Replacement Pistons/Camshaft for C2 327/300 Engine

[James W.]

Hello,

I'm starting to make a list of parts for the rebuild of my 327/300 engine in my '64 Corvette. I would like to get an idea of what the best replacement pistons and camshaft would be for my engine. I am looking at possibly the O.E. replacement Keith Black hypereutectic pistons or the Speed Pro power forged pistons available from Summit or Jeg's. I didn't see that Federal Mogul advertised any piston for a 327, only 350's.

I have no clue on the cam shaft since I'm not sure what the stock GM lift and duration is for the 327/300 cam. I do plan to drive the car and want to keep as close to the stock specs as possible.

Duke... Any suggestions???

Best Regards,

James West
NCRS #18379
NCRS Nebraska Chapter Co-Chairman
Omaha, NE.

[Duke W.]

Re: Replacement Pistons/Camshaft for C2 327/300 En

The cam used for your '64 327/300 was replaced by the 3826929 on the '67 327/300 and this became the service replacement for all prior base cam SBs back to '57.

It continued as the base engine cam through 1980.. It should be readily available from a number of sources, including Federal Mogul, but I don't have a current part number.

OE type cast replacement pistons are fine and should also be readily available from F-M and other sources. Hypereutectics are superior strength-wise, but the OE cast pistons have never been problematic that I am aware of. If hypereutectics are priced significantly higher, I don't think they would be worth the additional cost.

F-M should have everything you need in the standard replacment parts catalog. The Spreed Pro catalog only includes "speed parts" some of which were OE in SHP engines such as the SHP cams and forged,domed pistons. Your engine is not considered a "performance" engine in this context.

As with any engine overhaul, you want to check piston crown to deck clearance BEFORE you pull the pistons out. GOT THAT!!! These dimensions, plus the specs for available pistons and head gaskets will allow you to dial in a target compression ratio, which I recommend in the range of 9.5-10:1. The advertised CR for the 327/300 was 10.5, but actual as built Flint 327/300s are likely closer to 10:1?

Assuming it is the original compression ratio, does the engine run okay on premium unleaded? On teardown take the measurements to compute actual as built CR and don't exceed this if runs okay now.

The 327/300 was a very reliable engine, and a lot of guys raced them without much ill affect. OE or OE equivalent parts are the way to go. If you want more top end power, get the heads massaged by a good vintage Chevy head guy, or get the books and do it yourself. The crankshaft is forged and should not require turning. Be wary of shops that say "we always turn 'em." Find a machinist who will do it your way, and observe the rule: "Don't machine it unless absolutely, positively, necessary. Of course this includes the block deck. Other than pocket porting, port matching, and a multiangle valve job, if you wish, do not surface the heads unless it's absolutely necessary. Any warpage is easy to measure, and a modern composition gasket will take about .003" warp. Unless your engine has been seriously overheated sometime in its life the head surfaces are probably true to less than .0015". This easy to verify with a machinists bar and .0015" feeler gage. You don't need screw in studs and you don't need 2.02"/1.60". valves. If the valve stems have no more than .0005" wear, I think they are acceptable for reuse assuming they have enough margin for a grind, but it's a good idea to replace exhaust valves apriori since they are subject tho thermal fatigue.

There have been recent discussions on valve guide rebuilding, and there appears to be some controversy and differences of opinion, so you need to do some research. Go with the best quality valve guide rebuilding scheme available regardless of cost. Also follow the valve guide manufacturer's sealing recommendations.

As with all other pre-'66 327s your engine was built with the early design rods, which have a tendency to break at the bolt head seat. The later design small bearing rods that went into production circa 1966 have more material in this area and are much more durable. On a high revving SHP engine I recommend Crower Sportsman rods. For your modest revving engine, just buy a set of new OE replacement rods, which should be of the later design and install them as is. Use the originals to fabricate a boat anchor or do some "rod art" for your garage.

E-mail me if you want some comparison photos of the rods, so you can positively ID what is in the engine and what you buy.

The 327/300 is a very nice engine - smooth idle, gobs of low end torque, and it will respond to head massaging similar to SHP engines to yield an equivalent percent increase in top end power, which will allow it to rev strongly to 5500.

Duke

[James W.]

Re: Replacement Pistons/Camshaft for C2 327/300 En

Duke,

Do you have any info regarding the Crane Blueprint Musclecar camshafts? Crane Cams makes a hydraulic cam replacement for the 327/300 engine. The Crane Cams P/N 270-968711 has an advertised duration @.050" of 195/202 and lift is .390"/.410" with an RPM range of 1,000 to 3,200.

This cam is advertised as an exact duplicate of the OE cam. Is it worth the money or should I just go with the OE replacement that you suggested? Again, I'm looking to keep the smooth idle.

I am planning to do some head work to improve flow and a good 3-angle valve job.

Thanks again,

James West

[Joe L.]

Re: Replacement Pistons/Camshaft for C2 327/300 En

James-----

The Crane cam that you described is an OEM replacement for the original GM #3896929 cam used for your engine. You can purchase it in a kit with lifters under GM #12364051. This kit is a great value.

For pistons, I'd recommend Keith Black-Silvolite #KB-156. These will give you a compression ratio of about 10:1, which is about the maximum that I'd recommend. A set of these pistons, without rings, can be purchased from suppliers like Summit and PAW for about $225. With Speed-Pro moly rings, figure about $325 for the engine set.

[Mark H.]

Re: Replacement Pistons/Camshaft for C2 327/300 En

I purchased this exact set-up for my '64 last year and have been very happy with it. The cam/lifter kit from GM is a terrific value and I recommend it.

[Duke W.]

Re: Replacement Pistons/Camshaft for C2 327/300 En

Those specs sound like the 929. I don't see any difference in quality or tolerance, so purchase the cam from any quality vendor. Federal Mogul is a
"tier 1" OE vendor, and I would tend to trust their quality more than one of the "hot rod cam companies".

The pistons and price Joe mentioned sound like a decent deal. Get the specs and line up the source, because you won't know what oversize you want until you measure the bores and determine how much overbore is required, if any, then size to the smallest available overbore piston. You also want to make sure your machinist hones the bores to the proper clearance recommended by the piston manufacturer, which may be different than Chevrolet's recommended clearance for the OE cast pistons.

Duke