Block help !!!

JSF55 · Post by **JSF55** » Mon Mar 26, 2007 12:45 pm

I'm having a day of it, the SD1 block i have is well scored up ! i've got a spare P6 under the bench, i'm going to pull it apart as soon as i finish writing this, there the same other than the rope seal on the rear of the crank? the front will be the SD1 cover, so no problem there, and the comp ratio change is in the heads ......... aaarrrghhhhh !!

Post by **katanaman** » Mon Mar 26, 2007 1:00 pm

SD1 is a stiffer block, it has a lot more webs cast into it. The compression is set by the pistons and not the heads so unless you change the pistons you will get the high compression. Sd1 heads are loads better than P6 ones so use them. P6 pistons are also the weakest of them all but they still survive fairly well unless pushed hard. There are loads of other small changes between SD1 and P6 but nothing major, basically the SD1 is better all round but the heads and front cover are the big ones to keep SD1.

JSF55 · Post by **JSF55** » Mon Mar 26, 2007 1:55 pm

Cheers marki, doesn't seem like a p6 block, looking from one to the other it seems the same, and it has a normal oil seal not a rope one? number is 48or it may be a 9 112628d 9.25:1 !! nothing on the list, pretty sure it was a manual spec rover p6 if that helps, trying to get hold of the guy i had it off, john

Post by **katanaman** » Mon Mar 26, 2007 2:20 pm

The webs are inside the engine. The webs running through the lifter valley are much thicker and there are extra webs under the timing cover giving extra support to the main bearing area. Its no big deal as there have been plenty fast P6 engines in the past, more if your starting from scratch your better using the later one.

You could also have a very late P6 which was pretty much the same as the SD1 engine.

If anybody recognises the number let me know and I will add it to the main list.

chodjinn · Post by **chodjinn** » Mon Mar 26, 2007 2:22 pm

well if you want a 3.5 SD1 block I have a nice chemically cleaned one sitting in my garage. I use it as my thinking stool, but I keep stubbing my toe on it so it really should go! Gota full rotating assemblyu too if ya interested, don't want much for it like

Ask Gav on here, he's had a goose at it about a month ago. Bores could prob do with a hone, that's it really.

JSF55 · Post by **JSF55** » Mon Mar 26, 2007 2:39 pm

Cheers guys, the spare motor will go in as it is, one day i might treat myself something a little more exotic !! but for now it's just a case of getting from one show to another, so relativley stress free ..... unlike today !! john

chodjinn · Post by **chodjinn** » Mon Mar 26, 2007 3:19 pm

hehe okay no worries

jrv8 · Post by **jrv8** » Mon Mar 26, 2007 5:20 pm

JSF55 wrote: doesn't seem like a p6 block, looking from one to the other it seems the same, and it has a normal oil seal not a rope one? number is 48or it may be a 9 112628d 9.25:1 !!

What you have is a very late P6 block. 9.25 :1 cr
These blocks were identical to the early SD1 blocks with a neoprene rear seal , only the heads and timing cover were P6 items. the pistons were a low compression version of the P6 items with the thick rings.
It will be fine for a rebuild, and you can use the SD1 pistons from your original engine to give a 9.35 :1 with the SD1 heads.
Jim

JSF55 · Post by **JSF55** » Mon Mar 26, 2007 7:56 pm

Thanks for the info, i just changed the rear seal and the SD1 i had in the kit was spot on, i'll be leaving it as is, i'm running out of time on this ! john