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327/300 cam suggestions

 
Old 07-25-2002, 04:54 PM
  #1  
Yello67
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Default 327/300 cam suggestions

I recently got the vette running after many years in storage. It is a 67 with a 327/300 engine that is 100% stock, except for the Lectric Limited breakerless ignition conversion. The car is a 4-speed with a 3:36 posi rear end.

The car runs PERFECT. As Duke has said many times, it's hard to improve upon the performance of a properly tuned original engine. I totally agree in this case as I really enjoy the driveability of my car.

What I was wondering is: Does anybody have any experience or have any suggestions for a cam swap that might give the car a little rumble but not effect the driveability? The car is really a blast to drive now, I just would like to give it a little bit of "personality"

Thanks in advance for your comments. I really value your opinions.

John Visner :cheers:
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Old 07-25-2002, 05:20 PM
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Bluestripe67
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Default Re: 327/300 cam suggestions (Yello67)

I don't think you can go wrong with the next cam up from Chevy, the 350HP cam known as the "151". Good low end torque and midrange, and that noticable exhaust note. I think others here on the forum would agree, especially Duke. Hope this helps. :yesnod:
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Old 07-25-2002, 05:28 PM
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clearrun
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Default Re: 327/300 cam suggestions (Yello67)

If it's a lopey idle you want for driving through the A&W on cruise night, I found that disabling the spark to one of the cylinders works well. When my 65' was only running on 7 I actually had a guy come up and ask me what kind of cam I was running. It wasn't funny at the time but it is now :lol: I have a nasty cam in a 383 I have in my 67'. It doesn't have all that much lift but the lobe separation is only 108 degrees and man that thing lopes along at idle. But the 383 has a lot more bottom end than the 327 and I have 3.70s inthe 67' so it still performs well at lower RPMs. I would imagine that if you start going to a cam that is designed for a higher RPM band you are going to have to increase your gear ratio.
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Old 07-25-2002, 06:02 PM
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SWCDuke
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Default Re: 327/300 cam suggestions (Bluestripe67)

I agree. The 151 cam is the way to go. It will essentially convert your 300 HP into an L-79 as 80 to 90 percent of the difference is the cam.

Be sure to swap the 300 HP vacuum can for the Echlin V1810 (marked B28), which provides full vacuum advance at 8". Since you have to disassemble the distributor to install the vacuum can, overhaul it with a new breaker plate, check the bushings and regrease the upper bushing well, and shim up the end play to two to seven thou. Top if off with a set of high breaker arm tension points such as the Borg-Warner A112HP.

Leave everthing else alone except for setting the initial timing at about 8 degrees (vaccum can disconnected). The '67 300 HP distributor has about 30 degrees of centrifugal, so 8 initial will give you 38 total. Set the idle speed at about 800, and go through the mixture setting procedure. Observe a 6000 RPM rev limit.

Upgrading a base 327 or 350 "300HP engine" to essentially SHP spec just requires the 151 cam for 327s and the 962 cam for 350s and the 8" vacuum can. That's the best bang for the buck. Replacing carbs and manifolds won't do much, and the base carbs usually will work with the stouter cams with just some tuning of the idle mixture at a suitable idle RPM in the range of 750 to 900.

Duke
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Old 07-25-2002, 06:19 PM
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grumpy55
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Default Re: 327/300 cam suggestions (SWCDuke)

SWCDuke,
Crane lists a 327/350 h.p. "blueprint" cam.
Is this as good as the factory issued cam?
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Old 07-25-2002, 07:03 PM
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Yello67
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Default Re: 327/300 cam suggestions (grumpy55)

Thanks everyone for your responses.

Duke, I will follow your instructions concerning the distributor. I also appreciate the step by step directions, the only way you could make it easier is to come over and help me with the swap!!!

It looks like a 151 cam is in my future.

Thanks again,
John Visner
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Old 07-25-2002, 07:06 PM
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bcwaller
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Default Re: 327/300 cam suggestions (SWCDuke)

I had a similar cam to the L79 in my 327 and it had great power all over the band. I did have the 327/350 intake as well, but this is less of an impact on performance than the cam. I could start the car from a dead stop with no gas pedal, or start it in second gear with no trouble. It had power up to 6,500 RPM (I did have a forged crank/piston set and I shifted at 6,500 or above) and was somewhere around the 350-375 hp level.

You could also wake up the engine a bit with headers to take advantage of the bigger cam. I am sure the carburetor is fine, although you might need to re-jet it after the cam (and header?) upgrade.

If you really want to go for it, you could do a roller cam, but that will bump the price up big time compared to hydraulic cam swap. And remember, the smaller engines don't need as much cam. One that is aggressive for a 350 will be really rough in a 327 and mild in a 383, so be conservative if you go beyond the L79 cam specs.
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Old 07-25-2002, 09:41 PM
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Default Re: 327/300 cam suggestions (bcwaller)

Just to play Devil's advocate here, my 67 had a 327-350 with the legendary 151 cam. You stated you wanted a little rumble without giving up driveablity
Well, you will gain a nice lope with the 151 but be prepared to give up your bottom end torque. This is a great cam from 3000 rpm right up to redline but a little doggy off the line and I had a 370 rear end.
Thats not to say,with those gears, that you can't just ease out the clutch and drive away but you won't snap your neck when you punch it unless you rev the engine and drop the clutch.
Right now I have a fresh 327 waiting to go in to replace a 283 with a stock cam that i actually enjoy driving more than that 327-350. Nice little torquey engine with a short duration/lift cam.
When the temp drops around the first of october,107 in the shade today,i'll install that 327 equiped with a Comp Cams XE 256. I hope to get a motor with a better bottom end than the 151 and be able to still spin to 5000 rpm. I do know, that the 151 cam is not my cup of tea. Just my opinion.
If you can wait until October I,ll let everyone know how the Xe 256 works out. Lotsa luck with you decision
Bob
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Old 07-25-2002, 10:20 PM
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Default Re: 327/300 cam suggestions (Yello67)

I also think the 151 would be a good choice, especially if no other mods are planned and drivability is important. The bigger cams need further mods before you'd get their full benefit and drivability would most likely suffer.
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Old 07-26-2002, 12:02 AM
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Default Re: 327/300 cam suggestions (grumpy55)

SWCDuke,
Crane lists a 327/350 h.p. "blueprint" cam.
Is this as good as the factory issued cam?
I have to say that I'm leary about the aftermarket hot rod parts industry, and question whether their manufacturing standards are up to OEM quality. This is a general concern, and I am not pointing fingers at any particular outfit, but I understand GM's quality requirements, and they are rigorous.

My first choice to buy and OEM cam would be GMPD if it is still available, and my second choice would be Federal Mogul, who make exact replacements.

Duke
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Old 07-26-2002, 11:05 AM
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chris ritchie
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Default Re: 327/300 cam suggestions (SWCDuke)

Please don't consider this reply argumentative. I'm just trying to understand better.

You advocate replacing the cam only and leaving the intake manifold the same. To replace the cam, you've got to remove the intake manifold. Wouldn't you want to replace it then with an aluminum high rise. That's what Chevy did, among other things, when the motor went from the 300 HP up to the next higher HP rating.

You state that the intake manifold doesn't make much difference. I thought that the whole package had to play together.

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Old 07-26-2002, 12:43 PM
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SWCDuke
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Default Re: 327/300 cam suggestions (chris ritchie)

There's not a tremendous amount of difference between the 300 HP manifold and aluminum L-79 manifold. Even aftermarket manifolds that will fit are not that much more efficient. There's only so much you can do when 8 runners have so little space to occupy. Have you ever seen objective data presented by aftermarket manifold vendors on how much better their manifolds flow than OEM? I never have!

As I said, about 80 to 90 percent of the difference between the 300 and 350 HP engines is in the cam. The rest is the higher compression ratio, slightly larger valves (the ports are the same, just the valves are a bit larger) and manifold. Both use essentially the same Holley 600 CFM carb. Every little bit helps but the cam is the vast majority of the deal.

Also, the OEM manifold/carburetor/air cleaner has all the proper connections for all the OEM hardware, - fuel lines, vacuum lines, PCV, oil fill tube, choke signal, etc. so no " bubbaeering" is going to be necessary, and the nice clean looking OEM look and reliability will be maintained. The one thing that I would consider is cleaning up the manifold, painting it silver and toppinig off the engine with a set of "Corvette" aluminum valve covers.


Duke
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Old 07-30-2002, 01:29 AM
  #13  
StrayDog
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Default Re: 327/300 cam suggestions (Yello67)

Yello67, hate to burst the bubble on the L72 cam, but get a hold of the May 2002 issue of CHEVY HIGH PERFORMANCE magazine, page 66, specfically compares "new vs old" , in cam design & states a Crane powermax 266/272 will give " ton" more tourque & same hp as L72 & better driveability, note the L72 cam was designed almost 40 years ago................the entire magazine deals with Cams, anyways good reading...........The Dog. :seeya :flag :seeya
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Old 07-30-2002, 04:53 AM
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Default Re: 327/300 cam suggestions (Desertvette)

Just to play Devil's advocate here, my 67 had a 327-350 with the legendary 151 cam. You stated you wanted a little rumble without giving up driveablity
Well, you will gain a nice lope with the 151 but be prepared to give up your bottom end torque. This is a great cam from 3000 rpm right up to redline but a little doggy off the line and I had a 370 rear end.
Thats not to say,with those gears, that you can't just ease out the clutch and drive away but you won't snap your neck when you punch it unless you rev the engine and drop the clutch.
Right now I have a fresh 327 waiting to go in to replace a 283 with a stock cam that i actually enjoy driving more than that 327-350. Nice little torquey engine with a short duration/lift cam.
When the temp drops around the first of october,107 in the shade today,i'll install that 327 equiped with a Comp Cams XE 256. I hope to get a motor with a better bottom end than the 151 and be able to still spin to 5000 rpm. I do know, that the 151 cam is not my cup of tea. Just my opinion.
If you can wait until October I,ll let everyone know how the Xe 256 works out. Lotsa luck with you decision
Bob
Well, I installed XE262 in my 327 and that was a good choice! Plenty of low end torque, good WOT power AND nice idle, too. This is a cam I can recommend.

My set-up is: .030 over 327, around 9.5:1 CR, 1.6 rockers, 2.5 rams horns, 4 speed WR, 3.36 rear end.
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Old 02-10-2019, 12:59 AM
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Duke
Where can I purchase the 151 cam, is that a GM parts number, or do I order from auto parts store
I have read so many of your posts, very informative
Thankyou
Bill V
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Old 02-10-2019, 11:42 AM
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Buy a Sealed Power CS179R manufactured by Federal Mogul. It's manufactured to the L-79 cam blueprint print and is Parkerized. If GM still offers this cam it is probably the same Federal Mogul manufactured part. Crane manufactured this cam for GM prior to their bankruptcy, but I don't think they do now.

A better choice would be the 350/350 HP cam advanced four degrees. I has nearly the same specs other than the IPOML, which is 114 deg. ATC compared to 110 for the L-79 cam. The F-M number is CS1095R. It must be installed with an adjustable timing set to bring the IPOML back to 110, and I recommend the Cloyes C3023X OE replacement truck roller chain that has a provision to advance or retard the cam 4 degrees.

I prefer the CS1095R( advanced four degrees on short stroke engines) because it was designed a few years later and has better lobe dynamics. If you need springs, Sealed Power VS677, and I think the lifter part number is HT817. These are the standard hydraulic lifters used with all hydraulic cams.

Verify the part numbers at napaonline.com or any other site that offers F-M parts and shop around for the best price.

Duke
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Old 02-10-2019, 03:01 PM
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One more reply to your query.... Most of the replys are correct ....almost. A blueprinted L79 cam (from Crane Cams) is absolutely the away to go. It worked in '67 and will work just fine today. Keep in mind that just swapping the 300HP cam for an L79 cam will yield a loss in compression of about one point because of the increased duration and overlap. If you swap the cam you really ought to replace the pistions with the L79 11:1 pop-up pistons as well to maintain the engines static compression ratio. I have done this 'conversion' before and have been completely satisfied with the results. As for the distributor, I recommend using a B20 which will start the pluinger advancing slightly sooner (6"-7"in) than the 300HP canister, but is not as 'aggressive' as L79 canister that would probably cause some detonation (if used with the L79 pistons) under moderate acceleration in the mid-rpm range. No, there really is no need to use the L79 intake manifold OR the larger valves that would ONLY give a wee bit more horse power above 5500-6500 RPM at the expence of a slight loss in low-end driveability and increased fuel consumption because of slightly lower low-mid range flow velocity.
Swapping the cam with the L79 version, using the L79 pistons and a B20 vacuum, and setting the initial timing to about 10 degrees should result in a steady, reliable 'L79' 700 RPM idle, NOTICEABLY more power to 6000-6500RPM (no more 'nosing over' at 5200RPM), and excellent low-end response with little to no loss in fuel mileage.
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Old 02-10-2019, 09:04 PM
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Has anyone here tried or know anything about the CompCams N+300HP camshaft. I have not seen any reviews on CF for this one yet, although Lars did a post using the CompCams L79 “Nostalgia” cam (P/N 12-671-4). Sorry about the highjack.
http://www.compcams.com/Company/CC/c...?csid=106&sb=2
https://www.corvetteforum.com/forums...oto-essay.html
LINK FIXED TO LARS POST

Last edited by jet-tech; 02-11-2019 at 05:27 PM. Reason: fixed link
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Old 02-10-2019, 11:03 PM
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R66
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I have a 350hp Crane cam in our 68RS - 350 cu in. It was a poor in town cruising car as it has a 3.08:1 gear and had a M21 Muncie. It had very poor off line performance in town but ran great on the interstate and got 18 mpg. It idles well and the 600 cfm AFB works well. I had a 600 cfm Holley on it for a few years and it did well too. I have 1.94 intake and 1.60 exhaust valves in double hump heads with 10.5:1 flat top forged pistons. I recently changed out the M21 for a M20 and it really helped the bottom end. Of course the Camaro is heavier than our 66 corvette.
What I am trying to say is your gearing of the rear end and transmission will have a great effect on the need for low end torque. Consider that in your cam selection unless you intend to change the gearing anyway.
The Crane cam has over 100,000 Interstate miles on it. When I put the Eldebrock intake on, I could find no wear in the lobes. The 350 still carries 190# compression with less than 15% leak down.
Just for your information.

Ron
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Old 02-10-2019, 11:26 PM
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Duke,
Maybe I missed it but what is IPOML?
Thanks,
Joe
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