VR Oil Pump and Timing Chain.

[Stag76]

I'm fitting a VR V6 to a Triumph TR7, and am fitting a new timing chain and tensioner kit due to noise in the timing case area.
The timing cover wouldn't come off, but eventually did after a lot of juggling and wriggling, revealing incompatibility between the pump and timing chain cog.
The oil pump driven plate has 2 sets of 3 rebates approx 8mm wide and 8mm apart, with two 27mm drivers between the two sets of 3.
The crankshaft timing chain cog has no rebates, just parallel flats on two sides.
This has caused substantial wear on the driving cog, jamming the cover on, and is probably the source of the noise.
The new timing chain kit I bought has 6 equally spaced rebates, approx 12.5 mm wide and 10mm apart.
What I need to know is which is the correct combination for a VR V6.

[vlad01]

You probably have an early VR engine that is the same chain system as late VN and all VP with the two flats on the pump drive.

You can retrofit either type as long as you have the matching oil pump and balance shaft drive gear that goes behind the cam sprocket as the earlier type is thicker at the hub to compensate for the thinner sprocket and chain used in the early engine.

The bit that can get you undone is the chain damper, there is 3 types, even possibly 4 and not all interchange between the blocks as the spring hole and the bolt hole are either all the way through the casting, or blind in the case of eariler engines. Being VR regardless of early vs late, it should have the drillings all the way through so it should take all types. Early blocks only take the short early types. The late VR damper are wider and offset in the front/back direction to accommodate the wider chain they use. This wider setup is the one that uses the 6 spline oil pump.


I upgrade my engines to those type, not for the chain as I go double roller chain from Rollmaster, but becasue the 6 spline oil pump is less prone to chatter on start up and doesn't wear anywhere near as bad as the 2 flat design. In theory the 6 spline is also far more immune to harmonic induced failures like seen in many Jap cars and the Barra. The 2 flat design is prone to breakage due to massive loads at the two small contact points and uneven loading along the corners of those two spots when pounded back and forth during harmonics and torsional vibration. The V6 having a big solid and short crank doesn't generate enough of these destructive forces as a 4cly or a inline 6 especially, so it's never been as issue other than wear on these engine's pump and drive. But I like the 6 spline drive, it's much better engineering.


To keep things simple, you just need to get the early type, so late VN to early VR if yours has the 2 flat drive. Your damper is probably the narrow type with long bolt and spring. Just check your old one against the new one. I ordered one and it was the wrong type iirc. Mine was the shorter old narrow type but I ordered the narrow late type as at a glance they all look the same. My block had the blind holes so the newer types did not fit. Sure I could drill them through but not in situ as I didn't want swarf in the sump! I thought about cutting the spring and bolt, but the shorter type runs a stiffer spring for what I presume is because it doesn't go far into the block.


Interestingly, I found good chains that are tight to make the balance shaft rattle and old worn ones to be quite. I figured this out to be how tightly the balance shaft was coupled to the crank, the tighter the coupling, the more the gears and bearings rattles from the back and forth rapid backlash due to millisecond scale rpm variation most seen at and around idle. There is absolutely nothing wrong, that's just a quirk of the mechanical design that are these engines. So it's actually often the opposite to what people say, it's actually a rattly top end is a healthy low wear engine, smooth is worn.

When I replaced my chain during a gasket change, the engine was quiet, the chain and sprocket was worn heaps as it was close to 400k. New chain and sprockets and damper, the engine rattles like a MF, the balance shaft rear bearing is where most of the noise comes from.

Some 40-50k later it sounds exactly the same, like a cement mixer.

Lifter rattle is another subject entirely and I reckon I know the reason that happens too, it's not lifter related as I have without doubt ruled that one out. My old bomb is absolutely perfect on the lifter front always has been, others with new lifters on super low K engines tick, nothing to do with wear or lifters for the most part.

[immortality]

Vlad, you know this topic well, maybe you want to do a quick guide with some pictures to make all of this clear as mud?

[vlad01]

I could but I don't have any of the parts on hand and I only have one early type block on hand, so it's hard to be accurate going off my acquired shoddy memory. I might be able to cobble something from online pics and some saved pics I have, but I really need all of the stuff in hand to do it accurately.

I'd like to have a vn series 1 covered, but I only even had the one engine which I sold complete, I only know some about them limited to my research and pics I found online. They are quite the beast when it comes to differences, they were way different in a lot of ways to the later engines, especially valve train stuff. The rest was similar enough.

I have some VN series 1 heads that got sent to me by mistake 3 days ago, interestingly it confirmed the hunch that I had that their rocker arm bosses are way bigger than all the other engines, so they make ideal heads to upgrade to the adjustable Yella Terra rockers since they use 7/16" bolts and need to be drilled out bigger, there is limited meat on the VN II and later heads, it still works but I feel that the VN I heads have more head room (no pun intended) for that mod.

I want to see if their springs are double or not.

[Gareth]

VN1 Heads need to be drilled for crank case vent in order to use them on series 2

[immortality]

VN series 1 heads do have double springs and the larger rocker bolts. I have series 1 heads here if you want pics.

They also have different cranks auto/manual.

[vlad01]

Yes they can be drilled, negative on the double springs, this pair has the same ones as all other Buicks I've had, so I still can't verify the double spring thing. My shitbox has new double springs from crow though that will be put onto the replacement heads.


The heads I got are stuffed and the wrecker agreed to swap them over, or I should be able to pay the difference and get ones that have been tested and guaranteed good to go.

[immortality]

I've had a couple of Series 1 motors and they definitely have double springs fitted.

[Gareth]

I second that

[vlad01]

Maybe they were early ones like 88 and 89. The only series 1 I had was a 1990 model. It didn't even have the alloy covers as most people say all series 1 have. Actually nearly all series 1 out in wreckers I had been to over the years didn't have alloy covers either, it was maybe 1 in 5 cars had them, so I believe 88 and maybe 89 were far less common than 90 models and the springs might be part of this difference.

On the subject of chain dampers, VN saw a change I read on a pontiac or olds forum a few years back about the damper, and they had early on one that was just a nub of plastic on a arm of sorts, then they went to the familiar design we're used to. So over VN to VR there is likely over 4 different types of dampers.