74 replies to this topic

[lawrie124]

All

 

I'm going to build me a 'good' 998 engine to put in the van. Fast road weekend use, occasional trips to Nurburgring, Coombe Action Day etc. NOT a hill climber, so 2.95 or 3.1 diff on 10's.

 

So far I've got to collect a refurbed gearbox from Guessworks (thanks John), and having routed around in the shed last night I have 3 good bare blocks to choose from, and 2 cranks, and numerous flywheels!

 

So my thinking is to take the block, crank and flywheel over to my trusty engine man to:

 

. rebore +20

. balance crank, new pistons and flywheel

 

I'll then put it all back together with Kent 266 cam (also in shed!), time it up, and find a good big(ger) valve head and get that checked/flowed.

 

So what am I missing in terms of things I need to spend money on (apart from gaskets etc)? Aldon dizzy? Rockers?

 

any thoughts and advice much appreciated.

 

Mike

[blacktulip]

decent rad? good set of ARP bolts?

[Stiggytoo]

To do it properly, you'll want:
-Pistons. (Don't have to go mad with these, never had any problems with county pistons)
-All gaskets and oil seals, some kind of gasket goo etc. Maybe something like a Bk450 head gasket. EDIT: not Bk450 unless going for a 1275 head.
-Main/big end bearings
-Better cylinder head. Consider 12g940 conversion? or reworked 998 casting etc.
-Cam bearings (will need to be reamed out.
-assembly lube
-Deck block to pistons. WORK OUT CR
-Old head studs will be fine to use again.
-Obviously have your matching stage 1 kit or whatever lined up ready to go on. Consider using original air filter with k&n element/holes drilled.
-Duplex timing chain and set cam timing.

Have you considered what carb you're going to use. Maybe an hif 38 or hs4, or twins if you want it to look damn sexy.

Edited by Stiggytoo, 22 October 2014 - 03:54 PM.

[Cooperman]

BK450 head gasket won't fit on a 998.

You could bore to +0.080" which gives 1060 cc.

A FDR of 2.95 or 3.1 is awfully high for a 998 which has a narrower torque band than a 1275, and with further mods it will not accelerate well. A 998 will be capable of sustaining higher revs than a 1275, so maybe a 3.44:1 or even a 3.76:1 FDR might suit your applications better. With that engine you will be able to use up to 6500+rpm safely, so why strangle the acceleration with a high FDR?

[jaydee]

If building on cost, i wont be using +20. Go +.80 or use the standard pistons if bores are still good.

And deck the block to accept one of the later 940 head, will be cheaper than modifying whatever small bore head, and the baseline will be very good in terms of chamber shape. 

Standard bolts will be fine for use up to 6k rpm and occasional 7k. Do not use aftermarket bolts if not of the best make (ie ARP) but these will be expensive and an overkill if your engine will see a redline of 6k rpm.

[lawrie124]

Thanks all. I have alloy rad, new big ends and mains etc.

Was going to go plus 20 to take out any tolerance in existing bores, and get new pistons and rings.

I think I have heads to use rather than going down the 940 route.

As for FDR, I am fed up with the existing 3.44 as those long motorway journeys are a right pain at 5000rpm. I have 3.1s in stock!

Wasn't thinking of new bolts, and will check and get CR right.

Any thoughts on the Aldon dizzys, as really don't know much about them as usually use standard with bripart elec ign.

Thanks again for the input. I had forgotten cam bearings, and was going to use hs4 with k&n in standard housing as that's what it has now and the cone filters are not pleasant.

Mike

[lawrie124]

And forgot, will use separate inlet and lcb to existing single box mani flow.

[Stiggytoo]

That sounds good

[Carlos W]

I've got a head which you could have worked

[lawrie124]

I've got a head which you could have worked

Cheers Carlos. Think I have one on my spare race engine.

[Carlos W]

 

I've got a head which you could have worked

Cheers Carlos. Think I have one on my spare race engine.

 

 

Cool cool, if you're over this way and you want it give me a shout

[Gr4h4m]

If you want to run a 1275 head you will need to pocket the block.

[lawrie124]

If you want to run a 1275 head you will need to pocket the block.

Understood.

[Dusky]

Aldon yellow dizzy will suit your application.
Or try contacting ACDODD om here, he can recurve your standard dizzy.

[lawrie124]

Aldon yellow dizzy will suit your application.
Or try contacting ACDODD om here, he can recurve your standard dizzy.

 

thanks, but what's special about the Aldon dizzy? I can't see anything on their web site about the features of them.