Lynn E. Hanover

When buying Machine tools, it is allways a good idea to buy the most capable piece you can afford.



You seldom hear anyone in a machine shop saying “I wish this thing cut too slow” Or “I wish this thing would lock up in the hole more often”



A table that can rotate and roll is good. The most power you can buy. Multi speed of course. If it is a floor model you can swing the table out of the way and drill holes in really long items. I used to drill and tap the bolt holes out of piston engine cranks to upgrade to Chrysler 440 flywheel bolts. Try that in a table model.

You start the tap in the drill press as well. To make sure it starts dead straight. Stick the end of the chuck key in a hole and turn the chuck by hand.



The rolling table may allow you to bolt the housing directly onto the table to do the drilling. So, not having to build a jig to hold it solid. In any machine tools, it is the rigidity that separates the boys from the men.

This eliminates chatter, and keeps cutting tools cutting not skipping and gouging. Mast diameter and spindle diameter the biggest you can buy. You will never regret it one second. Grizzly has an on line catalogue. http://www.grizzlyimports.com/products/





There may be a fallacy in the drill press thinking. I drilled a series of holes with a hand drill and connected them with a die grinder, by hand with no help from a drill press.



There is no requirement to use a press or a hole saw. Once you make the hole perfect or not, you can shape the liner to the hole, being sure to supply a slight press fit along the sides of the hole, so clamping forces don’t crack any chrome. I used .062 Exhaust pipe the first time, and it worked OK. But it looked like hell.



The entire cavity must be filled with an aluminum filled epoxy when completed.



I would suggest a thick walled aluminum tube. This will support the clamping loads and allow for an other than round port into the housing if you so desire. Round is fine up to 9,000 RPM then a big late closing rectangle is more likely to be seen. But there will be no bottom end at all.



When the revs are up velocity is still important. The round runner and port can match the slower flowing rectangle up to huge revs, and still have a good mid range.



Lynn E. Hanover

sen2two

thanks Lynn.





i was thinking about just drilling through by hand myself. im only cutting through the water passage. the one that everyone blocks off with some quarters and some silicone. then just matching that hole to a RB manifold using the gasket as a template (semi-pp)...seems easy enough.



but i am going to wait on a drill press. im using 1 1/4 piping right through the coolant passage and only polishing the stock ports. NO porting on them. not sure of the wall thickness on the tube. oh, and its a 12a by the way. no sure what to do with the exhaust port. i was gonna pull the sleave. but that would take away from my streetability. any recomendations? this is not a track car.



like this...the stock gasket is your template.



damn it...i cant upload any pics, im sure you know what i mean though...

Lynn E. Hanover

The exhaust ports from the factory Pport and the high priced builders seem to look the same.



A rather square port, with the liner removed but replaced with an aluminum replacement to fill in the half of the port toward the exhaust flange. The neck on the liner makes a bad discontinuity right at the flange that must be smoothed out. An easy way to do it is to leave the liner in place, and just change the port face in the rotor housing. For the street I would not make big changes in the port face. Up a few Mms and down a few Mms with a nice radius and that’s it. Most of the exhaust has left before the port is fully uncovered anyway.



It is supersonic, so how long can it be before the whole thing is empty? Porting up makes more overlap which you don’t want in a Pport, so going wider and down a bit is your only choice. The 245 HP Drummond housings have very small square ports.



Lynn E. Hanover

sen2two

i wasnt going to port up at all. just bevel it slightly, and square it off.



only going about 3-4 mm down, also squared off.



what would you reccomend as a starting point on jet size in my holley 600 (not a double pumper, jets in primary side only)

RX200013B

why would pulling the sleeves make it less streetable?

heretic

Starting point for a Holley, on an engine with few and strong intake pulses, and poor idle/cruise vacuum, and you want to drive it on the street?



You will not like the answer but the best starting point is to sell the Holley and use the money to do something with EFI. You can have EFI for under $500, and you never have to buy jets.



Holleys are some of the worst carbs for tunability until you get into the race (four figure$) style carbs and then they improve to mediocrity. Even when they work great, they're not really all that good. I say this as someone who specializes in tuning Holleys to cope with bogus driving conditions, like having a really nasty crunchy poor idle but still kinda try to make it drivable please? It can be done but it ends up being one compromise after another with band-aid fixes compounded on other band-aid fixes. EFI is so much better it is disgusting, but nobody wants to see EFI on a 455 Olds so they want a Holley for underhood cred at the cruise-ins.

sen2two

i thought about going EFI. its obviously better. but with that comes the cost of a tuner, ECU, Harness, fuel rail, injectors, ect...



im trying to find a weber (or similar) set up. cause i know they have more tunability. but people treat them like gold.



just curious, how do you build an EFI set-up for 500?



i can weld, and am pretty decent at making things fit that didnt originally go together. but i cant tune...

Lynn E. Hanover

The sleeves are installed to insulate the hotest exhaust gasses from dropping heat in the rotor housings, to keep them more stable. and reduce emissions. The sleeves are pinned in place with roll pins. And the over sized rim is clamped in by the exhaust manifold. On a 12A removing the sleeve changes the port size from about 1 7/8" to about 2 1/8" or 2 3/8" depending on the year of manufacture.



The best match for headers is 1 7/8" ID tubing for the primaries. A 2 3/8" ID primary tube is way too large.



As we have learned from the Bernoulli's principal web site you have been playing with, (http://home.earthlink.net/~mmc1919/venturi.html) That when velocity is reduced as in a big runner right out side of a high pressure port, that pressure increases. So we would then have a higer pressure slug in the pipe moving slower. Bad for scavenging when it gets to the collector, and bad for surface drag inside the pipe. Hard on the exhaust gasket. And the engine is blowing gasses into a high pressure source, even if there is no muffler. If you make the pipes too big you get flow back into the chamber before the port can close. Very bad mojo.



On the other hand, a 1 7/8" ID tube maintains the port velocity right to the collector. The velocity is very high, the pressure is very low. If you get an exhaust leak with a low back pressure system, you will suck air into the header flange joint, not blow gasses out of it. I use no gasket on the race car. Just a bead of 100% GE silicone II from a caulking gun. So now the high velocity (supersonic) slugs merge in the collector and the pressure is still low and velocity supersonic. The velocity can stay high until the pipes get into the muffler, The velocity drops to subsonic, and the sonic boom is contained inside the very strong stainless muffler. Once inside the muffler, the velocity drops way below supersonic, and the energy is reduced as it strikes features inside the muffler. Much of the sound energy then becomes heat in the muffler.



So if the port face has less area than the sleeve opening, leave it in. If the port face has a bunch more area, and you really need the few extra horses, take it out and build bigger headers. This will move peak power uphill a bit.



Lynn E. Hanover

heretic

Take 2. Take 1 was eaten by the reboot monster.





If you can't tune then trying to get a Holley to work well will be an exercise in futility. They are extremely difficult to tune because every change you can make will interact with at least one other tuning parameter. It takes a thorough knowledge of all of the different systems and how they interact in order to get a Holley running right. It is far more than simply changing jets.



I don't mean to knock Holleys. All carburetors are like this. The problem is that Holleys allow you to adjust some things and not others, and not every adjustment's affect is intuitive. And, when playing with "touchy" engines, some of these non-intuituve changes are downright subtle.



For example: the standard Holley bog or stumble just off idle in an engine with poor manifold vacuum. (Raising the idle speed will actually make this problem worse!) You can play with accelerator pump cams and squirters and other things until you are blue in the face or empty in the wallet or both. Usually both. And never get rid of that problem. However, as subtle and seemingly unrelated a change as 1/8th turn of the secondary throttle plate stop screw can have a very noticable effect. Combined with proper adjustment of a 4-hole-idle system (something you can not do with a metering plate setup) and the tune will be spot on. Assuming you haven't gone off into left field with changes already made to aforementioned other, more "intuitive" systems, that is.



Another problem is that Holley's production tolerances are maddening. About every third carb we get from them can't be made to run "right" no matter what. Send it back, get another one, and like magic it's fine. Maddening!



You could just do it the Barry Grant way: Make the carb run pig rich all the time. Get to know your gas station attendants and buy spark plugs by the case. They managed to design their circuits so that an engine can starve for fuel and still foul out the plugs with soot at the same time. My money's on horrible atomization.



Now, let's look at what we do with EFI. Tweak a number in the acceleration enrichments, and get on with your life.



I put together an EFI system with a MegaSquirt system for under $400, starting with an EFI engine. Half of that was in the fuel pump, which I went overkill on. You will need to upgrade your fuel pumo anyway, right?



Used MegaSquirts are common and can be found for $100-150, and flying-lead harnesses can be had for $50-60. You can junkyard everything else if you have to. Grab the injectors from an RX-7, throttle bodies from anything with a nice size bore, hack up steel fuel rails from a Chrysler for your own custom rails if you don't want to make your own aluminum ones. I am assuming you plan on making your own manifold. Alternatively, you could try using one or two throttle-body injection units from a Chevy truck. I have no experience with those but they seem tempting. And plentiful. And they kill many birds with one stone.



I hope I don't look like I am trying to tell you what to do. I'm just trying to show you what's possible.



And so, in closing, that's why you'd rather use a mill than a drill press.

sen2two

lol...love the last line.



thanks for the tips...