Shoptalkforums.com

Does anybody know how much clearance there should be between the valve stem and the inside of the guide?
The reason I ask is because I seem to have more sideways movement of the valve inside the guide than I was expecting. I am used to working on more modern engines, and to me there seems to be more movement than I am used to seeing.
I can basically get the shank of a 9mm drill bit which measures 8.95mm inside the exhaust guide, and I can get the shank of an 8mm drill bit which measures 7.95mm inside the inlet guide.
My exhaust valve stems measure 7.98mm and my inlet valve stems measure 8.90mm.
I have to say, these valves are so heavy compared to what I'm used to!
Many thanks.

you are bang on with sizes, guide bore is 8.00- 8.06, there is no official wear limit by direct measurement, the standard test is to look for excessive rock through the lifted range, this is as good as it gets and there is always some rock even on new guides, but the norm is 1mm max rock, but thousands have more and run fine with no oil burning from being sucked down the guides. you are right, the valves are heavy and need more spring pressure than a T1 build for comparable performance, you cant just shim them because the spring deck is tight, i have lighter/longer valves made for race engines, but you could cut the spring seats one mm, and use proper h/d doubles, the stock springs will go to 6.500rpm but wont seat bounce that you would hear, but they will over speed the cam nose and clatter the guide tops/retainer, next stop is a dropped valve broken at the grooves by the contact, so 6000 is absolute the limit with stock springs and valves.

Dam double posting slow computer.

Thank you for taking the time to reply, you seem to be the font of all knowledge lately. I'd searched for this info in various places on here and found no definitive info.
I had the guides replaced a couple of years ago, but as I'm now going over the engine again double checking all the clearances, I saw this movement of the valve inside the guide and thought I'd better make sure it was ok. Started thinking maybe the machine shop had fitted the wrong guides or something.
I guess these engine don't suffer as badly from sucking oil down the guides due to them being horizontal and also being located at the top of the heads away from the oil.
Regarding the rpm limit. 6000rpm is way more than I need (for now) as I don't thrash it. This engine is fitted in a camper van, and is usually driven with the wife and kids rattling around in the back. Good info to know though.

same findings here on used WBX heads. BBB
On a couple of my R&D engines i have used heads with noticable play in the stems which were pulled out of cars with 200.000+ KM and used no oil. my thoughts were if they dont use oil and revs and runs normally it's OK in most situations.
U wan't more play on the exhaust

the heavy hydro lifters, steel pushrods and heavy valves requires a lot from the valvesprings.
put in light parts and the stock dual springs keeps up to ~8500 on boost

fastback wrote:same findings here on used WBX heads. BBB
On a couple of my R&D engines i have used heads with noticable play in the stems which were pulled out of cars with 200.000+ KM and used no oil. my thoughts were if they dont use oil and revs and runs normally it's OK in most situations.
U wan't more play on the exhaust

the heavy hydro lifters, steel pushrods and heavy valves requires a lot from the valvesprings.
put in light parts and the stock dual springs keeps up to ~8500 on boost

Some of my observations differ:

Hydro lifters are considerably lighter than plain Type4 lifters.

Wbx dual valve springs are really pretty light at only 100# with stock valve closed, and 180# with about .400" of valve lift. Running stock valves on some cams with steep lifts, such as the CB 2280, they can require shimming at as little as 5000rpm to raise those figures by about 20#. Lighter valves would obviously lessen or eliminate that need, the particular combo will tell you.

Given how many seized intake valves I see on wbx heads, but never an exhaust, as long as guide seals haven't been installed I personally prefer a little more guide clearance on the intakes.

well there has been some years ago i weighed them but , IIRC the hydros (filled with oil as in working state) was heavier than the solid ones (filled with oil also)
i'll check it up

but i was wrong

but i also weighed the Luba-a-lobes for type 4 back then but don't have them anymore .
anyone has the weight of those?

I have converted the hydro lifters to solid on some builds requiring a modest cam, it makes a nice light lifter, i find zero valve clearance on race wassers works well with cr/mo pushrods, and remain quiet when hot, they expand at a more compatible rate compared to the air cooled motors, we have ever de creasing noise tests at events, and have to register 105 D/B this season, the water jacket kills a lot of mechanical noise, another plus to the wasser over aircooled, i have 3 race hours logged on the Okrasa 2.5 and the valve clearances have remained as set at loose zero, i did have a seized inlet on start up when new, so that may have been too tight on tolerance, it was just on the one inlet. I run the much maligned T1 lightweight lubalobes in lifter bore bushes on web 86c, 87 gms, my rev ceiling is pegged at 7200 rpm, as it HAS to run all season and thats the cam max which i selected for that reason, i could run more cam and pick up another 10/15 hp at higher revs, but torque is king with circuit racing. has any one any info the rev limit of the stock hydros? .. would need an R&D test engine with heaver valve spring and i would think the stock cam would nose over before any meaningful data could be extracted, so that would need to be more adventurous and so it goes on to beyond the point where its all suitable for bus use...unless it had a turbo Fasty