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Initial cam setup on a way interface engine

R

runslikeapenguin

Member
Joined
Sep 10, 2008
Location
Tacoma WA
I'm wrapping up my engine so I can get it installed this weekend and one final worry I have is my cam timing.

My head was milled .080" or so and I had about .006" taken off of the block, stock head gasket and an V15 cam. I have JVAB pistons and rods and I'm at -.006 deck.

I have the shorter pinto timing belt and I have the IPD cam gear.

From what I understand the rule of thumb for milled heads is 1 degree for every .010", so I'm looking at advancing my cam 9? correct? I'm super worried about this because of how interference my engine is. If I remember correctly at max lift my valves were sticking out past the surface of the head over .100". With that being the case how far can I advance my cam from the 9? advance position, (which is my new zero)?

Can anyone validate me here? Put my mind at ease?
 
The only way to really know how much clearance you have is to use modeling clay on the top of the piston and then rotate the engine over.
Best bet is to find TDC and then align the timing marks the best you can. Or throw a dial indicator on the lifter and set it up using the cam card. You do have a cam card for the cam right?
 
culberro said:
The only way to really know how much clearance you have is to use modeling clay on the top of the piston and then rotate the engine over.
Best bet is to find TDC and then align the timing marks the best you can. Or throw a dial indicator on the lifter and set it up using the cam card. You do have a cam card for the cam right?
Click to expand...

I do not, and the engine is assembled and sealed up.
 
runslikeapenguin said:
I do not, and the engine is assembled and sealed up.
Click to expand...

Okay....
Well what valve springs are you running? If they are stock, you can rotate the engine over and when the piston is at TDC between the intake and exhaust stroke, and then push them open by hand or with a valve depressing tool (like what IPD offers). When they valves hit the pistons. you'll have an idea of what the piston to valve clearance is. You'll also want to probably go 10 or 20 degrees both ways of TDC and check as well.
 
culberro said:
Okay....
Well what valve springs are you running? If they are stock, you can rotate the engine over and when the piston is at TDC between the intake and exhaust stroke, and then push them open by hand or with a valve depressing tool (like what IPD offers). When they valves hit the pistons. you'll have an idea of what the piston to valve clearance is. You'll also want to probably go 10 or 20 degrees both ways of TDC and check as well.
Click to expand...

The bugpack high rate springs.
So I could just put the cam gear at 0 and rotate it with the center bolt until I feel contact right? The marking going up on the IPD gear at the contact poi t would be the point I would want to stay away from right? I mean a few degrees from that point.
 
Not sure what you're after here. Sounds like you've determined you have an interference engine, ok. So that's at max lift which is when the cylinder is farthest from the valve.
Adjusting the cam timing 10 degrees one way or the other isn't going to make the valves any closer to the piston. Valves are no where near fully open when piston is TDC
Just don't get anything 90 or 180 degrees off and you'll be fine. We'll, except where Volvo says don't machine their heads more than 0.020" but that's another story.
 
None of that applies if you change the length of the timing belt. If you keep the timing belt the same length and mill the head, then reassemble, your cam timing will be out because when you create slack in the timing belt, the tensioner takes up that slack on one side, which rotates the cam. Shortening the timing belt counteracts this change. It may completely counteract it, or partially counteract it. You will know when you set the cam gear straight up and observe where the mark is when the crank is at 0.
 
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Canuckvolvo said:
Not sure what you're after here. Sounds like you've determined you have an interference engine, ok. So that's at max lift which is when the cylinder is farthest from the valve.
Adjusting the cam timing 10 degrees one way or the other isn't going to make the valves any closer to the piston. Valves are no where near fully open when piston is TDC
Just don't get anything 90 or 180 degrees off and you'll be fine. We'll, except where Volvo says don't machine their heads more than 0.020" but that's another story.
Click to expand...

You are totally correct. I'm so use to setting clearances on engines with domed pistons. Those will deffinitely be close near TDC.

Volvo will be totally fine. Set the timing at 0deg and adjust from there.
 
Don't forget the other rule of thumb;
before you try to start it, roll the engine over twice by hand and feel for binding, or have your thumbs cut off so you never foolishly destroy a motor again.
 
I think I fired a B234F 180degrees out one time once... pretty sure it lived. I don't recall. That was in my barefoot mechanic days.
 
Canuckvolvo said:
Not sure what you're after here. Sounds like you've determined you have an interference engine, ok. So that's at max lift which is when the cylinder is farthest from the valve.
Adjusting the cam timing 10 degrees one way or the other isn't going to make the valves any closer to the piston. Valves are no where near fully open when piston is TDC
Just don't get anything 90 or 180 degrees off and you'll be fine. We'll, except where Volvo says don't machine their heads more than 0.020" but that's another story.
Click to expand...

My valves can come into contact with the cylinders. This makes the engine interference.
I'm just worried about advancing the cam and ****ing up.
 
Captain Bondo said:
None of that applies if you change the length of the timing belt. If you keep the timing belt the same length and mill the head, then reassemble, your cam timing will be out because when you create slack in the timing belt, the tensioner takes up that slack on one side, which rotates the cam. Shortening the timing belt counteracts this change. It may completely counteract it, or partially counteract it. You will know when you set the cam gear straight up and observe where the mark is when the crank is at 0.
Click to expand...

Good point, I wasn't thinking about that. This is why I'm asking questions.
 
Correct me if I'm wrong, but running a short timing belt when you've milled a bunch off the head is so that the belt tensioner comes back into play, NOT to correct cam timing. The belt still has the same tooth count from the cam gear to the crank gear, but the cam has to rotate anti-clockwise (retarded) to make up for the marginal amount that the cam is closer to the crank. If you are concerned about the cam being installed "straight up", I would, as badvlvo says, get a degree wheel and dial indicator. The specs I would use are those in the Green Book, as it's the only official documentation I've ever seen.
 
shoestring said:
Correct me if I'm wrong, but running a short timing belt when you've milled a bunch off the head is so that the belt tensioner comes back into play, NOT to correct cam timing. The belt still has the same tooth count from the cam gear to the crank gear, but the cam has to rotate anti-clockwise (retarded) to make up for the marginal amount that the cam is closer to the crank. If you are concerned about the cam being installed "straight up", I would, as badvlvo says, get a degree wheel and dial indicator. The specs I would use are those in the Green Book, as it's the only official documentation I've ever seen.
Click to expand...

Except they don't apply to wierd ass cams.
The best i think is how the You're-a-peein' do it..
The give you a "Cam lift @ TDC" checking figure....
And it is dependent on the cam

For mild little cams like 99.9% here run the figure might be a whopping 0,7 to 1,2mm valve lift @ TDC

Take 1,2mm as "checking" figure

So you establish TDC accurately, position the cam and the dial indicator and with you handy adjustable cam wheel, ease the cam back and forth till the dial indicator reads "1,2mm" then lock the cam wheel down..

But how many times do we have to go over the same thing?
Head is over 12mm from face to top of combustion chamber. Gasket 0,7-1,2mm for a total of over 12 to 13, sumpin mm

Only way for a valve inline with bore like the 8v is to have more lift than that 12 to 13, sumpin mm in LIFT

Theoretically it might become interference if say he misses a corner and fells a big pine tree that cashes across the hood and brakes the vale cover na d breaks the cam and pushes down on the bucket more than 12-13, ?

But how many times a week does that happen?

Don't worry. be happy.
 
John V said:
Except they don't apply to wierd ass cams.
The best i think is how the You're-a-peein' do it..
The give you a "Cam lift @ TDC" checking figure....
And it is dependent on the cam

For mild little cams like 99.9% here run the figure might be a whopping 0,7 to 1,2mm valve lift @ TDC

Take 1,2mm as "checking" figure

So you establish TDC accurately, position the cam and the dial indicator and with you handy adjustable cam wheel, ease the cam back and forth till the dial indicator reads "1,2mm" then lock the cam wheel down..

But how many times do we have to go over the same thing?
Head is over 12mm from face to top of combustion chamber. Gasket 0,7-1,2mm for a total of over 12 to 13, sumpin mm

Only way for a valve inline with bore like the 8v is to have more lift than that 12 to 13, sumpin mm in LIFT

Theoretically it might become interference if say he misses a corner and fells a big pine tree that cashes across the hood and brakes the vale cover na d breaks the cam and pushes down on the bucket more than 12-13, ?

But how many times a week does that happen?

Don't worry. be happy.
Click to expand...

John, you're spot on for checking cam timing. Most americaneski cams will have 0.xxxin lift at xxx? to help you get them timed correctly (gotta love offset ground dowel pins and woodruff keys!). I do like the mm of lift at TDC, that would be a really handy measurement for looking at piston to valve issues.

Major bummer on this poor lads cam is that he didn't get a "cam card" or a setup sheet. Womp Womp.
The heads been milled 0.080in and the decks been cleaned up 0.006in. That's definitely interference range, even with a stock k-cam.
 
Set the timing to the marks +/- a half tooth, and it'll be golden. At .086" you will have one less belt tooth between the cam and crank and the tensioner will be basically maxed out, don't use the printed marks on the belt use the timing marks on the pulleys. Change the belt at 40-50k, maybe 30 if you're flogging it and it'll be fine.
 
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