10
votes
Accepted
What are the various kinds of tappets / lifters and the advantages / disadvantages of each
Not sure if this is what you were asking, but there are several configurations where there are no lifters (or at least, no push-rods) in an engine, where the valves are driven either through rocker ...
- 1,708
7
votes
Accepted
What exactly is Honda's i-VTEC technology
In addition to Zaid's answer.
VTEC - Variable Valve Timing and Lift Electronic Control)
In essence, it selects between two different cam profiles depending on the RPM.
Here's an animation -
This is ...
- 2,186
6
votes
1997 Honda Odyssey - How do I know if the valves are still good after both the timing belts broke?
I'm assuming you have a 4 cylinder.
You need to remove the valve cover. If the valves are adjustable then unadjust them until all the valves are free. Remove the spark plugs. Use a leakdown tester ...
- 15.9k
6
votes
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Changing Firing Order in a 4 Cylinder Car
Surely, to get a Subaru (or any true boxer engine) to run in this kind of configuration is relatively easy. Bear in mind that you are talking about an engine with two horizontally opposed cylinder ...
- 23.3k
6
votes
What exactly is Honda's i-VTEC technology
This diagram does a decent job of explaining VTEC:
In a nutshell (paraphrasing the Wikipedia article), you have two cam profiles, one designed for low-RPM operation and fuel efficiency, the second (...
- 39k
5
votes
Changing Firing Order in a 4 Cylinder Car
Do any of the four cylinder car guys out there run this configuration?
Not that I can find, with the simulated exception of some "scatter cams" referenced by @Steve Matthews, and given a great answer ...
- 12.2k
5
votes
4 stroke valve timing diagram: if valves are open during TDC, wouldn't they hit the piston?
First, remember that we are talking about four different engine cycles here: Intake; Compression; Ignition/Combustion; Exhaust. Top dead center (TDC) happens between two of these cycles: between ...
- 140k
4
votes
How to test timing chain/belt assembly before sealing engine closed?
The best way to test to see if your engine is timed correctly is to rotate the crank shaft through 720° of rotation then check your timing marks again. Since you (supposedly) have a non-interference ...
- 140k
4
votes
Accepted
Meaning of Timing valve is open
The P0018 code is related to your cam and crank showing incorrect timing
There are two sensors involved in this error.
Cam Position Sensor
Crank Position Sensor
These two sensors detect the angle ...
- 32.8k
4
votes
Accepted
Tick Tick sound from a Royal Enfield Classic 350 at idle
Most probably the sound is from a loose TAPPET in the cylinder block, usually it goes away after a few thousand kilometres but if it still persists then you need to open up the header and tighten the ...
- 8,926
4
votes
Is there a risk of igniting the incoming charge with wasted spark systems?
If the inlet valve opens 20 deg before TDC, will fresh mixture be going in or not? As there is still pressure in the cylinder - the exhaust leaving is helping to "draw" the fresh mixture into the ...
- 34.4k
3
votes
Is there a risk of igniting the incoming charge with wasted spark systems?
The wasted spark will likely be 30 degrees or so before TDC. There would be no fresh fuel charge at this point.
- 294
3
votes
Why don't valvetrains use an idler gear between the cam gears
Bottom line is: It's been done.
Here's one for a small block Chevrolet engine:
Just as you describe, there's an idler gear (well, maybe two) which keeps things in time.
These gears are used mostly ...
- 140k
3
votes
Last year my timing chain had broken
As Brian commented, your question and the information we have is a little vague.
Not repaired already:
It won't drive at all if the timing chain is broken. No amount of cranking the engine will start ...
- 658
3
votes
Tick Tick sound from a Royal Enfield Classic 350 at idle
Tick Tick Sound you here during Idling is from Auto De-compressor. This Auto Decomp starts functioning below 350RPM. If RPM is raised this sound should vanish (This is applicable for new UCE engines). ...
- 31
3
votes
4 stroke valve timing diagram: if valves are open during TDC, wouldn't they hit the piston?
Question 1: This depends on engine design.
In an interference engine, the valves can collide with the pistons, so you need to design the timing diagram to prevent that.
In non-interference engines, ...
- 4,402
3
votes
Why is there no valve overlap on 1987 V4 Honda?
In 1987 vehicle manufacturers were struggling to meet the emissions standards
Valve overlap, while a performance gain, is not necessary for an ICE to run properly. Valve overlap will allow un-burned ...
- 32.8k
2
votes
Prevention against turning of the camshaft during the tensioner replacing in 1 cylinder 2 valves 4 stroke engine
While I don't have an answer regarding blocking or stopping the cam, You can work around it without too much trouble.
With the chain still in place, You can mark on the crank and cam gear teeth and ...
- 1,646
2
votes
Noisy 4.6L Mustang engine
I know this question is old, but I thought I'd provide some feedback for future.
Cam phasers make noise due to a lack of oil pressure in two cases:
The inner rotating piece connected to the cam ...
- 21
2
votes
Is this valve toast or could I possibly salvage it without tearing into the engine?
I think I'd first be doing a compression test here just to help perhaps rule out an internal engine problem like a burnt valve etc. Assuming pressures are good though... I'd then be considering ...
- 5,022
2
votes
Why don't valvetrains use an idler gear between the cam gears
Short answer: follow the money.
Long answer. Cutting gears and ensuring the mesh correctly is incredibly expensive. You've got to rough form, final form, heat treat then final form again. Then ...
- 6,479
1
vote
How to do a timing job on an engine that only has timing gears
First step is to get number 1 piston at TDC.
Once you have done that then you can engage the camshaft gear with the crank gear using that mark and looking at the camshaft so that you have it in the ...
- 34.4k
1
vote
VW 2.0 TSI jumped time, could the valves be ok?
There may be a position where the chain can slip and there will be no damage, but will it have happened there?
So possibilities:
Use a camera through the plug hole to investigate for contact
You ...
- 34.4k
1
vote
TDC on DOHC but with cams removed
On a 4-stroke engine, when #1 is at TDC, it's at TDC. It doesn't matter at that point if the cam(s) are not connected. Once you align the cam timing mark(s), then you'll set which stroke you are on.
...
- 140k
1
vote
Accepted
Is this valve toast or could I possibly salvage it without tearing into the engine?
Here's what happened to the engine in this case as found when I tore into it:
That roller on that burnt looking rocker arm locked up. It wouldn't turn any more. So it overheated and also dug a lot of ...
- 227
1
vote
Prevention against turning of the camshaft during the tensioner replacing in 1 cylinder 2 valves 4 stroke engine
What I have found with some OHC interference engines is that there are special dealer tools to hold the cam. They usually bolt to the head and have pins that slide into holes on the cam gear. I ...
- 1,308
1
vote
Accepted
Noisy 4.6L Mustang engine
How about substituting one quart of motor oil with Marvel Mystery Oil? You may have a little varnish somewhere on a valve lifter, valve stem, oil pump, etc.
- 1,509
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