No PTV clearance on LQ4?
03-02-2014, 06:40 PM
#1
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No PTV clearance on LQ4? I ordered a Speed inc SI5v2 cam 231/237 .617/.607 112+4 lsa for my 2001 LQ4 using stock length pushrods and 1.7 rockers stock 317 heads etc and long story short there is no piston to valve clearance 1-15 deg past TDC on the intake valve and .080" on the exhaust valve. I've checked my work 10 times and others verify my work and it looks correct.
My issue is, I can't believe there is no PTVC on this combo since it has dished pistons and big combustion chambers (stock)?
And does anyone know the thickness of the top of the stock piston, is there enough to fly cut them even though they are dished?
And last anyone know the stock valve sizes ?
My issue is, I can't believe there is no PTVC on this combo since it has dished pistons and big combustion chambers (stock)?
And does anyone know the thickness of the top of the stock piston, is there enough to fly cut them even though they are dished?
And last anyone know the stock valve sizes ?
Last edited by Ksths2; 03-02-2014 at 06:47 PM.
03-02-2014, 07:11 PM
#3
Most of the times the lobe numbers are inscribed on the back of the cam, unless they want to try to be super secretive and grind them off. I dont get the point in that, but oh well.
03-02-2014, 07:17 PM
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I haven't degree'd the cam yet, I stopped once I realized it didn't have any PTVC.
I am using the stock timing chain and sprockets, is there anything wrong with that would change anything?
Anything else I should check?
I am using the stock timing chain and sprockets, is there anything wrong with that would change anything?
Anything else I should check?
03-02-2014, 07:27 PM
#5
If you dont have them lined up 100% you can run into issues but not on both intake and exhaust.
Is the engine in the car or out? I would pull the cam and check to see if there are lobe numbers on the back. Check the cam box also. See if there is any info in it.
Is the engine in the car or out? I would pull the cam and check to see if there are lobe numbers on the back. Check the cam box also. See if there is any info in it.
03-02-2014, 07:47 PM
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Not sure if I know what u mean bout "if they are not lined up" what's lined up?
Engine is in car but easy to get to. The back of cam says the same numbers the cam card says, by the way this is A new cam directly from comp
Engine is in car but easy to get to. The back of cam says the same numbers the cam card says, by the way this is A new cam directly from comp
03-02-2014, 07:50 PM
#7
The timing set.
I think it was understood this was a new cam from what you were saying. You can match up those lobe numbers in the comp cams lobe book and the last digits will normally be the LSA and advance.
I think it was understood this was a new cam from what you were saying. You can match up those lobe numbers in the comp cams lobe book and the last digits will normally be the LSA and advance.
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03-03-2014, 10:55 AM
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FYI, I just called Comp & TSP to verify that this engine should have PTVC and they both confirmed it should with this cam so I guess I'll start over tonight and pull the cam out to verify its marked correctly on the back of it then redo it and degree it in to see if I end up with the proper 108 Intake centerline.
03-03-2014, 08:23 PM
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We verified everything long story short there's only about .032" PTVC on the intake, we degree'd the cam in and it's within 1.5 degrees of matching the 108 per comp cams, we got 109.5
Either way PTVC is not enough and we don't understand how this can be considering everybody says there should be plenty with his engine
Either way PTVC is not enough and we don't understand how this can be considering everybody says there should be plenty with his engine
03-03-2014, 09:15 PM
#16
We verified everything long story short there's only about .032" PTVC on the intake, we degree'd the cam in and it's within 1.5 degrees of matching the 108 per comp cams, we got 109.5
Either way PTVC is not enough and we don't understand how this can be considering everybody says there should be plenty with his engine
Either way PTVC is not enough and we don't understand how this can be considering everybody says there should be plenty with his engine
Now turn the crank 360* then push tip of the rocker till the valve touches the piston. You should have way more than .032 PTV on the intake. I had a 234 XER cam on a 110 ICL that had .056 PTV with 62 cc 243 heads & 2.02 valves .052 head gasket on a stock LS6 short block.
Russ Kemp
03-03-2014, 10:07 PM
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Ok update, took the cam out, it has all the correct info per cam card, it has the grind number SI5V2 and the serial number.
We reinstalled everything found TDC on the degree wheel and piston stop etc, then degree'd cam in a more accurate tools and it was 107.5 ICL and it should 108 ICL, very close
The dots line up perfectly, crank gear at 12 o'clock and cam gear at 6 o'clock (looks just like the above pic other than it's using stock chain and gears)
Measuring on the intake retainer w/ dial indicator it has .050" PTVC at TDC and turning the crank clockwise at 5 degrees it has .032" PTVC cuz the intake valve is opening already (basically zero'ing dial then pushing tip of rocker until contact with piston)
We are 100% sure this is right but we are at a loss since everyone says there should be more than that
We reinstalled everything found TDC on the degree wheel and piston stop etc, then degree'd cam in a more accurate tools and it was 107.5 ICL and it should 108 ICL, very close
The dots line up perfectly, crank gear at 12 o'clock and cam gear at 6 o'clock (looks just like the above pic other than it's using stock chain and gears)
Measuring on the intake retainer w/ dial indicator it has .050" PTVC at TDC and turning the crank clockwise at 5 degrees it has .032" PTVC cuz the intake valve is opening already (basically zero'ing dial then pushing tip of rocker until contact with piston)
We are 100% sure this is right but we are at a loss since everyone says there should be more than that
Last edited by Ksths2; 03-03-2014 at 10:23 PM.
03-04-2014, 06:58 AM
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Here is a few pics, one of the cam card and one of the back of the cam, they match.
The cam says SI5v2 and D4670-13 - sorry its rotated, it looks right but then it turns when i post it.
Any other suggestions on what to do cuz the way I see it is the numbers don't lie, I don't want to flycut these pistons but its looking like its the only option.......
The cam says SI5v2 and D4670-13 - sorry its rotated, it looks right but then it turns when i post it.
Any other suggestions on what to do cuz the way I see it is the numbers don't lie, I don't want to flycut these pistons but its looking like its the only option.......