10 votes
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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 ...
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  • 1,708
7 votes
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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 ...
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  • 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 ...
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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 ...
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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 (...
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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 ...
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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 ...
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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 ...
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4 votes
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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 ...
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4 votes
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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 ...
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  • 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 ...
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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.
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  • 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 ...
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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 ...
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  • 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). ...
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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, ...
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  • 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 ...
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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 ...
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  • 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 ...
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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 ...
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  • 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 ...
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  • 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 ...
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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 ...
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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. ...
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1 vote
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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 ...
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  • 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 ...
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  • 1,308
1 vote
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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.
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