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LQ4 Build, custom cam spec explained

Old 09-08-2018, 09:03 PM
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I am sticking with this cam just to see how it does. Will keep any results posted. Thanks for input on the specs even though most do not agree.

As for lifter; ls7 / morel 5315 / Johnson 2110 ?

im sure all will work, but which one is the most practical choice?
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Old 09-08-2018, 10:10 PM
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Any of the above lifters will do OK, but make sure the pushrod length is right for the selected lifter. I understand the lengths vary for each lifter mfr.
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Old 09-09-2018, 03:57 PM
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If the numbers suck, make the engine builder put another cam in.
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Old 09-09-2018, 04:55 PM
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general rule of thumb I have been told is ls7 lifters are good to 7000 rpm and about 380 lbs on the nose

I have shifted them at 7400 with jesel sportsmans, btr duals, and manton 201's
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Old 09-10-2018, 08:56 AM
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We have a LS7 lifter, tray and bolt kit part number SUM-HTLSKIT. We get lots of positive reviews on them and would be great for this application.
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Old 09-11-2018, 02:39 AM
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In for results.

If you have a chance to talk to whoever spec'd the cam I'd love to know why they chose to go with relatively high lift and low duration on that intake lobe.
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Old 09-11-2018, 08:45 AM
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Originally Posted by NSFW View Post
In for results.

If you have a chance to talk to whoever spec'd the cam I'd love to know why they chose to go with relatively high lift and low duration on that intake lobe.
The intake events would be pretty good for a sleeper cam if they did it intentionally...fairly smooth idle. The exhaust closing is the one I'm wondering about and not quite as critical. It won't run "bad", but agree it will be interesting.
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Old 09-11-2018, 10:33 AM
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it's almost like a PD blower cam on a tighter lsa? I'm interested too.
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Old 09-11-2018, 11:20 AM
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Originally Posted by truckdoug View Post
it's almost like a PD blower cam on a tighter lsa? I'm interested too.
This cam is strange enough we can't really look at duration or lobe separation to gauge behavior. We're looking at four individual timing valve timing events. We haven't heard yet how much advance was ground into the cam, so let's say it's 0 on the intake opening. The valve isn't open much so we're not getting reversion (from piston motion at least). This would have a very mild idle. The intake closing at 43 after bottom dead center. In may ways this gives the powerband and idle typical of what you think when you hear 223 intake duration.

The exhaust opening is also pretty conventional at 53 bbdc and it's the least critical of the four events, so I'll leave that there. The odd thing about this cam is the exhaust closing point. It's at 9 atdc...which at first glance appears to have a lot of overlap and what makes the exhaust duration "look" long in relation to the intake duration. In reality, the intake valve isn't open much and reversion is less than what overlap would suggest. A nitrous cam would put those 6 extra degrees on the exhaust opening side...which would be seen as more lobe separation.

To compare this cam to our SUM-8707 stage 2 cam (226/238 113 + 3), ours has the following events IVO 3 btdc, 43 abdc IVC, 55 bbdc EVO, 3 atdc EVC. By the numbers, ours would have a more aggressive idle, similar powerBand (not power), and the exhaust closing would be nearly the same (you could think of that as loudness)...then we've closed our exhaust valve 3 degrees earlier. We did that for a couple reasons. One of which is most cars this cam will go in have a closed exhaust system with slightly higher back pressure than open headers. With our intake valve opening btdc, it's more sensitive to overlap both from piston motion and residual exhaust from blowdown.

So his cam is a little strange if you are just looking at the duration split, but no one-thing is going to kill it strictly in terms of timing events. The lift is on the higher side. If JoeNova is correct about the lobe choice, using an aggressive EHI lobe on the intake and supersoft SLW on the exhaust for this application is strange if that's indeed what they are..
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Old 09-11-2018, 11:29 AM
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Awesome, great info guys. Hoping to have this motor assembled in the next month or so. Results hopefully by Oct/Nov if all goes well.
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Old 09-11-2018, 12:38 PM
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Originally Posted by sierrals2 View Post
I have a 6.0 lq4 with a 231\239 tsp cam lt headers under drive pulley k&n 243 heads but i wanna use a dorman ls2 intake but i dont know what injectors i need for that intake, ls1 or ls2?
i run a dorman intake. It comes ready to run ls1 style rail and injectors but it comes with the adapters and o rings to run ls2 rail and injectors. So honestly whichever you choose
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Old 11-06-2018, 10:54 PM
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Originally Posted by Summitracing View Post
This cam is strange enough we can't really look at duration or lobe separation to gauge behavior. We're looking at four individual timing valve timing events. We haven't heard yet how much advance was ground into the cam, so let's say it's 0 on the intake opening. The valve isn't open much so we're not getting reversion (from piston motion at least). This would have a very mild idle. The intake closing at 43 after bottom dead center. In may ways this gives the powerband and idle typical of what you think when you hear 223 intake duration.

The exhaust opening is also pretty conventional at 53 bbdc and it's the least critical of the four events, so I'll leave that there. The odd thing about this cam is the exhaust closing point. It's at 9 atdc...which at first glance appears to have a lot of overlap and what makes the exhaust duration "look" long in relation to the intake duration. In reality, the intake valve isn't open much and reversion is less than what overlap would suggest. A nitrous cam would put those 6 extra degrees on the exhaust opening side...which would be seen as more lobe separation.

To compare this cam to our SUM-8707 stage 2 cam (226/238 113 + 3), ours has the following events IVO 3 btdc, 43 abdc IVC, 55 bbdc EVO, 3 atdc EVC. By the numbers, ours would have a more aggressive idle, similar powerBand (not power), and the exhaust closing would be nearly the same (you could think of that as loudness)...then we've closed our exhaust valve 3 degrees earlier. We did that for a couple reasons. One of which is most cars this cam will go in have a closed exhaust system with slightly higher back pressure than open headers. With our intake valve opening btdc, it's more sensitive to overlap both from piston motion and residual exhaust from blowdown.

So his cam is a little strange if you are just looking at the duration split, but no one-thing is going to kill it strictly in terms of timing events. The lift is on the higher side. If JoeNova is correct about the lobe choice, using an aggressive EHI lobe on the intake and supersoft SLW on the exhaust for this application is strange if that's indeed what they are..
my cam does have 2 degrees advance ground in which I did not state before. Engine is pretty close to being fully assembled. Hoping to have dyno numbers sometime in December
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Old 11-07-2018, 09:23 AM
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IVO 1.5, IVC 41.5, EVO 55, EVC 7. The exhaust closing remains a little odd, but the other numbers are inline to make for a nice camshaft. The sky isn't going to fall, It will run fine and we look forward to hearing what it makes.
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Old 11-07-2018, 09:39 AM
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from the cam doctor sheet
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Old 11-07-2018, 10:31 AM
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Originally Posted by mjackson92rs View Post

from the cam doctor sheet
Ok, I see it now. 224/242 112 and almost 4 degrees of advance. It's going to make some pretty strong torque at the expense of some top end horsepower and it's going to have a pretty strong idle to it too. With that advance to it, the exhaust closing doesn't look as strange as before. Let us know how it goes!
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Old 11-09-2018, 12:38 AM
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Originally Posted by Summitracing View Post
Ok, I see it now. 224/242 112 and almost 4 degrees of advance. It's going to make some pretty strong torque at the expense of some top end horsepower and it's going to have a pretty strong idle to it too. With that advance to it, the exhaust closing doesn't look as strange as before. Let us know how it goes!

In for results also...
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Old 12-27-2018, 03:35 PM
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Got the car up and running finally (vid below). Should have #s in a few weeks for you guys. In regard to the cam, is the lift safe for stock rockers? Iíve read a lot about valve guide wear and am just looking for some input.


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Old 12-27-2018, 03:39 PM
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Congrats. Looking forward to seeing the results.
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Old 12-27-2018, 07:08 PM
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For anything over .600 you might consider roller tip rockers as stock rockers start digging the nose of the rocker into the valve tip at that high a lift.
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Old 01-03-2019, 01:21 AM
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Originally Posted by Summitracing View Post
Ok, I see it now. 224/242 112 and almost 4 degrees of advance. It's going to make some pretty strong torque at the expense of some top end horsepower and it's going to have a pretty strong idle to it too. With that advance to it, the exhaust closing doesn't look as strange as before. Let us know how it goes!

You mean there is more to a cam than just the @.050 numbers?

Internet you failed me.....

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