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 1973 96v4 with a modern twist
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 12 Apr 2021 :  18:50:38 Show Profile Reply with Quote
Thanks Melle, I was thinking about the heat expansion of the shaft and the clearances when engine is hot. That is why center spacer is made of steel and not aluminium. Then I looked at the solutions made by VW bug guys and thought if I just set correct clearances the heat expansion might not be the problem, because similar solutions are used in inline-4 engines with longer rocker shafts as well.

I adjusted 0.2-0.3mm total clearance for center spacer including both valve rockers between fixing bolts and 0.1-0.15mm to end of the shaft. Same kind of values used in other cars. Lets see how it works

In mass production this kind of clearance adjusting would take too much time, so the original solution with springs is much cheaper solution and also spring solution needs less maintenance.

Here is an article regarding similar modification in 2.9 engine and I have also read the Sven Pruett's V6 book as well:
https://www.therangerstation.com/tech/kunz-korner-2-9-performance-tips/
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melle
V4 Guru

United Kingdom
3343 Posts

Posted - 12 Apr 2021 :  21:59:48 Show Profile Reply with Quote
I think this modification makes sense, I have to admit I'd never considered it. I was looking for Sven Pruett's book a few years ago, it was already out of print then and really expensive second hand. I just did a quick search and the situation seems to be the same today... Iirc the book got very mixed reviews, but I can't remember why.


Have a nice Saab Sport and Rally works valve train out of a Simo Lampinen 96 at Gasparatos in Hamburg, Germany.:



www.saabv4.com

Edited by - melle on 12 Apr 2021 22:00:05
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 13 Apr 2021 :  05:53:14 Show Profile Reply with Quote
Yes that is the ultimate version used in rallying. Also there is lighter version of it manufactured by TGmotor in Sweden using the existing rocker shaft fastening bolts:
https://www.tgmotor.com/vi-erbjuder/topplock/saab/

I actually have drawn identical design with TGmotor version using CAD, but decided not to implement it because I have no tools to manufacture it by myself and it is so expensive to get it machined in machine shop.

All the rocker shafts and valve rockers that I have are quite worn. Current plan is to to buy new rocker shafts from Motomobil some day and maybe valve rockers as well to get more precise and noiseless control of valves.

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melle
V4 Guru

United Kingdom
3343 Posts

Posted - 13 Apr 2021 :  09:43:25 Show Profile Reply with Quote
I may be interested in a TG-type set too and I may have a lead for affordable machining, email me at saabv4[at]saabv4[dot]com

I know some people use shortened V6 rocker shafts because they're cheaper than V4 ones. Have you thought about roller rockers?

www.saabv4.com
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 13 Apr 2021 :  12:36:48 Show Profile Reply with Quote
I have to look, if I find the CAD drawing of the rocker shaft installation at home. It is just draft without very specific dimensions

I have thought about the roller rockers, but so far I have not found proper ones for Cologne V4/V6 engine. And usually roller rockers are quite expensive and the most benefits are in very high rev range. But it would be interesting to reduce friction using roller rockers. One step to reduce fuel consumption as an experiment
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 14 Apr 2021 :  18:44:43 Show Profile Reply with Quote
I have Crane cams 99257-2 valve lifters installed with 7.2 camshaft. Those are originally intended to Ford 289/302 V8 engine, but they fit very well to V4. Those are 4mm higher than original, but adjusting screws are in decent adjusting range with 7.2 cam and 0.5mm shorter Peugeot valves. Those are 97 grams each and original lifter is 104 grams. Only 7 grams lighter, but to right direction anyway. There are also lighter lifters available in market, which fit to V4.

I have also ordered TG 245 272/ 11,55mm modern camshaft about 7 months ago from TGmotor. Haven't received it yet Looks like they have little bit longer delivery time, but I think I'll drive with 7.2 cam next summer anyway. Do not want to open the engine in near future. This cam shaft has much more lift and shorter duration, which should give more stable idle,better fuel economy and more low end torque.

For this camshaft I have Crower 66915X980-1 valve lifters. Those not lighter than the original, but they have tiny EDM hole machined to camshaft contacting surface, which should lubricate the camshaft better. I think this might be useful for cam with high lift.
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Derek
V4 Guru

United Kingdom
2019 Posts

Posted - 16 Apr 2021 :  12:10:25 Show Profile Reply with Quote
Could you use Teflon tubing to replace the springs? The sort they use for gudgeon pin buttons? As Melle says cutting down V6 shafts is commonly done but you have to keep an eye on the lubrication holes. I'm not sure if the V6 rockers are interchangeable with the V4 ones?
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 17 Apr 2021 :  09:17:20 Show Profile Reply with Quote
quote:
Originally posted by Derek
Could you use Teflon tubing to replace the springs? The sort they use for gudgeon pin buttons? As Melle says cutting down V6 shafts is commonly done but you have to keep an eye on the lubrication holes. I'm not sure if the V6 rockers are interchangeable with the V4 ones?



Teflon, aluminium and bronze might work. All of those have lower friction coefficient between cast iron and steel than steel to steel or cast iron to steel if I remember correctly.

In Motomobil web shop v4 shaft is about 47euros/pcs and the V6 is little bit over 40euros so there not much price difference in there. Burtonpower sells the same rocker arm to V4 and V6, so it should the same in both.

I did some ignition tuning acceleration test with couple of ignition maps by accelerating with 3rd gear from 1500 to 5000 rpm. According to megasquirt logs it takes about 8 seconds with 1.7 engine and last summer it took about 11 seconds with 1.5 engine. All the other components are the same except the rocker shaft spacers. I am very surprised how much faster the 1.7 engine is 250cc higher volume and approx 10.5:1 compression ratio.
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 22 Apr 2021 :  09:56:52 Show Profile Reply with Quote
Parts have arrived from machine shop. Quality looks very good for the purpose and I already installed one rear drum. I put the sleeve and bearing to freezer before pressing the sleeve using hydraulic press to drum. Interference fitment was used between drum <-> sleeve and sleeve <-> bearing. And it looked like that I succeeded in the clearances At least it felt like there was adequate amount of resistance when pressing the parts. I am planning to make a presentation for MOT of the bearing structure vs. original and later on can post it here.



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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 24 Apr 2021 :  16:58:57 Show Profile Reply with Quote
First version of rear drum structure:

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melle
V4 Guru

United Kingdom
3343 Posts

Posted - 24 Apr 2021 :  19:20:25 Show Profile Reply with Quote
Very useful information, thanks for sharing.

www.saabv4.com
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 29 Apr 2021 :  06:16:28 Show Profile Reply with Quote
First kilometers driven with updated driveshafts, hubs, brakes and wheels. First impression is that the car is now better to drive In example: less vibrations, better stability i.e. in motorway and more stable feeling in steering wheel.

Still some minor adjustments need to be done like brake disc shields and brake hose fastening placement modification to chassis, but close to the final anyway. I have shown the modified hubs and parts to finnish vehicle inspection engineer and he said that looks good, just bring the car to inspection when it is ready

A lot of work, but now the car is almost ready for summer

Edited by - AnttiK on 29 Apr 2021 06:28:25
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melle
V4 Guru

United Kingdom
3343 Posts

Posted - 29 Apr 2021 :  09:06:14 Show Profile Reply with Quote
What model years Megane are you using the brake drums from? I'm actually quite surprised they still had rear drums and not discs. Or are they originally only used for the parking brake? Have you considered installing discs on all four corners?

www.saabv4.com
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AnttiK
V4 Beginner

Finland
64 Posts

Posted - 29 Apr 2021 :  09:40:05 Show Profile Reply with Quote
Rear drums are from Megane I hatchback 2.0 8 valve in 1998-2003. Renault was using drums also in some Laguna models, which is quite surprising. Inner diameter of Megane drums is 203.3mm and 203.2mm in Saab 96. I bought the drums from german webstore and the brand was the cheapest Ridex (about 20/each). The outer inside diameter might be different between the brands, because 52.24mm is probably not specified dimension.

I first thought about the rear discs, but I looked about the budget and the work needed for the discs I decided to stay with the drums. It is ridiculously easy to install the rear drums, when bearings and sleeves are installed to drums. And now I have new rear drums Original drums were pretty worn out.

But of course there is always option for upgrading to the disc and in future I might do that. Evolution of my 96 is continuous

Edited by - AnttiK on 29 Apr 2021 09:41:27
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melle
V4 Guru

United Kingdom
3343 Posts

Posted - 29 Apr 2021 :  10:01:02 Show Profile Reply with Quote
In all fairness, I think drums will be perfectly adequate under most circumstances. I feel the single thing that's letting the brakes on my 96 down is the Lockheed mater cylinder (the type with the cylindrical reservoir). I've already overhauled an ATE one (including servo as that's different too) a few years ago, still need to fit it...

www.saabv4.com
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