need cam help!!
09-23-2008, 02:58 PM
#11
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
... what determines the working rpms range in an engine? .... is it a cam exclusive function? 
... if you look at some of the important specs on both cams mentioned (XE274HR and 51025LUN)..... you have both cams with the same duration @.050" (224°/232°), the same LSA (112°), the same overlap @.050" of +4° (intake biased) and the same advance ground into the cam (+4°, ICL is 108° for both). This means you have the exact valve events at .050" (4/40 Int. and 52/0 Exh.) with both cams.... are they "identical" cams?..... 
.... lobes are different. So how could they have the same "rpm range"? ..... what about the intake? .... the exhaust?...... valve train?..... Making selections or recommendations of components based on the advertised "working rpm range" by the manufacturers, will not ensure such will be obtained, it will depend on the rest of the combo, and is not the most intelligent way to setup a combination.... BTSTDT...... and it doesn't work, specially when budget is critical, or is simply....... present.
09-24-2008, 08:13 PM
#12
Thread Starter
Join Date: Sep 2008
Location: Oklahoma
Posts: 8
well i bought the XE276HR today and i plan on tearing it down tomorrow. The cam will be in friday and edelbrock gaskets in saturday. ill let you guys know if it fits. it is measured with 1.7 rockers so it will be .513/.513 lift and duration is 276/282 and 224/230 at .050. comp cams said it will fit, we will see. here is a link to the dyno sheet:
http://compcams.com/Technical/DynoSh...6HR-10_001.asp
it should yeild a simailar power curve and get my heavy truck off the line and rolling. it seems with my unaerodynamic body all my time is lost or gained in first gear. well see, trial and error right
. everybody hold off on the bashing till i have it done and i promise good or bad ill tell you what happens.
http://compcams.com/Technical/DynoSh...6HR-10_001.asp
it should yeild a simailar power curve and get my heavy truck off the line and rolling. it seems with my unaerodynamic body all my time is lost or gained in first gear. well see, trial and error right
. everybody hold off on the bashing till i have it done and i promise good or bad ill tell you what happens.
09-28-2008, 12:37 PM
#13
Thread Starter
Join Date: Sep 2008
Location: Oklahoma
Posts: 8
All I can say is WOW
, what a night and day difference. My whole truck was built around a camshaft that i didn't have. It really pulls hard all the way from when my stall engages at 3000 till i hit the rev limiter. i am putting my slicks on today and taking it for a ride.
Well anyway about clearance issues i didn't even come close. i didn't want to tap all the valves so i only took most of them to the lowest cylinder reading.
Here it is for everyone on a budget:
1: .115 (lowest)
2: .120+
3: .120+
4: .120+
5: .120(exact)
6: .120+
7: .125(exact)
8: .190(exact)
So, as you can see i had absolutely no clearance issues. seeing as how I need .080 minimum that means i have .035 more lift i can run on this particular cam. meaning I can put some 1.7 rockers in place of my 1.6's and go from .513 lift to .544 lift and run .084 clearance. So, pretty much if anyone tells you it is impossible to fit a cam in an engine with 2.02 valves they are straight up lying to your ***
. I have not gotten to get to the track yet but seeing how it pulls harder then ever at all rpm, with no dead spots, i am guessing to drop a massive amount of time. honestly, all motor pulls like it is on a 150 shot.
, what a night and day difference. My whole truck was built around a camshaft that i didn't have. It really pulls hard all the way from when my stall engages at 3000 till i hit the rev limiter. i am putting my slicks on today and taking it for a ride.Well anyway about clearance issues i didn't even come close. i didn't want to tap all the valves so i only took most of them to the lowest cylinder reading.
Here it is for everyone on a budget:
1: .115 (lowest)
2: .120+
3: .120+
4: .120+
5: .120(exact)
6: .120+
7: .125(exact)
8: .190(exact)
So, as you can see i had absolutely no clearance issues. seeing as how I need .080 minimum that means i have .035 more lift i can run on this particular cam. meaning I can put some 1.7 rockers in place of my 1.6's and go from .513 lift to .544 lift and run .084 clearance. So, pretty much if anyone tells you it is impossible to fit a cam in an engine with 2.02 valves they are straight up lying to your ***
. I have not gotten to get to the track yet but seeing how it pulls harder then ever at all rpm, with no dead spots, i am guessing to drop a massive amount of time. honestly, all motor pulls like it is on a 150 shot.
09-28-2008, 02:01 PM
#14
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
... seeing as how I need .080 minimum that means i have .035 more lift i can run on this particular cam. meaning I can put some 1.7 rockers in place of my 1.6's and go from .513 lift to .544 lift and run .084 clearance. So, pretty much if anyone tells you it is impossible to fit a cam in an engine with 2.02 valves they are straight up lying to your *** . I have not gotten to get to the track yet but seeing how it pulls harder then ever at all rpm, with no dead spots, i am guessing to drop a massive amount of time. honestly, all motor pulls like it is on a 150 shot.
. I have not gotten to get to the track yet but seeing how it pulls harder then ever at all rpm, with no dead spots, i am guessing to drop a massive amount of time. honestly, all motor pulls like it is on a 150 shot.
....PtV clearance and total valve lift does not "relate" directly as the way you are mentioning. In any 4-stroke engine when max valve lift occurs, the piston is down the hole +60% of the total stroke (3" for a 302 = 1.8" below the deck).How did you establish the clearance numbers?
09-28-2008, 05:39 PM
#16
Thread Starter
Join Date: Sep 2008
Location: Oklahoma
Posts: 8
to get the ptv i used the dail indicator method after i compressed the hydralic lifter. The .120 on 5 and .190 on 8 is due to how square the deck is, piston, crank, connecting rod, head deck levelness, ect. the tolarances add up and thats what i got. remember my deck has never been leveled and i am running all factory 150,000 mile internals. my short block has never been touched. There is a possibility that the dail indicator moved as i went up from .120 but it doesn't really matter. All that matters for future valvetrain ideas is the .115 on number 1.
Joel, i beleive the following to be true but im not certian. If the lobe steepness is the same, as it would be with just changing to 1.7 rockers. then the conact danger point will just take that valve lift at that point plus the extra .1 ratio of lift. i had .115 clearance at the contact danger point so i beleive i could add .035 more lift at that danger point. which i beleive would mean i could run even highier maximum lift.
Joel, i beleive the following to be true but im not certian. If the lobe steepness is the same, as it would be with just changing to 1.7 rockers. then the conact danger point will just take that valve lift at that point plus the extra .1 ratio of lift. i had .115 clearance at the contact danger point so i beleive i could add .035 more lift at that danger point. which i beleive would mean i could run even highier maximum lift.
09-28-2008, 06:21 PM
#17
3rd Gear Member
Join Date: Nov 2007
Location: Washington, Seattle
Posts: 551
I would bo back and double check #8.
If you get .190" again, then it is time to pull the motor down and find the problem.
You are talking about a difference of ~.065"
That may as well be a mile.
If your 'tolerances' are that loose, then you will have issues of one kind or another.
It's worth double checking anyway...
You addressed Joel directly on the rockers, so I'll let him address that question...
09-28-2008, 06:21 PM
#18
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
to get the ptv i used the dail indicator method after i compressed the hydralic lifter. The .120 on 5 and .190 on 8 is due to how square the deck is, piston, crank, connecting rod, head deck levelness, ect. the tolarances add up and thats what i got. remember my deck has never been leveled and i am running all factory 150,000 mile internals. my short block has never been touched. There is a possibility that the dail indicator moved as i went up from .120 but it doesn't really matter. All that matters for future valvetrain ideas is the .115 on number 1.
Joel, i beleive the following to be true but im not certian. If the lobe steepness is the same, as it would be with just changing to 1.7 rockers. then the conact danger point will just take that valve lift at that point plus the extra .1 ratio of lift. i had .115 clearance at the contact danger point so i beleive i could add .035 more lift at that danger point. which i beleive would mean i could run even highier maximum lift.
Joel, i beleive the following to be true but im not certian. If the lobe steepness is the same, as it would be with just changing to 1.7 rockers. then the conact danger point will just take that valve lift at that point plus the extra .1 ratio of lift. i had .115 clearance at the contact danger point so i beleive i could add .035 more lift at that danger point. which i beleive would mean i could run even highier maximum lift.
PtV issues happen during the "overlap" cycle (exhaust-to-intake changeover).... this is when the valves (both of them) are partially open (never at full lift), and the piston is in the TDC vicinity (closest point to the valves). Now.... if you measured valve drop at compression TDC, those figures are not indicative of the real PtV clearance. If you don't clay the pistons with a HR lifter made into a solid at zero lash (3D profiling for height and radial clearance)..... or use the checking springs method (height only PtV check), you could have PtV issues caused after the engine is revved a few times.... or something like....
Which was a B303 cam with some 2.02 intake valve heads.
The fact that such a huge difference between pistons (which I missed) of .075" exist (a block deck cannot be that fubar'ed)..... means the clearance numbers are not...... PtV clearance numbers. You may want to check this article. LUK
09-28-2008, 08:19 PM
#19
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
09-29-2008, 12:18 PM
#20
Thread Starter
Join Date: Sep 2008
Location: Oklahoma
Posts: 8
the method i used to check the ptv is i put the cylinder on compression stroke. set a dial indicator up and set it on my valve spring, then tightened the rocker. let the valve return to zero then did it agian until the reading stopped returning and the valve was staying open then i continued to tighten the rocker until it was at .120( so on the compression stroke the valve was open .120 more then closed and as with all other points on any stroke the valve was .120 past normal) then i cranked the engine over and if it didn't hit then i tightened the rocker down to .125 and so on until it touched. ok, i agree that .190 was a high but i measured the .120 then i got careless with it and it probably moved. but i my brother has personal experience on a 360-408 mopar build that the deck can be off that much. the best machine shop in Tulsa was not at all surprised by these numbers. the deck is still flat it is just machined on a different plain then the crankshaft. i will be running this setup now and i have springs good to .600 lift and no float is occurring at 6,250. disregard the .190 and lets move on it was the only cylinder i had to attach the dial indicator up to the header instead of the valley.