K-Series Timing/offset dowels

K-Series Timing/offset dowels

Author
Discussion

SlowStig

Original Poster:

839 posts

170 months

Monday 21st September 2015
quotequote all
I am hoping that somebody can shed some light onto this, but I currently have a VVC K-Series which has had some head work and a Piper 270 exhaust cam fitted, however I have been told that the engine won't make full use of the exhaust cam due to the timing not being correct for it. Apparently I need a set of offset dowels making to fit to the main cambelt end of the engine, however I have no idea if this is correct and/or where to source them from?
From readings, the timing needs to be advanced on the exhaust cam(I am happy to be wrong) but if this is correct, does that mean that the other cambelt needs to be adjusted or the timing kept the same?

Sorry if it doesn't make sense, I am a little confused by it myself.

leighroy

69 posts

142 months

Monday 21st September 2015
quotequote all
You might still be able to source them from Dave Andrews (of DVA Power) as I did with mine. I believe they can vary in terms of how much they are offset but 6 degrees springs to mind? I think to do it properly you would experiment with various offsets and check the timing to see what suits.

I'd have to check to be 100% certain but believe you'll put a pair into the exhaust cam only, it's been a few years since I did it. The 270 exhaust cam is something I've never been entirely sure of but I didn't have a direct comparison so I'd be intrigued to know how you get on.

Hope you get it sorted.


DVandrews

1,315 posts

282 months

Tuesday 22nd September 2015
quotequote all
Latency in the belt drive system leads the cams to be around 6 degrees retarded(on average). The use of two 6 degree offset dowels,,one on the front VVC mech and the other at the front of the exhaust cam realigns the whole system and gets th cam timing very close to optimum, the rear VVC mech is connected to the exhaust cam at the rear so realigning that also realigns the rear mech.

In case of interest I keep a few in stock.

On regular K series engines a 15 degree dowel can be used , this can be rotated in the hole to give any offset between -15 to +15 degrees, I keep these in stock as an alternative to verniers, they are fiddler to fit but they save the cost of verniers.

Dave

Edited by DVandrews on Tuesday 22 September 08:10

leighroy

69 posts

142 months

Tuesday 22nd September 2015
quotequote all
Quality information from the best possible source.

* I might be inclined to check I put mine together correctly!

SlowStig

Original Poster:

839 posts

170 months

Wednesday 23rd September 2015
quotequote all
DVandrews said:
Latency in the belt drive system leads the cams to be around 6 degrees retarded(on average). The use of two 6 degree offset dowels,,one on the front VVC mech and the other at the front of the exhaust cam realigns the whole system and gets th cam timing very close to optimum, the rear VVC mech is connected to the exhaust cam at the rear so realigning that also realigns the rear mech.

In case of interest I keep a few in stock.

On regular K series engines a 15 degree dowel can be used , this can be rotated in the hole to give any offset between -15 to +15 degrees, I keep these in stock as an alternative to verniers, they are fiddler to fit but they save the cost of verniers.

Dave
The perfect answer my question, right from the horses mouth too! With your experience would you suggest getting a set of 6 degree dowels from yourself to get the most optimum from my uprated exhaust cam then? When timing the engine, would I do it from the TDC marking or from the other timing mark on the lower pulley?

I would fit a set of verniers but my concerns are that without a rolling road local, I could potentially cock up the timing and make the performance worse!

DVandrews

1,315 posts

282 months

Wednesday 23rd September 2015
quotequote all
You cannot fit verniers to a VVC as the inlet pulley design is different and the exhaust pulley is dual mass to absorb the irregular pulses in the belt. The engine should be timed with the stock timing marks at 90BTDC as shown in the manual, however, before attaching the pulleys the offset dowels need to be fitted.

6 degree dowels should do the trick, if you can't source them elsewhere then I will happily supply them.

Dave

SlowStig

Original Poster:

839 posts

170 months

Friday 25th September 2015
quotequote all
Hi Dave,

Just for ease, how can I get a set of the dowels from yourself? Do you have a contact number to order through etc?

Thanks

DVandrews

1,315 posts

282 months

Friday 25th September 2015
quotequote all
It is always dodgy talking about commercial dealings on a BBS such as this. If you send me a private message I can send you contact details.

Dave