Tappet Clearance

Paolobuchberger · #1 (**permalink**) 11-28-2007, 10:59 AM

Morning All,

Tappet adjustment time for the great engine rebuild. However the Haynes manual suggestions seem way too wide to my engineer friend and my mechanic suggested keeping them much tighter to avoid very noisy tappets(true Rob?).

Haynes says 0.35 - 40 mm for inlet and0.45 - 0.50 for exaust. Maybe this is for early engines?

The ome I'm building is from an 1986 type 33 105hp.What are people setting their clearances at?

evilgidget · #2 (**permalink**) 12-04-2007, 02:22 AM

I set mine to near enough .3 inlet & .4 exhaust. In theory there is a possibility of the cam overlap & duration being slightly different because of the cam lobe coming in contact with the lifter sooner & for longer - but I doubt it makes THAT much difference. Mine seems a little perkier in the 4-5000rpm zone, but it may also be ignition setup related.
It tends to spit a bit when cold & when trying to accelerate from a stop.
Trying to reduce noise - I doubt the lifters will make much difference - the whole engine is bloody noisy

Paolobuchberger · #3 (**permalink**) 12-04-2007, 02:54 AM

Thanks for that. Found another source that suggested .38 and .48, so pretty close to the Haynes suggestions. We'll try and keep them a little tighter to reduce noise a bit, but your right the whole thing is noisy - part of the charm!

**Alfar7** · #4 (**permalink**) 12-04-2007, 05:54 AM

Setting the lash with a smaller gap does quiten them down.
The increase in overlap while they are open riding on the closing ramp of the cam is tremendous. As a result, more spitting, loss of performance accross the board, and burned exhaust valves. To reduce overlap and improve drivability (torque) set the valves at the large end of the lash measurements if stock. On performance cams they should be degreed in to mfg specifications.