Visual differences between 3.5 and 3.9 carby motors

[STIKA]

Can anyone tell me of any visual differences between a3.5 and 3.9 carby motors

[RUFF]

What Brett needs to know is there an external difference in the Block. Not including the engine Number. I know my 3.9 was obvious because it has the indexed(pin punched look) engine number commonly used in late model cars around the world now.This engine has letter stamped numbers but so did the early 3.9s. Brett has bought an engine and is not sure if it is a 3.5 or a 3.9. It has a Carbed manifold on it and he hasnt removed it to see if the heads have the slight cut outs for the injectors in the intake ports.

It is supposed to be a 3.9. Is there a way to tell externaly?

[p76rangie]

There is no real way externally to tell the difference between a 3.5, 3.9, 4.0, or 4.6. As you can use 3.5 heads on any of these blocks, looking at the heads will not tell you much.

[landy_man]

the 4.0 and 4.6 have a small opening on the lower side of the block...can't remember what for.. perhaps sensor...
but AFAIK their is no distinguishable difference between 3.5 and 3.9
grab engine number and search for listing

[Rainbow Warrior]

the 4.0 and 4.6 have a small opening on the lower side of the block...can't remember what for.. perhaps sensor...
but AFAIK their is no distinguishable difference between 3.5 and 3.9
grab engine number and search for listing

Some 3.9 blocks like mine had about 4 more head bolt holes in the block each side than earlier heads, well at least mine did, 10 head bolts each side on my 76 heads and we could see the extra holes after assembly, I had no problems fitting a 3.5 timing cover & mainifold.

[Bush65]

the 4.0 and 4.6 have a small opening on the lower side of the block...can't remember what for.. perhaps sensor...
but AFAIK their is no distinguishable difference between 3.5 and 3.9
grab engine number and search for listing

Some 3.9 blocks like mine had about 4 more head bolt holes in the block each side than earlier heads, well at least mine did, 10 head bolts each side on my 76 heads and we could see the extra holes after assembly, I had no problems fitting a 3.5 timing cover & mainifold.

Other way around - later heads have 4 less head bolts (10 vs 14).

Here is a pick of my 4.6 with 3.5 heads. You can see heads of bolts for cross bolted main bearing caps and the sensor opening that landy_man mentioned (cover fitted on flywheel side in my case).

[Rainbow Warrior]

the 4.0 and 4.6 have a small opening on the lower side of the block...can't remember what for.. perhaps sensor...
but AFAIK their is no distinguishable difference between 3.5 and 3.9
grab engine number and search for listing

Some 3.9 blocks like mine had about 4 more head bolt holes in the block each side than earlier heads, well at least mine did, 10 head bolts each side on my 76 heads and we could see the extra holes after assembly, I had no problems fitting a 3.5 timing cover & mainifold.

Other way around - later heads have 4 less head bolts (10 vs 14).

Here is a pick of my 4.6 with 3.5 heads. You can see heads of bolts for cross bolted main bearing caps and the sensor opening that landy_man mentioned (cover fitted on flywheel side in my case).

Hmmm, maybe either my heads were later model than I thought or I'm just remembering wrongly from 7 years ago. The original block was supposes to be a Rover car motor, maybe the heads were too. Anyway, the 3.5 heads went well on the 3.9