1098 with new intake, ex manifold and carb

[MikeNash]

Well, thanks for that, friends!

Soon I'll be putting the engine back as fully standard and then later I intend to go the path generally recommended of fitting the 1.5 SU with the "Flowtech" aluminium alloy intake with a cut down standard exhaust manifold. I'm not happy about butchering standard parts even if they're very plentiful but from what you say that's the best choice - at the moment! Later I'll play further with the idea of the Metro exhaust manifold and a home made exhaust. (Probably copper, Roy!)

Re a 940 head, Roy, I perversely wish to stay "nearly" standard - I'm not sure why. And regarding how often is full throttle required, well, around here we've many hills and I don't like to hold up traffic too much on A roads. And as I drive out immediately onto the A343 with a 1 in 7 hill at either end of the village it's foot to the floor soon after I'm on my way.

Once again, thank you for all your advice and comment, MikeN.

[bmcecosse]

Seriously Mike the 940 head makes a HUGE difference and will solve your hill climbing problems - especially if you stay with the standard final drive ratio. It is 'standard' as far as anyone but an 'expert' can tell....

[mike.perry]

I know the hills you are refering to. If you want extra hill climbing ability at the expence of a bit of top speed then just drop in a 4.55 diff and the speedo from a 1098 LCV.

[MikeNash]

You're right Roy. Got one for sale?
Regards, MikeN.
PS Mike P - you're just being silly!

[bmcecosse]

Fraid not Mike - I had a few but sold them earlier this year. I have a 202 head which has been modified to use the larger MG (295 head) inlet valves - and I have fitted new guides (which it desperately needed) - but that's as far as it has gone so far. If I get it finished off it will be a good head for a 948 engine - but hardly worth it for a 1098.

[philthehill]

Mike
You have a PM.
Phil

[MikeNash]

Phil.
Reply despatched. MikeN.

[MikeNash]

In answer to my question up above, Phil states categorically that "With the standard cam there is no chance that the valve openings will overlap so causing the exhaust pulsations to go back up to an adjacent cylinder". However, look at this picture of my rocker gear. I've placed a steel ruler as a straight edge across the valve spring retainers to show the position when any valve is fully closed and you'll can see the gap beneath the ruler for any valve that's open.[frame][/frame]

Above, the far right valve is No1 cylinder (the front of engine)'s exhaust and the 5th valve from the right is cylinder no. 3's exhaust; both are open so clearly there's overlap. The same happens for the exhausts of no.2 cylinder and no.4. I reckon they can be about 1/8 of an inch open at the same time which, to me, suggests quite an opportunity for interference. Judging by my valve timings which are close to the standard cam's inlet of 5/45, exhaust's 51/21 (I'll put up actual figures on another thread shortly) I assume I've the standard cam. (I bought the engine from moggyland's Most Famous Scotsman - our Roy - so he might correct me!) The performance suggests a standard cam too.

Perhaps interference isn't obvious because of the design of the exhaust manifold; it's much superior to the "log" type common in the 1940s to 60s e.g. Ford Consuls and Zephers. However, it makes me think that further separation might be a Good Thing.

Comments? Regards, MikeN.

[bmcecosse]

It was just the standard 1098 cam in that engine Mike.

[MikeNash]

Well, who'd have thought it! The standard cam has overlap! Thanks for the response, Roy.
Regards, MikeN.

[philthehill]

Mike
If my posting above is read fully the content is correct in that with a standard cam and standard exhaust manifold any overlap will not be enough to allow the exhaust pulsations to go back up and through an adjacent open valve port.
All of the BMC cams fitted to the 'A' Series have some overlap, some greater some less.
See Vizard for cam/valve opening/overlap specification and cam lobe timings/degrees.
If the overlap was beyond a certain limit say with a non standard performance cam the exhaust pulsations with the standard exhaust manifold could travel back up and through an open valve into an adjacent cylinder - the result would be that the engine would run terrible.
Only when you get overlap that is seriously in excess of the standard do you require the LCB type manifold. Having the LCB type exhaust manifold assists the scavenging of the exhaust gasses and makes sure that any pulsation of the exhaust gas flow put simply does not have time to go back up the LCB exhaust manifold pipe and through a open valve into an adjacent cylinder.
Phil

[MikeNash]

Sorry Phil! Of course I have read your post most carefully; I was being mischievous in my response, esp with my word of "categorically" attached to my quote. I apologise.

But I'm still surprised at the amount of lift on each exhaust valve at the overlap (and which is impossible to deduce from the valve timing figures). Observing valve lift against piston stroke shows these things much more clearly, an action easily done with sidevalvers with the head off but impossible, of course, with overhead valve engines. I put the lack of impact of this overlap on our engine running and the lack of improvement by fancy exhaust manifolds down to the quality of the standard system. Long ago and far away I saw a Raymond Mays four branch exhaust fitted to a Ford Zephyr which gave an immediate improvement. With the standard carb and intake there was no increase in speed but the idle, low and mid range performance was significantly better. Of course being a six cylinder engine overlap was clear and obvious, but the step from a tubular "log" just bolted to the side of the engine to the Mays system was an eye opener. And the Mays system in its forward branches was not much bigger than the Minor's.

Unfortunately, discussions on branched systems all seem to be about improved power and not interested in economy which is my interest. I'll think on it further. Regards, MikeN.

[bmcecosse]

It won't improve economy!

[Chipper]

Apologies for the holy thread revival, but do you have any more photos of the FlowTech inlet manifold, Mike?

I have one on my Traveller, but have yet to see another in various online searches.

[shoebone]

Nothing wrong with thread revival .... I'm intrigued ... Hey MikeNash ... How did that copper exhaust turn out?