A friend who knows 850s very well drove our car around for a few days and noticed that the throttle response and torque seemed a little off on our 96 NA 5 speed. He said to check the cam timing and adjust both the intake and exhaust cams to 3 degrees advanced. The stock whiteblock cam gears have about 10 degrees of adjustment in both directions so its relatively easy to eyeball 3 degree advance. When I first checked my timing, I found the intake was dead center and the exhaust was about 5 degrees retarded. I brought both cams to 3 degrees advance (about 1/3 of the way between dead center and full advance). It made a difference. The throttle response is a bit better between 2500 and 4500rpm with more torque in every gear and about 1mpg better FE. Obviously this is all very subjective but if you drive your 850 every day, you should be able to notice this kind of difference. I think it applies equally well to both turbos and non turbos. Check your timing and adjust accordingly. If you do the adjustment post your opinion to this thread.
cheers
Justin
Check your cam timing
-
GrumpyOldMan
- Posts: 40
- Joined: 13 December 2008
- Year and Model:
- Location: Awestralia
- Been thanked: 1 time
um, sorry, but i dont understand just what i'm looking at.
I understand that it's the cam sprokets, but are there marks i'm looking for ?
Can you do a step by step or some sort of walk through
?
I understand that it's the cam sprokets, but are there marks i'm looking for ?
Can you do a step by step or some sort of walk through
?
-
FCPEURO
- Posts: 3002
- Joined: 17 June 2009
- Year and Model: 2006 XC90 V8
- Location: Milford, CT
- Been thanked: 19 times
+1, this sounds very interesting and I would like to check this on my 850, but I am not sure how to do this correctly. Is it possible you could give us a little bit more information to work with?
-
Ozark Lee
- MVS Moderator
- Posts: 14798
- Joined: 7 September 2006
- Year and Model: Many Volvos
- Location: USA Midwest
- Has thanked: 4 times
- Been thanked: 75 times
Last edited by matthew1 on 10 Feb 2011, 10:04, edited 1 time in total.
Reason: Edited link... QBM is out of business and their site is toast.
Reason: Edited link... QBM is out of business and their site is toast.
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe
Most 850 turbos will have the exhaust cam timing just a hair advanced, and the intake right in the middle. To advance the timing 3 degrees you will need to move the cam enough that the bolt is 3/4 of the way to the right.
By the way, when the bolt is more toward the right side of the cam then the left side it is advanced, if it's closer to the left side it is retarded.
You can advance the cam timing by simply removing the camshaft cover and bring the can gears around so the the exhaust cam (rear cam) timing mark is at 1:30 position and the intake cam (front cam) timing mark is at 10:30 position. The cams have a little line as the timing mark. use a marker to make them stand out.
When you loosen the camshaft bolt you can see the opening on the camshaft and how much adjustment can be made. From side to side it equals 14 degrees, so from the middle to the side it is 7.5 degrees. You should be able to eyeball 3 degrees. it's a little less than half way between the middle and the end.
On turbo cars the exhaust cam makes the biggest difference, so loosen one of the cam sprocket bolts about a 1/4 of an inch like in the photo above, barely loosen the other 2.
Turn the steering wheel all the way to the right, loosen the flap that covers the crank pulley behind the right front wheel. Using a large socket (can't remember the size) rotate the bolt slightly clockwise. I say slightly because the cam only has to move 1/16 of an inch to make the adjustment. I would start with about 2 degrees on the exhaust cam.
If your car is real slow coming off the line then this will help the car drive a little easier, but not necessarily faster. In other words getting up to speed will just seem easier, and yes there is a big rush of power at about 3000 rpms. I only advanced the exhaust timing on my 850R because it was so much slower than my 850 turbo I thought it wouldn't hurt. The car is easier to drive slow and made it a nicer car to drive.
By the way, when the bolt is more toward the right side of the cam then the left side it is advanced, if it's closer to the left side it is retarded.
You can advance the cam timing by simply removing the camshaft cover and bring the can gears around so the the exhaust cam (rear cam) timing mark is at 1:30 position and the intake cam (front cam) timing mark is at 10:30 position. The cams have a little line as the timing mark. use a marker to make them stand out.
When you loosen the camshaft bolt you can see the opening on the camshaft and how much adjustment can be made. From side to side it equals 14 degrees, so from the middle to the side it is 7.5 degrees. You should be able to eyeball 3 degrees. it's a little less than half way between the middle and the end.
On turbo cars the exhaust cam makes the biggest difference, so loosen one of the cam sprocket bolts about a 1/4 of an inch like in the photo above, barely loosen the other 2.
Turn the steering wheel all the way to the right, loosen the flap that covers the crank pulley behind the right front wheel. Using a large socket (can't remember the size) rotate the bolt slightly clockwise. I say slightly because the cam only has to move 1/16 of an inch to make the adjustment. I would start with about 2 degrees on the exhaust cam.
If your car is real slow coming off the line then this will help the car drive a little easier, but not necessarily faster. In other words getting up to speed will just seem easier, and yes there is a big rush of power at about 3000 rpms. I only advanced the exhaust timing on my 850R because it was so much slower than my 850 turbo I thought it wouldn't hurt. The car is easier to drive slow and made it a nicer car to drive.
-
tjts1
- Posts: 673
- Joined: 13 November 2007
- Year and Model: 96 855 NA 5 speed
- Location:
- Been thanked: 4 times
From my own experience and from talking to others that have done it, this is a trial and error process. It will take multiple tries to find idea setting for your car. +3 and +3 was recomended to me and it worked quite well for my NA 850 but I used an accelerometer to measure and compare in gear acceleration before I settled. Having an Ipone or Ipod touch can make the process much easier. The way my cams were setup from the factory was definitely not ideal.
Ambitious but rubbish
-
- Similar Topics
- Replies
- Views
- Last post
-
- 1 Replies
- 1705 Views
-
Last post by br0dy519
-
- 0 Replies
- 1467 Views
-
Last post by EuroDriver