Cam recommendation for 327/300hp
 

I have a stock 1966 327/300 hp engine. The car has 3:08 gears and an M20 trans. I'm interested in getting more performance from the motor without having to do a complete rebuild (just want a noticeable increase). Cam selection seems to make the biggest difference. My motor is 10.5:1 compression while the 350hp L79 engines are 11:1. Would use of the L79 cam in my motor improve performance or lower it because of the compression difference? Has anyone out there done this conversion and, if so, what were the results? Would you suggest a different cam than the L79? If so, please specify. Recommendations on other bolt-on changes (intake, carb, headers, roller rockers etc.) would be greatly appreciated!

Use the L-79 cam. Change the gear ratio to something lower like 3.70.

Your best move would be to move down to the bottom of the mountain and get out of that rarified air.:D

If that were my car, I'd change the differential. Something as mild as a 3.55:1 rear would really wake it up without spinning the engine excessively at hiway speeds.

Jim

I wouldn't change the carburetor but you need to make sure it's jetted for that high altitude. I'm sure you have some experts around that can advise the best way to go.

You can also probably bump the engine ignition timing.

I will offer two changes:
1. Agree with others, 1st gear ratio need to be in the 9.0 to 9.5 range (1st x rear end ratio) so a 3:55 or 3:70 would be great
2. Go with Comp Cams Nostalgia Plus cam #12-671-4. Sound and characteristics of the original L-79 but modern technology makes more power.

Good Luck, Dave

I've been through a lot of cams trying to make 327s more powerful and i still prefer the stock grind camshafts over newer cams.
If you are using all original components stick with stock. some of the newer cams will not work well with the rams horn manifolds, low flowing heads, etc. I had to learn the hard way. Change the rear gears to 3.55 and put in the 350hp stock grind hydraulic camshaft. Remember to add your break in lube with loads of zddp and one bottle of ZDDP plus per oil change.
Good luck!

Rear end gears (336 or 355), a blueprinted Crane L79 cam and drive and enjoy the car. If you don't do alot of highway driving try the 390 gears................

Great info
 

Thanks everyone for the feedback- very helpful!

the factory L79 cam bleeds off a lot of dynamic compression, it does not play well in lower compression motors, the 300 hp cam is agreat cam and will respond well to 3.55 gears. This the first change I would make.

yep..
 

Agree... Cam is part of engineered system of components. My recently rebuild L75 pulls strong with factory cam, heads, exhaust, carb... Gear change would yield immediate low end results. Note that the 1965 L75 has the same torque rating (360ftlbs) as the 350hp (L79) only at a lower RPM. 3200 vs 3600RPM. Don't fall for the speed part hype...it is a system.

Duke Williams has designed "Special 300 HP cam" for 327/300 engines. Please see NCRS technical archives for user reports. Interesting stuff! :thumbs:

I'd swap out the diff - the 3.08 is great for the highway, but not around town; I have the original 3.36 in my '67 300hp with M20, and it's a nice all-around combination. The stock "929" 300hp cam has great low-end torque. :thumbs:

Agree with 1, but not 2.

modern tech only makes ore power if you have the matched componants to "Play well" with the increased efficiency.

i just went through this whole debacle with my 302 in my Z28. and a few years ago with a pair of roller cams in my L76.

in the end, unless you are willing to increase the effeciency of the intake, heads, and exhaust... wasting money of a fancy arse modern cam is just that... wasting money.

things like advancing the cam 4-6 degrees and optimizing gearing, jetting, and ignition will do wonders for these cars.


i'm debating building a 383 shortblock for my 69z to hide under the original heads/intake/carb/exhaust etc... if I go that route i'll either use the 097, or a LT1 on a 114 so that I can utilize the exhaust manifolds and still have some top end fun.

A

Your mile high address for where this car resides will dictate more then anything on what cam to put in you mill. Your would want something with moderate to high lift on the intake lobe to open the valve as quickly as possible and shove as much of your "thin air" into the cylinder with a relatively fast closing. The exhaust lobe will not need to be as much lift nor the split as large because with the thin air you won't have much to exhaust. I would suggest a 1.6 or 1.65 ratio on the intake and stick with 1.5's on the exhaust.

All three of these guys are spot on. Leave the cam alone, you'll get better low end torque with the 300 hp cam than with the L79. If you want a little more performance, I'd recommend the 3:36 rear gears, it'll waken the car up and still give you decent fuel mileage, and the engine won't be winding so high at highway speeds.

I've got exactly the same setup in my '65 coupe, I put the 350 hp cam in when the engine was rebuilt. It develops a little more power I suppose at the higher rpms, but I seldom if ever drive there. It's lost some of the lower end torque the 300 hp had, and if I had it to do again, I'd go back with the 300 hp cam. Personally, I like the 3:08 gears with the 300 hp engine, great highway car in my opinion. My other has 3:36 gears with the same engine, a little peppier.

I'd swap the differential!!

:iagree:

I don't think all three guys said the same thing.

Question for you. Since both the 300 cam and the 350 cam will idle down to 15 mph in high gear and then pull away, why worry about "low end" torque with a 3100 pouind car?:D

There's only a few hundred rpm difference in where the two cams work on the bottom end and the difference in torque is negligible. Lot's of difference where they work on the top end.

:iagree: . . . . to a point. All three do agree however with the differential swap, which was the thing I said, and would certainly improve low end acceleration.

I also believe the 300 hp cam has better torque in the lower rpm range, which is where most of my driving is done. I think Donny Brass is on the right track, leave the cam alone at least until you can determine if the differential gear change isn't sufficient to get the performance you're looking for.


:thumbs:

Mike
my 'seat of the pants' experience back in the day when we street raced; my 327/300 would outrun a 327/350 until 3rd gear; then the 350 would pull on by when the 300 ran out of breath.
Bill

I put a gerneral kenetics cam in a 300 hp stock motor that was pretty big, with 3.36 gears....

I do not remember the specs, but the car was such a dog it would not spin the tires on ice.

i once tried a comp xe250 206/212
it could pull out from a stop in 4th
here, an xe256 212/218 could be better