6 bolt vs 7 bolt?

JasonAG · Post by **JasonAG** » Wed Mar 12, 2008 8:12 pm

ok, so can someone link me to a good page with all the differences. or if you feel like telling me thats cool too, and also, is a 4g64 from a 95 mighty max for sure a 7 bolt? cuz i just bought one for a donor and now i need to re think it.
thanks!

slowquest · Post by **slowquest** » Thu Mar 13, 2008 9:05 am

a 95 should be a 7 bolt. Quickest way to tell is to look at the flange between the oil pump and oil pan on the very front of the engine. If it's perfectly flat, it's a 6 bolt, if it is curved under the balancer pulley, it's a 7 bolt.

On a side note, if it's a 7 bolt, and your not going to use it, I would be interested in getting it from you.

JasonAG · Post by **JasonAG** » Thu Mar 13, 2008 1:38 pm

well, i just need to know if i can still swap a dsm head on it. im gonna keep it for something though, so sorry.

slowquest · Post by **slowquest** » Fri Mar 14, 2008 2:30 pm

2g dsm head should bolt right up. evo 8 and 9 MAY bolt up. some of us are doing the research at the moment.

have you verified whether it's a 6 or 7 bolt yet? if it's a 7, how about a pic of the deck surface of the block?

JasonAG · Post by **JasonAG** » Fri Mar 14, 2008 4:10 pm

well, im picking the truck up tomorrow morning, and it runs so i plan on driving it for a little while until i get my conquest road worthy so im not gonna take apart the motor just yet. either way im almost positive its a 7 bolt since it is a 95 model year and acording to the chart on this site all of them past 92 or 93 were 7 bolt.

i really hope the evo head works! id totally builld a 2.4l mivec turbo for my quest!

JasonAG · Post by **JasonAG** » Thu Mar 20, 2008 8:12 pm

ok, i have most of it figured out. heres my next big question. how different is the 7 bolt crank from the 6 bolt? is it just journal sizes or what? there isnt much...or any, options for 7 bolt wide block flywheel/clutch so if i could get a 6 bolt crank to throw in there that would be much better.

DSM Eric · Post by **DSM Eric** » Tue Jun 21, 2011 3:25 am

I am like 99% sure that you can not use a 6 bolt crank in a 7 bolt block..

JasonAG wrote:ok, i have most of it figured out. heres my next big question. how different is the 7 bolt crank from the 6 bolt? is it just journal sizes or what? there isnt much...or any, options for 7 bolt wide block flywheel/clutch so if i could get a 6 bolt crank to throw in there that would be much better.

Bill Hincher · Post by **Bill Hincher** » Tue Jun 21, 2011 7:47 am

there has always been talk about crankwalk in the second gen 7 bolt cranks, but I am not real familiar with it
the problem seems to go back to the oiling system
a lot of DMS sites claim to have fixed the problem

The casting on the EVO and the second gen engine are the same, the difference is in the oil return holes from the head are not drilled in the second gen engine block casting

the first gen engine casting has no place for the oil return holes required for the EVO head

I have all the different engines, I just havent had time to play with the different parts

jeffball610 · Post by **jeffball610** » Tue Jun 21, 2011 3:37 pm

The 2G DSM has 2 versions of the 7-bolt block. The EVO is basically the second version of the 2G DSM block.
The first run of 7-bolt blocks used a thrust bearing as part of the center main bearing. This is the area that most believe is the cause of crank walk. There are other reasons, but this is where it really shows the effects.
The second version of the 7-bolt has a thrust washer that is separate from the main bearing. This is usually called the 97+ version. The washer is made of steel instead of the bearing material and is much more resistant to thrust loads.
The answer to the first question is NO. 6-bolt and 7-bolt cranks are not interchangeable in any way. The journals are all different as far as I know. 6-bolt rods can be machined to fit the 7-bolt crank if desired. (common "upgrade")
I personally like the 7-bolt crank/block design, as it has a main bearing girdle which is found in almost all high HP performance motors. Proper setup of the 7-bolt motor is crucial in helping to eliminate crank walk. Jack McGee of Jackstransmissions.com says he has a crank-walk proof setup on all his motors. I believe him.