1.8 head teardown

[mitdr774]

I picked up a spare head to take apart and look into what can be improved upon. I can see that I will need a special tool for valve spring removal, but so far no other major surprises. I will update as I get measurements and pull more apart.

Overall shots:

Exhaust port:

Intake port:

Lifter:

Valve spring retainer (well what can be seen of it):

Cam shafts and bearing/caps:

update 1:

Valve information.

Pulled one intake and one exhaust valve and its associated parts today.

To make sense of that picture here are what the numbers are.

Intake valve head diameter: 1.227"

Exhaust valve head diameter: 1.083"

Valve stem diameter: 0.194" (approximately 5mm)


Retainer:

OD: 0.786"

Diameter for locating inside spring: 0.519"

Overall height: 0.379"


Valve spring:

uninstalled height: 1.658"

wire diameter: 0.124"

OD top of spring: 0.781"

ID top of spring: 0.542"


OD bottom of spring: 0.901"

ID bottom of spring: 0.654"


Crude measurement of installed height: 1.404"


Update 2:

Camshafts

Intake camshaft:

Lobe base circle: 1.259"

Lobe lift: 0.395"



Exhaust cam:

Lobe base circle: 1.259"

Lobe lift: 0.352"

 

[$ub$onic]

Nice pictures

 

[Natesriv]

I really don't know....do our engines 1.8 or 1.4 have any sort of variable valve timing?

 

[mitdr774]

Yes. The cam gear has a cam phaser in it that is controlled via oil pressure by the solenoids mounted in the front cam cap/bearing. The camshaft is rotated in relation to the gear up to 30* if I recall correctly.


As I figure out some dimensions I will try to keep the first post updated. Removing the valve spring retainers will be an issue though. Either going to have to make a custom tool or hope to come across the number for the Kentmoore J tool.

 

[Scot]

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[Scot]

BTW - looks like lots f benefit to be had opening up the exhaust port.

 

[ChrisJ]

I really don't know....do our engines 1.8 or 1.4 have any sort of variable valve timing?

As was said, yup.
And it's continuously variable on both exhaust and intake if I recall correctly as opposed to Vtec which was 1 big change often only on the intake if I recall. I'm assuming modern vtec is more like ours if not identical.

I'm going by memory so there is a chance I'm at least 50% wrong.

 

[Natesriv]

hmmmm I notice some slight hesitation at certain RPM's could this be the cam changing phase...my old SI Vtec did that around 4K RPM...just a slight shudder, then boom!

 

[ChrisJ]

hmmmm I notice some slight hesitation at certain RPM's could this be the cam changing phase...my old SI Vtec did that around 4K RPM...just a slight shudder, then boom!

As far as I know, no, it's done in real time all of the time just like ignition timing.

No sudden changes.


BTW, maybe mine was broke but my J series Honda did it around 4500 but I never noticed this alleged "boom!" everyone talks of. Just a change in exhaust sound and maybe a little more power but not much if any. I always assumed Honda did the change where it had the least effect during the switchover and it just allowed your power to continue at higher rpms.

 

[SonicSteve]

i would politely like to ponder where does one find a 1.8 head all by its lonesome.

I myself cannot locate a head or engine for that matter anywhere under the "ouch it hurts" price range on all of the ebays and craigslists.... where my friends...where.....:blankface:

 

[River_Rat]

Try car-part.com

 

[Scot]

As was said, yup.
And it's continuously variable on both exhaust and intake if I recall correctly as opposed to Vtec which was 1 big change often only on the intake if I recall. I'm assuming modern vtec is more like ours if not identical.

I'm going by memory so there is a chance I'm at least 50% wrong.

You're confusing variable valve lift with variable valve timing. VVL commands a different cam profile to alter valve lift; VVT changes the cam phase with respect to the crankshaft.

 

[Preloader]

Shouldn't need a special tool to remove the valve spring retainers. A telescopic magnet through the center of a socket works great. Push down on the socket and pull the retainer clips out with the magnet.

I watched a couple youtube vids of guys doing it before I tried it. It really is as easy as it looks.

 

[Preloader]

Excellent thread by the way. Did it come with the valve cover? If so, any pics?

 

[ChrisJ]

You're confusing variable valve lift with variable valve timing. VVL commands a different cam profile to alter valve lift; VVT changes the cam phase with respect to the crankshaft.

I always assumed the second cam lobe was simply timed different in respect to the crank on the older vtec?


I would like to know how lift effects flow vs timing. I've never understood how more lift could hurt anything, and yet it seems to really matter.

It always seemed like you would want valves to always open as much as mechanically possible.

Our valve timing, what exactly does it do? Does it add overlap as rpm's increase? What is actually going on?

 

[mitdr774]

i would politely like to ponder where does one find a 1.8 head all by its lonesome.

I myself cannot locate a head or engine for that matter anywhere under the "ouch it hurts" price range on all of the ebays and craigslists.... where my friends...where.....:blankface:

Ebay. Price was not outrageous given the things included. Mileage is unknown as it was listed at 0 miles, yet has obviously been used a fair bit. Generally the 0 mile listing is expected when they dont know actual. It was about $265 shipped to my door. Eventually I will pick up a complete engine, but having a head to check out and hopefully improve is a start.

Shouldn't need a special tool to remove the valve spring retainers. A telescopic magnet through the center of a socket works great. Push down on the socket and pull the retainer clips out with the magnet.

I watched a couple youtube vids of guys doing it before I tried it. It really is as easy as it looks.

Getting things back together would be an issue I would think. If I just wanted to get things apart the quick and easy way I would use a deep well socked and a dead blow. Very quick way to get retainers out.


Decent sized lifter and smallish hands.

No valve cover unfortunately. I knew that going in though. It would have been nice to have.


It looks as though there is a lot of room for improvement, but I dont think there is as much room as the gasket opening would suggest. I have to compare to the header some time, but I seem to recall the opening in the header flange being smaller than the gasket. I am really interested in what can be done to improve air flow. I need to find a place that can flow bench the head as is, and then look into having the cams built up and reground to a new profile.

 

[Preloader]

You can reinstall the retainer clips the same way. You rest one half of the clip against the stem and the retainer and push down on the socket. It should fall in place. I saw guys doing it on youtube.

 

[mitdr774]

This is the Kent Moore rig I have for the Family II engines. Pardon the mess on my brother in laws work bench

Just ordered and am waiting for one of these to arrive.

 

[Scot]

I always assumed the second cam lobe was simply timed different in respect to the crank on the older vtec?


I would like to know how lift effects flow vs timing. I've never understood how more lift could hurt anything, and yet it seems to really matter.

It always seemed like you would want valves to always open as much as mechanically possible.

Our valve timing, what exactly does it do? Does it add overlap as rpm's increase? What is actually going on?

The VTEC may also change timing a bit when it rides in the second cam profile, but the timing is still fixed WRT the crank.

Valve lift is all about flow - and high flow hurts low end power / intake air velocity. Higher velocity at low engine speeds helps maximize the trapped air mass in the cylinder - this is why a 2V engine usually produces torque lower in the RPM range than a 4V engine does. Having a higher lift at high RPM let Honda use a lower lift than usual to optimize low end torque. As engine speeds increase, and the engine starts to be throttled at the intake valve, VTEC kicks in YO! and the flow increases.

I worked several years on Chevrolet's VVL - which is currently in the Malibu and Impala with the 2.5L. The principle is a bit different the way we use it; we use a very low valve lift that allows us to throttle at the valves and run a larger throttle position that reduces pumping losses (fuel economy). The engine switches to a "nominal" lift level when more power is needed.

VVT (in the production automotive world) is more for emissions performance and best idle stability (customer satisfaction). We want a specific overlap at engine start and at idle that provides good trapped residual (internal EGR) that isn't too large to upset combustion stability. That's where you "park" the camshaft phasers, where "parking" means the mechanical locked "zero" position the the spring will return the phasers to if they are not commanded to a position.

The parked positions are never optimized for power - so that's where phasing away from park nets us better engine performance off of idle. There can be two ways to do it:

Dual equal - intake and exhaust cam move together, and the overlap is fixed. Phasing this setup is just like "degreeing in a cam" - look it up, my fingers are getting tired. GM's small block V8s use this method since the intake and exhaust lobes are on the same cam.

Dual independent - what most DOHC engines use. We can control similarly to how dual equal does, but we can also phase independently to increase trapped residual (lower NOx) AND promote scavenging in certain areas to help spool up the turbo faster.

 

[ChrisJ]

The VTEC may also change timing a bit when it rides in the second cam profile, but the timing is still fixed WRT the crank.

Valve lift is all about flow - and high flow hurts low end power / intake air velocity. Higher velocity at low engine speeds helps maximize the trapped air mass in the cylinder - this is why a 2V engine usually produces torque lower in the RPM range than a 4V engine does. Having a higher lift at high RPM let Honda use a lower lift than usual to optimize low end torque. As engine speeds increase, and the engine starts to be throttled at the intake valve, VTEC kicks in YO! and the flow increases.

I worked several years on Chevrolet's VVL - which is currently in the Malibu and Impala with the 2.5L. The principle is a bit different the way we use it; we use a very low valve lift that allows us to throttle at the valves and run a larger throttle position that reduces pumping losses (fuel economy). The engine switches to a "nominal" lift level when more power is needed.

VVT (in the production automotive world) is more for emissions performance and best idle stability (customer satisfaction). We want a specific overlap at engine start and at idle that provides good trapped residual (internal EGR) that isn't too large to upset combustion stability. That's where you "park" the camshaft phasers, where "parking" means the mechanical locked "zero" position the the spring will return the phasers to if they are not commanded to a position.

The parked positions are never optimized for power - so that's where phasing away from park nets us better engine performance off of idle. There can be two ways to do it:

Dual equal - intake and exhaust cam move together, and the overlap is fixed. Phasing this setup is just like "degreeing in a cam" - look it up, my fingers are getting tired. GM's small block V8s use this method since the intake and exhaust lobes are on the same cam.

Dual independent - what most DOHC engines use. We can control similarly to how dual equal does, but we can also phase independently to increase trapped residual (lower NOx) AND promote scavenging in certain areas to help spool up the turbo faster.

Like the vtec comment, and wow.
Perfect writeup, thanks!

I had assumed having VVT was sort of like having a mild cam and a hot cam in one.

Apparently that's not completely true. I'm guessing we get some of the benefits of both, but don't get everything such as high lift.

I'm also guessing thanks to VVT we no longer have EGR bull**** to deal with like plugged valves \ passages and or leaky valves. I learned fast how to tell if you had a leaky or wrong EGR valve installed (awful idle and or stumble off the line).

I never had a problem with a proper working EGR valve as it seems many backyard mechanics did, but I hated it when they didn't work right. What I had found was 9 times out of time when I bought an aftermarket EGR valve it was wrong. I seem to recall the GMs I owned having some type of special 2 part valve that went by vacuum and exhaust pressure and the aftermarket simply opened on vacuum. We're talking mid to late 1980s Gbodies here, both 3.8 and 305s.


Sorry for going off topic mitdr774.