Hey guys--

Looking at the 300 block I can see how crucial a tight lifter bore is to proper oil pressure.

I was wondering who has measured their lifter bore during a rebuild?

 

anyone have anything to say?

 

Sounds like its one of those "should do's" but I dunno anybody who does.

Friend got bit with his dirt track chebby. He bought a used block, it went all the way through machine shop and didn't find out it had been bored out for ford lifters until final assembly. When his new lifters were too small.

Brigart

 

So, did he use Ford lifters?

 

i sure would hope so. the ford lifter is larger diameter than the chevy lifter, enabling you to run a more agressive cam without gouging the lobe. its not as popular as it used to be with the increasing popularity of roller cams. normally done on engines that have to run a flat tappet for their class

 

I have a roving gang of machinist gnomes in my neighborhood. They measure lifter bores.

What is the propper way to check them? One might get a ballpark reading using a divider and a mic. If not maby a rigid bore gauge set but that is not a cheep tool.

 

ahhh, the little gnome b....s!

 

You get a pretty good idea when you take the old ones out,If they were worn on the sides at all,then you would be suspect and do some checking.I have seen worn lifter bores on Harley Davidsons,but they had lifter blocks and roller lifters,really looked funny running with the pushrod tubes open,they kinda dance and rock back and forth and really get expensive (the owners never laughed).First off,the hydraulics wouldn't work right,so your valves would clatter,because of oil pressure loss causing the lifters to not pump up.I think it would be kinda rare to see them worn that bad,as they work in ideal conditions,constantly in oil film and it would take a lot of running in filthy oil to wear them to a point that they couldn't hold oil pressure.When you run way too low on oil,the first sign you get,other than lower oil pressure,is noisey lifters.I would really doubt that your lower pressure is from oversize lifter bores.On a lot of engines,you may have to "cut" the varnish off by pulling and turning them to even get the old ones out.I doubt that hardly anyone mics the lifter bores unless damage is seen to the old lifters and I sure wouldn't point any fingers at anyone that didn't.

 

I don't know anyone who measures, I have taken a brake hone to the bores before, to clean them up, and have never had any ill effects fom it. I think the oil kinda makes a seal. if the bore was big enough to make a difference, the lifter would just drop in and wobble around. you would notice this when you pushed the lifter in when assembleing it.

 

Something interesting: The 300, according to Napa, uses the same lifters as the 289, the 240, 302, and the 351 (I forget if was the 'W' or 'C'.)

OEM is .874 bore. The lifter is .873! I thought one thousandth of an inch was pretty impressive.

 

I knew it was pretty tight,they have that"zero clearance " feel when they are in with oil on them.They almost have to be tight,because if you had much clearance,with the pressure and direction put on them,they would want to wobble and cause wear,and they have to have a good seal in order to function the hydraulic part.