Hello tech help,
i am in need of some exacting help on locating a a supplier of the correct type drill bits for removing valve guides. My guides are 8mm bore (but slightly worn), the OD of the guides are 13mm. Aluminum heads of course with bronze style 60's era valve guides. I understand a "pilot" drill bit with an 8mm guide is what i need to take out the bulk of these guides prior to knocking them out. Maybe 12mm bit.

I have been told the technique is to drill away 80% of the internal bronze material, then using a custom punch to fit this new internal "step", heat the head to say 275F and punch them out.

Who would supply a piloted drill bit? any help would be wonderful. thanks
Craig

Contact BAUM Tools, they should have everything you need that is made by NEWAY Valve Tools. Neway might have their own site, they are the Manufacturer of Head Tools, including the drills, drifts and seat cutters.

HTH's

Didn't see Neway, but there are other choices for the Step Drill & Drifts you need :

http://www.google.com/search?hl=en&i...+Tools&spell=1

Thanks Itadmin, i found Neway at - http://www.newaymfg.com/frame.htm
they show valve seat and valve face tools, but no reference to guide step drills or drifts.

i have gotten advice, from another source, to skip the drill out . Just heat to 300F and air hammer out the guides. Even tho it sounds like good engineering practice to relieve the fit of the guides by predrilling, i have to admit i have never heard of anyone actually doing this. The drill and drift tooling certainly cannot cost much, it mite take more time, are the rewards worth the trouble?

Is anyone working with 2 valve Lamborghini heads that can recommend exact guide, seat and valve replacements? Maybe SI Valve? Manley Valve? I realize that these companys offer custom products, but can someone share some exact information on what to put into V12 Lambo heads?

Is there a tech reference area of this fantastic Lamborghini-talk site that has this info?

Thanks to all for help on this.
Craig

I sent Neway an email about the Step Drills and Drifts. And I can make a call on Monday for other sources.

The rewards Are Definately worth the effort of drilling first.

Personaly I would NEVER simply air hammer out a guide. There stands a very good chance that technique can Gall the Guide Bore and Expand it because the Guides have a Press Fit into the head that actually Squeezes them, causing the new standard sized guide to fit loosely and/or crooked or both. That is a very unprofesional way to remove guides with plenty of risk of causing guide bore issues and damage. The Squeeze fit actually deforms the inner guide bore after instalation and is the reason the guides need to be reamed (with special internal guide bore reamers) slightly to get correct Valve Stem to Guide Bore Clearance.

Normally seats don't need to be replaced, only recut (slightly, with cutters like Neways) flat and true after the new guides are installed (the Neway site has a picture of the expanding Guide Bore Alignment Shaft w/The Cutter Tool attached). If any Seats need to be replaced you will definately need a Head Shop for this operation for quite a few reasons such as fit, alignment and the fact new seats have to be cut considerably as they come flat om both sides and it takes a special grinder to put the initial angles and cut to the proper depth, before the finish facing is done.

I've used SI Valves for a number of Ferrari & Lamborghini engines and never had a problem. For Titanium Valves I use Del West Engineering.

HTH's

JRV
www.PinnacleMotorsports.com

ps: I would rather loan you my tools rather than see you butcher a Lamborghini Head with an air hammer

Thanks JRV,
i am running this Lambo V12 question as generic V12 thru several group postings - most say predrill to relieve the fit, but several say they have never had problems with cold air hammer technique.
Predrilling guides for removal looks like the best technique for removal and i have found a bunch of tools in the Goodson catalog which is available at -
http://www.pirate4x4.com/tech/billav...ne%20tools.pdf
piloted core drills on page 42
maybe these are items for consideration, however i dont see piloted drifts to follow the drilling.

also i have mixed recommendations about heating the aluminum V12 head for removal of bronze guides. Some advise that thermal expansion of bronze is greater than aluminum and may make things worse, rather than better.

My Miura heads have OEM guides, seats, valves. The stems seem to be okay for reuse, the seats are bronze. i am considering refacing valves, recutting seats, just knurling the guides. This is a 300 mile a year play car not a commuter or race car.

I certainly appreciate your time and help on this.
Craig

here is look at my typical intake exhaust valve heads on a 68 Miura V12.
i am not sure how informative this type photo will be.
Craig

I highly reccomend against "knurling" the guides!! I'm surprised you are getting such crap rigger information!!!!! Obviously these "riggers" haven't spent a lifetime or even a few minutes trying to effect perfect repairs!! Very Sad! But unfortunately these lazy riggers outnumber the old time craftsmen!!

It really saddens me how lazy an entire generation has become, they are so lazy that even the slightest bit of quality, difficult, time comsuming work makes them break out in hives like Maynard G. Crebbs (from Doby Gillis)! What a bunch of lazy worthless fukks that would butcher a Lamborghini Miura!!!

ps: the valve faces (especially the ex. valves) look shot and by the time you CUT everything, you will not find shims to adjust the valves properly, the shims are not availible in an infinate variety of sizes which is why careful measuring at every step along the way is so critical!!! In fact, if I was you and even considiering any of the "rigger" advice I'd find out what thickness (sizes) of adjusting shims are actualy availible before touching anything..

Thanks JRV, it is just me considering this path as an option. i want to understand this type work and make sensible decisions. I am glad you are so passionate about this as well. You seem to be a superb technical resource for Lamborghini work. I am thrilled, as i hope many others are, that you are available to advise on Lamborghini.

So if you do a valve job on any overhead cam engine , say Alfa or Lamborghini, and you reuse the oem components by refacing and recutting, the valve then sits lower in the hole and the stem is closer to the cam, therefore needing thinner shims, or maybe, most likely, so close to the cam it is out of shim range.

It seems the valve stem end would need to be ground off an appropriate amount to allow available shims to be used.

Also the preload on the valve spring would be less by the same amount, as the keeper slot has moved further away from the spring. So valve spring shims would have to be considered to allow proper spring preload.

If new seats were installed and new valves purchased, it would seem the same fitment process (trimming the stem end and shimming valve spring) would be used.

I see Alfa/Lamborghini valve shims (MD01072) are readily available either individual or you can get a whole set.
I do not see generic valve spring shims (MD02903) offered anywhere that fit the Lambo application
(40.9mm OD x 21mm ID x ?). Is there a resource for these? Are they the same as other automotive applications?

Thanks
Craig

It looks like Alfa/Lamborghini valve clearance shims are available from International Auto Parts -
http://www.international-auto.com/in...?fa=p&pid=3151
They say "Individual shims for all 1960-on Alfa Romeo overhead cam engines. Alfa shims are available from 1.300mm to 3.500mm in 0.25mm increments. Shims are also available in sets."

Also there is a nice tech article on selecting correct shims.

I have not purchased from these folks yet, but they have a nice website and pdf catalog.