| Author |  Topic  | |
Borstlap
V4 Fanatic
Norway
334 Posts |  Posted - 13 May 2010 : 15:57:09  
| Some years ago I bought in my quest for performance parts an 8.6 cam from Mel at Highgate. I never installed it because I haven't gathered all the other bits needed, but I am wondering what it would do with a 1.5 engine with standard size valves. From what I read on Genty's website breathing is a combination of valve lift and valve diameter. If I understand correctly, high lift combined with larger diameter valves robs driveabillity at lower revs. What would it do when standard valves are used?
It is not often that the engine does more than ± 3000rpm; the maximum speed on most motorways here is 80km/h. For overtaking a bit extra oomph would be nice. In 4th, starting at 3000rpm, the engine feels a bit flat til it hits 4000rpm. In 3rd, starting at 4000rpm, the engine is lively and very responsive up to 5000rpm; then upshifting is needed.
What is wisdom considering the driving conditions I am faced with? Try swapping the 8.6 for something less radical? 
Alex |
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rsimps
V4 Guru
United Kingdom
1616 Posts | Posted - 13 May 2010 : 16:38:28
| | You dont want an 8.6 s on a road car, its very flat under 3500 rpm then goes like a train up past 7000 rpm. A 7.6 cam is ok for road use, but you want some v6 valve springs and make sure your timming gears either in good condition or uprated. |  |
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Woody
V4 Guru
United Kingdom
2764 Posts | Posted - 13 May 2010 : 20:32:38
| It would seem a road/rally cam would be more beneficial. The SAH cam I used was ideal for road use and good on rallies back in the 70's. Saab's 7.2 has a higher lift than the SAH and I have yet to try it for comparison. The 7.6 again could be used on the road but I suspect may be a bit flat under 3500rpm.
I haven't yet decided which option to go for. My 7.2 appears new but came with spacer and key installed and the 7.6 is brand new. They came from Motorsport Sweden in 1990.
Left to right below : 7.6, 7.2, SAH, Standard. You may notice that the central oil groove on the SAH cam was enlarged to increase oil flow to the rocker shafts.
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Edited by - Woody on 13 May 2010 20:35:45 | |
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rsimps
V4 Guru
United Kingdom
1616 Posts | Posted - 14 May 2010 : 08:07:05
| The 7.6 pulls well from around 2300 rpm to a good chunk of power at 6200 rpm. You will want a better carb than a FoMoCo, ideally a twin barrel one.
I never find myself using much more 6300-6500 rpm in the Green Rally car even with twin webers. This cam in my opinion suits the gas flow of the v4 engine the best providing max torque and bhp low down. I carnt really see the point in the 7.2, the 7.6 is not that cammy.
What I would do is port the heads to the Saab rally manual (at least on the inlets) to provide the correct cross sectional area to make the max flow out of the std valves. If you can add a three angle cut to the seats and back of the valves. Use something like a 1-1.2mm seat width, you will see that this opens out the port and valve area a little.
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Borstlap
V4 Fanatic
Norway
334 Posts | Posted - 14 May 2010 : 08:42:10
| Thanks for the replies guys. The engine is fitted with a Weber 32/36DGV-5 carb, K&N air filter, Pertronix and Highgate exhaust with headers and flanges opened up to 38mm (diameter of the connecting exhaust pipe), so another cam should be the next step. I have a set of Sonett valve springs in stock. The timing gears are the type with metal wheels and fibre cogs and are in excellent shape. Anyone in for a swap of an 8.6 cam for a 7.6 :)?
Alex | |
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 14 May 2010 : 09:07:24
| quote:
Originally posted by Borstlap
The engine is fitted with a Weber 32/36DGV-5 carb, K&N air filter, Pertronix and Highgate exhaust with headers and flanges opened up to 38mm (diameter of the connecting exhaust pipe).........
Alex
Did it come with ear-defenders as well???
--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" | |
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2strokereg
Starting Member
16 Posts | Posted - 14 May 2010 : 09:59:42
| If it is of any use to you, there is a 7.6 cam currently on eBay in France, starting bid EUR€200.
Martin | |
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Borstlap
V4 Fanatic
Norway
334 Posts | Posted - 15 May 2010 : 09:52:14
| quote:
Did it come with ear-defenders as well???
--
Pete
HUH? It did get noisier but not that much actually (maybe the ear damage is already worse than I thought  ).
Alex | |
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 15 May 2010 : 12:41:59
| quote:
Originally posted by Borstlap
quote:
Did it come with ear-defenders as well???
--
Pete
HUH? It did get noisier but not that much actually (maybe the ear damage is already worse than I thought ).
Alex
I ask, because when I bought my car it was fitted with a Highgate exhaust! The noise was unbelievable! Lovely sound, but just TOO MUCH of it!
I use the car for journey work, and one 300 mile round trip was enough to convince me to fit something more civilised!
I'm sure Chris (Transit80) will confirm how loud it was!!!
--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" | |
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Borstlap
V4 Fanatic
Norway
334 Posts | Posted - 15 May 2010 : 20:34:24
| At grownup motorway speeds (at least 120km/h) it is noisy, but not so noisy that my ears can't handle it (and I am really not deaf). The only thing one shouldn't do is trying to keep up a lively conversation. But since I moved to Norway grownup motorway speeds are a thing of the past; 80km/h is the rule here. Then the noise isn't too bad.
Alex | |
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rsimps
V4 Guru
United Kingdom
1616 Posts | Posted - 17 May 2010 : 07:55:00
| | XP classic racing have all the profiles for the Saab cams, I think Newman cams also have them. Just get a regrind on a std cam, all the Saab cams were regrinds. | |
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| | Topic | |
8.6 cam
