Hi - looking for some zetec guru's out there.

I'm doing my first full engine build - my 2lt block is away being bored out to suit some forged pistons and I have some steel rods to go with them. The head has been fitted with some bigger valves and thoroughly ported and I have some high lift cams which are suitable for hydraulic followers. The pistons are pocketed, etc, etc. It should be a nice engine when finished.

However, while the block is away, I've started thinking about the next stages and I got to researching the valve - piston clearance method and have hit a snag. When the engine is running it will have oil pressure - when I check it it won't. So, my understanding is you swap the hydraulics followers temporarily with some solid followers so that the valve opens correctly. Along with some soft checking springs you can check the clearance easily with some plasticine.

But - how big/thick should the temporary solid followers be? Am I right in my understanding that the follower will be slightly pumped up even when the valve is opening? How much is this amount? Is it constant? The follower then pumps up further as the valve lift reduces, thus taking up the 'valve clearance' you normally shim to achieve on a solid engine. Is that right or am I missing something obvious?

My followers are drained down so I can't measure them, and even if not, how would I know I was measuring what the valve would see as lift? The Haynes manual only states the diameter of the follower... so I'm feeling a little baffled

Doesn't only apply to Zetec's either I guess, anything with a hydraulic follower would give the same problem. Anyway, I'm confused - can anyone enlighten me?

Cheers,

Phil

One for Uncle Albert...
Sure he'll be along soon with a pearl of wisdom or two

You are going to need a couple of solid followers, there are several sites that show how to modify an hydraulic follower for this purpose.

Does the camshaft manufacturer give no info on the mods required, most do in their blurb.

But why go the expense of steel rods, forged pistons, bigger valves and then saddle yourself with cams that use followers that will seriously restrict your rev range and thus your ability to use the expensive components to their full potential.

Some years ago I built a Silvertop that made 208 bhp and still had standard valves, sensible porting (by Scholar), cast pistons (2.1 overbore), standard rods, Kent FZ2002 hydraulic cams/springs and a 7500 rev limit. Cost peanuts for the power.

Caterham zetec
How many peanuts for 208 BHP?
My Silvertop would like to know
Totally agree with you regarding overspeccing the engine though - Steel rods/crank etc for racing engines only IMO
I've always been happy with my 160BHP silvertop but hey for peanuts why not have 208BHP

At the time (9 years ago) I think the costs were:

£300 for porting to Stage 2 which included recutting valves seats, reshaping the combustion chamber, fitting new valve springs and skimming the head to give the correct compression ratio (I provided the volume above the piston including the gasket). Work was carried out by Scholar Engines thus not a back street or DIY job.

£400 for Mahle pistons including balancing fitting to rods.

£60 for rebore to match pistons.

I already had the cams/followers and the labour was my own time. Other parts were usual parts required for a rebuild thus not included.

So I went from about 175 bhp to 208 bhp for under £800.

Or if you wanted to modify an engine from 160 bhp to an engine of my spec it would have been probably £1200 at the time.

But its pointless unless you have 45's and a decent exhaust, which I already had.

CatZ
I have TB's, Emerald and decent exhaust already fitted.
So maybe £1200 worth of peanuts it is

Don't forget that was at 2004 prices, they have risen since I am sure. And don't forget about all the gaskets, bolts etc, they add up to quite a sum. Make sure you have a local trusted engineering company to carry out your machining and ensure they will send back parts cleaned, sealed and ready to use. Cleaning a block in the bath is not a good idea, the engine fluid stinks for days and blowing compressed air through the galleries makes a right mess. Did it once about 20 years ago, never again, took it to the local engine shop and let them wash it properly whilst I cleaned up the mess.

Another thing to consider is how many times do you actually enter the rev band where spending the money benefits you. Following a calamity with the 208 bhp engine it is no more, the car is now fitted with a totally standard Blacktop using Jenvey 45's with a MBE ECU. For 99.9% of the time the car is probably faster, the low down pick up is instantaneous and there is no hesitation anywhere is the rev band. The 208 was later fitted with the Jenvey system so it is a direct comparison, both have been mapped carefully by the same person. The Blacktop is putting out approx. 175 bhp and I do not feel short changed, I expected to be and planned to get the head sorted by Scholar but 5 years on there is simply no need. I can drive to Cadwell on some of my favourite roads just as quickly and overtaking is probably easier, no need to drop as many gears. Best bit is fuel economy, OK, on a 7 its not a top priority but its nice to see that the car does 31 mpg with the Blacktop instead of 26 mpg with the 208.

My advice is to think carefully before you spend, having big BHP's looks good on paper and gives you bragging rights in the pub but it does not necessarily make the car more enjoyable. In truth I could have just as much enjoyment with my original Caterham which had a lowly 1700 x-flow. And never forget that more BHP buts extra load on other components which will fail if not upgraded, been there, done that.

CatZ
Of course you're right - you make very valid points relating to engine power, Many say less is more and like you I've been well pleased with my 160BHP, Pleanty for road use & especially when wet 160 maybe too much, I like driving the wife's 125BHP sigma you can wring it's neck in complete safety yet get great satisfaction after a drive, even in the wet!
So even though 208 sounds good on paper the car would probably be a pain to drive OTR. I don't need any bragging rights in the pub nobody else locally has an S4 everyone has the distinctly common S3 :ducks: