LSX is ready to be dropped in tomorrow (PICS!)
I'm guessing the cam has too much lift but now I'm going to have to take off the timing cover just to be sure. Can't I adjust the timing with the chain to help the problem as well? It's adjustable to advance up to +4 and retard up to -4. I have no idea how that stuff works though, I always just put it on 0.
Here are some pics. You can see the valve marks on the piston, worst one. The heads are holding the water with no leaking so far which is weird.
Here are some pics. You can see the valve marks on the piston, worst one. The heads are holding the water with no leaking so far which is weird.
cam specs: 246/250 .632/.635 on a 112+4
I also had 7.4 pushrods in it and after measuring with a pushrod checker, I need 7.35 and that's with .075 preload so if I went with less preload like .05, I could even go shorter. I'm wondering if that's my problem right there, the longer pushrods are causing all my problems. It just doesn't seem like .05 would make enought difference but maybe since my cam is already cutting it close, it was enough to cause problems? I thought the lifters eat most of that though, I wonder how much would bottom out the lifter? With 7.4 pushrods, I had .125 preload on the lifters which is too much but enough to bottom them out, I don't know.
I also had 7.4 pushrods in it and after measuring with a pushrod checker, I need 7.35 and that's with .075 preload so if I went with less preload like .05, I could even go shorter. I'm wondering if that's my problem right there, the longer pushrods are causing all my problems. It just doesn't seem like .05 would make enought difference but maybe since my cam is already cutting it close, it was enough to cause problems? I thought the lifters eat most of that though, I wonder how much would bottom out the lifter? With 7.4 pushrods, I had .125 preload on the lifters which is too much but enough to bottom them out, I don't know.
Joined: Oct 2006
Posts: 2,608
Likes: 0
From: Webb City, MO...out in the garage
lift is important, but your duration is what will usually cause clearance issues. i'm not a cam expert, but even still, i would think your cam is fine. pushrods could DEFINATELY be the culprit here.
...and that little nick on the piston is going to create a hot spot, and possibly a lof trouble i think...
...and that little nick on the piston is going to create a hot spot, and possibly a lof trouble i think...
That LSA is a bit tight. What kind of clearance did you have when you clayed it? You need to check with a solid lifter too. They are easy to make with a hyd. lifter, just pop the snap ring out and take the spring out and replace with something solid so the plunger cant move. If you used regular lifters when you clayed it, the could have bled down. A cam with a 115 lsa or more, would be more desirable for FI, and could give you more PTV clearance.
And...
If the piston hit hard enough to ding them, you need to check all the valves. Pull them out, and check them to see if any are bent.
And...
If the piston hit hard enough to ding them, you need to check all the valves. Pull them out, and check them to see if any are bent.
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Verdad Gallardo Joined: Oct 2006
Posts: 2,608
Likes: 0
From: Webb City, MO...out in the garage
That LSA is a bit tight. What kind of clearance did you have when you clayed it? You need to check with a solid lifter too. They are easy to make with a hyd. lifter, just pop the snap ring out and take the spring out and replace with something solid so the plunger cant move. If you used regular lifters when you clayed it, the could have bled down. A cam with a 115 lsa or more, would be more desirable for FI, and could give you more PTV clearance.
And...
If the piston hit hard enough to ding them, you need to check all the valves. Pull them out, and check them to see if any are bent.
And...
If the piston hit hard enough to ding them, you need to check all the valves. Pull them out, and check them to see if any are bent.
this is an excellent point, i forgot this was a procharged motor...
dude, if i were you, i'd have the heads checked out by a shop and flowbenched, and have a new cam ground FOR YOUR APPLICATION....but that's just me.
The weird thing is that I never once felt any resistance when turning the engine over with a wrench. I would have thought to put dings in the pistons from contact, I would have been able to feel something.
The other thing I don't get is the heads are holding the water I put in them, not one drip seeped through the valves in the last 7 hours they have had water sitting in them. If the valves were not sealing wouldn't the water find the leak?
As far as the damage done to the pistons, can't I just flycut them to clear the valves? I want to try this cam, I know it's not typical for boost but I'm not going for typical. If it doesn't make power then I'll change to another cam.
The other thing I don't get is the heads are holding the water I put in them, not one drip seeped through the valves in the last 7 hours they have had water sitting in them. If the valves were not sealing wouldn't the water find the leak?
As far as the damage done to the pistons, can't I just flycut them to clear the valves? I want to try this cam, I know it's not typical for boost but I'm not going for typical. If it doesn't make power then I'll change to another cam.
I think the cam will make power just fine, you just need to get it to clear the pistons. I'd get the heads checked out for sure though.
Hopefully someone with more knowledge than me will chime in on what to do about the pistons. I don't see why you couldn't cut some valve reliefs though.
Hopefully someone with more knowledge than me will chime in on what to do about the pistons. I don't see why you couldn't cut some valve reliefs though.
Damn been watching this thread for a while and hoping to see it all up and running but keep it up your almost there! As for flycutting the pistons, im not positive but wouldnt that be a no-no on a High HP FI application? Figure with that much pressure on the pistons you wouldnt want anything done to jepordize their structural integrity? Just a thought.
Damn been watching this thread for a while and hoping to see it all up and running but keep it up your almost there! As for flycutting the pistons, im not positive but wouldnt that be a no-no on a High HP FI application? Figure with that much pressure on the pistons you wouldnt want anything done to jepordize their structural integrity? Just a thought.
I agree, you need to recheck PTV clearance with the right PR. If you don't have the right clearance I would find another cam, I personally wouldn't flycut my high boost pistons. Also, did you check all your other valvetrain clearances? How about open and closed valve spring seat pressures? How about coil bind?
BTW, the factory valve relief in those pistons may have been for a bigger valved head which may explain why it was off like that. IMO, even if you had a .050" shorter PR, you would not have proper PTV clearance anyway judging by the divits made. Here is a good read from Katech on preload https://ls1tech.com/forums/showthrea...ghlight=lifter .
Dan
BTW, the factory valve relief in those pistons may have been for a bigger valved head which may explain why it was off like that. IMO, even if you had a .050" shorter PR, you would not have proper PTV clearance anyway judging by the divits made. Here is a good read from Katech on preload https://ls1tech.com/forums/showthrea...ghlight=lifter .
Dan
I'm not sure about that. These are high boost pistons from the factory and they came with valve reliefs, they are just in the wrong spots as you can see from the picture. Now that I have marks on them already, I'm not sure what option I have other than to fly cut them and then smooth off the edges. I wonder if I can just smooth off what's there now and leave them as is? Then if I have to, I can switch to another cam so I don't have to worry about the ptv clearance.
Right but with any high boost application you need to be weary of the structural integrity of the piston, which is why Ive been told that if your pushing a lot of boost you dont want pistons with too much valve relief. Since they are already dished if you are going to flycut them on top of that I dont see anything good coming from it. If you want to give it a try by all means go for it as it may hold, id just be cautious if your going to be pushing 18+ psi with that F2. JMO and good luck man you will def have a badass machine once your done!
are the pistons installed the right way.... I believe that they should have a mark on them saying which way they should be facing. If the piston have valve reliefs and they are not in the right spot then they are installed incorrectly and that may be your issue with the valves touching. However I am not sure that this would stop the car from starting either so you may have another issue also
are the pistons installed the right way.... I believe that they should have a mark on them saying which way they should be facing. If the piston have valve reliefs and they are not in the right spot then they are installed incorrectly and that may be your issue with the valves touching. However I am not sure that this would stop the car from starting either so you may have another issue also