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Old 10-12-2004, 01:37 AM   #1
ZVOLV
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Default 16valve piston-valve clearance

OK. So I got my timing belt tensioned on my 16v head on the b230 block. I put play-doh on the top of the pistons and spun the crank around with the timing belt tight. No contact between the valve and the piston. However, it was close.

My question is: do the lifters need to be full of oil for my test to be valid?

EDIT- if you dont feel like reading all the crap below: i measured clearances as little as 1mm between the valve and piston. That was with cold unpressurized lifters. The 16v pistons have 3 and 4mm deep cuts in them. My conclusion is that there is NOT enough clearance to run without cuts. EDIT
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Old 10-12-2004, 01:44 AM   #2
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Another semi-crude way to test would just be to take the head off and turn it upside down. Turn the camshaft and watch the valves, then measure how much above the head surface they protrude. You'd also need to know the squish clearance of your shortblock.

Just for comparison, Stealthfti told me that on an SOHC head an A-cam would make the valves stick out past the deck about .020". And a compressed headgasket is I think .047".

Good luck figuring this out, it's interesting!

John
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Old 10-12-2004, 01:47 AM   #3
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Quote:
Originally Posted by The Aspirator
Another semi-crude way to test would just be to take the head off and turn it upside down. Turn the camshaft and watch the valves, then measure how much above the head surface they protrude. You'd also need to know the squish clearance of your shortblock.
I was going to do that, but i figured in real life the valve will never be fully open when the piston is at TDC. However, it would tell me if I had an interferance engine, but I know that it already is.
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Old 10-12-2004, 01:57 AM   #4
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it would be a good idea to have the lifters pumped up, yes
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Old 10-12-2004, 03:07 AM   #5
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I could pressurize the oil pump by spinning the aux shaft with a drill, but that would require the timing belt to be removed and then I couldnt do my clearance test.

If I pressurize the lifters, wont they just go flat again when I remove the oil pressure?

Anybody know where to get solid lifters for the b234? The 8v lifters are too fat.
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Old 10-12-2004, 03:17 AM   #6
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Old 10-12-2004, 03:22 AM   #7
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I am assuming the b204 also used hydraulics...? Well, they are at least listed as such in that link. I just remember a euro guy say that they cut the crap with the hydrualics and go solid, but i dont know where to get em.
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Old 10-12-2004, 03:24 AM   #8
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Old 10-12-2004, 02:18 PM   #9
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Quick 16v question.... are the intake and exhaust flanges the same pattern? Or are they different like the 8v ones?

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Old 10-12-2004, 05:34 PM   #10
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I dont know to many specifics about volvo engones but can probably give some general pointers. I know that you need more than for the valves to just barely clear. The valve stems will expand with heat and strain, probably more than you might think. In the pictures it looked like you had pretty much clearance (~3mm) but this is hard to see just from pics. I did this exact thing on a porsche engine this summer and tried playdoh but found that silly putty is much better because it isnt as soft so you can actually take it of the pistons and measure it. Also I dont know about the lifters in the volvo head but I would think that if they are hydraulic that with no oil press this test doesnt really mean to much (unless you know how much the lifters expand with pressure.). Would it be possible to get pistons with valve cut outs, arent these usually needed on interference type engines?

sorry if you read this and it didnt really help you. I just wanted to share my bit of knowledge.
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Old 10-12-2004, 06:18 PM   #11
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Quote:
Originally Posted by The Aspirator
Quick 16v question.... are the intake and exhaust flanges the same pattern? Or are they different like the 8v ones?

John
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Old 10-12-2004, 07:11 PM   #12
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I am sorry that the pics are kinda poor but those are the only pics I have right now. I wanted clay, but i the store only had play-doh.

I have a set of 16v non turbo pistons with valve cuts, but they are 10.0 compression which i dont want to run since I run 91 octane pump gas.

The test revealed that the valves did not hit the pistons, but it is VERY close. That is why I posted the pics so people could critique my tests and give feedback.

I need to know if the valves are going to get closer to the pistons because of reasons like heat expansion, lifters filling with oil, or anything else.

The non turbo pistons have cuts in them, so they are there for a reason....

EDIT- here is a link to my pics that show the NA pistons with the valve cuts in them. Those suckers are deep. EDIT http://forums.turbobricks.com/showthread.php?t=26597

I REALLY cant afford 16 bent valves so I need to be 100% sure those valves arent going to hit.

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Old 10-12-2004, 09:18 PM   #13
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OK, so i did another test with the playdoh. This time I pulled the playdoh off the piston and cut it in half so I could look at the cross-section. I took pics, but i cant focus in well enough to show you guys. The valve gets within 2 mm of the piston. Is this enough clearance?

EDIT- According to my manual shims for the 8 valve come in a range from 3.30-4.50mm so from this info I would imagine the most a lifter will affect the lift value is about 1mm. Since I have about 2mm to work with I should be in the clear, right? EDIT


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Old 10-13-2004, 10:09 AM   #14
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Why not get the low comp pistons cut. My shop said $60-$80. You will probably already have them out to re-ring them right? I can give you the specs on mine or just take the 16V piston to the shop so they can compare. The bent valve problem is bigger than an $80 headache. You will probably need more dish anyway because of the chamber size differences. Depending on what compression you are trying to run, of course.
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Old 10-13-2004, 11:03 AM   #15
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Don't assume that because the adjustment shims only come in a range covering 1mm, that the lifter will only affect that same 1mm. It could be lots more.

There's lots of stories of people setting up their hydraulic lifters cold and dry, and then starting the engine to only have it run for about 15 seconds and then when the lifters pump up, it shuts off.

I think the guideline is .050" minimum clearance with solid lifters - I'd go for at least 0.100" with hydraulics. At high RPMs you could still float or bounce the valves, or you could pump up the lifters, or you could miss a shift... Better to be safe than sorry. Cut the pistons, but don't cut so far that the top ring land gets thinner.

And don't assume that 10:1 will be too high for a turbo using that head. People are F+Ting 8 valve heads up in that C/R range, and that combustion chamber and spark plug location should allow much higher cylinder pressures and should have better detonation resistance than the 8 valve heads do. That central spark plug will go a long way towards making things better, and the evenly-shaped chamber will allow quick, unimpeded flame travel. I'd go higher rather than lower C/R when building a turbo 16v Volvo, unless you have the support for lots of boost at high flow, i.e. turbo and IC.

My views, as always.
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Old 10-13-2004, 02:08 PM   #16
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I was going to use the b234, but i need to:

plug the aux shaft holes (gonna plug em and weld em)

make custom motor mount on exhaust side (to fit turbo and oil filter)

make custom oil feed and return lines (well, i have to on the 8v too but i wouldnt have to tap into the block or oil pan for the return like i do on the b234)

run high compression

and swap out crossmember (or make really custom mounts. But I have the b234 X-member)


I would like to run the 8.5 CR if possible. I can already detonate easily with pump gas and my 8v set up. However, the b234 is still an option. In the factory manual it also explains that higher compression can be run with the pent roof chamber with center spark plug.


However, the b234 looks like its in better shape than the b230. The b234 has lots of crosshatcing left on the cyl walls and the b230 has little to none. I am not even going to bother re ringing it yet because I can get another used block for 70$ and this is my prototype engine anyways. I am not putting big power thru it yet.

This is budget build. So I wont run the cuts if i dont need to. However, since a new set of valves is about 300$ i gotta be careful. Looking at my pic with the ruler and the clay it looks like i have plenty more than .1" to work with. I measured it at 2mm which seems very close to .1". I posted the 2mm spec so that people would comment if it is enough. You guys mentioned valve float which was one of my concerns. It doesnt make sense to me why the pistons on the b234 are cut so deep and I would be able to run without them on the b230.

Let me know if you guys think i can get away with running the b230 block with the b234 head with 2mm of measured clearance between the piston and the valves.
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Old 10-13-2004, 06:37 PM   #17
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hey...lets get ours cut together and save ourselves the possibility of screwing stuff up. $50...remember??? Lets do it next week and stop worrying about it and get this 16v monster running!
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Old 10-13-2004, 08:29 PM   #18
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Because if I dont need to do it, why would I waste the time and money to do it and have potentially weaker pistons.
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Old 10-13-2004, 10:11 PM   #19
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Any reason you can't just swap the B234 pistons in? Bore is the same.. and I think the wrist pins should be the same too. At that point though, you could just get your B230 pistons cut for reliefs.. should be less then $100 for all four if you have a B234F piston as a good example.
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Old 10-13-2004, 10:34 PM   #20
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http://wwwrsphysse.anu.edu.au/~amh11...urbo_volvo.htm
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Old 10-13-2004, 11:04 PM   #21
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Well, I did some more tests:


I did some more measurements on my 16v clay pieces and found a spot where the valve gets closer to 1mm from the piston. (that may have been with a lifter with some oil in it).

The b234 pistons should fit my b230 bore, but I doubt they will have the correct clearances if I swap them over.

I measured the cuts in the b234 pistons and they were 4mm deep on the exhaust and 3mm on the intake (give or take). That is a lot more clearance than the 1-2mm clearance I measured between the b234 valve and the top of the b230 piston.

The other test I still need to do is measure the distance the valve protrudes from the bottom of the b234 head.

Also, the b234 pistons are tight in their bores. On my b230 block the pistons have a LOT of play in them between the wall and the piston. I also have a lot of oil consumption in my b230 motor.

I am starting to lean back towards the b234 as my base. I just gotta make custom motor mounts and other crap listed above. The b234 also seems like its in a lot better condition than my b230.

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Old 10-14-2004, 03:14 AM   #22
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Don't know if this will help because it's not volvo related but still:

When i was building my 2056cc aircooled boxer 4 for my vw beetle i used clay to measure the v to p clearance. Instead of taking the clay of, i cut it in half and remove one bit, then you can see and measure the thikness easier. A local engine builder told me that with the cam and springs (single HD) i was using i could run 6-6.5k before valve float. I used 1mm clearance on the intake and 1.5 on exhaust. It's more importent to have clearance on exhaust because when piston is coming up on exhaust stroke, valve is going down. Other way around on intake. With single springs and 1mm and 1.5 mm clearance i could hear v touching p at 6000 rpm. I tore down engine and made reliefs in the pistons so that clearance was 2mm and 2.5 mm. Now i could rev to 6.5k before i could hear v to p hitting, wich is not a nice sound


End of story is that i switched to double springs and with p to v clearance of 2mm and 2.5 mm, i took the engine to 7.5K without problems

The guy who dynoed my engine (who is a respected engine builder) has made engines with 1mm v to p clearance that revs to 9k. This is with exhotic valve train of course. And he told me that if you missed a shift or went 200 rpm's above redline then BANG!!
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Old 10-14-2004, 09:11 AM   #23
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Quote:
Originally Posted by guidom12345
The b234 pistons should fit my b230 bore, but I doubt they will have the correct clearances if I swap them over.
I can't see why they wouldn't if you did a quick hone to your block and installed and gapped new rings. Just a thought.

Also, remember if you can get better springs you can run much tighter valve to piston clearance. I'd run no less then 0.050" if you plan on revving it up past the stock limiter.
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Old 10-14-2004, 01:04 PM   #24
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I am still looking for aftermarket parts for this head too. Stiff springs, cams, solid lifters, adjustable cam gears, bigger valves, etc. So if you have any leads please let me know.


I only run it to the stock rev limiter right now, (6200) but i really dont want to risk my valves since they are close to 25$ each new.

I think I might just swap the b234 pistons into my b230 block. I keep changing my mind all the time, but I just want to make something that isnt going to bend valves.

Please feel free to add whatever advice or comments you have. As long as they arent condescending or negative in any way. I would like as much input on this as possible. I was hoping dick prince would let us know about the clearance issues when using the b234 head on the b230ft block. Stealthfi seems to be the clearances guru around here so I was hoping he would chime in too.
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Old 10-14-2004, 02:08 PM   #25
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Stealthfti is on vacation till the 20th or 25th of Oct.

The B234 pistons into the B230 block sounds like the way to go, except for the high compression. Now, Matt was saying some good things above about high compression and the 16v head, so you might be good. I take it you're still running LH (Lame as Hell)?? Just don't go too wild on it.

Ohh, and Dale makes adjustable 16v gears. He might not have any in stock, so you'd have to send him yours. But he'll hook you up!

And if for some reason you have to get all new valves, you'd be silly not to upgrade to bigger ones. Probably the same price for the valves, plus new seats and installation.

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