Thread: a bigger engine in a 101?

A 4.6 would be an easy conversion - everything will bolt up. I assume you'll stay with carbs. I guess they'll need new needles to suit the 4.6

As you can see Iain and I have been discussing the issue of replacing his 3.5 carby V8 - 101" F/C using a 4.6 short motor.

The 101 is currently on dual fuel.

The question arose about a couple of items:

• Are the 3.5 heads compatible with the 4.6 block?
• What about the exhaust manifolds will they sit out wider or higher like in the 4.4?

Diana

Diana, if you'd like to compare them, I have a 3.5 short motor and a 4.6 short motor sitting here in the garage. I think you'll find that they are outwardly dimensionally the same, unlike a 4.4.

Should I merge these threads - see

http://www.aulro.com/afvb/fcs-milita...ine-101-a.html

Ron

That was my understanding until some confusing / conflicting information came along, so thought I'd get a consensus. (Not that consensus is the way to engineer vehicles or that I'd get consensus on an internet forum! )

I seem to remember a thread which talked about differential in the number of head bolts, but haven't been able to find the post.

Diana

Most (and despite documentation that says otherwise) 4.6 block and later heads only have provision for 10 head bolts. The outer row of 4 are not used. This isn't a problem. On old blocks it is recommended that the outer row only be lightly torqued just to fill the holes. Torquing to the manual-specified torque is now known to cause problems with head warping and gasket failure.

I same most 4.6 blocks because my block has 14 head bolt holes, it has the outer row of holes even though the heads don't.

I have some 3.5 heads you can try on the 4.6 block as well if you like.

Diana - I do not know about the heads or the physical dimensions of the 3.5 compared to a 4.6. But you need to be aware that a 101 3.5 is externally slightly different to other 3.5s. The oil filter is in a different position and the exhaust manifolds exhaust to the rear of the engine rather than in the centre like other rover v8s.

Having said this I am not sure whether fitting a standard 3.5 (or 4.6) would be an issue. I do not know if the oil filter on a standard engine will foul anything - and as far as the exhaust is concerned changes to the exhaust will definitely be required.

Likewise if the 101 is still 24v some of the brackets off the front of the 3.5 for the alternator may be needed. If you are going for 4.6 fuel injection mods to the gear lever will be required to clear the plenium chamber.

Garry

Gary

Iain tells me that the engine is already from a 91 vehicle so possibly not the original 3.5. My suggestion is that we get the engine number then we can see where it actually came from.

Regarding the other issues, I know that when Graeme Cooper Automotive converted my '85 RRc to a 4.6, the front timing covers, oil pump and other bracketry from the original engine were fitted up to the new short motor as were the extractors. Unless the 101 engine is a complete orphan I am assuming the process will be the same for Iain's 101. My concerns were the heads and the exhaust manifolds sitting out wider (which is what happened with the 4.4 I had for a while) and whether the ports on the 101 exhaust manifolds would be of sufficient internal diameter not to choke the 4.6.

Diana