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  #1  
Old Feb 16th, 12, 8:32 PM
abone3273 abone3273 is offline
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Default another cam question

I'm looking for some performance suggestions and/or cam advice. I have a numbers matching 67 el camino with 327/325 bored .040 over. I Believe the compression ratio is about 10/1. Originally 11/1 but my grandfather used the lower compression pistons for gas quality purposes. Since I've had the car with the modified pistons, it has been very sluggish off idle. I would like to know if the reduction in compression plus removal of smog equipment has changed the cam requirements and would like suggestions on replacement cams if necessary. I would like to mildly upgrade the cam anyway. The rear end is 3.31 posi with what I believe to be a m22 trans. because of the whine. I don't know what other questions to ask or what info to give. I drive it ocassionaly to town. Not much more. I'm not looking for a racer just a tiny bit more performance.
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Old Feb 16th, 12, 9:11 PM
mr 4 speed mr 4 speed is offline
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Default Re: another cam question

Hi Aaron,what is your base timing timing set at and what is the total? The lowered compression has very little to do with off idle performance but timing has everything to do with it.
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  #3  
Old Feb 17th, 12, 2:43 PM
abone3273 abone3273 is offline
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Default Re: another cam question

Over the years I've had the timing set all over the dial adjusting in small increments. I recently put a mallory unilite distributor in it. I have the distributor out and the intake manifold off right now to solve an oil leak which is why I am considering a cam swap right now. From what I've seen online I am considering one of the Isky megas. Any suggestions.
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  #4  
Old Feb 17th, 12, 4:53 PM
mr 4 speed mr 4 speed is offline
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Default Re: another cam question

the 270 megacam is a good one
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  #5  
Old Feb 18th, 12, 9:32 AM
mr mr is offline
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Smile Re: another cam question

Quote:
Originally Posted by mr 4 speed View Post
lowered compression has very little to do with off idle performance, but timing has everything to do with it.
X2

FYI ... stock hi-performance GM camshaft specs.
1.) stock 327/350HP camshaft specs = (221/221 @.050 duration w/.447/.447 valve lift @ 114*)

2.) stock 350/370HP camshaft specs = (234/246 @.050 duration w/.459/.485 valve lift @ 116*)

3.) stock 302/290HP/Z28 cam specs = (246/246 @.050 duration w/.484/.484 valve lift @ 114*)
Quote:
Originally Posted by mr View Post
Change Cam - Gain 77 HP ..... "article on page 22, in the magazine" [Best of Tech /Winter 2003]

A few years ago there were claims by a magazine of adding 77 horsepower to a wimpy 8.6:1 compressioned 355 sbc equipped w/"the usual hot rodding parts" headers, 750 Speed Demon carb, Edelbrock Performer RPM Air-Gap intake, 2.02/1.60 Summit aluminum heads, MSD, ect.

Just using an Erson TQ40 cam kit [218/228@.050 duration][.472 valve lift, w/1.5:1 rockers]
instead of the stock small block Chevy [195/202 duration] factory type [.390/.410 lift] camshaft ...


Using this Erson TQ40 cam, it showed gaining a maximum of 77 hp @ 5,600 RPM = [403 hp/maximum] .....
and gaining 20 pounds of torque, @ 4,400 RPM = [418# torque/maximum] over the stock low lift camshaft.

Oddly enough, from 2,000-to-3,900 RPM, results were [-1 horsepower] and [-4 pounds of torque].

Average gains from 2,000-to-5,900 RPM, were 44 horsepower & 35 pounds of torque .....

This Erson TQ40 cam showed gaining 78 hp & 78 pounds of torque, from about 4,000-to-5,900 RPM.
Quote:
Originally Posted by novadude View Post
.....Read that part carefully.
Quote:
Oddly enough, from 2,000-to-3,900 RPM, results were [-1 horsepower] and [-4 pounds of torque].
A TQ40 cam would be a TERRIBLE choice for a heavy El Camino, stock converter, 3.36 gears. Think about it,
... on the street and during a 1/4 mile pass, that car will spend a LOT of time in the 2000-3900 rpm range.

If ALL torque gains are above that RPM range, any real performance improvement will be minimal, and the car won't feel much stronger SOTP when screwing around on the street.
You want to keep the duration much smaller IMO (< 215 @ 0.050).

Isky 262 Supercam or 264 Megacam would be a good choice .... Re: Mild "budget" 350 cam ... suggestions
Quote:
Originally Posted by novadude View Post
Get a Crane 274H06 or Isky Mega 270. It will give a lopey idle without totally killing performance, assuming you only have stock 76cc heads and dished or flat-top pistons (8:1-9:1 CR).
Honestly, even those are a bit big for that low CR, but much better than the ones you picked above.
Quote:
Originally Posted by UDHarold View Post
All facts, or theories, change with RPM. What is true at low RPM is not true at high RPM ...

The longer you can keep an exhaust valve closed, the longer power stroke you have, and the more torque gets put into the crank. Single-pattern cams keep the exhaust valve shut longer, so more bottom-end torque.

At high RPMs, past peak torque, the most important thing is getting the exhaust out of the cylinder so a fresh charge can get in. If you can't get all the exhaust out, you can't fill the cylinder as full, because old exhaust is still in it.

"You notice this most often when you hit peak power" ....
The torque/horsepower curve takes a bigger drop, caused by an inefficient cam or exhaust system.

Single-pattern cams make good bottom-end, but limit the top-end horsepower.

Dual-pattern cams make good top-end, but give up a little bottom-end torque.
Aaron, this hydraulic roller is probably too big for your purposes, but it might help someone looking to go bigger ...
Quote:
Originally Posted by 1997bird View Post
I have good results from Erson cams. They do have a hydraulic roller that is perfect for your application. I would work on getting the compression up a little over 9.5:1 with a 2,000rpm to 2,500rpm stall which will drive great.

Here are the camshaft specs:
Erson 272*/280* seat duration, 218*/226* @.050" .512"/.480" lift with 1.6 intake rockers and 1.5 exhaust rockers.
The lobe center is 108* degree's. The part number for this Erson hydraulic roller cam is E119840
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  #6  
Old Feb 18th, 12, 11:33 AM
Tom Mobley Tom Mobley is offline
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Default Re: another cam question

what they said, make sure the initial is around 18, this will likely force a mod to the advance to limit it to 18. Make sure the carb has a good healthy accelerator pump squirt with any movement of the throttle.

be sure that leak isn't the sending unit for the oil pressure gauge or the tube if it has a mechanical gauge.
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  #7  
Old Feb 18th, 12, 1:09 PM
elektryc102 elektryc102 is offline
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Default Re: another cam question

What heads are you running?what intake and carb?and is the bottom end of your motor strong i.e. rod bolts,balanced? there are alot of variables that determine what cam to run,didnt you say you had an M22 manual tranny?If you have an automatic if you run to wild of a cam you may have idle problems in drive without a stall converter, the closer you get to a .500 lift cam you may need screw in rocker studs. I am not nearly as knowledgable as most of these guys on here but i think a little more info is needed before you make a cam decision, but like Tom mentioned you may just have a timing issue,what cam do you have now?
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  #8  
Old Feb 19th, 12, 10:35 PM
abone3273 abone3273 is offline
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Default Re: another cam question

Thanks for all of the suggestions. I will try to give as much info as possible to narrow this down. The car is an original 327/325. It has a 3.31 posi with an m22 muncie 4 spd, 2.02 double hump heads, around 10/1 CR, factory aluminum medium rise intake, factory holley list 3807 595 cfm which I could I will probably as for some help with the tuning. It has the factory exhaust and a mallory unilite distributor. The factory cam specs which I have stolen from one of the above posts are (221/221 @.050 duration w/.447/.447 valve lift @ 114*.) The car already has a mild lope. Like I said I'm only looking for a mild bump in performance or maybe a little more without completely ruining drivability. I mostly will be just driving it around town. I just like to be stuck to the seat every once in a while. Let me know if there is any other info that that I can give. Thanks.
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  #9  
Old Feb 20th, 12, 8:11 AM
Timmy Timmy is offline
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Default Re: another cam question

The Crane 216/228/112 - .454/.480 will make more torque and more power than the original cam. Similar cams are the Summit Racing 214/224/112 - .442/.465 and my favorite the Engle Cams 216/226/112 - .458/.468 Crane Cams part number 113941 Summit Racing part number SUM-1103 Engle Cams part number 1018H - grind number EP-18/20HYD For the most idle lope with the highest torque try this cam that was originally designed by Cam Dynamics for the 327. Now sold by Summit Racing and Crane. 218/218/106 - .450/.450 Summit Racing part number SUM-1785 Crane Cams part number 10017 Note this camshaft is on sale at Summit Racing for much cheaper than the Crane price. There is also the Crower 218/226/112 - .462/.470 Crower part number 00903 This Crower cam runs a bit "bigger" than the other cams.

Last edited by Timmy; Feb 20th, 12 at 8:58 AM.
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  #10  
Old Feb 25th, 12, 1:14 AM
abone3273 abone3273 is offline
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Default Re: another cam question

I really appreciate all of the help. With my limited knowledge, what I could really use is a collective "ya, you should use that one." I'm having a hard time with all of these choices. I have a couple of influences that are pushing me towards Isky. I'm feeling that the 270 mega would be max or maybe too much.
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  #11  
Old Feb 25th, 12, 10:30 AM
Tom Mobley Tom Mobley is offline
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Default Re: another cam question

Isky 270 a little aggressive for stock exhaust engine.
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  #12  
Old Feb 25th, 12, 11:08 AM
66 BRONZE 66 BRONZE is offline
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Default Re: another cam question

Quote:
Originally Posted by abone3273 View Post
I really appreciate all of the help. With my limited knowledge, what I could really use is a collective "ya, you should use that one." I'm having a hard time with all of these choices. I have a couple of influences that are pushing me towards Isky. I'm feeling that the 270 mega would be max or maybe too much.

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  #13  
Old Feb 25th, 12, 1:22 PM
CDN SS CDN SS is offline
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Default Re: another cam question

First let me say .a 4 spd Elky with a factory L79 327 is a very nice car ... that engine in a coupe or elky back in the day was a very strong street car .... 3.73 gears would be real nice but 3.31 is still fine

Sounds like you want to keep it stock appearing with stock carb and exhaust manifolds etcetc and rear gear ratio

"I drive it ocassionaly to town. Not much more. I'm not looking for a racer just a tiny bit more performance. "

IMHO ( i have had a L79 ) assuming the rebuild was done right cam is in good shape and valve springs on spec ......... keep that cam with that stock carb and manifolds it will give you very good street performance All you need is a good performance tune .... performance distributer advance curve and some carb tuning ........ especially if it was a smog car and the carb / dist is still stock ...... start withe basics ......make sure your timing mark is at true TDC etcetc ........... even if you do change the cam you will need to recurve your dist and do some carb work plus new valve springs ....... and yes with the flat top pistons you lost some low end ....IMO tune for the new combination before a cam change ...... FWIW

Mallory dist .........does it have a vacuum advance can on it ?? and is it hooked up ........... do you still have the original dist ?
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Last edited by CDN SS; Feb 25th, 12 at 1:37 PM.
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  #14  
Old Feb 27th, 12, 8:21 PM
abone3273 abone3273 is offline
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Default Re: another cam question

Thanks Bill. I was on the fence about messing with the cam. I think now that I will concentrate on getting the right tune. The Mallory does not have a vacuum advance. I do still have the stock distributer. Should I put it back in. I had always just started with the factory 10 btdc followed by small adjustments and test drives without ever being 100% satisfied. I also tried a different power valve without noticeable difference. I am capable of doing the work but I could use advice on the step by step process of performance tuning. Also, yes, this was a smog car. Thanks again.
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  #15  
Old Feb 27th, 12, 8:47 PM
CDN SS CDN SS is offline
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Default Re: another cam question

I'm in a bar in Mexico watching the Daytona 500 in Spanish !! online to get race info in english .... lots here who can suggest a good curve for your dist been awhile since I had a mild sb .I can suggest a curve later ..you definitely want vacuum advance ........for right now check to ensure your mark on timing tab is correct when #1 piston at tdc do have a dial back timing light ? if not then get a timing tape for your balancer so you can check to see what your curve looks like
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