Heckeng

Any news?

I really like the true trac diff. Like Bill, I have been looking forward to hearing some reviews of it with people putting down some power.

Hey Jim, it is not hard, just takes time and some thinking. I have set up 5 or 6 and the best one I've ever done was my last one and the difference was that I used one of Ratech's pinion depth setting tools. This is a pre-measured tool to help get your pinion depth as accurately set as possible. Here is the tool. You'll have to get one specifically for whatever rear end you have in the Tahoe. I also use a set of set-up bearings to allow me to use some trial and error fitments to the pinion like Winston showed in his recent rear end rebuilding thread. If you spend a little extra and buy or make the setup bearings, and get that rattech tool, you will (I think) be thankful later. Oh, one other thing. . . When you have the carrier bearings pressed on or when you do it yourself, make sure they slide ALL the way onto the carrier. Otherwise the backlash will change as you drive it and you'll potentially ruin the gears. A friend had that happen--nothing got ruined but it cost him time to take it back apart and 2 quarts of lube

Jetting and CFM are not things you can change to compensate for each other. Every carb will need to be tuned to get the right air to fuel ratio, regardless of CFM. Most 950s won't really flow 950 cfm, I think they actually flow around 850 or something, this is where people get all confused, and carb companies sort of suck. ANY of the carbs that have been talked about can be tuned to work just fine, including your 870. Have somebody knowlegable take that 870 apart and see what is wrong with it, or send it back.

Nice write up Winston, and great pictures.

a 950 would get you a little more top end potentially, but I would think a 750 would be fine too. Jets only need to be adjusted to get the right air/fuel mixture, they aren't really used to tune for upper rpms vs. lower. If the carb is set up right, you will have good upper and lower rpms.

Like Andy said, there is nothing wrong with that carb generally speaking, you just need to tune it, or in this case, maybe figure out what the problem is with the one you have. I would guess crap in the bowl clogging jets, or potentially shavings in the air bleed lines or something. OR. . . you could just send it back like Summit said they would do. I have run a 750 vac sec holley and a 750 Speed Demon on my car and they have both been excellent. I would stick with the 750 as opposed to the 850/870 because I believe they use larger main body venturi diameters which will lose velocity. If you didn't want to do the 750, I would get a 950 Holley which uses smaller venturi diameter than the 850 but a larger base plate. Just my $0.02

Words to live by!

Get it. Those are getting harder and harder to find, you'll be glad you spent an afternoon wrenching on it sometime! Heck, I'll give you $50 once it's out, what a deal huh?!!!!

Looks like somebody is about to have some fun!

Nice job Winston, I'm with Wallaby here. You always start out with good intentions of getting pics, then it is too much of a pain in the @#$ so you just get it done!

Have you played with the vacuum secondary pod and or spring by chance? It sounds like you could have an intermittent vacuum leak on the carb and the secondaries are playing games on you. You can get a bog if the secondaries open up too quickly and then once airflow picks up again, the engine will come back to life. What spring is in it now? There is a cork gasket that seals the vacuum pod to the main body that can dry up or crack sometimes. Also, the seal around the secondary diaphragm could be leaking, and if you have a quick change kit, the rubber seal under the quick change cap could also leak. Could also be distributor like mentioned already. Maybe your mechanical advance weights are sticking sometimes?

That post was supposed to be in Fastkenny's post about getting pulled over going 200 mph! I'm not sure how it got stuck in here but I apologize for it making no sense here Bill!

I use a radiator probe thermostatic switch like this one: http://www.summitracing.com/parts/DER-16769/ I use the switch to turn on a relay which is where my fan gets its power from. The switch is adjustable too which is nice, that way you can tailor it to whatever thermostat you run.

I have the solution. It's time to install some 4.56 gears in that thing! You'll never go that fast again.

Nick (Quarterbooty) installed it on his car, and it works great. It does lug down the engine if you hit the brakes hard though. A mechanic told me to make sure you had a good pump too, as some of the shafts GM was using on the Diesels were shearing off due to too much torque demand from the HB. It works very well, just as good as the vac assist, really there shouldn't be any difference to them at all as they should (I believe) all be designed to give you about the same line pressure if operating properly.

Dave, that thing does sound mean! And that last video's wait was hilarious!

1 Vote for Chris

I like having my temp probe in the radiator, that way when the thermostat opens, the probe heats up and the fan kicks on. Otherwise, you may be having the fan on, but the stat never opening and you just really cool down the radiator water. Also, having the sensor in the head will usually show 10-15 degrees cooler from what people on the forum have said too, so you're probably ok there.

Did you guys try any different stuff like carb spacers and different timing settings? I can't wait to see this thing in the Monte and see what kind of a beast it is!

It can definitely make metal on metal noises. I've had converter bolts loosen up and cause noises too, kind of a rattely rocks in a can sort of sound.

Awesome Dave! 574HP is not too shabby! I wish you could've squeezed that extra 26hp out of her though! And on top of that, you didn't have to spin it very high either, simply awesome. Now, are we going to have a "What do you think she will run" thread?

Drum rolls everybody. . . . I think tonight is the night, or at least I hope it is! Dave, don't give up until you hit my mark!

Yeah Bill, balance and weight for traction

Call Chris Straub, Comp Cams, and Lunati. They may back up what your guy said, or you might prevent making a big mistake and burning up some pistons!