Large journal, small journal

[Chuffmeister]

I'm really sorry for my idiocy and lack of knowledge, but how do you tell the difference??? Does it refer to the diameter of the crank shaft? How do I tell whether my car is small or large journal and what are the differences between the blocks? I've seen some blocks with different caps that don't meet the sides of the block. Is this the difference? I'm getting slowly there with the understanding of terminology, so please have patience!

I have a 97 500. It isn't X-bolted, but has the bosses on the side. I want to know if it is small or large journal. I'm planning a few mods (when I eventually get paid). Can you tell from the pic below?

Thanks in advance!

Edited: I'm trying to research the block used. Original Rover Serial Number is 47A0****P 9.35CR, so not sure if this is an original factory 3.9 block as put in the Morgan +8 (so not a 3.5). The TVR serial is 37A50P*****, which is listed as a 5.0L Chim/ Griff engine at 10.1CR. The heads are HRC 2479's, which have the 10 bolt retention.

Having done some reading, there was a regular cross-over of engines being churned out. As mine isn't currently X-bolted, but has the larger caps, would I be right in assuming that it is a type 6 or a type 8 block as described here? So a block type 38A/ large journal?

Edited by Chuffmeister on Sunday 2nd February 12:57

[spend]

Large Journal & large Caps are totally different (and appears to be the source of your confusion?).

Large journal only in factory cross-bolted bottom ends

Large caps refers to last small journal blocks where the caps fill the block & are candidates to be cross-bolted by aftermarket machining / work. ie most TVRs apart from 450s which are factory fat journals (don't get confused by Robs hybrids where he makes 'frankenstein' 5.0s from big mains + small ends combos)

[Chuffmeister]

Thanks spend. I'm still a bit confused... What is the term 'journal' referring to then? What are the differences between the large and small journal blocks? Is it possible to use a standard x-bolted block with a 5.0l crank?

[spend]

Chuffmeister said:

Thanks spend. I'm still a bit confused... What is the term 'journal' referring to then? What are the differences between the large and small journal blocks? Is it possible to use a standard x-bolted block with a 5.0l crank?

Journal is the round bit that fits in the bearings, 3.9's, 4.2's, 5.0's (Rob reports there are some large journal ones but I've never seen one) all have the smaller 2.3" dia whereas the later 4.0's & 4.6's have the larger 2.5" diameter. So the cranks, block and caps are different for each crank type.

To answer your question, no... if you mean a factory x-bolted block (that wants a 2.5" mains crank & most 5.0 cranks will be 2.3")
Yes if you use a block with the x-bolt casting & fuller caps (most TVRs) with machine shop work to block & caps.

[Chuffmeister]

Thanks spend. I've just learnt a little more! So what is the benefit of having a larger journal? I'm assuming it makes the crank stronger, yet results in less flesh in the block. So X-bolting a normal 2.3" TVR block should be more than adequate for all but the most extreme applications?

Edited by Chuffmeister on Sunday 2nd February 17:41