Engine/Gearbox alignment angle

[akelly]

Hey all,

having an issue with my IIA with holden conversion others may be able to assist with. The engine/gearbox is angled up at the front to put the holden intake manifold horizontal, but this angle causes the gearbox to foul on the tunnel cover diaphragm and puts the gearstick so far back it fouls in the tunnel cover. The total 'setback' of the gearstick is about 25mm. If I remove the engine mounts (they are homemade ones as far as I can tell) and lower the front of the engine so the gearbox is horizontal everything sits in the right position, although the intake manifold is very slightly angled down at the front - maybe a couple of degrees.

The car previously had a 6cyl bulkhead and bastardised tunnel cover and floor panels to make everything fit. I've replaced all that with 4cyl panels but the result is the aforementioned 25mm discrepancy.

I've been searching for pics of a holden conversion from the side without all the panels in the way but can't find anything. What I need right now is the angle on gearbox in a properly fitted 4cyl SWB with a holden conversion. From what I can see in the pics and diagrams in the manual and online it looks like the gearbox is more or less horizontal and when I position mine like that everything seems to fit properly.

Cheers,

Adam

[JDNSW]

Because it is not a standard engine installation, there is no such thing as a "properly fitted" Holden engine installation. That said, ideally the angle of the gearbox should not change with the engine installation (should be horizontal relative to chassis datum), because changing it means the angle of the universal joints on each end of both drive shafts will no longer be equal, resulting in drive vibration and potentially rapid wear of the joints.

However, retaining this angle usually will mean that the front crankshaft pulley interferes with the front crossmember. Most conversions deal with this by modifying or moving the crossmember, but a few have dealt with it by raising the front of the engine just enough to clear the cross member, with all the problems you note. A very few, I suspect manage by moving the gearbox back slightly and generally using maximum manufacturing tolerances. Whether this is possible will depend on the actual flywheel housing adapter - they vary somewhat.

[Homestar]

Yes, cutting a 2” section out of the front crossmember solves the issue so the whole lot can sit flat. When I did this years ago the Engineer just got me to weld in a section of angle iron where I cut the crossmember and then weld a bit of 100x50x3mm RHS in front of it to regain any lost strength.

[akelly]

all that has already been done, the engine clears everything by a country mile. I think they had the front jacked up to level the intake manifold and then made a bunch of Frankenstein floor panels to make it all fit. I'm trying to undo the butchery as much as possible.

[Homestar]

Ah, that’s makes sense. [emoji106]

Make them sit flat and deal with the manifold angle if it becomes an issue - I can’t recall it being one on mine when I had it.

[akelly]

Yeah I can't see a couple of degrees on the manifold being an issue at all.

[JDNSW]

No, any issue will be with the carby angle, and that should not matter either. If it does, a wedge under it would seem to be the go.

[mick88]

Adam,
when i recently refurbished a couple of my Holden powered Land Rovers i decided to drop the engines down so that the crankshaft was aligned with the the centre of the port in the front cross member, so i made up a tool for the job.
My cross members has not been recessed for the engine conversion, so it was an easy task.
Also the engines i have do not have the tilted inlet manifolds, so the carby sits perpendicular to the engine.

The face of the tool bolts onto the harmonic balancer and the wooden wheel, goes into the crossmember port.
Then I set about "tweeking" the engine mounts to suit. Worked a treat.


Cheers, Mick.