Danny Bellmore
Active Member
Is there anyone who knows how to center the overlap triangle over TDC?
Overlap Triangle
- Thread starter Danny Bellmore
- Start date
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SSG_Karg
Enhanced member
Newbomb Turk
Well-Known Member
Post your cam numbers and I can tell you where the ICL needs to be to center the overlap triangle.
So seat to seat if you have it, LSA/ICL, @ .050 numbers and lift.
Danny Bellmore
Active Member
I will give you what I have from the cam card.
Comp Cams 20-718-9
Gross Valve lift (in 654) (ex 655) add 1.6 rocker arms.
Duration @50 (in 269) (ex 276)
Lobe Lift (in .436) (ex .437)
Valve Timing @50 (in open 45) (in close 77)
(ex open 81) (ex close 48)
Lobe seperation 106
Camshaft Calculator & Valve Overlap Profiles | MGI SpeedWare
An interactive camshaft calculator where engine builders can see how valve overlap (and boost efficiency) is affected by a camshaft’s physical design.
mgispeedware.com
Newbomb Turk
Well-Known Member
I'm going to assume that Comp called for a 102 ICL. So 4 degrees advance.
To center the overlap triangle you need to install the cam at a 105 ICL.
Danny Bellmore
Active Member
Thank you for your help. It is much appreciated.
Comp does not specify what it called for, I have it in at 104 currently. I am just trying to get my combination to work optimally with what I currently have.
Newbomb Turk
Well-Known Member
At 104 you are close enough to let it go. I wouldn't change it. Plus its damn hard to find one degree. You may end up with the cam a bit retarded.
don't call his cam retarded! It's doing the best it can
Newbomb Turk
Well-Known Member
don't call his cam retarded! It's doing the best it can
lol yeah, I’m not politically correct.
BTW, i assume the overlap triangle would be centering the valve events so they happen with tdc right in the center? Just a guess.. had never heard of it before.. kind of curious where my cam would land but it will just make me overthink and go nuts over something that doesn't matter at this point
Newbomb Turk
Well-Known Member
BTW, i assume the overlap triangle would be centering the valve events so they happen with tdc right in the center? Just a guess.. had never heard of it before.. kind of curious where my cam would land but it will just make me overthink and go nuts over something that doesn't matter at this point
Go to mgispeedware.com and click on the camshaft calculator.
You can enter your cam numbers and look at the graph and see what you have.
Danny Bellmore
Active Member
Well, I guess I will need a new cam and lifters. I pulled the intake off today to mill for more clearance for the valve covers and it appears that I have a bad lobe and another starting to wear. Brand new Comp cam and brand-new Bam bushed lifters.
Newbomb Turk
Well-Known Member
Ouch!! What happened??
Danny Bellmore
Active Member
I'm not really sure what happened here. I cut all my oil filters open, and I found bronze the middle of the summer. I pulled the Milodon shaft and gear and it was pretty much chewed up. I replaced the gear with one from Comp. I flushed the system as best as I could.
Newbomb Turk
Well-Known Member
The good news is if you like the cam it can easily be welded and repaired.
I’ve never run that style of lifter but I’ve been told they are very sensitive to any dirt. Maybe some of that gear found its way past the filter and killed the bushing.
That’s a damn shame for sure.
I’ve never run that style of lifter but I’ve been told they are very sensitive to any dirt. Maybe some of that gear found its way past the filter and killed the bushing.
That’s a damn shame for sure.
"Mr. George, how much you pay the new guy?"
Danny Bellmore
Active Member
I am currently starting from scratch. I will be bumping up my compression and would like to get a custom ground cam for my application.
Who would you recommend for designing a cam?
TT5.9mag
Two atmospheres are better than one
Damn that sucks sorry. Can you tell me if it’s a needle bearing axle or a bushed axle lifter? Either way it definitely stopped rolling.
TT5.9mag
Two atmospheres are better than one
BTW, i assume the overlap triangle would be centering the valve events so they happen with tdc right in the center? Just a guess.. had never heard of it before.. kind of curious where my cam would land but it will just make me overthink and go nuts over something that doesn't matter at this point
See the image above for a visual, but the overlap triangle is the time the exhaust valve hasn’t closed yet, and the intake has started to open. Centering the triangle is just moving the cam around to get those events to happen on the same side of TDC. In the pic above the triangle is NOT centered.
Danny Bellmore
Active Member
They are BAM DLP bushed
TT5.9mag
Two atmospheres are better than one
Very sensitive to debris. One of the only downsides to that kind of roller lifter.
Newbomb Turk
Well-Known Member
Newbomb Turk
Well-Known Member
Post your view, stroke, rod length, compression ratio and at what RPM you want peak torque and peak power and I’ll run some numbers.
Also car weight and converter stall speed. And header size.
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