97 850 cam timing specs

[div4scpro]

If this has already been answered in a different post, apologies. Have a 97 NA850, US market, non Calif. if that makes a difference. If the cams are aligned with the cover marks, exactly what timing is that supposed to represent? Have looked in Vadis and AllData and cannot find the answer. What are the factory spec cam numbers for this model? It's all well and good to talk about advancing this and retarding that but if we don't know what the baseline marks represent or where true zero is we can't know how much change we might be putting in.

[jimmy57]

The cam setup on that engine is not via keyed cam gears and solely based on crank markings. The crank has a ground indexed pad on a counterweight that you reference with an inserted pin into block under starter. The back of the cams are indexed after they are ground via the offet slot on back end of cam. A tool positions cams while crank is set against index and the timing belt is tensioned all while the cam gears are mounted but with loose bolts allow gears to "float" via the slotted bolt holes. Then with tight timing belt you torque the cam gear bolts. The slight hash marks on gears are for timing belt changing. If the gears are ver removed the setup procedure needs to be used to assure correct cam timing. The cam and crank referencing is not at TDC for cyl #1. It is not at TDC period. It is a setup position where cams will stay put for belt changing and also where piston valve contact can't occur during heavily robotic assembly.
If the marks where bolts have been tightened look undisturbed it may be safe to assume it is still in stock postioning and the cam advance and retard tricks can be done using what you have as starting point. If evidence of changed bolt position is on face of gears then who know....

[matthew1]

Here are a few cam timing-related topics that may help:

• Advancing/retarding timing on Volvo inline-5 engines for performance
• Setting cam timing after timing belt job
• Performance cam timing adjustment didn't help hp... an account by a trusted Volvo tech
• More Cam timing tips with photos
• Quick Brick Cam Timing Tool documentation added 2/2011

[tjts1]

If this has already been answered in a different post, apologies. Have a 97 NA850, US market, non Calif. if that makes a difference. If the cams are aligned with the cover marks, exactly what timing is that supposed to represent? Have looked in Vadis and AllData and cannot find the answer. What are the factory spec cam numbers for this model? It's all well and good to talk about advancing this and retarding that but if we don't know what the baseline marks represent or where true zero is we can't know how much change we might be putting in.

Volvo never published cam timing specs. The cams are adjustable about +/- 7 degrees at the point where the cam bolts onto the cam gear. In stock form the cams are timed dead center relative to the gears. Some of us have adjusted the cams to move the torque curve up or down in the rev range.

[div4scpro]

Sorry guys but I feel like I'm still in "a little bit here, a little bit there' land. Some posts I read talk about how accurate the timing cover marks are, and then you look at the pictures of different peoples jobs and none of them match precisely. Some say that there are 10 degrees adjustment each way, then the same person will say 7 degrees each way in a different post. Is that 10 or 7 degrees either way from the factory setting or TDC. Some say that alignment with the cover marks represent factory timing, which is what? To be advancing or retarding on intake or exhaust from a reference position when you don't know even what that reference position represents. I bought the IPD tool because it is the most precise tool that I can find, but now people are arguing whether it represents adjustments from TDC or from factory settings. In other words, just an example, if I adjust the exhaust to 2 degrees advanced with this tool, am I adjusting 2 degrees advanced absolute, or advancing the exhaust 2 more degrees from factory settings. Maybe I spent too long in the aviation industry but nothing is adjusted from a baseline if we don't know what it represents.

[div4scpro]

have been working on this for a while:
here is at least one perspective on the stock cam timing for a 97 NON-turbo. With the factory cam locking tool and the crankshaft locking tool installed the following numbers were observed using the IPD cam-timing tool, developed by Lucky @ Volvospeed I think. The reading on the intake cam was 0 degrees advanced on the timing tool, the reading on the exhaust cam was 4.5 degrees retarded. Remember, I cant say what amount of advance or retard this actually represents but this at least gives the factory baseline and a starting point using this timing tool if you intend to do any timing experiments.

Before anyone criticize these numbers, make sure you read how I said the numbers were obtained, that they are for a non-turbo and what they represent on this timing tool only!

[jimmy57]

On the non-cvvt gears on white motors the gears can be fitted in three places, the three slotted holes are at 120 degree spacings but the teeth on gears are not in the same spots relative to each of the slots. If you want to call the slots A, B, and C I'll give you an example. If my car has slot A up from factory then I may have the gear CCW most of the slot range so the the bolts are almost all the way to right at right end of slots. I have almost no ability to move cam advanced and maybe 11 degrees to go retard direction. You may have slot B up and the bolts are in the middle and you can go 6 either way. Ozark Lee may have slot C up and his bolts are at left end and he can move 11 degrees advanced and almost nothing retard.
To make this further confusing Lee and I could have our gears put on one tooth repositioned and our range of adjustability would reverse.
The gears are put on randomly but in time and then the faint little hash mark is punched then, no consistency. Then there is the question I have not answered: are the bolt holes in cams consistent or are those random too? If the holes are uniform then it is a one in five chance that some one else could give you a range that is also true for you. If the holes are not uniform then who knows. I have experimented to know the gears will fit in all three positions. The slots were made long enough to do that. If it is not allowing what you want to do you get the lock tool for cams and ignore the hash mark and put the gear on in one of the other two slots and if the teeth allow it, also to the desired tooth to get you what you want. If it is more range you want then a machine shop milling the slots longer is another choice.