4 Bolt Block? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

RevHeadRon · 10-13-2003, 21:25

what to they mean by the 4 bolt block, yeah i know that there extra bolts that hold the crank in, but were they an engine block made by ford or are they an aftermarket modification? its not something that i'm considering on doing i'm just interested in the history behind the ford motors.

XC351 · 10-13-2003, 21:48

Ron, the 4 bolt blocks were made by ford. They were used in the 1971 Boss 351 mustang and they also used them through to '73 in the Cobra Jet Mustang's and Mercury Cougars. The idea of the extra outer bolts was to stop the crank walking at high revs for long periods (NASCAR) They are not needed for dragracing unless it is supercharged or a massive amount of nitrous which is unlikley anyway.

RevHeadRon · 10-13-2003, 23:02

so for street use its pretty much pointless, unless like u said your going to supercharge something?

xdc351 · 10-14-2003, 00:21

True they were designed for constant high RPM applications... But hey, if you can find one, its never going to hurt having the extra bolts there!

They were made by ford, unfortunatly not many. Cleveland 4 bolt blocks are rare as rocking horse sht and way beyone the budget of most street machiners.

TTNOS8 · 10-14-2003, 17:50

Yeah, rare as. They are known as 'Nascar' blocks, or 'Race' Blocks, and some other terms.

There were more than that scattered through some productions up until XE's and some late 70's, early 80's F-Series. Not many, but they were around.

Have seen std bore 4-bolt blocks, with caps only, for $2000 +

Anyone know where theres some??

XC351 · 10-14-2003, 18:41

I've got 2 at home one is '72 Mach1 CJ std bore other is '73 Mach 1 CJ +030. Not for sale.

Fat F100 · 10-14-2003, 23:24

Can a standard block be modified to accept the 4 bolt caps if you were considering supercharging?

XC351 · 10-15-2003, 01:25

Yes but it can actually weaken the bottom end if not done perfectly if the load isnt spread evenly across the caps. There are a lot of 8 sec cars that run 2 bolt blocks they are not weak in the bottom end like a 2 bolt small block chev.

laminge · 10-15-2003, 01:33

if you have a look through my thread I have a couple of pics of one

xacoupe · 10-15-2003, 01:52

I have a 4 bolt block in the XA ( CJ/Boss). ALL cleveland blocks can be drilled and tapped to accept 4 bolt caps. Unless the machinist is a complete klutz it can only be a good thing.

Is the 4 bolter necessary?? no way .. as stated plenty of quick cars run 2 bolt blocks/caps. It was just the thing to do at the time.

There are 'NASCAR' blocks and 4 bolt blocks. The NASCAR blocks ( with the XExxxxxx casting numbers ) are rare and expensive.
Unless you want a Boss motor for a reason I would be getting a std bore 2 bolt block and converting it.
A NASCAR block setup would want to be for a very serious effort due to the cost.