New engine :) - Which exhaust?!

[TomLS]

Hi all,

I have, this very evening, collected my Traveller's new engine to be.
It's a 1098 10CC block with +60thou regrind, and reground crank, with full harmonic balance, pocketed block, Cooper S 12G940 big-valve head, and an as yet unidentified Piper cam, believed to be 285 profile. (It revved cleanly to 7000rpm in his A35 )
All the work was done in 2000, with full receipts totaling over £800, and the engine has done a believed 3000 miles since then. From the fact that the bores are still machine-shop condition, I can well believe it!
It was quite a steal at £260 too!

The only shame is that the guy, who was clearing out his old garage (read hayshed with space for 5 cars and a big workshop, plus mesamine space!) in order to move house, clearly didn't know some of the gems he had. It transpired that he'd chucked (yes, as in sent to landfill) a pair of Wolseley 9" drums, and 2 3.9 Diffs just the week before!!! His exact words were "You could've just taken them, but they got chucked last week." GUTTED!

Any way - with the above setup, what type of LCB would people recommend? I've seen 'large' and 'small' bore LCB's for sale for minors, but there only seems to be about 1/8" difference between the two. Is this really going to make much difference? Or have I fallen in the annoying middle ground between the two? Before anyone suggests it, I can't really afford to buy both and test it. Certainly not this month any way!!!

Cheers,
Tom.

[bmcecosse]

I would fit the larger LCB and system - your engine has the potential for 80/85 maybe even 90 bhp . But I strongly suggest you severely limit excursions above 6000 rpm if you want it to last........ Which means of course that the 285 cam is not ideal - you would do better with a 276 - or even a 266. The 285 cam is a lovely cam, don't get me wrong - just not suitable for a 1098 engine with it's very long stroke and weak conrods. A 285 gives it's best power in the 5 - 8 k range, so limiting it to 6k in your engine means you lose power in the 3 - 6 k range - to gain power in a range where your engine is not safe to use.

[TomLS]

I was expecting, and to be quite honest, happy with the idea, of a power around the 70bhp mark, but I won't say no to more! Just means I will have to upgrade the 8" drums sooner than imagined...
I'm glad you said big-bore; they seem to be easier and cheaper to get hold of! I did think 285 sounded a little much. I'm not certain any way until I can pull off the front cover and have a look. The seller did say it was a very capable road car, which would also lead me to think a 285 was rather unlikely. 265 (or a Kent 266) is what I was planning for the 'standard' 1098 with a normal 12G940 head I was originally going to use, so maybe a 275 will go quite nicely.
Any way, I'll see whats in it over the next few days and make my decision from there.
As for the revs - I didn't intend to take it past 6000 any way, thats plenty for me!!

[bmcecosse]

You will need an HIF 44 on a good alloy manifold

[TomLS]

Hmm. I have a freshly rebuilt HS6 with an ally manifold - will that do the trick? At least to start with?

[bmcecosse]

Oh yes - HS6 = HIF 44 in flow terms. Just the HIF is better at handling surge. The carb would benefit of course from careful attention as described by Vizard.

[TomLS]

D'oh, I meant an HS4 (1.5"?)
But no matter. With a bit of rough porting, the ally manifold from the HS4 will fit one of the 4 spare HIF44 carbs I have from my V8 (just checked), I just need to use a left-hand-side one to get the linkage on the correct side. I'll plonk them all on the dining table tomorrow night and see if I can't make one good one out of 4 scrappers!

I'd better go and re-read my big yellow bible, I can't remember what he says about tweeking the carbs!

Cheers Roy.

[bmcecosse]

An HS4 will work - but will limit the power -maybe a good thing for a long life engine !

[TomLS]

Thats also good to know - but I like HIF44's and have a lot more experience of stripping them down!
Read the carb mods in Vizards book - seems to be quite worthwhile.
Any idea what needle I could use as a start point in an HIF44 with the above specced engine?

[bmcecosse]

Can only suggest the BDL as a starting point.