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T O P I C    R E V I E W
rannsachairPosted - 20 Mar 2016 : 14:50:24
When I originally stripped down my engine, the fibre cam gear was damaged, so I replaced it with a quaife steel timing gear from Burton. Currently only the balance shaft gear is still fibre.http://www.ebay.com/itm/Quaife-Steel-Timing-Gear-Ford-Cologne-V4-V6-Saab-TVR-Capri-Granada-2-8-/151920551496


I now have another set of steel gears with an aluminium cam gear.

So the question is what cam gear do I use?

Thanks

1971 96
2005 9-5 Aero
2003 Defender 90
1969 Triumph T120
1956 Matchless G3LS
1972 BMW R75/5
1991 Triumph Trident 900
1992 Triumph Trophy 900
13   L A T E S T    R E P L I E S    (Newest First)
mellePosted - 09 Apr 2017 : 00:11:35
The S&R manual has instructions on modifying the combustion chambers for bigger valves. I bet you have it, if not download it from my website: http://www.saabv4.com/files/www_saabv4_com_Sport_Rally_catalogue_1972_English.pdf (Section 6 is what you're looking for, page 116 onwards). I've drawn up the S&R templates (and a few extra) in CAD, also printable from pdf: http://www.saabv4.com/index.php/engine-gaskets/sportrally-templates/

www.saabv4.com
rannsachairPosted - 08 Apr 2017 : 23:33:24
quote:
Originally posted by melle
I would be curious to know what a 1500 balance shaft weighs, it should be a tad lighter than the 2kg 1700 item but I haven't been able to check yet. I'm off to the workshop tomorrow, so don't feel pressed to put in on the scales as I'm happy to weigh one myself next week and report back! S&R manual advises the 1500 balance shaft for >1700 race/ rally engines.

Something else I'm curious to learn about is the effect of V6 valves on low rpm torque. Are you planning on "unshrouding" (if that's a word) the valves? If so, I guess you'll have the heads skimmed as well? I don't rally my V4s and rarely get over 4000rpm, so I've always stuck with std size valves because I'm afraid bigger ones will rob bottom torque. I'll readily admit my knowledge comes from books (e.g. by Des Hammill, David Vizard and Graham Bell) rather than personal comparison (read: I don't have the money to modify another pair of heads to be sure).

www.saabv4.com


Hi Melle, I think I have the same books as you plus my Phil Irving books from late 1940's to the 70's!
I have a spare set of heads, so took a perhaps simplistic view that the slightly larger capacity of the 1700 would benefit from larger valves than the 1500, though as a % increase in capacity it is not so much.

I am hoping to create a slightly sportier engine than standard, though I am starting to recall the tuned Escort Mexico of my youth that became impractical with very little power below 3000 rpm, sub 20 mpg fuel consumption and great difficulty driving in the wet without wheelspin (1740 cc, big valve head, rally cam, twin DCOE40's).

I may try the standard valves first and match the ports to the manifolds and see how that goes. I am not looking for over 100 hp.

David Vizard's "how to port and flow test cylinder heads" has a section on shrouding,I was not considering it as such.

Hopefully I can whip out the 1500 balance shaft shortly, have had the flu for the last week and am just starting to feel better.
mellePosted - 08 Apr 2017 : 21:54:41
I would be curious to know what a 1500 balance shaft weighs, it should be a tad lighter than the 2kg 1700 item but I haven't been able to check yet. I'm off to the workshop tomorrow, so don't feel pressed to put in on the scales as I'm happy to weigh one myself next week and report back! S&R manual advises the 1500 balance shaft for >1700 race/ rally engines.

Something else I'm curious to learn about is the effect of V6 valves on low rpm torque. Are you planning on "unshrouding" (if that's a word) the valves? If so, I guess you'll have the heads skimmed as well? I don't rally my V4s and rarely get over 4000rpm, so I've always stuck with std size valves because I'm afraid bigger ones will rob bottom torque. I'll readily admit my knowledge comes from books (e.g. by Des Hammill, David Vizard and Graham Bell) rather than personal comparison (read: I don't have the money to modify another pair of heads to be sure).

www.saabv4.com
rannsachairPosted - 08 Apr 2017 : 20:20:49
Thanks to Melle, I will now be building a 1700:


Just need to check if the new rings I bought for my 1500 pistons will be the same as the 1700 ones and a question -

which balance shaft will I use? - as I now have both 1500 and 1700.

Engine spec will be: 7.6 cam, mildly reworked heads with V6 valves and springs, Jetex exhaust and initially a 28/36 DCD Weber (which I put together for the 1500 engine, so may need to rethink for the 1700) and a Malbrad diaphragm clutch. Just for road use.

Any thoughts appreciated.
rannsachairPosted - 23 Mar 2017 : 21:49:07
quote:
Originally posted by rsimps
Nope the alloy gear is metric as its v6. Burton know bugger all about v4 engines. Malbrads get a set of v6 metric gears and have a balance shaft made in metric.

Finally splashed out on a set of Malbrad gears. As suggested one is slightly different, so glad I went to the expense
rsimpsPosted - 04 Aug 2016 : 15:57:12
Nope the alloy gear is metric as its v6. Burton know bugger all about v4 engines. Malbrads get a set of v6 metric gears and have a balance shaft made in metric.
rannsachairPosted - 23 Jul 2016 : 00:24:49
quote:
Originally posted by rsimps
The 2.8 gears are metric and the saab are imperial. There is only a slight difference but in theory the toothe profile is different. The way round this was making a metric balance haft gear t fit the 2.8 twin gear set and that's what Malrads stock. The other way was to make a specific steel balance shaft gear of steel, which is what I had made as a batch years ago.

looks like Burton's description is wrong: http://www.ebay.co.uk/itm/Quaife-Steel-Timing-Gear-Ford-Cologne-V4-V6-Saab-TVR-Capri-Granada-2-8-/151920551496?hash=item235f2ba648:g:OqcAAOSwk1JWdE~s
I have partially re-assembled with the alloy gear, which I assume was designed for the engine.
rsimpsPosted - 22 Jul 2016 : 18:37:06
The 2.8 gears are metric and the saab are imperial. There is only a slight difference but in theory the toothe profile is different. The way round this was making a metric balance haft gear t fit the 2.8 twin gear set and that's what Malrads stock. The other way was to make a specific steel balance shaft gear of steel, which is what I had made as a batch years ago.
beardydavePosted - 09 May 2016 : 08:29:41
Aluminium on steel will wear the aluminium out faster than if it were aluminium on aluminium.

You could get it anodised which will help a little.
rannsachairPosted - 08 May 2016 : 15:32:20
I can just get a .4mm feeler gauge between the gears on both. there feels slightly less backlash on the steel gear. Think I will go with the aluminium one as it is lighter as I do not think the extra wear resistance of the steel gear is required?

1971 96
2005 9-5 Aero
2003 Defender 90
1969 Triumph T120
1956 Matchless G3LS
1972 BMW R75/5
1991 Triumph Trident 900
1992 Triumph Trophy 900
rannsachairPosted - 20 Mar 2016 : 19:28:11
Thanks for that woody, will try it with both and see what has the least backlash.

1971 96
2005 9-5 Aero
2003 Defender 90
1969 Triumph T120
1956 Matchless G3LS
1972 BMW R75/5
1991 Triumph Trident 900
1992 Triumph Trophy 900
WoodyPosted - 20 Mar 2016 : 18:14:03
Use the set of three that came together ideally.
Sorry duplicate post as on the train from Edinburgh. An worthwhile check would be to offer steel cam gear up to verify teeth align and check backlash between crank gear and balance shaft gear.
WoodyPosted - 20 Mar 2016 : 18:12:02
Use the set of three that came together ideally.

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