GTAmazing

KMJ sells a similar TB for about $220. Not sure if it's domestic for imported though.

88gunmetalgta

iTrader: (1)

^ Link?

GTAmazing

http://www.ebay.com/itm/CNC-Machined...1ea6b6&vxp=mtr

It's probably imported. Seems like most of their stuff is.

travis401

iTrader: (1)

kmj performance has seen many bad reviews for junk parts over the years too.

The_Punisher454

The KMJ TB looks a bit crude compared to yours. You have a much smoother bore entry radius and most importantly the KMJ has no IAC.

88gunmetalgta

iTrader: (1)

Yes, that KMJ piece leaves a little to be desired....

Soon I'll get the cables and bracket to install it permanently, and then I'll be able to tell if the design is really a success or not. If it works well, I will investigate whether or not I can revise the design to fit it in between the Vic jr fuel rails and not interfere with the runners without a spacer. I can add a vac manifold to the front of the TB, and then it should have everything that the bigger brand pieces have if it can be made to work without a spacer, it can be used in conjunction with an extreme velocity carb hat to provide for a full 4" cold air intake without any hood interference whatsoever!!

pvr007

iTrader: (1)

Nice Work man... how old are you.. just wondering?

88gunmetalgta

iTrader: (1)

Alright, so here's my summary on this project:

I'm still not quite finished tweaking it to my liking, but I've had some wheel time getting used to it.

There are a combination of things that are making the throttle opening way too jumpy.
Idle Spark Advanve
Direct throttle linkage
Angle of the blades at closed throttle
Rigged throttle cable bracket

These issues work together to make it impossible to smoothly bring the RPMs up off idle. it come from idle to 1800rpm instantly. If course this makes driving around in parking lots and gravel driveways fun. Most of these issues should be able to be resolved with a little more tweaking.

The IAC is not doing anything currently. It stays fully closed all the time. If I didn't lower the spark advance at idle, it would run at 1000-1100 rpm at idle. This could also be solved with a progressive linkage.

WOT is awesome. This thing definitely flows enough to keep my engine happy. I haven't had it to the track yet, but compared to the other TB, it feels a TON more responsive. (not sure how, but the exhaust note seems different as well.

I didn't make my goal of having enough room for an extreme velocity or similar carb hat fit on top. Currently, I'm using an open element filter 3" tall, and it might actually fit if I didn't have any hood insulation. Right now it's getting kinked a little.

So in conclusion, the Accufab TB would be worth it, but still doesn't quite do everything I would want it to do.

If I get a chance to make another one, I would make these changes:

Progressive throttle control with a cable track style linkage.

More compact IAC and throttle bracketry to permit everything to fit between the fuel rails, and distributor and water neck to eliminate the 1" spacer I'm running. That way I can fit the almost 5" tall carb hat under my stock hood.

gbayfisher

So why is the iac not opening? It must be binding. You definately want the iac operating for proper idle down, and idle control.
Will you continue to use this tb, or back to the ls1/elbow combo?

So.. Are you going to make all these changes to the existing, or start with a new core?

88gunmetalgta

iTrader: (1)

The IAC stays full closed at all times there is too much air moving past the blades due to the direct linkage and both shafts not being on their own return spring.

I would start with a new chunk of stock. I'm also tempted to do a monoblade.

gbayfisher

Thats right, forgot about the air going past the blades. Are the throttle blade to bore clearances good?

If you want to tighten up the dimensions, could consider remote IAC, get it right out of there.

88gunmetalgta

iTrader: (1)

Well I revised my cable brackets and return spring setup, and now the IAC has control of the idle speed again.
Now I'm having issues with the throttle hanging up a little bit at like 1-2 %TPS. I think the shafts have little too much side play, so I'm going to work on getting shaft collars on the throttle shafts outboard of the bearings.

Overall, the throttle feels much better.

88gunmetalgta

iTrader: (1)

Made some progress on my hanging idle issue today. What I'm seeing is that as the throttle closes, the secondary arm angle gets into a "dead zone" where about 3-5* of secondary blade angle almost doesn't move the primary linkage at all. Since my return spring acts on the primaries only, the spring exerts less and less force on the secondaries as they approach full closed. I need to lengthen the link bar so the dead zone is at WOT instead of idle. Since at WOT, there's more than enough airflow for my engine, a couple degrees of "error" in the secondary blades won't be as significant, whereas at idle, a couple degrees is the difference between a 750 rpm idle, and a 2500 rpm idle.