The idler arm stop does not allow the tensioner load under 10 to 15 lbs (dependent on the initial static load adjustment) because the idler cannot deflect to a low force or, unloaded condition. The fact that the belt tension changes from the bottom side (pwr on load) to the top side (deceleration) will reduce belt contact trac force, and, pulley slip potential. I get zero slip with the stop @ about 0.060" stop clearance, and, a light load adjusted on the idler-arm spring (not even close to the ATI spring adjustment mark). This also reduces cantilever load on the crank shaft which is always a good feature for reducing the potential for fatigue failure.

I also cut the idler pulley flange(s) off. ATI should have used a key-insert on the alum idler arm, but, cost margins probably eliminated this. The idler pulley bearing insert was the root cause problem with my excess vibration.

I am currently runing a D1 head with a 4.44:1 ratio. The D1SC is a newer unit with a slightly lower gear head ratio. There is a possibility that your D1SC idler/ mount plate is slightly different than the D1 mount. The D1 has external oiling.

I prefer higher gear head ratios like the F1A/ F1 (5.4:1). The vendor @ Thunder racing quoted me $3.3k for an F1A head unit (said it would fit the D1 bkt mount.) I would have to make a 3.8"pd pulley to run it with the cam I am currently using. To each, their own solution. HTH.
B.

 

Can you post a pic of your setup? Worth a thousand words.

 

I've spoke w/ SDCE and they've reduced their turn around time. I'm thinking of sending my bracket off for one myself as I can't see shelling out a cool G for a new w/out sending mine in. I thought about just maching some brackets but like others the ATI idler arm isn't the greatest.

mzgpx5, I'm still trying to figure out your stop mechanism too. LOL!

Ah, I think I figured that out now. How exactly did you go about determining how much the arm will move before reaching the stop point? You mut be some engineer or something.

 

I have some pics, but, not to great. Check it out. http://s306.photobucket.com/albums/nn244/mzgp5x/
Yes Engineer. Thousands of robots @ gm and other mfg's. Also a gear head. Not a ricer or euro. Can't do that to myself. Remember... "Friends don't let friends do rice."

The simple Stop... a piece of 1/2"x1" x ~1-1/2" delrin mounted to a single 3/8-16 threaded rod.
The threaded rod replaces the ATI bolt just above the WP. I use studs and hex-couplers in the cylinder head. They are stonger and use steel threads, not, aluminum. The typical ATI unit uses steel bolts threaded into the alum cylinder head. I'm sure you are all aware of this.

Each stop (or just one) is machined or cut for a running gap to the idler arm. You could fab this by hand. Tighten the idler where you would for your specific belt length. Measure distance from stud to arm top surface. Cut the stop to include this gap as measured from the ID of the 3/8 dia mount hole. I am running 1.059". This is a 0.060" gap on my setup. I have found good success with this. The ATI Procharger with large step-up gear ratio has alot of inertia (impeller/ gear-box and all that air). Air has mass. This loads the belt in the opposite direction and the top side has tension due to engine decell and compresser air movement @ idle and cruz. Under engine load, the idler runs with low aplitude.

Anyway, quite simple, but, to each their own solution. I have purchased plastic from use-enco.com. Just thrown this stuff your way to help you save some cash. Nothing against SD. Hey, anyone interested in a VAC pump mod for the street or track??? Ha. Pics also.

HTH B.

 

B, You ever build/sell those Vac pumps I'll be 1st in line. I know GZ makes em' for the LSX but they left us out! I've asked them about making one for us but no dice. Sucks too.....I'd rather have that then the evac kit I'm running but it is what it is. I'm no engineer...just a crusty old MSgt in the AF w/ 21 yrs in.

 

Yep. I like the vacuum pump too.

 

AIght dag nabit, not to hijack this thread but 97WS6Pilot post some pics in a new thread. Can't make a comment and NOT post pics!

 

I can't take any pics of my car right now because I'm in Iraq with the US Army! I'm a crusty ole CW4 flying helos.

 

Thanks for your service to the US. We owe alot to you.

I am also an old gear-head from the 60's, but, not working now due to gm and D_3 troubles. I have alot of time on my hands now.

I could duplicate the parts for the gzms vac conversion. You blower guys would like the added cylinder pressure (great with a large step-up ratio). You would have to buy the pump and pulley directly from GZMS, and, there are a number of "make" details that would be a kit. Not an easy mod since you have to move the rad forward to do it. Also, the crank drive stack-up dimension is critical for the crank shaft drive. Definitely a winter project. So far, it has worked great on the street with the re-circ oil mod and a centrifugal oil separator. I could do a write-up if more were interrested.

The idler pulley mod is very easy. B.

 

I'm deployed as well right now. I lucked out this time and I'm in Kuwait but his also my 18th deployment. Stay safe over there brother.

How far forward does the rad require. Still the stock rad though right? No biggie there as mine is pushed forward and I'm switching my fans out in favor of a Flexlite thin setup to give me more space down there.

 

The rad I have is a Be_Cool 4-core 4th gen stock replacement. Larger than the typical Griffin rad mod. The top of the rad is located where the stock rad mount was. The lower rad mount was also cut out, and, re-fab. The rad is angled bottom forward. The hood latch was cut and support modified to tie in to the front bumper. The windshield washer tank and pump are gone. I have no AC as the condenser was eliminated, but, I run an up-front air-air oil cooler. I also run two (2) flex-lite 12" low profile fans which have been modified to fit the rad area. They are assembled as a complete rad unit. I always run them @ high speed all of the time.

I have alot of room up front, and, I can get to all the acc drives and the blower drive/ pulleys. You can see the whole front of the motor. I can pull the driven pulley if I have to with no jacking or rad moves/ or adjustment.

I think the additional air-space helps to get the heat off the front of the engine, and, helps the air flow thru the rad. My IC (measures... 25x3x14) is mounted low under the car with air scoop. IC is located in front of the engine cradle (not a conventional front bumper mount). I have gone to Evans waterless cooling media with no thermostat (custom modified unit for the gm bypass long-WP). Be safe. HTH. B.

 

You don't have PM so I guess I'll ask here. So how many people would you need for you to build some of these IF you were to do this? I may have 8 folks or more but I wanted to find out 1st.

Have some folks on LS1tech in the LT1 section looking for one.

Silas,

 

I would have to make @ least 8 to 10 kits. Not worth it to make by 1 or 2 due to tool set-up time. I would probably use my spouse Co name. Also, I'm thinking you all understand that this was the only way I could get the Vac pump mounted with the ATI head unit on the left side. The Vac pump drive runs in-front of the LT1 Acc drive. I requires move of the rad. I had also posted some pics on the rad move (photobucket).

Once you cut into the top/ lower rad support, you are commited. After you finish, you will be glad you did it. The additional air space is worth it.

I am not sure about fabrication of the rad supports as a kit. I'm not sure all you gear-heads are up to a little self fabrication. You would need a MIG welder (I use a Millermatic 130). The mod is really not a true bolt-on.

Also, there are different methods to attach the ATI blower drive to the crankshaft. The Vac pump crank drive requires design flexibility relative to your hub/ pulley/ damper stack-up dimension. I did not use the GZMS crank pulley mount as is shown on their web-site. It mounts to a piloted hub secured by the ATI 12-rib drive pulley. A 3/8-16 unc threaded rod is used a a tensile element to retain the modded GZMS Vac drive pulley.

I would fab most of the Vac brackets, spring retainer, plugs-fittings, and the centrifugal air receiver (fits inside the front bumper) (Note: Use of a front mount IC may be a possible interfearance, and, alt location would be necessary).

I would refer you to buy your own Vac pump (GZMS VP103), pulley, and, crank drive pulley. This would drive your cost down by not having me handle the procurement & handling of this piece.

I have a bud who can help me with the machine of some parts on a larger qty. I'm not looking to make alot of cash on this, but, cover the material and some labor costs + beer since there is no work here in D_town.

Also, discount for those who serv our great country. Thanks for your service. I've been thinking of giving my ride away to a vet. Yes, I'm an older guy that's not afraid of computers and a bunch of bolts. Alot of youngsters talk to me @ these car meets. My opinion... FI application needs neg pressure in the crankcase, and, intake ingestion of case oil is never a good thing for combustion.

I think a document is the next thing I should do to convey the mod idea.
B.

 

I'm going to rally the troops and see about hitting your number. Now if you wanted to build just one, I'd be more than happy to compensate you up there in the big D.

 

I'm out. Gotta keep my AC and not willing to do the radiator mod. Thanks anyway.