Remarking '63 cam gears for use on 2.4. LOOK!

[EclipZ]

I have these pictures to share with you guys because i looked all over the place and couldnt find anything. i finally found these pictures which helped me out alot, i forgot who took these pics but thanks. remark the timing marks half a tooth in advance, the engine spins clockwise.

Intake cam gears:

You must be logged in to view this image or video.

Exhaust Cam gears:

You must be logged in to view this image or video.

 

[Lunch_Box]

Sweet, thanks for the pics. That will help me out in about a week when I start putting my engine back it.

 

[poorboyj]

Remarking them to check ignition timing would be fine. But the cams will still be off location unless you get the Galant cam gears, as I understand it.

Jay

 

[gaddis]

If you have removed your balance shafts there is a much easier method for using the 4G63 cam gears on a 4G64 without remarking them. All you have to do is set piston #1 at top dead center, and then make sure the marks on the cam gears line up. This way you are making the adjustment at the crankshaft sprocket. You don't even have to remark the crankshaft sprocket, since it's so easy to take out spark plug #1 and check TDC with a dowel rod.

 

[Whiteshadow]

2 years later...im trying to figure out why everyone thinks remarking the cam gears is the thing to do..any explanation?

 

[EclipZ]

its completely fine if you dont have the money for adjustables or cant source the dohc 2.4 gears.

 

[Whiteshadow]

yea i mean i know its fine...im going to do everything as if it were a 4g63 block marks and dowels the whole 9...but who felt the need to advance half a tooth and why? I can understand adjustable cam gears, those will benefit in any situation, but why remark the 2.0 cam gears

 

[EclipZ]

because the 2.4 deck height is taller than the 2.0 deck height and they use 2 diff timing belts. i wouldnt go playing roulette with my valves!

 

[Whiteshadow]

because the 2.4 deck height is taller than the 2.0 deck height and they use 2 diff timing belts. i wouldnt go playing roulette with my valves!

thats exactly my point...the deck height has nothing to do with remarking the valves nor does the length of the timing belts so if someone could give me a nice educated answer that makes sense id appreciate it

...well i mean if you could explain how the height and length of the belt come into play thatd be nice as well

 

[spinz4]

Yes the cam gears are different than the 2.4's so you mark your 2.0's like they were 2.4's.

 

[Whiteshadow]

how does height play a role though...wouldn't the 6mm (or 12mm however you wanna look at it) extra your getting and the fact that the block a 6mm taller cancel each other out? Putting me back to my point that the height shouldn't play a role or denote any reason for changing the marks on the cam gears. Which brings me back to my main question, why remark the 4g63 cam gears, its a 4g63 head so why would you change them...

 

[drivemusicnow]

.. the difference in heigth between the camshaft and cranksaft DOES change with the added deck height. This means that the camshaft sprockets need to be slightly offset when compared with 4g63 sprockets. You can mark them, or just us the 4g64 cam sprockets. Either way works fine.

If you were to set your timing while lining the stock 63 cam sprockets up, your timing would be off.

 

[Whiteshadow]

like i said i know the deck height changes...but the side of the crank also changes...therefore the 12mm extra stroke get zero'd out by the extra 6mm of deck height...so really nothing changes at all...the pistons also move faster because of that, meaning the timing should stay the same, the piston speeds make up the rest....please someone give me a good reason other than the obvious "its a taller block/longer timing belt"

 

[drivemusicnow]

like i said i know the deck height changes...but the side of the crank also changes...therefore the 12mm extra stroke get zero'd out by the extra 6mm of deck height...so really nothing changes at all...the pistons also move faster because of that, meaning the timing should stay the same, the piston speeds make up the rest....please someone give me a good reason other than the obvious "its a taller block/longer timing belt"

Think about this for more than 5 seconds before you dismiss it.

You are changing the distance between the camshaft, and crankshaft.

Still thinking about it? Okay, now think about the fact that when using the 63 block, with the 64 crank you just use the stock 63 sprockets. Why? because even though the crank is different (longer stroke) the DISTANCE (literally) between the crankshaft and cam shafts is the same, which means you don't need a different belt etc.

So different number of teeth on the timing belt-different belt length-different cam sprocket alignment.

 

[Whiteshadow]

Think about this for more than 5 seconds before you dismiss it.

You are changing the distance between the camshaft, and crankshaft.

Still thinking about it? Okay, now think about the fact that when using the 63 block, with the 64 crank you just use the stock 63 sprockets. Why? because even though the crank is different (longer stroke) the DISTANCE (literally) between the crankshaft and cam shafts is different.....go experiment for me. get a set of gears with a 1:2 ratio and get a belt 50 miles long...guess what, the gears are still a 1:2 ratio

So different number of teeth on the timing belt-different belt length-different cam sprocket alignment.

the cams are IDENTICAL... the ratio between the crank and cams will always stay the same whether it be a 2.0 block or 2.4 block...with that being said there is no reason for the timing to change...ok ill ask this. What exactly does advancing both cam gears a half tooth benefit from? .....go experiment for me. get a set of gears with a 1:2 ratio in relation to each other and get a belt 50 miles long...guess what, the gears are still at a 1:2 ratio

What are the benifits of the 2.4 on the 2.0 block?

what the?

 

[drivemusicnow]

the cams are IDENTICAL... the ratio between the crank and cams will always stay the same whether it be a 2.0 block or 2.4 block...with that being said there is no reason for the timing to change...ok ill ask this. What exactly does advancing both cam gears a half tooth benefit from? .....go experiment for me. get a set of gears with a 1:2 ratio in relation to each other and get a belt 50 miles long...guess what, the gears are still at a 1:2 ratio



what the?

THE RATIO doesn't change, the distance between the effing crankshaft and camshaft does.

Advancing both cams a half tooth would be changing the cam timing approximately 3.5 degrees. which changes how it runs.
So, you line them up so that the are at 0 degrees, which requires the different timing marks.

Each tooth is a significant change in timing, so if it's half of a tooth off, that's a problem.

 

[Whiteshadow]

hahah so like i said if the ratio doesnt change then it doesnt matter how long the"effing" belt it...the cams will still be turning at the same time in respect to the crank. If you think distance is making the difference please back it up with some good info other than just stating the obvious that the block is taller...and yes i know how much a tooth off can affect timing

 

[Evan K.]

hahah so like i said if the ratio doesnt change then it doesnt matter how long the"effing" belt it...the cams will still be turning at the same time in respect to the crank. If you think distance is making the difference please back it up with some good info other than just stating the obvious that the block is taller...and yes i know how much a tooth off can affect timing

^lord...

 

[delta448]

I don't think I can accurately describe the difference any better than I already tried, so I drew a picture. Hopefully this will help clear things up.

To explain the pic a little, it's kinda tough to see since I just hacked up and reused a diagram off of the timing belt VFAQ. The 2.4 engine's cam gears are marked with green lines to show where I speculate that the 2.0's cam sprocket timing marks would be. Blue lines indicate directions of motion. Yellow lines show angles.

Edit: I removed my first post in this thread due to gross misinformation and removed things from this post for misinformation, my first post was originally post number 11, and Whiteshadow replied to it in what is now post 11. Also, the drawing below is incorrect. The green lines are in the wrong places on the 2.4 engine and the yellow lines mean absolutely nothing to cam timing.

 

[steel_3d]

Delta, can you show some calculations showing that the triangle you drew is at all relevant to cam timing changes? Ie: cam advance = some function of distance of crank axis to the line through the cam axes. To me it looks irrelevant, and you could move the crank as far away as you wanted (infinitely far away, really) and the timing marks wouldn't need to change. Assuming you used a belt with infinitely small teeth.

I think the issue lies either in the fact that the length of the belt changes by a non-integer number of teeth per side, or the markings on the crank are different than the 2.0's?? I don't know since I've never seen one. But you'd have to show geometric proof, not just a scribbled drawing, to make your point.

 

[delta448]

Delta, can you show some calculations showing that the triangle you drew is at all relevant to cam timing changes? Ie: cam advance = some function of distance of crank axis to the line through the cam axes. To me it looks irrelevant, and you could move the crank as far away as you wanted (infinitely far away, really) and the timing marks wouldn't need to change. Assuming you used a belt with infinitely small teeth.

I think the issue lies either in the fact that the length of the belt changes by a non-integer number of teeth per side, or the markings on the crank are different than the 2.0's?? I don't know since I've never seen one. But you'd have to show geometric proof, not just a scribbled drawing, to make your point.

I do apologize for the quality of the drawing.

You may be right, I am only repeating what I am able to remember from prior experience and research, I myself am a little lost on where to begin to crunch out any sort of formula. However my intent wasn't to provide a end-all-be-all mathematical solution, but to show the differences that mitsu engineers made in the 2.4 DOHC cam gears compared to the 2.0 DOHC gears. I won't pretend to have a complete understanding of all the math, but maybe we can put our minds to work here and figure it out.

I think that the timing change has something to do with less distance between the two cam axes in relation to the crank axis. ie: the rate of change of the piston's position produces less (or perhaps more?) percentage difference in the position of the cams to each other, in simpler terms; valve overlap is lessened (increased?) slightly because the difference in the ratio of the valves instantaneous position compared to the instantaneous position of the piston.

Any thoughts on this?

 

[snox135]

I understand what you are saying steel 3d. I don't understand why the distance between three gears changes timing. I don't think it is in the crank markings or the 2.3 would need to remark there gears. You might be on to something with the number of teeth, but I'm unsure yet.
I know for fact the the 4g64 and 4g63 gears are maked different. I'm not debating that. I have always wonder if that was because of the 4g64 cams. Has anyone ever actually checked the cam timing (with dial indicators) and verifed which marks are correct? I have always just accepted that you have to remark them and never really understood why. Logically it sounds correct to take a 2.0l head and set it's timing and set the 4g64 crank timing where it should be. But the by moving the mark half a tooth it doesn't sound like that is possible.

 

[steel_3d]

I actually won't speculate anymore, since I've never seen a 2.4.

I just wanted to mention that the distance of the crank to the cams doesn't seem to have a geometrical bearing on cam timing. Also, overlap wouldn't change, since that's controlled by the amount of belt teeth between the tops of the cam gears, which doesn't change with deck height. Also, both cam gears are marked with the same half-tooth advance, so again overlap doesn't change. Overlap only changes if you retard one cam and advance the other.

Is the 2.4 crank timing plate not different from the 2.0?

 

[delta448]

I actually won't speculate anymore, since I've never seen a 2.4.

I just wanted to mention that the distance of the crank to the cams doesn't seem to have a geometrical bearing on cam timing. Also, overlap wouldn't change, since that's controlled by the amount of belt teeth between the tops of the cam gears, which doesn't change with deck height. Also, both cam gears are marked with the same half-tooth advance, so again overlap doesn't change. Overlap only changes if you retard one cam and advance the other.

Is the 2.4 crank timing plate not different from the 2.0?

That's not what I meant. I know there's no way the actual overlap value changes from head to head.

I meant the overlap/valve lift values with respect to the piston's position in the cylinder might change. Since the 2.4's piston covers more distance in the same time as a 2.0's piston at the same rpm, the amount of valve overlap/lift per change in piston position may also change. Meaning there is less time the piston assists with airflow, but a greater force it assists with at the same rpm, -even if you negate the bore increase. This theory could support the fact that the strokers and 2.4s are extremely air-hungry compared to a 2.0. I'm done speculating too. I'll let one of you mechanical engineers out there figure it out.

If you are building a 2.4 DOHC, you will be using the same front case, crank and oil pump timing marks, accessories, etc. as a 4G63. You just swap everything over from the 2.0 block.

 

[Whiteshadow]

im a mechanical engineer(in progress) which is why i brought the whole thing up A few good points were made but if all is true...then there would be no reason to remark the cam gears, if in fact distance doesnt play a role and we know piston speeds do increase which will negate the longer stroke, meaning the piston will get to the same point at the same time a 2.0 would, but just faster given the stroke...you'd run the same timing you would on a normal 4g63...yea?