Poor man's method to better belt wrap on an fbody

ChevyChad · 10-21-2009, 12:50 AM

Alright, so after looking at these nice aftermarket tensioner brackets out there like SDCE and the cool custom one Aster made, I decided to make my own attempt at something that would be more effective than the stock single idler/ tensioner setup that procharger blessed (or should I say cursed) us with. I decided to add an additional idler into the mix, but keep the manual tensioner in place- atleast for now... (I have an idea on how to get a spring loaded tensioner on the stock bracket that will still allow the stock waterpump to be used and retain the procharger 7.65 crank pulley, but I'm not getting into it just yet.) So the very simple, yet surprisingly effective, solution was to turn down one of the standoff's to accommodate an extra idler pulley.

I took my measurements of a spare bigger idler that I had layin around to get the depth required figured out to lathe the standoff, then marked it up and my dad was able to get it machined at his work for me

Here is the machined standoff:

Here is the standoff by itself mounted on the block:

This is the 3.5" pulley mounted on the standoff on the bracket in conjunction with the procharger 2.5" idler as I had envisioned in my concept:

Seems like a TON of belt wrap huh!

And.. well, it is. Actually, as I discovered after measuring for a belt size, it turns out that its TOO MUCH belt wrap with this setup because it only allows for about .25" of adjustment with the manual tensioner. Note the adjustment bolt on top in the above pic. It is all the way up, and the distance to the bottom jam nut to the top of the bracket is all it has in adjustment. This resulted in a belt length range of 43.125 - 43.375. I did actually find one belt that would fit- its a gates K080433HD (43.36 effective length) which unfortunately my local auto parts stores didnt have, and it would have been a special order item (so probably expensive- and I'm a cheap bastage

so I didn't want to spend too much on this project). Also, the belt was almost at the max length I was comfortable with putting on there. At the max measured length of 43.375, that leaves .125" of space between the insides of the belt on the opposing idlers.

I was actually surprised that that 3.5" pulley fit! I didn't think that it would clear the 7.65 crank pulley, but as you can see here, sure enough, it does!

Alright, so I didnt have another 2.5" idler pulley laying around to see if it would work, but luckily, mr 'Trust' has a spare he is going to send me so I can try it out as well. Thanks buddy!

I'll report back on that option as soon as I get it in the mail.

I did throw the 2.5" idler on the modified standoff tho just to get a picture of it:

As impatient as I am, I decided to move on. As I was laying on my back under the car looking up, I noticed the stock accessory idler just chillin there. I took it off just for grins to see if it would fit my new custom standoff, and I'll be darned, it DID! It is actually the exact width of the 8 rib procharger belt too

So I decided to throw it on just for kicks and take another measurement of minimum and maximum belt lengths that it would accommodate. This time it gave a range of 42.75-43.125" with my 4.25" head unit pulley. And also, there is a gates belt that my local Oreilley's DOES have that fits. K080427 (which has an effective belt length of 42.87"). That works out perfect because its near the smaller size of the range which means I'll have more room to tighten it as the belt breaks in and stretches a bit, and also it leaves a little more room there between the opposing pulleys. Here are the pics for that setup:

^^^ above: note that the tensioner pulley is at the top of its travel again. The jam nuts are adjusted to bottom out when there is only .125" clearance between the belt to itself where it gets closest between the two pulleys. So there is a bit more room for adjustment as you can see.

Here is the stock accessory idler on the modified standoff:

Now since I don't have an extra stock accessory idler laying around at my disposal yet (have another friend sending me a spare one of those too tho LOL). And my dad offered to make me a custom pulley at his work tomorrow, I figured I'd take him up on it because they seem to be having so much fun there doing this stuff for me

I went ahead and spec'd out a custom pulley that is a tad wider than the stock accessory pulley just to have a little meat on either side of the belt. However, a stock accessory idler would work here just fine, and I'm sure that a standard procharger 2.5" pulley would work as well. Like I said, I'll have to verify that as soon as I get the other one in the mail from Reza...

One disadvantage to this setup is that it blocks the very last bolt hole that one of the small bolts go into to hold the procharger to the bracket. Not sure if this would be a big problem or not. It still has 3 of the little bolts, and the one big one in. If I really wanted to, I could drill out another hole in the bracket and pick up one of the other tapped places in the head unit for the last bolt. I may end up doing that..

Anywayz, enjoy the pics (sorry for the crappy cell phone pics, I left my camera at a friends house last weekend

) Not bad for the only cost of this whole entire project is a new belt

And also of course I'd have to add in the cost of a new stock idler (or a procharger 2.5" idler) if I didn't have a custom pulley being made.

Exotic Performance Plus · 10-21-2009, 06:00 AM

Nice work, looks good! Bob

BIG_MIKE2005 · 10-21-2009, 07:49 AM

LOL, your always workin on some little project, LOL. Pretty cool idea man.

ChevyChad · 10-21-2009, 08:37 AM

Thanks guys. Yea, I know I'm constantly piddling around with things on my car. I like to always be a little different from the crowd, and honestly, the tweaking and custom stuff is what I think I most enjoy about this hobby. I like figuring things out and innovating. I've always been fascinated with stuff like that. Guess thats why I went to school for mechanical engineering

SilverSS · 10-21-2009, 09:36 AM

Same exact thing I did on my stock J-Bracket. It actually came with the standoff like you have and and extra idler when I bought the J-bracket but no instructions.
I ended up adding another mounting hole at the top for the charger since the extra roller covered up the one you use but it was a PITA to tighten without some modded tools. A two-piece stand-off was used where the top left mounting bolt goes to hold the bracket. This made servicing much easier. I had zero belt slip. Changing belts was also much easier if you can squeeze the belt past the clearance between the BP and alternator pulley.

ChevyChad · 10-21-2009, 09:47 AM

Man, thats great news! Glad to hear that this method has worked before and been proven! Wish I woulda heard of it before, I'd have done it a long time ago

ChevyChad · 10-21-2009, 11:39 PM

Well, I got everything back together. I wasn't able to get the custom pulley today- some stuff came up, and it may be another week or so before I can get it on, so for now, I borrowed a stock accessory idler pulley from one of my buddies that had an extra one layin around. The belt is so tight of a fit that I had to remove the crank pulley, wrap it around it, then swing it back up into position and bolt it on, but it worked out well. I adjusted the tensioner about 70% of the way down of the 3/8" I had available (so about ~1/4"ish). That leaves me with a good 1/4" of belt clearance between the idler and tensioner pulleys.

Upon initial start up, I was already VERY impressed just because there is ZERO bracket chatter now! I didn't even think I was getting the famed chatter before, but I must have been getting some because it now idles sooooooo much smoother, and now all I can hear is the piercing sound of the F1 whistling

It also immensly improved throttle response. I have no clue in the world how this affected that, but now, I can tap the throttle real quick and let off and it INSTANTLY responds. Before, it would kinda lag with a delay, but no more!

I didnt get to test drive it because it is raining out right now tho

I'm hoping that the rain lets up here soon and hopefully I can have more results to share by the weekend. But even if I don't see 1psi more of boost, I still would HIGHLY recommend this very simple mod to anyone running a procharger on a 4th gen f-body! Its just so much more crisp and smooth now all around. I'm happy I did it

conan · 10-22-2009, 12:00 AM

Nice work chad, that pully is wraped well for sure

Aster · 10-22-2009, 12:20 AM

Looks good Chad, I hope it works out well for you. I'd be a little concerned about losing the bolt, but it isn't like you're spinning that blower to the moon yet.

ChevyChad · 10-22-2009, 12:28 AM

Thanks guys. Hey conan, did ya ever get your meth nozzle placement worked out?

Aster- yea, thats the only thing that I'm concerned with right now with the whole setup is that one missing bolt. When I get the custom pulley, I may go ahead and drill the extra hole in the bracket while its off to pick up one of the other locations. Ill definitely be adding it when I put the smaller 3.7 pulley on if I haven't by then.

Aster · 10-22-2009, 12:32 AM

Let me know if you would like a schematic of the blower bolt positions with the measurements.

ChevyChad · 10-22-2009, 12:43 AM

That would be awesome Chris! Yea, I'll take it, and if you have it layed out in any sort of CAD format, that would be cool. If not, I can lay it out myself based on dimensions from the schematic

my email is chadchevy@yahoo.com Appreciate it man!

Aster · 10-22-2009, 12:55 AM

You have mail. It is just a PDF document I was able to get out of one of the guys at Procharger. Hope it helps some.

Rickys S/C Z28 · 10-22-2009, 01:15 AM

oh my god man that is bad ass!! so all i need is to have the stand off cut down and get a stock idler pulley and new belt and id be good to go right? also i have the SDCE 7.25 crank pulley will that effect anything?

conan · 10-22-2009, 02:43 AM

Quote:

Originally Posted by ChevyChad

Thanks guys. Hey conan, did ya ever get your meth nozzle placement worked out?

Aster- yea, thats the only thing that I'm concerned with right now with the whole setup is that one missing bolt. When I get the custom pulley, I may go ahead and drill the extra hole in the bracket while its off to pick up one of the other locations. Ill definitely be adding it when I put the smaller 3.7 pulley on if I haven't by then.

Ya its going to fit in the front like trusts pic you posted up for me

Thanks again man! Hopefully this weekend I can play with the car... My old man suckered me in to re-roofing their house the past 2 weekends

ChevyChad · 10-22-2009, 08:40 AM

Chris (Aster) thanks a ton for the email! Very helpful info to have for sure

Ricky- Yep, thats exactly what I did.

It works on my 7.65 crank, so it will for sure work on the SDCE 7.25 crank pulley no problem

Chris (conan) glad you got it to fit there man!

BIG_MIKE2005 · 10-22-2009, 09:43 AM

Quote:

Originally Posted by ChevyChad

Well, I got everything back together. I wasn't able to get the custom pulley today- some stuff came up, and it may be another week or so before I can get it on, so for now, I borrowed a stock accessory idler pulley from one of my buddies that had an extra one layin around. The belt is so tight of a fit that I had to remove the crank pulley, wrap it around it, then swing it back up into position and bolt it on, but it worked out well. I adjusted the tensioner about 70% of the way down of the 3/8" I had available (so about ~1/4"ish). That leaves me with a good 1/4" of belt clearance between the idler and tensioner pulleys.

Upon initial start up, I was already VERY impressed just because there is ZERO bracket chatter now! I didn't even think I was getting the famed chatter before, but I must have been getting some because it now idles sooooooo much smoother, and now all I can hear is the piercing sound of the F1 whistling

It also immensly improved throttle response. I have no clue in the world how this affected that, but now, I can tap the throttle real quick and let off and it INSTANTLY responds. Before, it would kinda lag with a delay, but no more!

I didnt get to test drive it because it is raining out right now tho

I'm hoping that the rain lets up here soon and hopefully I can have more results to share by the weekend. But even if I don't see 1psi more of boost, I still would HIGHLY recommend this very simple mod to anyone running a procharger on a 4th gen f-body! Its just so much more crisp and smooth now all around. I'm happy I did it

Might have to call in a favor & have you ask your dad if he could turn down a piece for me as well once I get my hardware kit. Pretty please w/cherry on top, LOL. Does he also take pizza & DR. Pepper as payment, LOL.

ChevyChad · 10-22-2009, 09:54 AM

I'll see what I can do Mike. I'm gonna try to get one for Reza too for helpin out with the pulley. It's probably do-able, just gotta wait til they have some down time to be able to do some under the table work

And yes- they would take pizza as payment I'm sure!

BIG_MIKE2005 · 10-22-2009, 10:06 AM

Quote:

Originally Posted by ChevyChad

I'll see what I can do Mike. I'm gonna try to get one for Reza too for helpin out with the pulley. It's probably do-able, just gotta wait til they have some down time to be able to do some under the table work

And yes- they would take pizza as payment I'm sure!

LOL, awsomeness. You know I'm in no hurry so waiting for him to get some down time isnt a issue at all.

Will I need that bolting pattern for the D1 as well or is it just the size of the F1 stopping you from getting the bolt in?

'Trust' · 10-22-2009, 10:14 AM

Looks good sir! Do you still need the idler? Lol .