Tappet bore alignment


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By Don Woodruff - 17 Years Ago
One of the areas to look at in building an ultimate engine is the correct positioning of the tappets with respect to the camshaft. We see boring and sleeving of the tappet bores to correct any misalignment on "serious" engines.

As we are looking at 50's machining on the Y block I am wondering if Ted or Hoosier (anyone) have looked at this on the Y block and have experience correcting problems if they indeed do exist.

Don W.

By Ted - 17 Years Ago
Don.  I haven’t looked at the tappet bore alignment on the Y’s in particular but with a 1.000” lifter pad, it’s going to be less of a problem on a Y than with an engine that uses a smaller diameter lifter in regards to any accelerated lobe or lifter wear issues that may crop up as a result.  I’ll typically just check the camshaft lobe action for consistency on all the cylinders and if that checks out, then I’m good to go.  If there is a bank to bank difference being found when degreeing in all sixteen lobes, then tappet alignment would be at the top of the list but I don’t see this on the Y engines.  In the Y’s defense, it was actually designed and put into production at a time when engineering and quality at FoMoCo were put ahead of the bean counters which explains to some degree as to why there are still so many 1954 239’s still around.
By Don Woodruff - 17 Years Ago
Thanks Ted. My first 57 Bird had a very good engine,with the carb off my 390/375 and 4.57 gar it ran 92+ in the quarter. Altho I did not measure it when torn down it appeared to be very close to a 0 deck engine. My current 57 has been rebuilt and the pistons are well down the hole and vary .018 from end to end. As was only doing a valve job(and correcting some core shift) I did not go any farther. I am currently planning a rebuild to go with the Mummert heads and trying to get my ducks in a row. For my purposes, weekend cruiser, I am planning a mild engine. Building a paper engine using Engine Analyser Pro is a lot of fun but untill I get more componets in hand for better measurements it is just fun. So far 377 HP @ 5000 and in excess of 400 lb/ft of torque may be possible BUT small variations of intake tract lengths, header lengths, or altering of cam timing a few degrees it is back to the 350 hp range.

The EAP program is very accurate and helpful as proved on over 50 engines built from it (personal experience).