Thread: 3.5 with 3.9 crank

Not sure what you are trying to achieve as the stroke is the same on both engines - so if a 3.9 crank can go in you still end up with a 3.5 engine. The main difference between the two engines is the bore - the 3.9 is larger.

Garry

Besides, the crank in the 3.9 is subtly different to the 3.5. AFAIK it won't fit. There used to be a stroker kit to bump the 3.5 up to 4L, but that was generally only in the UK. If you want extra go,swap the short engine over to a 3.9 block - all the other bits bolt on ok. Pick a Disco 1 between 91-93. ( They have the little 3.9 sticker on the side)

Essentially the only difference is the length of the keyway on the snout of the crank.

thanks guys i think il just find a 3.9lt seems easyer

Be aware that 3.9s have a tendency to slip liners which 3.5s don't.

When I get the time / money / motivation I will complete the rebuild on my 3.5 which is getting a stroker crank but staying stock bore.

Originally Posted by BigJon

Be aware that 3.9s have a tendency to slip liners which 3.5s don't.

When I get the time / money / motivation I will complete the rebuild on my 3.5 which is getting a stroker crank but staying stock bore.

I always thought the same, but a mate just pulled the heads off his 3.5 a couple of days ago, and found several liners displaced.

It would be prudent to top hat any rover v8 you plan on rebuilding. Just not as feasible financially on the smaller engines.

Originally Posted by BigJon

Be aware that 3.9s have a tendency to slip liners which 3.5s don't.

When I get the time / money / motivation I will complete the rebuild on my 3.5 which is getting a stroker crank but staying stock bore.

Or you could sell me the crank you have stashed away...