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I picked up a Summit M2008 (Part #08600VS) for $100 a couple months ago. It's kind of an amalgamation of an Autolite 4100 and a Holley, with a single body casting including the bowls and metering systems, and a top plate above the fuel line. It has annular boosters like the Autolite, which is what I really wanted to see if I could fix my low-rpm driveability issues, but it uses easy-to-source Holley components like jets, idle restrictors, vacuum secondary actuation, etc.
Aside from some worn out needle/seat assembly o-rings, it was in really good shape, so I cleaned it up, plumbed in a pressure regulator (which I should've had anyway), set the idle mix, and it drives fantastic! I think it's a bit rich under cruise, but it's much more driveable under 3000rpm, all the way down to 2000rpm, which I'd call a good day for my cam.
Im going to start with primary side jet extensions. these move the jets forward to the front of the bowl. Its possible that during braking fuel is being pulled away from the primary jets this move the jets further forward so fuel cant get away from them.
jet extensions did dick
I then bridged the vent tubes from front to rear bowl that did nothing either.
I checked the float level again. The rear was actually high about 3/4 the way up the sight glass. The front was dead center in the sight glass per QFT recommendations.
I set both floats to be about 15% above the base of the sight glass this appears to have made a very noticable improvement without causing any apparent tune issues other than a slight lean idle which I gave 1/16th turn to each of the 4 screws and that brought it back.
I noticed that AFRs would hold slight rich under heavy braking then gradually progress to low 10s as speed decreased and the engine would soon die.
Now with the lower float levels its holds upper 12s a lot longer and doesn't dip into the 10s as quickly. I only got it to die once out of 4 instead of 3 or 4 for 4.
I bet if I ran just below the slight glass like 10% below it would be golden. So thats next.
I also found that the rear brakes become less consistent and one side is more likely to lock sooner up as they get 2 or more hard stops on them. It appears one side like to lock up at different times based on heat. They'll be out of there soon enough.
Thanks for the write up, considering bigger brakes too. BTW, wilwood states their brakes move the hat (hub) out .250" in their specs. Regarding your carb, I too have a 4150. Your carb is stalling because you're flooding the carb through the vent tube. I think you nailed part of the problem by bringing you floats down a touch. Fuel is splashing forward when you hard brake and coming out the top of the carb into the venture and killing the engine. Jet extensions are good for the secondaries and hard launching by keeping the jet submerged in fuel as it gravitates to the rear of the bowl. What you need is a vent whistle (QFT) or vent baffle (Holley) in both pri and sec vent tubes. I also suggest since your in the bowls going to a spring loaded (off road) needle and seat. It helps to keep the seat planted to eliminate excess fuel delivery into the bowls through splashing, deceleration, etc. Been autocrossing my carb'd 302, and this combo has been amazingly reliable, no stalling or stumbling under acceleration or hard braking. You should be able to get both items for under $50 total.
I set the float level to just below the sight glass on the rear and maybe just touching the base of the sight glass on the front.
This solved the issue totally however I did get a set of spring loaded needles (off road) I'll throw them in for fun why not.
I usually run my idle mix around 12.8 to 13.1 this adjustment brought it up to around 13.8. However off idle accel is still spot on and so is part throttle cruise so maybe I won't mess with it.
So If I have jet extensions that didnt solve the problem at all in the primary bowl should I move them to the rear bowl, Leave them, or go back to stock??
These are 4 piston calipers with 12 something inch rotors. This rear brake setup is larger than what I used to have on the front prior to all of this excitement.
But **** me dead these rear brakes are 10x more trouble than the front to install not an issue with the kit just axles and e-brake stuff.
So first issue I had was the axles were a bitch to remove the DS came out using the drum installed backwards and using it as a slide hammer. The PS was a total turd and I had to get a slide hammer.
Found two bad axle bearings..which I was suspecting based on the slightly creepy sounds I was hearing from back there from time to time.
Cut the bearing retainer plates off the new ones are open on one side and just slide on so that awesome. The parking brake drum and backplate just side on and use the original bolts to secure everything so thats cool.
Next the disk just slide on but they have this alignment ring that LOOKS like it should index with the rotor and the little round cylinder thing in the center of the axle which the drums did align with and fit tightly over. But this ring is too large to index with the center raised cylinder and does bugger all...I talked to global west about this and they said it was normal and the studs align the rotor....Then **** the ring why bother including it?? (I forgot to ask this)...So naturally im skeptical of this and if it vibrates I'll know why...we shall see.
Next the old brake lines need to be cut down to lenght and you'll need a 37deg flair tool for AN fittings. They are pretty easy to access and this wasnt a difficult task. They did include 1 long AN fitting for each side that can go through a standoff with a radius cut in it that allows it to fit to the axle housing. I did not use them yet as the only way they will be worth a **** is if they are welded to the housing...Maybe ill fire up the tig welder here in a bit...
The final pain in the *** for today was removing the old e brake cable and drum brake assembly. It was only 107 out today and I was like naw yeah this is **** easy I got this...but I could not get the retaining clip to come out of the back plate.. In my defense I really did try to stay calm. I was like "hey I can sell this stuff its original and probably expensive to replace new. Its probably a few hundred dollars worth of fomoco stuff" Then sweat kept gettin in my eyes and then i was like **** this ****ing piece of worthless ****!! I grabbed the biggest pair of lesbians I could find and cut the ****ing cable in half ripped all that **** out from under the car and placed it direct in the trash...Im sure I'll later regret this but at least I can say I saw that coming...plus it was extremely satisfying to clip that POS dead!
After that I bled the system and took it for a quick drive with no e brake and ****ty wheel bearings. I get the bearings dialed tomorrow then work on installing the aftermarket ebrake cable which should be a royal pain..
LOL....sorry, but this is amusing objectively, mostly because I've had similar experiences
I want to say the rotor alignment shouldn't be an issue. It would be nice to locate it on the axle hub, but the wheel is the bigger concern. I bet the studs keep the rotor aligned well enough to prevent noticeable vibration.
I know what you're talking about with those e-brake clips. They're a PITA. I think I bent mine the last time I pulled them out, and I didn't have replacements (at 8pm in my shop class, needing to drive the car home that night) so I bent them back and threw them back in.
I got some fresh axle bearings which significantly reduced the amount of creepy noises from the rear of the vehicle. The new bearings also slide in much easier.
I tried to get a good example of how the parking brake cable should be routed / connected I couldn't find much. Global west said they would send photos asap so thats cool. I did come up with some solutions on my own but I figured I would wait and see how they did theirs because I can likley only trim that cable to lenght once.
Tried to get a few more heat cycles on the rotors it looks like the DS is locking up way before the PS on the rear...this Is kind of what the drums were doing but I dont have enough time on the rear rotors for them to be properly beaded yet Im kind of hoping it will go away once they get some time on them...not sure what else would be causing a bias issue like that.
06-20-2017, 01:15 PM
