'66 327/300 Rebuild

[Ed R.]

I have an original '66 327/300 engine that needs to be rebuilt and installed in my 66 Air Coupe. I have found a shop near by and while discussing the job I asked what would it take to 'kick it up a notch' and he suggested a 260 lift/duration high energy cam (whatever that means). Obviously, I am a novice at all the physics of engine internals and their relationships. Anyway, what would be the result if I went with this suggestion? This engine is stock with 4-barrel and will be driven on city streets and freeways. What I'm looking for when it's all done is something that is smooth idling, runs on pump gas, original outside appearance, and smoke the tires if I wanted to.

This shop has been in business for 30 years and rebuilding engines is all they do. Anyone ever dealt with Seattle Engine Rebuilders in north Seattle? Are there any other questions I should ask to make sure I'm getting a quality rebuild? All new parts will be OEM.

[Joe L.]

Re: '66 327/300 Rebuild

Ed-----

A 260 "High Energy" camshaft is a description usually applied to a line of performance camshafts sold by Competition Cams of Memphis, TN. This is a popular line of camshafts used by performance enthusiasts for many years. The machine shop may referring to this particular camshaft manufacturer or may be referring to this monicker in a "generic" way since many other camshaft companies produce competitive camshaft profiles and configurations.

For your engine application, a 260 degree camshaft would be a good choice for a performance upgrade. It will produce a nearly stock idle and no driveability problems, but it should increase your overall horsepower and torque by a significant degree. It will work well with all of your existing engine components, too. I would not recommend going with anything more "radical" (e.g. a 270, 280 duration). More "radical" camshaft configurations may produce more horsepower and torque, but at the risk of other engine qualities that you might not like. It's not worth the risk, in my opinion.

[Ed Jennings]

Re: '66 327/300 Rebuild

A 327/350hp cam (also refered to as a "151" cam) will slip right in your 300. It is an excellent choice for most street driven small block applications. That, along with a good solid rebuild would make your car a very nice driving street car with good manners and reasonable power. I would stick with flat top pistons, which should give you less than 10:1 compression. Cast pistons are now good enough to go in an LS1, and provide better oil control than forged. A good 3 angle valve job will also help.

[Dennis F. King]

Re: '66 327/300 Rebuild

Ed. A couple of tips from the automotive hobby that I used 15 years ago when searching for a machine shop are: is the shop neat and clean, or is stuff scattered about, junk etc. piled in corners, not a good sign. What type of equipment do they use, is it all digital set up or is it the old mechanical stuff. You might think of this like open heart surgery...now that's clean. Will the shop give you references. All this adds up to a well built motor that will last a long time. From experience the "151" cam referred to is a great choice. My .02$ worth. Good luck, Dennis

[Duke W.]

Re: '66 327/300 Rebuild

If you want to retain the benign idle characteristics of the 300 HP engine, replace the cam with the OEM equivalent, but have the heads pocket ported and port matched. This will give you about five to ten percent more top power and about 500 more usable revs. The 151 cam will idle at about 750 with a bit of lumpiness, but it should still be quite driveable and will give about 10 percent to 15 percent more top end power; about 20 percent with both the 151 cam and the pocket porting/port matching.

Duke

[Joe L.]

Re: '66 327/300 Rebuild

Duke----

Yes, actually this is one of the advantages of using a modern, dual-profile cam like the 260 "High Energy" (or similar cam from other manufacturers). You can achieve a near stock idle, good vacuum, and improved horsepower and torque in the lower RPM range. This is exactly where the 300 hp engines were otherwise designed to operate, anyway, and where most folks who drive their cars actually NEED and can use the horsepower and torque.

The '151' is a great cam, but its power advantage comes on at higher RPMs which most folks do not really use in everyday driving. Personally, I think having the stock idle, good vacuum, and improved power and torque in the under 5,000 rpm range is what makes something like these modern, dual pattern 260 degree cams so beneficial in a street engine, and, particularly, for upgrading an engine like the 300 hp.

[Pete Whelan]

Re: '66 327/300 Rebuild

Ed,
I have a Crane HMV260 camshaft in my '66 327/300, which fits the description that you provided. The engine idles smoothly and has lots of low end torque. I wouldn't use anything more radical if you want to maintain the characteristics of a 327/300 but want a little more torque. If you decide to go with a camshaft like this (other manufacturers have similar grinds)be sure to use the recommended valve springs (you need a little more seat pressure to prevent valve bounce at high rpms). Combined with a set of heads that have been pocket ported (a good machine shop can do this for you), your engine will also pick up some horsepower on the top end. Good luck with your rebuild.

Pete

[Ed R.]

Re: '66 327/300 Rebuild

Thanks to everyone that responded.

If the stock engine is rated at 360 lbs torque and 300 HP at 3400 RPM (I think that's right but, I working from memory) what would be the numbers by using the 260 cam. What about tune-up specs, any different that stock?

[Duke W.]

Re: '66 327/300 Rebuild

It's 360 lb-ft @ 3200 and 300 HP at 5000. A good one should make about 210 at the rear wheels.

As far as a cam change is concerned, who knows. Maybe the cam grinder will hazard a guess. As far as "tuneup" specs are concerned you may need the change the vacuum can and alter the centrifugal curve and initial timing to obtain optimum performance at all throttle settings and revs. The carburetor may also need some work. Welcome the the world of engineering development.

Duke

[Pete Whelan]

Re: '66 327/300 Rebuild

Ed,
I can't give you accurate absolute values for torque and HP but based on a comparison using Desktop Dynos simulation software, using a "260" camshaft in combination with a good pocket port and 3 angle valve job on the cylinder heads should give you an additional 20 lb-ft of torque from 2500 to 5000 rpm. Max power is also improved by about 20 Hp and occurs around 5000 rpm. What's especially nice about this combination is that the torque and horsepower curves are raised without shifting to a higher rpm range. My simulations and my actual engine have a 9.4:1 CR with the cast iron manifolds (int & exh). I also compared a simulation of a 327/350 engine built to factory specs to the 327 w/ a "260" cam. The 327/"260" engine outperforms the 327/350 up to about 5000 rpm. However, the 327/350 keeps building horsepower up to about 6000 rpm.

As far as tune-up specs go, I set the initial timing at 6 deg. BTDC and recurved my distributor to add an additional 30 deg. for a total of 36. This engine builds more cylinder pressure at low rpms so I wanted to be conservative with the timing. I've been able to run 92 octane pump gas with no problem. I left the carburetor jetting alone and the engine pulls nearly 20 inches of vacuum at 600 rpm. Needless to say it has terrific throttle response and is a real "sleeper."

Pete

[Mark Ring]

Re: '66 327/300 Rebuild

Pete and Ed,
Interesting to see someone else playing with desktop dyno and this combo. I have been working on the same setup this week with Scott Marzahl and his 327 rebuild. He was considering running a simmilar cam made by Crower P/N 224. 270/278 Advertised duration. Specs out at 222/230 duration @ .050, .470/.488 lift, lobe separation 110 degrees. His combo has 9.5 CR. I did some work comparing this cam to the "151" cam in several iterations. What I found was the Crower grind had big increases in torque/HP at low and mid revs and matched the power/torque output of the "151" at around 5200 RPM where the Crower started to fall off rapidly while the "151" was still making power. I tried advancing the Cams but the Crower liked to be run "straight up" while the "151" liked about 4 degrees advance. This added low end but strangely took very little from the top end. I like to use those Rhodes lifters with the "151" but it is difficult to model variable valve timing with this program especialy since I have no actual data to plug in for the variation in timing provided by the lifters. A rough simulation modeled by lowering the duration about 10 degrees showed some real improvement in the bottom end of the "151". I would not recomend the Rhodes lifters for a cam such as the Crower grind, or any other cam that makes good power at lower RPMs as the cylinder pressures may get too high. Volumetric efficiency was definately better with the Crower grind in the relevant driving RPMs. 9.5:1 C/R worked well with the Crower while the "151" liked a bit more compression at 10:1. Another thing in favor of the Crower grind was the dual pattern that theoreticaly would be better for a cast iron exhaust manifold equipped car. I used actual Chevy cylinder head flow data to try to make the results a bit more valid.

The software has some limitations but it is good for showing what happens when you make changes to your combo. I hope you can get something useful from this posting. Good luck with your rebuild!
-Mark.

[Ed R.]

Re: '66 327/300 Rebuild

Thanks everyone. Great information and help.