Decisions! What would you do?

ihatesissycars · Post by **ihatesissycars** » Tue Jan 30, 2007 4:40 pm

I at some point in the furutre (not immediately though as i'm now skint!) will be fitting my 4.6 crank into my interim block and i have two options.

1. Line bore the block and at the same time fit the cross bolts.

£180 machine work, £xx for the bolts and about £30 for the bearings.

Advantages, bigger + better main bearing size and cross bolted caps.

Disadvantages, cost (about £250+) and risk a fooked block if they bugger it up.

2. Turn the mains down to the smaller size of my 3.9 block and fit studs.

Advatages, CHEAP!

Disadvantages, smaller bearing size, no cross bolts (in the grand scheme of things they are considered better than studs on their own its just if i'm going to be pushing things enough to need that extra security) less pub ammo.

What would you choose?

Anything to add to those?

Post by **Coops** » Tue Jan 30, 2007 5:05 pm

i always thought studs were better,
but what do i know

ihatesissycars · Post by **ihatesissycars** » Tue Jan 30, 2007 5:38 pm

But if i choose studs i get the smaller main bearing size so do you still choose option 2?

Post by **Coops** » Tue Jan 30, 2007 5:52 pm

i can only go by what i have now, (3.9 with studs)
and i have buzzed mine past 6.5k a few times at the pod and on the road and have had no problems with it from when i built it back in 03,

HairbearTE · Post by **HairbearTE** » Tue Jan 30, 2007 7:51 pm

X bolted blocks are great but dont get too carried away with the advantages of having larger mains. There are advantages with smaller mains too. The larger mains help strengthen and stiffen the crank, overlap between the rod journal and main journal is what helps this. Smaller journal cranks are lighter and reduce the amount of bearing surface area within the engine which in turn is desirable if your trying to squeeze every last pony out of the engine. Personally if i was faced with your dilemma i'd probably go with machining and x-bolting the block, unless your 4.6 crank has seen better days and could use a grind anyway.