2.4 with cams = interference?

[Turbocharged]

My 2.4 g4cs with stock cams is non interference. I would like to keep it this way but Im im interested in upgrading the cams. I lost the blueprint for my motor so I dont know the exact valve to piston clearance for my motor.

For you guys with upgraded cams in your g4cs or 4g64 blocks: Are your motors still non interference after upgrading the cams? Does anyone have the piston to valve clearance for a 2.4 motor with a stock 4g63 cams? I know everyones valve to piston clearance will be slightly different depending on HG and pistons but I was hoping that someone else had a setup similar to mine that may be able to help me get an idea. I have weisco pistons and a 0.054"" thick headgasket.

I really like the idea of keeping this motor noninterference.

 

[Big Woo]

From your proflie it looks as if you have used the 2.4L SOHC shortblock and added the 4G63 DOHC 4-valve 2.0L head. Is this correct?

If so your motor may no longer be a "non interference" motor.

A few things to consider.
1: No one lists piston to valve clearence specifications for non interference, because it is infinite. Basicily non interference means that if the indexing system used to time the crankshaft to the camshaft or camshafts fails, then there is sufficient room for any and all of the valves to be at full lift, and the pistons to be at top dead center without contact being made between the two.

2: The only reason to specify piston to valve clearence is beacuse it is capible of becomming less than zero.

3: Keep in mind that DOHC pentroof or hemispherical chambered heads may also capible of contact valve to valve. If time is lost between the two camshafts.

 

[Turbocharged]

From your proflie it looks as if you have used the 2.4L SOHC shortblock and added the 4G63 DOHC 4-valve 2.0L head. Is this correct?

If so your motor may no longer be a "non interference" motor.

A few things to consider.
1: No one lists piston to valve clearence specifications for non interference, because it is infinite. Basicily non interference means that if the indexing system used to time the crankshaft to the camshaft or camshafts fails, then there is sufficient room for any and all of the valves to be at full lift, and the pistons to be at top dead center without contact being made between the two.

2: The only reason to specify piston to valve clearence is beacuse it is capible of becomming less than zero.

3: Keep in mind that DOHC pentroof or hemispherical chambered heads may also capible of contact valve to valve. If time is lost between the two camshafts.

Thanks for the quick reply. Yes I have a g4cs with a dohc 4g63 head.

1. Valve clearance is the measure of the minimum distance between your valve and piston with the timing set up. That distance cannot be infinate. My machine shop measured the clearance using the clay method. I also had them test the clearance when the motor was at TDC and the cams were turned 360* so that I could determine how large of a cam I could use without going to an interference motor. Unfortunately I lost that number. The lifters were filled with fluid for this test.

3. The 4g63 head has no valve to valve clearance issues due to the small valve travel. The clearance is quite large.

Does anyone with a 2.4 and cams have any real life experience with this. I would like to keep this motor noninterference

 

[Big Woo]

If you have a non interference motor then there is no chance that the valves will hit the pistons, no mater what there repective positions are. Therefore it is infinite because the valves simply will not come down far enough to ever hit the pistons.

Yes piston to valve clearence is the minimum amount of clearence between the pistons and valves when timed, but if you change the cam timing or the cams so will the clearence. Which is why I assume you started this thread. However this minimum clearence does not happen when the valve is at full lift,

When checking piston to valve clearence you need to use a solid type lifter.

And yes I know that on a 4G63 type motor it is unlikely that the intake and exhaust valves will ever hit. I added that for anyone who may read this thread and try to apply it to differnt motors.

 

[Turbocharged]

arg... Piston to valve clearance is the distance from the valve to the piston. We agree on that correct? So that distance is INFINATE on a non interference motor? All motors have a piston to valve clearance. Its simply a measure of distance between the two moving parts. You understand how these measurements are made, correct? I also had the piston to valve clearance measured with the crankshaft at TDC and both cams rotated 360*. That particular clearance is the maximum amount of extra lift that I can add to my cams without becoming interference. Im doubting anyone on this forum has had that particular clearance measured on their 2.4. I DID have that clearance measured but I lost the number. Ideally, I could pick a large enough lift and still have some clearance under these conditions. That is my goal... to have the largest lift possible but stay noninterference.

I realize that the minimum distance does not occur at full lift. That is not what we are discussing. Im worred that when that lift is increase (with upgraded cams) and a timing belt breaks, there is enough clearance so that the valve does not make contact with the piston. Non interference motors will never make contact piston to valve contact. Im afraid that when I increase the lift, that my valves will be able to contact the piston if a timing belt breaks. Im sorry if I wasnt clear on this before.

My valve to piston clearance was measured with liquid filled lifters, effectively making them solid. Liquid is incompressible.


Can anyone help me out...?

 

[92awddsm]

arg... Piston to valve clearance is the distance from the valve to the piston. We agree on that correct? So that distance is INFINATE on a non interference motor? All motors have a piston to valve clearance. Its simply a measure of distance between the two moving parts. You understand how these measurements are made, correct? I also had the piston to valve clearance measured with the crankshaft at TDC and both cams rotated 360*. That particular clearance is the maximum amount of extra lift that I can add to my cams without becoming interference. Im doubting anyone on this forum has had that particular clearance measured on their 2.4. I DID have that clearance measured but I lost the number. Ideally, I could pick a large enough lift and still have some clearance under these conditions. That is my goal... to have the largest lift possible but stay noninterference.

I realize that the minimum distance does not occur at full lift. That is not what we are discussing. Im worred that when that lift is increase (with upgraded cams) and a timing belt breaks, there is enough clearance so that the valve does not make contact with the piston. Non interference motors will never make contact piston to valve contact. Im afraid that when I increase the lift, that my valves will be able to contact the piston if a timing belt breaks. Im sorry if I wasnt clear on this before.

My valve to piston clearance was measured with liquid filled lifters, effectively making them solid. Liquid is incompressible.


Can anyone help me out...?

You need to learn what the phrase "non interference" means before you start throwing it around trying to know what you are talking about.

Non interference means you will not bend any valves if the cam timing was off or the belt broke. Any and all 4g63, 4g64, g4cs, 4g61, etc are all interference engines with a dohc head on them. You would have to machine the valve relief all the way to the top ring land before it would become non interference. Of course, you should know that since you talk as if you are an engine machinist(I am)

And I hope you arent using the stock pistons from the g4cs. If so, you have been lucky not to burn the piston or bend a valve thus far. Dont try to push the issue by installing cams. I dought you will get a responce from anyone on here using the stock g4cs pistons with any boosted application because hopefully, noone else is that stupid. Buy a set of pistons before you worry about cams.

Now, none of us can answer your question for you. You will need to first contact you builder and find out what piston-to-valve was set at and what deck height was set to. Now, contact the cam manufacterer and give them those #'s along with what pistons you have (brand, size, compression) and they will tell you if you need to flycut the reliefs.

But being around them fro so long, I have yet to see any variations with popular cams have any issues with piston-to-valve. Hell, I have comp 101200's, .004" positive deck, 1mm os valves, head cut .010", and a cometic hg and still have well over .060"(minimum allowable) clearence on the exhaust size and more than .030"(again minimum) in the intake side. And all this with a stock 7.8-1 1g piston without any machining. The g4cs has more stroke but also has a taller deck block to accomodate for the extra stroke.

And yes, piston to valve clearence has to be checked with a solid lifter, not hydraulic. The hydraulic lifter will never give and accurate measurements. Sure, liquid won't compress, but will bleed down when force is applied to them. you also wouldnt have an oil pressure source to keep them pumped up while checking. Do you really think the lifter has the same clearence in an engine that is being turned by hand without any oil pressure compared to one that is spinning 6k rpm with 90psi oil pressure?

 

[Turbocharged]

Thanks for the reply. I should have known better than to ask others for their piston to valve clearance. And yes I know what a non interference motor is.

BTW, I have weisco pistons. The pistons had very large valve dishes. The total piston dish volume was 22cc. That is the reason for the large valve to piston clearance that my motor has. I have a lot of faith in my machinist/builder. He builds everything from motors for competition tractor pullers to stock cars. Its fun walking around his garage and checking out the cars and engines that he is working on. Last time I was there he was working on a turbocharged JGTC (he's known for his darton blocks). His claim to fame is the 1000hp mustang he built for the CEO of artic cat. I guess I will give him a call and try and get things worked out. I believe he kept a copy of my blueprint on his hard drive.

Thanks for the help and I guess this is a closed case... Im usually more careful than to start a thread like this.

 

[DSMLoverFromUA]

Ok it was like this. I have a friend (he is on tuners also) who has a 6 bolt 4g64 out of a galant with DOHC head on it from 1G. He uses stock crank and manley rods with wiseco pistons with FP3 with ferera 1mm oversized valves. Now here is the story. 2.4 are non-interfirance engines. How do i know you must thing. Well a vacuum line fell under the timing belt go on the crank pully and made the timing belt skiped 6 theet. The car made some serious noise. It all happen at idel and it was ideling for about 5 seconds. Now when he changed the timing belt, because it really destroyed it, he started the car and did a compression test. He did not lost any compression and the car pulls like crazy. So here it is now if that vacuum line would got on the cam gear then i dont know what would happen, that we havent tested yet. So yes it is non-interfirance engine.