486 replies to this topic

[PhilipGCaldwell]

the pictures arent showing up very well, there is cross hatching effect on the bores, admittedly though it could do with more cross hatching effect on it to help bed the new piston rings in

[PhilipGCaldwell]

pistons slop measures with feeler gauge at 4-5 thou
better cross hatching achieved, will get a pic on later

[PhilipGCaldwell]

ctoss hatching, better picture

[miniobsessed]

Where are you measuring your piston to bore clearance?

You should measure the 'pressure face' at the bottom of the skirt. If you have 4-5 thou at this point then unfortunately you will only succeed in blowing oil out of your exhaust. IIRC standard piston to bore clearance upper limit is about 1 thou... If you're measuring around the ring area and you weren't aware - you will find the piston is a smaller diameter here than around the skirt.

Edited by miniobsessed, 02 November 2010 - 12:07 PM.

[PhilipGCaldwell]

right, thanks for the tip, will measure the pressure area when i get in
i was measuring at the top around the ring area

[patlink]

looks great the cross hatching
keep up the good work pocket rocket on a budget love it

[PhilipGCaldwell]

looks great the cross hatching
keep up the good work pocket rocket on a budget love it

Thanks Patlink

[PhilipGCaldwell]

right, the smallest feeler gauge i have is 2 thou, and it wont go past the piston skirt so I think its guna be fine

[Jet_black]

It's looking good so far, I want to do this to the spare engine I have got.

[miniobsessed]

right, the smallest feeler gauge i have is 2 thou, and it wont go past the piston skirt so I think its guna be fine

Good to hear

[patlink]

sounds good new phil

[twrminisport]

Really liking this. Similar spec to what i plan to do. Currently i am running:
998 A+
Twin HS2'S Fully Rebuilt by me
Flowed and Modified Inlet Manifold
Bespoke Pipercross Race Foam Air Filter
Maniflow Stage 3 Type LCB Exhaust Manifold
RC40 Large bore exhaust (single box)

All of this was tuned by me and my dad and when i took it to the rolling road they couldnt get any more out of it! Shes making 55bhp at the moment.

Plans are
12g295 or 12g206 head
Lightened flywheel
1.3 roller rockers
276 Cam

The rocker assembly is well worth changing. Although they are stated as being 1.3 standard. Read VIZARD. They arnt they struggle to make past 1.26 at the best (the joys of BL)
So a good set of replacement 1.3 rockers is money well spent. No bigger because as said they dont work haha.

If you need anyhelp tuning the HS2's or rebuilding give me a PM mate happy to help






That air filter is god-like trust me:)

Some useful sites:
Cylinder head identification and porting sizes by casting number: http://www.calverst......sting_ no.htm
998 Tuning further options. http://www.calverst....her_options.htm

[PhilipGCaldwell]

hey, nice spec, I love that air filter, wish i could afford one though!the ITG ones off calvers website are about £100 (from memory)

I agree, I am looking into 1:3:1 rockers as the sintered iam using arent the best ratio, but this is something Im gonna do in the future. The plan is to do it up to the spec I have stated then when money is good get an ITG filter, 1:3:1 rockers and (maybe) megajolt, oh and a neg camber kit

12g206 head, I have never ever seen one in the flesh! very rare now, the 295 is probably your best bet, I hear people get good results from them, I went for the 12g940 just because i had the engine out of the car and have the facilities to pocket it myself they give similar results Ive been told

[liirge]

I'm a big fan of trying to get the most out of a 998 engine, or any smallbore for that matter. I will be watching this with intrigue! also good work on the Cross honing, seems to have done a fantastic job brining up those bores again!

[twrminisport]

Yes the ITG ones are about 80. My one was 98 and IMHO well worth the extra