| Author |  Topic  |
melle
V4 Guru
United Kingdom
3833 Posts |  Posted - 08 Apr 2020 : 19:25:43  
| I always find it really hard to tell if a head is for open or closed deck if it's on an engine. The open deck heads use shorter bolts (73mm vs 80mm); you can compare the height of the "bosses" either side of the exhaust if you have a known closed deck head to compare (or I can measure one for you).
Off the engine the difference is obvious:
www.saabv4.com |  |
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TTruckie
V4 Fanatic
United Kingdom
320 Posts | Posted - 08 Apr 2020 : 22:50:51
| open deck heads have short throw plugs and closed deck have long throw.
open deck heads won't fit a closed deck engine as you will get a water leak - the open deck heads have a deeper recess on the outer edges as you can see from the photos.
You (rather a professional) can weld up the recess but its expensive. | |
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Dirtbiker
V4 Guru
United Kingdom
1061 Posts | Posted - 09 Apr 2020 : 06:58:55
| Thanks for the pics Melle. I know you are not going to be anywhere near any heads right now but do you think you can tell by looking at the depth of the plug holes?
TTruckie - Thanks. Could you have a look at the picture on the previous page? I'm thinking these are closed deck heads and have been fitted with short reach plugs as whoever fitted them has fitted the correct plugs for the model year but actually the incorrect plugs for the engine. What happens if you try and fit closed deck heads on an open deck engine? This is the configuration I suspect I may have?
My hypothesis is that this is an early engine (based on the code 6J6) so open deck but has been fitted with later closed deck heads at the point when it was given hardened valve seats.
Cheers | |
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Dirtbiker
V4 Guru
United Kingdom
1061 Posts | Posted - 09 Apr 2020 : 07:08:18
| If you thought the grinding was scary imagine how much fun welding next to that dodgy fuel pipe was!
Actually, before I started all this I disconnected it from the tank, blocked off the union to the tank to contain vapour and blew some air down the fuel pipe.
Repair welded in.
Welding looks terrible in this pic. Even though that pipe was empty I was still paranoid so welded in very short bursts.
Cleaned up good though.
Still can't fit those nice rubber mats though!
Cheers | |
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Betsy67
V4 Fanatic
United Kingdom
409 Posts | Posted - 09 Apr 2020 : 12:48:06
| Welding patches - How familiar a story is that the moment for me !
What are you using as a 'host' for your pics ?
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Edited by - Betsy67 on 09 Apr 2020 12:51:01 | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 09 Apr 2020 : 13:18:40
| quote:
Originally posted by Dirtbiker
Thanks for the pics Melle. I know you are not going to be anywhere near any heads right now but do you think you can tell by looking at the depth of the plug holes?
I happen to have some closed deck heads here; just measured a boss at 53mm.
I get a ‘504 Gateway Time-out’ error message when I attempt to load the forum on my laptop, works fine on my phone though. Not sure what’s going on. Edit: it appears to be a Firefox problem, no issues in Safari on my laptop.
www.saabv4.com |
Edited by - melle on 09 Apr 2020 13:20:20 | |
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TTruckie
V4 Fanatic
United Kingdom
320 Posts | Posted - 09 Apr 2020 : 20:52:19
| | from what i can see they look like short plugs (open deck). If you could post a picture of the area around the outer most head bolts that would confirm. Open deck heads have a much deeper waist cut in around the bolt and closed deck this area is infilled. - see melle's 2nd photo. | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 10 Apr 2020 : 09:46:30
| | Melle. Just for interest would you be able to show the open deck head with both a short and long reach plug fitted? Using a long reach might put the spark in the wrong place for the best flame front but does it actually clash with valves or piston top? | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 10 Apr 2020 : 10:30:42
| I don't have open deck pistons here unfortunately.
www.saabv4.com | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 11 Apr 2020 : 11:58:08
| | I just meant showing the plugs in the heads. Showing how close they get to the pistons would be difficult. | |
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Dirtbiker
V4 Guru
United Kingdom
1061 Posts | Posted - 11 Apr 2020 : 22:00:20
| Hi,
Right, good news and bad news...
Good news is I had time to do some measuring and record my findings.
Bad news is my findings are one of each cylinder head!
Here we are measuring the height of the RH cylinder head boss which gives 48mm
And the LH side gives us 54mm. Wonderful...
Also, really hard to photograph but the plug holes are very clearly different depths. This is a link to the photo on page 2 so you can see it bigger https://flic.kr/p/2iN35Rk
If you zoom in you can see the wet bit of thread which is the length of a short reach plug plus a dry bit which corresponds to the extra length of the long reach plug.
Well, what to do about it? I mean, it runs pretty good. I think I'll just leave it for now and stick some proper plugs in the RH side.
What I would really like to try and figure out is if it is the original engine as that will certainly influence my long term decisions.
The other thing I would welcome advice on is what to do about the crankcase breather. Here is the diagram in the Haynes
Cheers |
Edited by - Dirtbiker on 11 Apr 2020 22:01:26 | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 12 Apr 2020 : 11:39:43
| If it runs well, I'd just leave it alone for now.
Regarding the PCV system: the images are the wrong way around, never noticed that before! Top is enclosed, bottom is semi-enclosed. You'll need to replace the filler cap on your engine for the system to work well, or if you want to retain the look block its filter. I suppose the original rocker cover didn't have a take-off for a hose to the air filter?
www.saabv4.com | |
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Dirtbiker
V4 Guru
United Kingdom
1061 Posts | Posted - 13 Apr 2020 : 10:04:03
| Melle - I am really glad so said the pictures are the wrong way around! I thought so too and this is why I was confused but didn't think Haynes would make a mistake!
Cheers | |
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Dirtbiker
V4 Guru
United Kingdom
1061 Posts | Posted - 13 Apr 2020 : 10:14:43
| Right, got the floor sorted.
Other than an uncooperative can of white paint I am happy with how it went and the result.
There were also two more dents, one in each front footwell. However, these were far less severe and I was able to gently massage out with a block of wood and the BFH.
I have an original bit of hardboard for behind the front seats and have to cut a piece for the front. Unfortunately the "Handy Size" sheet I have measures 1220mm so not quite handy enough. I will have to pick up a full sheet. That's a job for after lockdown but plenty more to be going on with!
Cheers | |
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Woody
V4 Guru
United Kingdom
2764 Posts | Posted - 13 Apr 2020 : 15:26:11
| Having consulted the parts book, a significant way to identify an a open-deck engine from the outside was that it had a crankcase breather into the block in front of cylinders 3/4. Short reach plugs, the blocks being painted silver/grey.
Early closed-block castings still had the breather hole but it was capped, as in above photo. these and subsequent blocks were painted blue. My first V4 a M69 Deluxe 96 had a blue engine but by then the capped breather hole had been deleted.
I therefore suspect that the above engine is a closed deck.
I have in the garage two pairs of cylinder heads, which I can measure for comparison. The cylinder heads on the Troll rally engine have been skimmed at least 1.5mm to raise the compression ratio. | |
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| Topic | |
1967 95V4
