raising compression

bodger · Post by **bodger** » Mon Jul 28, 2008 11:03 pm

its not a hotwire one by any chance is it Kevin ... ?

CastleMGBV8 · Post by **CastleMGBV8** » Mon Jul 28, 2008 11:29 pm

Keith

No it's the hardware from a Gems system, but I'll need to use a 3.9 plenum, the 4.0 one I have is much too high at the front to fit under my MGR V8 bonnet.

I haven't decided whats going to run it yet, it certainly won't run well on a standard hotwire set up, so will probably go Megasquirt with Edis 8 for the ignition.

When I eventually get the new engine in I'll use my existing Edelbrock 500 with a re-jet until it's run in and know there are no problems, and then switch over to the injection system and get it properly dialled in.

Kevin.

PS I do have a good 3.5/3.9 crank if you need one.

Darkspeed · Post by **Darkspeed** » Mon Jul 28, 2008 11:31 pm

I have a set of P6 pistons sitting in a block in the garden about to go to the dump - free if you want them.

Andrew

bodger · Post by **bodger** » Tue Jul 29, 2008 10:01 am

Hi Andrew , are they 10.5 :1 ?

my number 07758 739625

keith

Post by **katanaman** » Tue Jul 29, 2008 10:18 am

bodger wrote: can i tell if the pistons are 10.5 .. do they have any dish at all in them ?

10.5 pistons are virtually flat topped. They do have a very slight dish but its easy to spot them in comparison to others.

bodger · Post by **bodger** » Tue Jul 29, 2008 11:14 am

i have just discovered that the rings are differant on 10.5 P6 pistons , deeper ring groove ...
RPI do them ... £35.00 the set ...not too bad

ChrisJC · Post by **ChrisJC** » Tue Jul 29, 2008 11:55 am

They look like it, but really you need to zoom in a bit more on one piston. Maybe give it a clean too?

Chris.

bodger · Post by **bodger** » Tue Jul 29, 2008 12:06 pm

this is the picture off ebay Chris ... i'm only using the pistons and rods ...

they will be all shite and briny before they are fitted ... oven cleaner do's a lovley job on pistons

i used it on my senator pistons and they came up a treat

spot the before and after :

Darkspeed · Post by **Darkspeed** » Tue Jul 29, 2008 8:01 pm

Left you a message - yep 10.5's

Andrew

bodger · Post by **bodger** » Wed Jul 30, 2008 1:30 am

Hi Andrew , i got your message on my way to pick up the engine ...

i couldn't let him down as i promised i would have it

what sort of condition are your pistons in ... don't dump them

how much would you want to pop them in the post , probably better to leave them attached to the rods as the gudgeon pins are a press fit ...or stick them on ebay
you never know

regards ...keith

bodger · Post by **bodger** » Mon Aug 11, 2008 2:55 pm

right then , i'm NOT skimming the heads ... 10.5 :1 pistons ..

new rings and a light hone ..

and TIN heads gaskets ..

20 new bolts tightening the 2 rows to 25NM + 90 + 90 degrees ..

outer 8 to about 25 ftlbs ish ..

and new big ends & mains while i'm in there ...

anything i have forgotten ?

ChrisJC · Post by **ChrisJC** » Mon Aug 11, 2008 3:12 pm

bodger wrote:right then , i'm NOT skimming the heads ... 10.5 :1 pistons ..

new rings and a light hone ..

and TIN heads gaskets ..

20 new bolts tightening the 2 rows to 25NM + 90 + 90 degrees ..

outer 8 to about 25 ftlbs ish ..

and new big ends & mains while i'm in there ...

anything i have forgotten ?

My experience of tin head gaskets and stretch bolts is head gasket failure after about 20K miles. I would stick to the reusable bolts.

Chris.

Post by **katanaman** » Mon Aug 11, 2008 4:37 pm

don't use stretch bolts on tin gaskets, I would say dont use stretch bolts period but that's just me. If you want it to be bomb proof invest in an ARP head stud kit.

bodger · Post by **bodger** » Thu Aug 14, 2008 3:38 pm

All done ....

went with comp gaskets in the end , all new rings , mains , bigend bearing , oil seals and bolts

25nm + 90 + 90 degrees and they where tight on that last 90 degrees ..

and i did the outer 4 on each side to about 25 ftlbs ... ?

biggest nightmare , getting to the outer head bolts , it's a bit tight insitue , got round it by taking it off the front engine mounts and moving from one side to the other to get to them
wished i taken it out to do it , but no engine crane and doing on my parents drive ...oh well done now

did 20 miles then a 2nd oil and filter , seems to be ok ....

running in ?

not gone over 2500 revs yet and no loading the engine too much ?

ChrisJC · Post by **ChrisJC** » Fri Aug 15, 2008 7:09 am

bodger wrote:
biggest nightmare , getting to the outer head bolts , it's a bit tight insitue ,

I shortened a socket set extension bar to exactly the right length, and it was still very tight. Just doable though. Mind you, I never fitted the outer four bolts at all.

Mind you, you've not got the proper V8 bulkhead have you, as the std. one is a tad smaller in places. Not sure if it makes any difference to this job though.

Chris.