sure, I'll be finishing things here in a minute then I can focus on the chat for a bit :)

let me know

@Pᴀᴜʟsᴛᴇʀ2 I can have a small break now, I was looking a video on roller tappets and flat tappets. So the engine block you have can use either setup? But the flat tappet is the standard, so if you want to use the roller tappets you need to adapt some things in the block? The camshaft you have is going to need to have lobes that match the type of tappet you choose right?

@IanC - The roller tappets have what is called a "spider". It is a thin piece of metal which holds "dog bones" onto the lifters which keep the lifters oriented so the roller is square with the cam.

There are three bosses (pieces of protruding metal) which have holes drilled/tapped in them, which the spider is bolted down to. The bosses sit in the center of the lifter valley.

I'll see if I can find a picture for you real quick.

If you look at the metal piece running down the middle, you'll see three bolts. Under those bolts are the bosses. The metal piece is the spider. The dog bones are the pieces of metal which the ends of the spider come in contact with.

This is an ugly picture of the lifter valley without the spider in place.

You can see two of the three bosses in this picture. I had to drill/tap these today.

@IanC - And yes, the cam profile for the roller lifter is completely different than it is for a flat tappet lifter.

The camshaft on the left is roller, while the one on the right is flat tappet

I guess I got a bit confused with the first picture, the spider purpose is to keep the lifters (either flat or roller tappets) pointing in the right direction? So dog bones are actually the pieces that will help keep the spider in position, fixing two points together? And in the picture the lifters are hidden under the spider?

@Pᴀᴜʟsᴛᴇʀ2 I understood the camshaft profile though, the roller tappet can endure the round profile because it will roll over it, while the flat would get stuck and wear the pieces fast. So the roller tappet can actually hold the valves open for longer and open them faster right?

The spider is just for the roller tappets. Flat tappets have to turn or they will get destroyed.

And the dog bones orient the lifters ... the spider keeps the dog bones in place

The spider is an elaborate spring.

@IanC - That's absolutely correct, as well as allow them to close faster.

@Pᴀᴜʟsᴛᴇʀ2 Damn, I think I got it! The roller tappets come in pairs for that engine right? Because it's a 4 valve per cylinder? Then the dog bones hold 2 of those roller tappets pointing in the right direction when they are pushed by the camshaft, but are fixed in the spider so just the tappets rise and push the valves?

@IanC - It is only two valves per cylinder.

One intake and one exhaust.

It is an eight cylinder engine.

The dog bones do hold 2 roller tappets, though.

oh, the dog bones are holding pair of roller tappets but they move individually

The tappets move individually, yes.

if it was a flat tappet they would be fixed in a way that allowed them to move up and roll a little at the same time? Similar to the connecting rod of a piston?

@IanC - A flat tappet has to rotate. There's nothing holding the to an orientation.

Nothing like a connecting rod of a piston, though. It's still a cam, which means there is base circle (when the valve is closed) and a cam lobe (as the valve opens/closes).

I meant the way the flat tappet move to open/close the valve, since it can't be held to an orientation (so it doesn't break) I imagined it moving in a way similar to a connecting rod, like, rising and turning at the same time

or am I making some confusion with the tappet movement?

@IanC yes

I just realized the confusion I made

No worries :o)

the orientation you meant was the rotation orientation, so the roller is pointing to the right direction and doesn't get perpendicular to the movement of the shaft. The roller tappet cant rotate inside the cylinder that holds it, while the flat tappet can rotate inside it (and maybe this rotation prevents wear?)

@IanC - Sounds about right!

last doubt is, how do the dog bones keep them from rotating? The part of the tappet its fixed to has some hole or dent that keeps the piece from rotating?

The dog bones are along the bottom.

See how they are oblong with flat sides? (the holes)

Got it! They are not round like the flat tappets

Thanks a lot @Pᴀᴜʟsᴛᴇʀ2, took me a while but I guess I got it now :)

No worries

I'm almost sure my bike has flat tappets, because I know the camshaft profile isn't like the rolled one

What kind of bike?

it's a 150cc Honda

I'd bet it's flat tappet as well

Just gave it a nice wash today, it's been a while it hasn't seem some water, now I need to change the seat cover and I guess it wouldn't be a bad idea to change the spark plugs, looks rusty and it might be past the mileage recommendation

no signs of spark plug failure though, just a prevention

kewl

I've never changed a seat cover though, I hope I don't mess it up haha

Well, if it's any consolation, I've not done one either!

I'm watching some videos, guess the worse can happen is I make a bad job and it doesn't get very stretched, then I swallow my pride and pay someone to do it :p

LOL! Yup!

^^ Shopping question?

:-O

hardwarerecs.stackexchange.com :-P

say, if I got my MAF sensor, PCV valve, and engine gaskets replaced 6 months ago, and now I'm getting a "system too lean" engine code again, should I be mad at my mechanic?

maybe I should just try cleaning the MAF first. I wonder if some gunk from the old decayed gaskets could have just finally worked its way through the system and landed on the sensor

@alexw - What exact codes are you getting?

P0171

"System too lean bank 1"

fairly certain I pulled this exact same code in March before I took it to the mech

@alexw - What is the vehicle in question? Year/model/engine

@Pᴀᴜʟsᴛᴇʀ2 2008 Mazda 3, uhh

2.1L engine I think?

err, 2.0