Bob Hoover mods

[pupjoint]

i did a search, but nothing exactly the same came out.

http://translate.googleusercontent.com/ ... trVqSa2IlQ

http://bobhooversblog.blogspot.com/2007 ... -mods.html

1. how many here have done all the mods in their engine? block, lifter, rocker arm mods

2. since there are more "flow" to me, what oil pump size do you all run?

[Wally]

I am doing all mods now to a 1200 turbo, not running yet though.
Will be using the Shadeck dry sump pump which only has 21mm pressure gears.

[pupjoint]

cool. any chance of any pics, if you have. thanks!

[Wally]

Sure, I did the obvious one first: lifter mod and tested the groove making on an old lifter first (all big-foots are done now):


Its a pity Bob passed away last year for many reasons, but I also did wanted to ask him what he meant by the Ford-subie swivel feet adjusters. I will use the porsche ones, but was wondering if the ones he mentions have an extra groove down the threads or anything?

[Clatter]

Wally,

Pretty sure that Bob was talking about the Ford/Mazda type of adjusters.
a.k.a. "Mazda Courier feet" or such.
The kind with the ball that has a flat to contact the valve stem tip...

The good ones are cross-drilled at the threads to intersect the drilling through the rocker arm.
Then, the drilling goes longitudinally through the center of the adjuster screw to the ball at the end.
The ball is captivated by staking, but enough gap exists between the ball and receiver cup where it's not staked,
To create the 'spray' that Bob is talking about.

Aftermarket ball feet often do not have this correct drilling.

[Piledriver]

I have used those over the years, IIRC they are a Mazda part, that type held up well on a mild engine, but don't like large valve lifts.
(They don't have quite the range of the 911 adjusters ... have a much smaller contact patch... not as forgiving, can chew up softer valve tips)

I cut a shallow fine slot in the rocker arm threads using a very fine coping saw blade.
Provides plenty of oil to the top side//springs etc. with a little clearancing mid hole for an oil path around the screw.

[Wally]

Thanks for the detailed explanation Clatter, Pile! That made a lot of sense. I think the spray onto the valve retainer (-area) is what the Hoover mods were all about. Now, if you don't use the proper valve adjuster, its all in vain really.
Just how much grooving of the threads (assuming we're indeed better off using porsche swivel feet adjusters) can/should be done without loosing too much oil pressure (or flow)?
Do any of you have a pic of such a modified adjuster? I am particularly interested in the 'cross-drilling' or clearencing Clatter describes mid-screw so the oil from the rocker oil gallery can easily enter the groove in the adjuster screw.

Thanks!

In the meantime I was too hasty and although I trial drilled a dummy case which went really well, :


I ended up screwing-up my good (Mexican AS41) case because apparently the oil lifter gallery was way off compared (height) to the old german AS21 case....


Plug it up again and leave that part of the mods alone on this one me thinks.

[andy198712]

doh cant you get that small hole welded up then?

[Piledriver]

Drill stops are your friends. :

[Wally]

Drill stops are your friends. :

That was not the problem..

[Clatter]

If you fill that hole to the outside with some weld,
Then re-drill the hole you just did,
it intersects the oil passage from the cam bearing saddle correctly.
right?

Said another way;
Your holes are right,
The outside just needs filled in....

right?

[Wally]

No, afraid not. The original oil should have been about 6mm higher, i.e. more to the centerline of the case. Then it wouldn't have touched air. The casting was the same (which was the only thing I measured and thought I was good. Apperently, more errors could be made in Mex then I would have thought...
The drill won't make a new path 10 inches away into the case: it wants to follow the original bore I think.

The hole is best epoxy'd shut, I agree. First I thought of inserting an alu plug and loctite it in, plus using JB weld.
Maybe just using JB weld only? I dunno yet what would be best?

[Bugfuel]

Best? TIG weld it shut. You can close the external cavity with a plate welded over it. Then you'll have a dead-end cave that collects oil but the rest of the system will work as intended.

[Wally]

I know, but welding might warp things. I meant more what's the best epoxy to use for this?

[Bugfuel]

I know, but welding might warp things. I meant more what's the best epoxy to use for this?

Hot/cold cycles, Oil, Vibration, and under pressure... I wouldn't use epoxy or any other magical filler. Either a threaded plug or weld. Just my opinion.