hi all , wanting to know witch is better 108 or110 lobe seperation , iv always ran on a 110 thanks:thumbsup:
lobe seperation
p40
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I have ran the Earson TQ 20H in 2 engines . one was a 327" chevy and one in a 306" ford with 2 different heads.
That cam is way over on it's numbers.. it is in fact a slug.
I used to run the generic 204-214 duration cams with 112 LSA I usually gained 500 rpm on top and lost low end power Then a friend put together an engine and used the 268H comp cam.
WOW! That is all I can say that is an excellent cam.
So I ran one.. then ran the 270,280,292.305 tried them all and every time I went quicker and faster.
Then I got into solids. and set a cut off for hydraulic cam at 230@ .050 and if I need more cam I go solid.
I also tested the Performer vs the performer RPM on a 355" with the edelbrock 204-214 performer cam.
The RPM intake would fry the tires at any speed in first gear sighn off at 5500 rpm.
The performer intake would never fry the tires.. felt like you needed to get out and push the car I tried every timing curve and rejet etc etc ,, nothing worked.
It also would sighn off at 5500 rpm.
To this day I have also tested stock Q jet marine intake vs RPM and 268H was used and 2 different carbs The Q jet was down 30 wheel HP.
Then I ported one automotive Q jet intake for the same deal .. just plenum porting.
It made 20 HP more than the Marine intake ..10HP less than the RPM.
Currently running RPM with 1" spacer.. never tested the spacer.
Lots of little changes make a big difference.
That cam is way over on it's numbers.. it is in fact a slug.
I used to run the generic 204-214 duration cams with 112 LSA I usually gained 500 rpm on top and lost low end power Then a friend put together an engine and used the 268H comp cam.
WOW! That is all I can say that is an excellent cam.
So I ran one.. then ran the 270,280,292.305 tried them all and every time I went quicker and faster.
Then I got into solids. and set a cut off for hydraulic cam at 230@ .050 and if I need more cam I go solid.
I also tested the Performer vs the performer RPM on a 355" with the edelbrock 204-214 performer cam.
The RPM intake would fry the tires at any speed in first gear sighn off at 5500 rpm.
The performer intake would never fry the tires.. felt like you needed to get out and push the car I tried every timing curve and rejet etc etc ,, nothing worked.
It also would sighn off at 5500 rpm.
To this day I have also tested stock Q jet marine intake vs RPM and 268H was used and 2 different carbs The Q jet was down 30 wheel HP.
Then I ported one automotive Q jet intake for the same deal .. just plenum porting.
It made 20 HP more than the Marine intake ..10HP less than the RPM.
Currently running RPM with 1" spacer.. never tested the spacer.
Lots of little changes make a big difference.
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258 Posts
There is allot to matching a setup properly more then just lsa of a cam. Yes having accurate numbers is a must to compare off the shelf cams. I think I plan to try to run custom camshaft this time around on the engine I am currently building. Also look at the ramp speed on that Erson compared to the Comp. The Comp is gonna have more area under the curve. I look at the Erson specs would never consider that cam such a spread between @.050 and advertised. But I like more aggressive then most. Yeah vizards rule is to maximize power and torque not fuel milage. Again that is why there is so many cams. I have a 4 cylinder if I want gas milage. I also run an overdrive that helps allot also.
I had a stock '78 350 with one of these generic 204/214 cams years ago (in a '70 Nova). I had a Performer RPM Q-jet manifold laying around and decided to try it out as a replacement for a stock '70 cast iron q-jet intake. My thought was that it was probably going to be all wrong for that engine, but I had the manifold already (from another project) and gaskets were cheap. I was amazed at how well it actually worked on such a mild combo.
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246 Posts
Geoff, I totally agree.
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1,159 Posts
Just my 2 cents worth
Their not really that similar.
#1 is probably a hole compression point higher
The power pack heads w/1.72-1.5 valves and small ports have a high velocity at low rpm.
The 041's w/2.02-1.6 valves will be lazy and no velocity until upper rpm.
The same with the intake manifolds.
#1 high port velocity.
#2 low port velocity until upper rpm
That's the reason # 2 had the choppy idle and would smooth out at 1500 rpm or so.
Try porting out the power pack heads and install 1.94 -1.6 valves on engine #1 with cam from engine #2.
Should idle well and pull strong to 5500 or so.
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FWIW, I enjoy threads like this......
:thumbsup:
:thumbsup:
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11,006 Posts
Funniest part of cam selection is that whichever one is used it has to live in harmony with all the other parts of the puzzle which may have different goals in mind, Power vs economy or a combination of both which is a contradiction. Ad infinitem. This is why some people make big bucks to build specific combinations.
To get a decent explanation of the LSA and its effects on the unit just go to Comp's website, hit on "Learning Center", then hit on "Technical Info", then "Lobe Separation Angle".
It has some very interesting details covering the LSA.
Here's the gist of what it's saying:
1.-EFFECTS OF ALTERING CAMSHAFT TIMING
Advancing vs. Retarding
Begins Intake Event Sooner / Delays Intake Closing Event
Open Intake Valve Sooner / Keeps Intake Valve Open Later
Builds More Low-End Torque / Builds More High-RPM Power
Decrease Piston-Intake Valve Clearance / Increase Piston-Intake Valve Clearance
Increase Piston-Exhaust Valve Clearance / Decrease Piston-Exhaust Valve Clearance
2.-EFFECTS OF CHANGING LOBE SEPARATION ANGLE (LSA)
Tighter (smaller LSA number) vs. Wider (larger LSA number)
Moves Torque to Lower RPM / Raise Torque to Higher RPM
Increases Maximum Torque / Reduces Maximum Torque
Narrow Power Band / Broadens Power Band
Builds Higher Cylinder Pressure / Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock / Decrease Chance of Engine Knock
Increase Cranking Compression / Decrease Cranking Compression
Increase Effective Compression / Decrease Effective Compression
Idle Vacuum is Reduced / Idle Vacuum is Increased
Idle Quality Suffers / Idle Quality Improves
Open Valve-Overlap Increases / Open Valve-Overlap Decreases
Closed Valve-Overlap Increases / Closed Valve-Overlap Decreases
Natural EGR Effect Increases / Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance / Increases Piston-to-Valve Clearance
Thanks, Gary in N.Y.
P.S. I'll add this, for most of our "streeter's" we use wider LSA's, we are constantly building units with 112*, 113*, and 114*. Occasionally some even get a 116*, depends entirely on the package!
It has some very interesting details covering the LSA.
Here's the gist of what it's saying:
1.-EFFECTS OF ALTERING CAMSHAFT TIMING
Advancing vs. Retarding
Begins Intake Event Sooner / Delays Intake Closing Event
Open Intake Valve Sooner / Keeps Intake Valve Open Later
Builds More Low-End Torque / Builds More High-RPM Power
Decrease Piston-Intake Valve Clearance / Increase Piston-Intake Valve Clearance
Increase Piston-Exhaust Valve Clearance / Decrease Piston-Exhaust Valve Clearance
2.-EFFECTS OF CHANGING LOBE SEPARATION ANGLE (LSA)
Tighter (smaller LSA number) vs. Wider (larger LSA number)
Moves Torque to Lower RPM / Raise Torque to Higher RPM
Increases Maximum Torque / Reduces Maximum Torque
Narrow Power Band / Broadens Power Band
Builds Higher Cylinder Pressure / Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock / Decrease Chance of Engine Knock
Increase Cranking Compression / Decrease Cranking Compression
Increase Effective Compression / Decrease Effective Compression
Idle Vacuum is Reduced / Idle Vacuum is Increased
Idle Quality Suffers / Idle Quality Improves
Open Valve-Overlap Increases / Open Valve-Overlap Decreases
Closed Valve-Overlap Increases / Closed Valve-Overlap Decreases
Natural EGR Effect Increases / Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance / Increases Piston-to-Valve Clearance
Thanks, Gary in N.Y.
P.S. I'll add this, for most of our "streeter's" we use wider LSA's, we are constantly building units with 112*, 113*, and 114*. Occasionally some even get a 116*, depends entirely on the package!
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6,051 Posts
This does not hold true.
Advancing vs. Retarding
Builds More Low-End Torque / Builds More High-RPM Power
I have taken 2 different cams on a 355" with ported 601 heads excellent exhaust 3" and 4". Tunnel-ram 2 fours and single plane with 800 DP.
Each cam was different solid flat tappet 252@ .050 on a 106LSA and a 292H on a 110 lsa the comp magnum hydraulic.
Installed both straight up and then tested both 4 degrees retarded. Both engines lost Low rpm power and both lost Top end power when retarded.
The 252@ .050 was out of steam just before 7000 rpm where before it would charge hard to 7500 it was shifted early at 7000.
It ran 11.50's then when retarded it ran 12.20's.
The 292H the owner wanted more top end power..I said he needed more cam.. he thought retarding it 4 degrees would give him what he wanted.
Retarding was done and the car was a 11.94 car before and now 12.20 was all it had and that was after extensive tuning. and most passes were 12.40's at 110 mph. He stuck it back to straight up and went 11.94 at 115-116 MPH.
117 MPH was a best. The converter stalled to 2200 most days.
Another where Advancing a cam killed all power and this was a 400" Pontiac 236@ .050 ,, the cam had 6 degrees advance ground into it.
Engine builder (not me) told my buddy to stick the cam in another 4 advanced..I said NO!.
He did it and it would go 4700 rpm and level off there it was a huge TURD.
After 2 weeks he pulled the cover off and went for straight up. and was rewarded with gobs of low end and it signed off at 6700 rpm. 6x heads RPM intake and 750.
And wider LSA does not always broaden power band.
It matters how you get the wider LSA.
With my 268H with earlier closing intake valve and just pulling the ex lobe to make it a 112 LSA vs the 106 the power band on the 112 was way smaller in fact after 5700 rpm the power was down dropping rapidly on the 112 by 6500 rpm it was down 40HP vs the 106.
Both cams peaked at 4500 rpm for TQ and 5700 rpm for HP.. not 5 HP difference until after 5700 rpm.
It goes back to total combo or does it.
There is way more going on in camshaft specs than just overlap and LSA.
I think you need to look at all aspects.
That Competition Cams stuff they wright up has bugged me for many years as in my testing some of it does not hold true at all.
Only way to really find out is to do it and see what you get.
I swap parts like some swap fishing lures when fish aren't biting.
Always looking for that edge.
There have been times for me when playing with 4 cylinder engines retarding cam timing has resulted in way more Top end.
6500 rpm was the norm then retard the cam and they pulled to 8500 One was a ford and the other was an iron duke in a pontiac sunbird.
MPG went to crap but man the top end.
Advancing vs. Retarding
Builds More Low-End Torque / Builds More High-RPM Power
I have taken 2 different cams on a 355" with ported 601 heads excellent exhaust 3" and 4". Tunnel-ram 2 fours and single plane with 800 DP.
Each cam was different solid flat tappet 252@ .050 on a 106LSA and a 292H on a 110 lsa the comp magnum hydraulic.
Installed both straight up and then tested both 4 degrees retarded. Both engines lost Low rpm power and both lost Top end power when retarded.
The 252@ .050 was out of steam just before 7000 rpm where before it would charge hard to 7500 it was shifted early at 7000.
It ran 11.50's then when retarded it ran 12.20's.
The 292H the owner wanted more top end power..I said he needed more cam.. he thought retarding it 4 degrees would give him what he wanted.
Retarding was done and the car was a 11.94 car before and now 12.20 was all it had and that was after extensive tuning. and most passes were 12.40's at 110 mph. He stuck it back to straight up and went 11.94 at 115-116 MPH.
117 MPH was a best. The converter stalled to 2200 most days.
Another where Advancing a cam killed all power and this was a 400" Pontiac 236@ .050 ,, the cam had 6 degrees advance ground into it.
Engine builder (not me) told my buddy to stick the cam in another 4 advanced..I said NO!.
He did it and it would go 4700 rpm and level off there it was a huge TURD.
After 2 weeks he pulled the cover off and went for straight up. and was rewarded with gobs of low end and it signed off at 6700 rpm. 6x heads RPM intake and 750.
And wider LSA does not always broaden power band.
It matters how you get the wider LSA.
With my 268H with earlier closing intake valve and just pulling the ex lobe to make it a 112 LSA vs the 106 the power band on the 112 was way smaller in fact after 5700 rpm the power was down dropping rapidly on the 112 by 6500 rpm it was down 40HP vs the 106.
Both cams peaked at 4500 rpm for TQ and 5700 rpm for HP.. not 5 HP difference until after 5700 rpm.
It goes back to total combo or does it.
There is way more going on in camshaft specs than just overlap and LSA.
I think you need to look at all aspects.
That Competition Cams stuff they wright up has bugged me for many years as in my testing some of it does not hold true at all.
Only way to really find out is to do it and see what you get.
I swap parts like some swap fishing lures when fish aren't biting.
Always looking for that edge.
There have been times for me when playing with 4 cylinder engines retarding cam timing has resulted in way more Top end.
6500 rpm was the norm then retard the cam and they pulled to 8500 One was a ford and the other was an iron duke in a pontiac sunbird.
MPG went to crap but man the top end.
21 - 31 of 31 Posts
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