A labour of love

V8 engine build part 5 – oil pump base adjustments

V8 engine build part 5 – oil pump base adjustments

Not a major update today, but I ran into a confounding little problem whilst fitting up the front end of the engine which I thought deserved a bit more detailed coverage.

The factory GT V8 used a remote oil filter arrangement due to a lack of clearance between the front crossmember and the standard bottom right position of the oil filter on the Rover V8, and I had planned to replicate the same arrangement. It utilises an oil pump base with hose take-off connectors that connect to the remote oil filter and cooler, and it looks like this (also pictured, a brand new set of oil pump gears as my old ones were a little worn).

So far, so good. The problem became apparent as soon as I tried to fit it. I’m using a late 4.6 engine of course, rather than the early 3.5 used in the factory V8s, and one of the most notable differences in the block is the presence of the additional cross-bolts locating the main bearing caps in the 4.6 (and late 4.0) engines. And naturally enough, one of those cross-bolts sits right next to the oil pump casting on the front cover, making it impossible to fit the oil pump base, as illustrated in the photo at the top of the post.

After a bit of head-scratching, and possibly a little swearing, I admitted defeat and went to consult the books, and Google, in the hope of salvation. I couldn’t find any mention of this issue in the usual guides, but I began wondering if there was an alternate base available, or even some kind of spacer to bring the base further out and clear the bolt, but didn’t manage to find anything. Eventually I turned up a few forum posts discussing it, so it was good to know I’m not in uncharted territory, and it seems the usual “workaround” suggested is to grind back or countersink the cross-bolt to create clearance.

So I went back and removed the bolt to see how it looked without it. Even with the bolt removed, the head of the spring retaining bolt on the side of the pump base still fouls the boss of the cross-bolt on the block by a few millimetres, as pictured below, so it was clear it was going to have to be ground back a bit.

Before I got started I ordered a new cap-head bolt to replace the standard one. This is a genuine part used on the other end of the block to solve a similar clearance problem with the starter motor, so it felt quite appropriate to use the same trick here. It’s slightly shorter than the regular bolt to allow for it being countersunk into the boss.

Thus equipped, I bravely attacked the cross-bolt boss with a die grinder, taking about 3mm off of the face, just enough for the pump base to clear it. I then had to open up the bolt hole wide enough to allow the new bolt to be countersunk, which was much more difficult to make a tidy job of. Eventually I had it wide enough (and almost vaguely circular!), but then spent a bit more time with a fine grinding stone trying to make sure the bolt head and dowty washer still had a flat surface to mate against.

That all taken care of, I inserted the new bolt and torqued it back up to the right setting, and then it was time to test fit the pump base again. Very pleased that it now fits perfectly, if still a little snugly, and I can crack on with some more assembly.

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