Thursday, May 10, 2007

My head hurts from all the thinking

Poor vacuum, why would I have such poor vacuum on a new engine? I know it's been built right, valves and seats are new, as are pistons and rings. This has been going round and round in my head.

Valve clearances too tight causes low vac - prompted by a conversation with Dave Pearson I went and checked the Kent cams data - I couldn't see anything resembling what I was looking for so I emailed them - "It's all on the website" was the reply, I was just in the process of repying saying "oh no it's not" then I saw it - if you hover your mouse over "VC" it pops up with "Valve Clearance Inlet & Exhaust (mm)" with the values "I 0.56 E 0.61".

So I guess that's 0.56 for the Inlets and 0.61 for the exhaust. Converted to old money that's 22 thou for the inlets and 24 thou for the Exhausts - over twice what the workshop manual states for a standard cam. I'm kicking myself now I've realised this - one more thing to add to the list of things to fix :-) I may just experiment before I go this wide otherwise it's going to induce a lot of noise and some crappy characteristics on tickover.

Why do I have such a mental block with such a simple job as tappet setting?

Anyone know if those "click-adjust" gadgets are worth having??

Update 11/5/07 - Just had an email from Nigel Gair who's also running a Kent cam, higher lift version but same tech specs for vale to rocker clearance. He says he runs 15 thou inlet 17 thou exhaust - so I think I'll try those clearances.

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