Alfa Pages

[rallyboy77]

What sort of RPM can the hydralic tappets handle, consistantly? I am particularly interested in 8valve engine. And when a tappet does fail, what is the usual consequence?

thanks Guys

[Eddie W]

The hydraulic motors I've seen seem to rev quite freely with no signs of pump up at reasonable revs. At what numbers pump up would occur I have no idea but that is the usual limitation in racing applications. When they do start to fail it is usually not pumping up enough with consequent rattling. They are also pretty expensive to replace all round. The biggest concern for your application to my mind is the heavy wear that the ones I've seen stripped show. In the case of Ben's motor the cams and lifters were junk and that was at relatively low Ks . In contrast the solid lifter setups show negligible wear at much higher mileage. I have to ask, why would you bother in a competition motor?
Regards Eddie
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[rallyboy77]

Hey Eddie,
Thanks for the info. The cams, tappets and hydraulic were all worn out?? Are the tappets and lifters and integral unit or can the lifters be replaced separately?

Well there is competition and there is our level of motorsport participation The Alfasud probably has another "usable" year of club level competition before we move onto a more suitable car (at which time the sud will be retired to the occasion histortic tarmac run, possibly)... and I am exploring all avenues of getting some more power than we have now, for the year ahead. The more money spent on this motor means less spent on a more suitable car at the end of next year... I could see using a set of rebuilt 1.7 QV heads and carbies with my bottom end as a good compromise. Although if we need to replace cams tappets and lifters we may as well get some cams ground down and source some carbies. Your thoughts?



Regards,
Jeremy

[Eddie W]

Hi Jeremy, Ican see the attraction of the 1.7 heads and agree entirely with the concept but realistically you would need to up the cam specs to realise the full benefits of the bigger breathing. Unless you managed to pick up some heads that had very good condition cams and lifters you will be faced with replacement and the lifters alone cost somewhere around $70 each over here . You do the maths. Now the solid setups are thick on the ground over here and worth peanuts( I assume the same in Aus) and my contention is that you would get moreby putting your money into a suitable cam profile to go with the 1.7 heads rather than into replacing hydraulic components. Remember that I said that a lot of the extra timing that youve picked up on the hydraulic cams having is lost in take up of the lifters and doesn't appear at the valve.Got to go to watch Bathurst. Will come back later to complete.
Regards Eddie
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[Eddie W]

Hi Jeremy, back again. How about a Kiwi winning Bathurst two years in a row To business, wear on the hydraulic lifters means replacement, wear on the solid lifters means replacing the shims or simply reversing them. Much cheaper( the same shims are used in the VW Golf).
The chamber has slight shrouding of the inlet valve but less shrouding of the plug than the 1.5. Both would benifit from mild reshaping along the lines of the old Cooper S racing chamber which had quite good flow. The ports of the 1.7 heads are definitely better than the 1.5 in size and finish and are less obstructive in the valve guide area.. In my opinion, a good cleanup with slight pocketing under the inlet valve, 3 angle valve seats and a reshape of the chamber as above would give you the improvements you are looking for at little expense. Couple this with a mild to warm grind if the bankbook will stand it and the 40mm carbs of course.
I used to run a Cosworth A6 in my Escort ,112 degrees overlap and not a lot under 4000rpm but gangbusters from there to 8500. I'd be interested in what you have done for filtration before the carbs as I feel that the elbows from the filterbox add essential length to the inlet tract but the standard box can be improved.
Regards Eddie
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