Some recent posts have highly praised the combination of the 327/350 cam and Rhoads lifters. I'm certainly interested in learning a bit more; specifically, should I expect performance as great as I've read about if that combo is installed in a 1972 LT-1 350 engine, as opposed to a 327 application? The engine in question presently has an L46/L82 hydraulic cam installed. If anyone has any other suggestions or recommendations for a high torque at relatively low RPM hydraulic cam, I'd be grateful for that info as well. Thanks! Larry Maher, #10731
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Re: 327/350 Cam?
I have seen posts about using the 327/350HP cam with Rhodes lifters as well. If I ever have to rebuild my 68 327/350HP engine I will certainly consider this variation. Read an article some time ago in Chevy High Performance where they did a test between a Competiton Cams type similiar to the 151 and the 151 cam. If I remember the test, the Competition Cam did put put more horsepower at the upper limit of the RPM, but other than the upper limit, there was not enough difference between the two that I would go out and buy and install the Competition Cam if my current one was doing its job. I don't know the difference between the L82 and the 151, so can't say which one is better for your application. However it seems you are wanting more low RPM torque. The 350?300HP cam that came in my 70 is a good one. The torque as stated on the dash plate on my 70 rated the 350/300 as having 380 foot pounds, enough to chirp the tires going from first to second with the turbo 400 and a 308 rear end. Always wondered how this car would perform with a 370 ratio rear end. -
Re: 327/350 Cam?
The 151 cam was designed specifically for a 327 and is an excellent all around high performance cam. The L46 cam had just slightly more duration because of the 350's longer stroke. It will make a bit more top end power in a 327 with a slight loss of low end torque.
The LT-1 used a specific mechanical lifter cam that was a development of the 30-30. Inlet duration was reduced and the lobe center angle was narrowed slightly to create more low end torque. This cam is the best way to go if you are restoring a mechanical lifter engine.
DukeComment
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Re: 327/350 Cam?
Larry -
Back in 1972 I installed a 327/350 cam and Manley antipump-up hydraulic lifters in my '70 Nova SS, which had the standard 350ci 300hp engine and a set of headers. The cam really made a difference, and I had plenty of low end torque. With my 3.73 rear end, the car would idle up a steep hill in first gear. It also made short work out of 396 325/350hp Chevelles.
If I were building up a small block today, I would also look at the available roller hydraulics, as materials and design have come a long way in the last 30 years.Comment
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Re: 327/350 Cam?
The last mechanical lifter 350 inch I built was done with a Melling C-80P cam and I want to tell you NOTHING GM ever produced can compare! I also used an Offenhauser 360 degree dual AFB intake with two Carter Competition Series 500 cfm carbs on a progressive linkage. Off idle used only one set of skinny primary venturis and stump pulling torque resulted at low rpm. The top end was WAY out there! The more throttle, the more torquey rpm you got!
HOWEVER! Today, roller cams are quite attractive. Relatively short durations and high lift seem to do the job.
I have used the 151 cam with variable duration lifters in a 400 inch truck motor. (installed straight up). With all parameters remaining the same, the larger the displacement, the MORE bottom end you get with the same cam. There's a limit of course where cylinder filling becomes compromised. As a result, volumetric efficiency falls as does torque. At this point the cam choice becomes very poor indeed.
I see no reason not to try a 151 cam with Rhodes lifters in a 350 inch motor. I'd install the cam 2 or 3 degrees advanced. An iron intake and 2 1/2 inch ram's horn manifolds will help a lot as well. This procedure builds low end torque and you can still go 120 mph if you want to.
Dale.Comment
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Re: 327/350 Cam?
Folks - Thanks for all of your input. I'd like to keep the LT-1 engine externally correct with its aluminum intake, while at the same time keeping a hydraulic cam inside, although not necessarily the same L46/L82 cam that's been in there for 14 years. My intent is to get that stump-pulling sensation; the installed L82 cam seems to have better mid- and upper-RPM range power, which is not where the engine usually operates. I'm looking for more power from a start, not the high end HP, and it seems as if the 151 may be one solution. That raises another question: Is the version of the 151 cam currently available from GM the same grind as was originally produced? If not, is it 'better' or 'worse', that is, produces more or less power? Thanks again. LarryComment
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Re: 327/350 Cam?
The 1962 300 hp cam will give you what you want. Install straight up & use GM hydraulic lifters. It'll be quiet, last forever, and give you bottom end torque. You might want to talk with the folks at UltraDyne cams in Mississippi. They have a lot of savy. Look in the Melling catalog under the "Melling Torquer" series as well.
You want to close the intake valve early in the cycle and grind the lobes to have close centers with overlap, say 110 degrees. A short duration high lift is the way to go.
A hydraulic roller cam will work wonders with what you're trying to do. So will a 3.615 inch stroke!
However, I'll come back to where all bench engineering ends: GM did a damn fine job with the L-82 cam and all the stock stuff that goes with it. Why not just RESTORE and resist the temptation to improve?
Dale.Comment
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Re: 327/350 Cam?
Dale - Thanks for the note. Your point is well taken. I have no issues with the engineering R&D made by GM on the L82 cam. In my case, I'm not restoring, or trying to improve with an aftermarket cam. I swapped out the original solid-lifter LT-1 cam years back because I wasn't completely satisfied to have an engine with obvious lifter clatter, and one that required valve lash adjustments more frequently than I was willing to make (even though there may be others who view those characteristics as positives). I chose to install the L82 cam specifically because it was a hydraulic cam developed by GM for use in hi-perf 350 cubic inch applications, whether it was the '69-'70 350/350, or the later '73-and up L82. It's been responsive at the higher RPM range, which I'd expect, but since most of my driving is at lower RPM's, I want to explore the optional hydraulic cam possibilities offered by GM that fit in better with my driving habits. I have more fun with faster accelerations from a stop, than I do with the car's acceleration from 50 up to 80 mph. Before I make a decision for the next cam swap, I'm trying to determine if a cam designed for a 327 engine will function similarly in a larger displacement 350. Your remark about the 327/300 cam interests me, and at the same time surprises me. My initial reaction is that the 327/350 151 cam would provide more power (but perhaps less low-end torque?) than a 327/300 version, and therefore, would seem a more likely choice. If the 327/300 has the better bottom end, will it have sufficient lobe lift to fill a 350 cubic inch engine so that it doesn't run 'out of gas' on occasions of high RPM? Beating this topic to death, Larry.Comment
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Re: 327/350 Cam?
You require that an aluminum intake be used. This requirement defeats all-out bottom end torque as does the requirement of no lifter chatter as would be the case with Rhodes lifters.
Install a 151 cam (327/350) with stock lifters and phase the cam 4 degrees advanced. I think you'll make a tad more torque than a 300 hp 1962 cam and I know the top end will be at least as good and mabye better considering the volume of your manifold runners. It will definately be more streetable than the L-82. The term "High Performance" translates into HIGH RPM always. The terms, "Street/Strip" and "High Performance" have caused a lot of folks to trade their ear-to-ear smiles for frowns!
Dale.Comment
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Re: 327/350 Cam?
Thanks again for sharing your info. Seems as if the 151 will fit my needs, and it looks like I'll be playing in the garage before too long. Consider the wave saved. LarryComment
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