Ted,



Photos from the articles show a dial indicator jig/tool that slips over the rocker to measure open/closed contact variation. Is that a home made adapter, or a part that can be ordered? When I try to take those measurements free-hand (with a digital caliper) on OEM type rockers, I always get different/inconsistent #s.



Also, still trying to get a handle on what stem/seat-height variation tolerance is acceptable?






6 VOLTS/POS. GRD. NW INDIANA

The pictured dial indicator is a manufactured piece but I haven’t seen one available in a fair number of years now.  Was originally bought from a firm in Dallas, Texas.  Here’s a pair of more detailed pictures of it.

As far as valve tip variation on a shaft mounted rocker engine, I would consider 0.030” between the lowest to the highest being the tolerance for a grocery getter.   This would be for both the intake and exhaust valves as they are both sharing the same rocker shaft.  Any kind of performance application would dictate a tolerance somewhat tighter than this.

Lorena, Texas (South of Waco)

Many thanks Ted,



Will add that tool to my growing list of reasons to get up early for swap-meet/flea-market shopping!



Also trying to track down a telescoping, spring-height barrel micrometer that will fit over a stock Y-block guide boss. Do you know of a source?

6 VOLTS/POS. GRD. NW INDIANA

My own valve spring height mic doesn’t accomodates the stock Y guide boss so I share your pain.  But in most instances, I have been machining the Y guide bosses down for other reasons which then allows the conventional height mics to be used.  Unfortunately the I.D. of the height mics is not given in the sales fliers or catalogues so it's difficult to just arbitrarily purchase one of these with the Y head in mind.

Lorena, Texas (South of Waco)

I did come across a valve spring height mic that will work on the Y heads with unmodified guide bosses.  It’s steel in construction and the range is 1.800” to 2.200”.  This same company does offer a height mic for a shorter set of ranges but that particular mic does not fit over the valve guide boss on unmodified Y guides.  Here’s a pair of links.

Valve spring height micrometer

Sellers other items including height mic

Lorena, Texas (South of Waco)

Thanks Ted,



Do you know if these tools are made to order? If so, the height mic. could be cut a bit shorter, and the cut # added back to dial #s. I think 1.8" minimum might be too tall to be useful for many Y-block springs, unless the spring seats have been machined deeper?



Re: the min. guide clearance specs you once provided for bronze/stainless (.002"IN/.003"EX): I found a YBM article where J. Mummert set up a mild performance motor (?) with .0018" on both. Would YOU still stay with your clearance rec. if for a grocery-getter motor, or were you thinking full-blown race specs?

6 VOLTS/POS. GRD. NW INDIANA

You’ll have to get with the seller to determine if a custom height mic can be made.  Looking at the height mic that I received for the 1.400”-1.800” dimensions, you can potentially modify the inside threads so that it can slip over the stock guide.  In received form, this particular mic lacks about 0.175” from being fully seated when placed over the stock Y guide.  Looking at the mic, it will take ~0.200” removal of the threads on the outer portion while leaving the outside length dimension as is and then modify the inner portion threads just enough to get your desired minimum valve spring height reading.  Doing it this way will not require any number bias on the outside of the mic.  This will probably make more sense if you’re actually looking at the bottom side of the mic.

 

The 1.800”-2.200” mic in stock form just fits over the stock Y guide and seats okay.  Any modifications to this particular mic to make it read a lower value will require including a bias with the outside numbers or values when using it which means making modifications to the mic in 0.100” increments to keep the numbers quick and easy to calculate.

 

As far as bronze guide clearance goes, those are performance minded specs but if the engine ever overheats with the tighter specs being used, then the opportunity for a sticking valve will exist (especially on the exhaust).

Lorena, Texas (South of Waco)

Ted,



The specs. provided on that eBay listing link are 1.6"-2.1" (?), (not 1.8"-2.2"). Seller says custom tool cost too prohibitive. Gave him my boss measurements so he can double check fit. Will see what happens.



Re: bronze/stainless guide clearance specs.; wouldn't a fresh motor likely run hot until it's broken in? Maybe J.M.'s customer wanted longevity as top priority, and he felt secure enough that with good geometry, cam-lifter quality, and his level of break-in experience/attention, it was worth taking the risk?

In my case, I've decided my current .0015" exhaust clearance probably insufficient, and will likely hone them another .001" at least.

6 VOLTS/POS. GRD. NW INDIANA

Fellas- I've read and re-read the pressurized rocker shaft threads several times now and this is my question; If I don't do the camshaft groove mod, I won't have the increased oil volume to contend with.Correct? I'll only have the amount of oil in the rocker boxes that the factory intended- That's GOOD because I'm using OE "umbrella" seals. If I pressurize the rocker shafts ALA Tim's mod,(no overflow tubes) and add the "cross grooves" and reinstall the OE triangular oil "drip trays", I shouldn't have a situation where I have excess oil to the point of oil infiltrating the valve stem guides (and the excess oil consumption that would go along with that)- Correct? Or would I need to retain the overflow tubes to insure I don't flood the rocker boxes with oil? Any info/ opinions are appreciated- thanks /Duck




BOO- YA!!!

Duck:

You asked for opinions, here's mine.  I use the overflow tubes.  That insures a good flow of oil through the shafts to help keep them cool.  The excess oil flowing through the overflow tubes and down the pushrod hole does not overload the stock drain holes in the head, so it doesn't flood the head.  Ford designed the rockers to be "drip" oiled from the oil filled shafts, and I have found that to be fine, even with my 95/250 pound valve springs.  I know Tim, Ted, and others have different opinions, and I will not discount their methods if it works for them. 

John - "The Hoosier Hurricane"