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Discussion Starter · #1 ·
So got all the little piggies in their blanket (rods and pistons installed in the comfortable blanket of block) and next step while I still had the oil pan and head off was to replace my cam chain,,,

so popped the timing cover --- I did measure the chain wear, as you know critical for cam timing as it does retard the cam the more the wear,,, intake valve loves it for higher RPM's and exhaust valves hate it --- and since they are both rapped up into one due to it being a SOHC the intake is the dominant side - so does win out,,, well kinda,,,

trouble being is there goes your low end... but not only that - your shooting yourself in the foot - the two profiles (actually three due to the V-tec) are designed to all function in unison... ehhhhhhhhhh

hence for the post...

So --- in case anyone was wondering (like i have been the last year and a half)

I wonder how worn my cam chain is???

Ok here u go --- My car before teardown had 160,000 miles on it --- so along with all the other things in the rebuild I of course ordered a timing chain since I would already have the head and pan off and time to do it right?

Ok --- well believe it or not the new chain felt kinda loose to me --- so I compared it to the old one --- just simple compression stretch then tensile stretch on a flat surface....

bottom line --- the new chain had about .065" of stretch for HALF of it's entire length

and old chain had double that at about .130... But do keep this in mind - the new chain had ZERO oil --- so most likely more free play as even oil takes up space with all those links --- and the old chain was of course saturated --- so these figures would do nothing but get better for the new chain as far *** LESS slack...

so there ya go - How many degree's of retard is that? dunno.. somebody can probably figure all that out...

along with the pics im including a great find --- I searched around the shop for the perfect size "drum" to hold up the cam chain while the head was off - so I could rotate the crank to do the rod work without the chain snagging and jamming and guess what?

turns out a plastic container of Turtle Wax polishing compound was the perfect fit lol

and no I did not paint #1 piston green - just turns out it's shiny and got the exact lid reflection of green back in the process...

so there ya go...

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Discussion Starter · #2 ·
Side note I forgot to add, Honda says the engine has to be pulled in order to replace the timing chain?

I have no idea why, you do have to have the oil pan off but you just place a jack under the trans right close to where it meets the engine,,, the other two mounts are sufficient to hold everything in place along with the floor jack,,,

You do have to play with jack height a little to "weasel" the top engine mounting under-bracket out before popping off the cover, No big whoop really... in fact I left my rubber mount in while doing it...

The two bolts holding the under-bracket to the timing cover are kinda a PITA to get too but it's totally doable and not worth pulling an engine for...

after you get the under-bracket out you have all the room in the world to remove the cover...
 

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So got all the little piggies in their blanket (rods and pistons installed in the comfortable blanket of block) and next step while I still had the oil pan and head off was to replace my cam chain,,,

so popped the timing cover --- I did measure the chain wear, as you know critical for cam timing as it does retard the cam the more the wear,,, intake valve loves it for higher RPM's and exhaust valves hate it --- and since they are both rapped up into one due to it being a SOHC the intake is the dominant side - so does win out,,, well kinda,,,

trouble being is there goes your low end... but not only that - your shooting yourself in the foot - the two profiles (actually three due to the V-tec) are designed to all function in unison... ehhhhhhhhhh
V-tec on the Insight engine doesn't change valve timing. It activates the 2nd intake valve in each cylinder.

hence for the post...

So --- in case anyone was wondering (like i have been the last year and a half)

I wonder how worn my cam chain is???

Ok here u go --- My car before teardown had 160,000 miles on it --- so along with all the other things in the rebuild I of course ordered a timing chain since I would already have the head and pan off and time to do it right?

Ok --- well believe it or not the new chain felt kinda loose to me --- so I compared it to the old one --- just simple compression stretch then tensile stretch on a flat surface....

bottom line --- the new chain had about .065" of stretch for HALF of it's entire length

and old chain had double that at about .130... But do keep this in mind - the new chain had ZERO oil --- so most likely more free play as even oil takes up space with all those links --- and the old chain was of course saturated --- so these figures would do nothing but get better for the new chain as far *** LESS slack...

so there ya go - How many degree's of retard is that? dunno.. somebody can probably figure all that out... View attachment 94125 View attachment 94126
Measure the radius from the cam sprocket center to the center line of one of the chain rollers when the chain is mounted on the sproket.

That radius of the sprocket will be retarded by (0.130 -0.065 - (thickness of oil)) with the new chain.

To convert the change in sprocket angle by the above result (0.065 - oil thickness) using [algebra] tan 0 = (0.65 - oil thickness) / (radius of the sprocket).

Not knowing the cam sprocket radius I'll take a guess as 2" with 0.060" change in angle which would result in tan 0 = 0.060 / 2 = 0.03°.

I doubt our butt dynos will detect that change. :)
 

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V-tec on the Insight engine doesn't change valve timing. It activates the 2nd intake valve in each cylinder.


Measure the radius from the cam sprocket center to the center line of one of the chain rollers when the chain is mounted on the sproket.

That radius of the sprocket will be retarded by (0.130 -0.065 - (thickness of oil)) with the new chain.

To convert the change in sprocket angle by the above result (0.065 - oil thickness) using [algebra] tan 0 = (0.65 - oil thickness) / (radius of the sprocket).

Not knowing the cam sprocket radius I'll take a guess as 2" with 0.060" change in angle which would result in tan 0 = 0.060 / 2 = 0.03°.

I doubt our butt dynos will detect that change. :)

Quick question....what activates the VTEC mode? Hydraulics or electrical switch? If its electrical can we turn it on at lower speeds for more low end punch?
Thanks!
 

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Discussion Starter · #5 · (Edited)
V-tec on the Insight engine doesn't change valve timing. It activates the 2nd intake valve in each cylinder.
Correct - I did not state that it did, but it's directly connected to the timing chain, so if one valve is off they all are, that's intake and exhaust and V-tec intake, they are all running off of the same said cam that's experiencing a timing change due to the worn chain... so they are all in unison retarded by the same degree.
Measure the radius from the cam sprocket center to the center line of one of the chain rollers when the chain is mounted on the sproket.

That radius of the sprocket will be retarded by (0.130 -0.065 - (thickness of oil)) with the new chain.

To convert the change in sprocket angle by the above result (0.065 - oil thickness) using [algebra] tan 0 = (0.65 - oil thickness) / (radius of the sprocket).

Not knowing the cam sprocket radius I'll take a guess as 2" with 0.060" change in angle which would result in tan 0 = 0.060 / 2 = 0.03°.

I doubt our butt dynos will detect that change. :)
I agree probably not something to be overly concerned with but like I stated --- there is a "shoot yourself in the foot factor" with single overhead cams where both the intake and exhaust lobes are fixed lobes onto the same camshaft...

With DOHC's you can create your own perfected powerband in fact the Porsche's I used to set up had that wonderful option, want low end? you advance the intake and retard the exhaust - high end? you do the opposite,,, but with SOHC any deviation from stock is robbing peter to pay paul,,, Yet due to the intake valve being the dominant valve you can kinda "fake it" and make some performance gains at lower or higher RPM's but at the cost of reduced efficiencies do to the exhaust being way out of wack in the opposing direction of what would be "optimal"

So --- anyways FWIW and to whom it may concern,,, I did discover a method for getting an older chain back up to specs,,, this is not a perfect solution but it is as far as cam timing...

There are two chain guides, one is on the backside for tensioning and the other is actually on the drive side and under load whilst running,,, it just has a very mild arc and is designed to keep the chain from tension whipping from all the impulses that driving a lobed camshaft contributes,,, this guide has incredible slop in the bolt holes that hold it down!!!
I mean like a total of .030" back and forth --- so you can load in the direction of the chain and then tighten the bolts down to specs, It will take up quite a bit of deviation - and there's two, a top and a bottom - so you could really dial an older chain back into specs... the million dollar question would be is if the guide bolts would keep it from "migrating" back over time...

The only other pitfall is you need to keep in mind your still running an old chain that's not going to engage into the drive cogs as well - this will accelerate chain wear and cog wear to some degree....

but - better than not doing anything and having that happen anyways while your engine is not tuned to optimum...
 

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Discussion Starter · #6 ·
Quick question....what activates the VTEC mode? Hydraulics or electrical switch? If its electrical can we turn it on at lower speeds for more low end punch?
Thanks!
The V-tec is a computer controlled solenoid that actuates a hydraulic gate/valve directly linked to the engines oil pressure - the hydraulics push ultra precision/hardened spring loaded side pins into the receptor sides of the V-Tec rocker arms therefor engaging the V-Tec valves...

You will not achieve better results than what the factory has set (if your engine is stock)

in fact if you ever did feel the V-tec "kick in" drastically it means that it was being held back and restricting good flow, it's a system designed to keep the low end volumetric efficiency at maximum (something common four valve heads have a problem with) and then revamp at a select RPM to allow the proper flow dynamics for higher RPM's too...

the V-tec should be fairly seamless in engagement --- engage too soon and the engine will fall on it's face,,, engage too late and you shot yourself in the foot by not engaging it sooner...
 
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