51 replies to this topic

[Retroman]

    DV's yellow book is a reference bible, there are new cranks con-rods cams and pistons available since it was published and a few other useful components / mods but most of it is still very useful advice.

   Sadly [or glady haha] David is now retired but his partner Dave Anton still runs their speedshop APT in sunny California, we are bringing some APT parts across the pond shortly.

 

A 998 can now go to over 1100 cc with 68mm pistons and there is little to beat more cc's 

[JonnyAlpha]

Just adding to this thread. I picked up a 12G295 un-modified cyl head with the possiblity of fitting it on my 998. I understand that the standard 998 has dish top pistons which were different to the Cooper 998 (did this have flat top or D topped (convex pistons)). So the head would need to be skimmed to obtain the desired compression ratio which is?

 

Anyway - if I were to change my pistons and poss get a rebore what pistons would be best? 

 

Thanks

[WillCarter]

Omegas are always a good piston but I've heard the minispares megas are good too. Someone will know a lot more than I do about pistons but here's some info about a 998 rebore: http://www.theminifo...194-rebore-998.

[JonnyAlpha]

What I was getting at was that to decrease the amount of skimming needed would it be better to fit Flat Top Pistons?

[Retroman]

The 998 Cooper had raised D pistons

 

If you are considering fitting the 295 head you need to measure the cc's in the chamber and measure how far down the bore your pistons are.

 

You can then work out the compression

 

https://jscalc.io/ca...RNEglVkKLQir11T

 

Flat tops would probably help but measure what you have 1st

[JonnyAlpha]

Just resurrecting this thread I started.

 

I now have a 1275 engine that I was going to sell but am now considering holding onto it. Now I have a conundrum (which I have posed before), do I stick with the 998 that I know and upgrade that, or do I rebuild the 1275 and put that in instead. The 1275 A + has little to no history, came out of a Metro that had done 90K but the owner is adamant that it was a replacement engine. 

 

Difficult decisions.

 

998 would have 12G295 head skimmed to suit correct CR. 998 would be bored out to probably 1097 with dished or Flat Top Pistons, Evolution CAM, Electronic Ignition and Stage 1 kit. 7.5 Disc Conversion. May fit a lightened Flywheel and Duplex Timing Chain?

 

1275 - rebored, Evolution CAM, Electronic Ignition, not sure about the head, Stage 1 kit and again lightened Flywheel and Duplex (cost dependent).

 

Decisions, decisions.

[luismx123]

If I could id go for the 1275. It would end up cheaper - I think. However, I do enjoy my 998 stage 1 motor. Its either 'no replacement for displacement" or "you cant beat the revy torque of a well tuned 998"

Pick your poison ;)

[cal844]

For me it's 1275 every time. What you could do is use the 1275 motor and the 998s gearbox as you know that the 998 box works properly

[timmy850]

Honestly, if you have both go with the 1275. You need to do all the same work anyway (pistons, rebore, bearings, brakes etc) and even rebuilding the 1275 near standard will be better than starting with a 998

[andyapanel]

Did you think about sourcing a 1098 crank and converting the 998?

I put a 295 on a 1098 with a Kent 266 cam in my Pickup It was very torquey and ideal for the lanes and hills round me. Hope the bastards who stole it enjoy it.

My Cooper with a 1275 was excellent for longer distance cruising.

[JonnyAlpha]

Did you think about sourcing a 1098 crank and converting the 998?

I put a 295 on a 1098 with a Kent 266 cam in my Pickup It was very torquey and ideal for the lanes and hills round me. Hope the bastards who stole it enjoy it.

My Cooper with a 1275 was excellent for longer distance cruising.

 

I was considering boring it out to 1098 but do I need a different Crank? Is the stroke different?

I was considering an Evolution001 CAM.

 

to be honest I probably need more torque than long distance speed. 

[Mrpeanut]

Did you think about sourcing a 1098 crank and converting the 998?
I put a 295 on a 1098 with a Kent 266 cam in my Pickup It was very torquey and ideal for the lanes and hills round me. Hope the bastards who stole it enjoy it.
My Cooper with a 1275 was excellent for longer distance cruising.

I was considering boring it out to 1098 but do I need a different Crank? Is the stroke different?
I was considering an Evolution001 CAM.

to be honest I probably need more torque than long distance speed.

1098 is the 998 block with a different crank. Personally though I'd rebuild the 1275, fit a decent gas flowed head and sling in an evo1 cam. I've used one in a 1330 with a decent head and it was a phenomenal engine - bags of torque and power all across the revs.

[andyapanel]

 

Did you think about sourcing a 1098 crank and converting the 998?

I put a 295 on a 1098 with a Kent 266 cam in my Pickup It was very torquey and ideal for the lanes and hills round me. Hope the bastards who stole it enjoy it.

My Cooper with a 1275 was excellent for longer distance cruising.

 

I was considering boring it out to 1098 but do I need a different Crank? Is the stroke different?

I was considering an Evolution001 CAM.

 

to be honest I probably need more torque than long distance speed. 

 

 

It might be an idea to read David Vizard's books to get an idea of what is possible. There is a chapter on sample builds which might help you decide.

If you did go down the 1098 route, it might keep your insurance down as a bonus.

As has been stated by Mr Peanut, the 1098 is a longer stroke 998-you "just" need to swap the crank.

Good luck

[timmy850]

And different pistons for the 1098 too

[Retroman]

DV's book is obviously the engine bible, but the bigger pistons available now are not listed.

 

plus 0.100 and 68mm [+0.135"] make really big cc on 998 and  a 1098 will go to 1217cc

 

They make really good torquey engines with a decent head and carb