 427 rebuild

Mike-----

Also, for the smoothest idle, use either the Crane or Comp cams rollers I mentioned; the Speed-Pro grind will produce a little bit "lopier" idle.

To ensure compatibility with regular gas, you'll need to drop the compression ratio down to no more than 8.5:1. A 427 Chevy, being a big bore engine, is more susceptible to detonation at a given compression ratio than a smaller bore engine (like a 327 or 350). This is especially true for an all-cast iron big block. So, if you must use regular gas, then you'll have to go with a real low compression ratio. This creates other problems. One of those is the fact that neither Speed-Pro or KB make an off-the-shelf hypereutectic piston for such a low compression ratio with a 427 cid engine. 427 engine parts are a lot more limited in available choices than 454. Second, the camshafts that I mentioned will be marginal with such low compression, but will work.

**Joe L.** · February 22, 2003, 02:04 PM

Re: 427 rebuild

Tom------

Using current technology, it would be quite possible to build an L-76/84 engine into a smoother running, lower RPM engine which produced more power than the original engine. But, I would not do it. For these engines, I would rebuild to nearly stock specifications, using a reproduction of the original camshaft available from Crane and others. Stock valve springs, retainers, and metal shields.

For pistons, and assuming that the engine currently runs ok with pump premium gasoline, I'd probably recommend pistons similar to the originals. These would be Speed-Pro/TRW forged pistons of L2166NF. These pistons will produce a compression ratio of about 10.25:1. No available Speed-Pro/TRW piston will produce an 11:1 ratio with your stock heads. Pistons for 327 CID engines are now a lot more limited in availability than those for 350 CID engnes which are far more popular these days. However, I would not use a compression ratio much higher than 10.25:1, anyway. It's just not worth the chance of creating detonation.

The reason that I am recommending the forged pistons, which I seldom do, is because they were what was originally used in the engine and I'm assuming that it doesn't get driven very much. Forged pistons will NOT be as durable, as quiet, or as effective in oil control as hypereutectic cast. Period.

If you desire a more durable and quiet piston that provides better oil control, then I'd use a Keith Black KB 157 piston. This piston will produce a compression ratio of about 10.4:1 and will provide all of the strength that you'll ever need. Although I recommended the forged pistons for you, if I were building this engine for myself, this is the ONLY piston that I would use. Period.

For head gaskets, use Fel-Pro 1004.

For connecting rods, use stock rods, resized and fitted with ARP Wave-Lock, Pro-Grade bolts.

For rocker arms, use Crane Nitro-Carb, stamped steel rockers.

**Tom H.** · February 22, 2003, 03:14 PM

Re: 427 rebuild

Joe- Thank you very much for the information. I haven't had much luck with the local engine shops understanding why I would rebuild a 327. If my current and original forged pistons are re-usable, what head gasket would you recommend to lower the CR? I recall that Chevrolet packaged some information with the original literature that came with the car which recommended a head gasket substitution for use if the car was going to be used in Mexico where high octane fuel was not available. Thanks

**Joe L.** · February 23, 2003, 01:22 AM

Re: 427 rebuild

Tom-----

I really doubt that the pistons will be re-usable, even if you are able to maintain standard bore. Forged pistons, due to their looser fitment and type of material, are usually high-wear items. A VERY experienced machinest that I once knew (now deceased, unfortunately) who built 1000's of engines in his career, from stock to all-out racing, once told me that you couldn't really expect a forged piston to last much more than 10,000 miles. My experience, as limited as it is in this area, pretty much confirms his observation.

To reuse the pistons, they need to be carefully checked in all wear areas. For forged pistons, ring groove wear is a particular problem. If ANY piston dimension is out of spec, the piston is scrap. Plus, if you have a set of used pistons and even one tests out of spec, then it's very difficult to replace just one or 2 pistons. That pretty much means that the whole set is scrap.

For a thicker head gasket, use Fel-Pro 1044. This provides all the benfits of the 1003 or 1004, but is thicker. It's just about as thick of a head gasket as you can get. A Victor-Core gasket might be a little thicker, but not enough thicker to get me to use one over the 1044.

**Tom H.** · February 23, 2003, 09:11 AM

Re: 427 rebuild

Joe- Thanks for all. Also- How's RETIREMENT????!!! Hope your enjoying yourself.

427 rebuild

427 rebuild

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