daanbc

anything beyond 20-25 mph she's quick. This all started back some time ago when I switched from my original intake to the Weiand street warrior intake. I was never really able to get that spinning the tires off the line thing. Prior yes. Now I just finished the install of the Comp Cam XE268H. I have my timing at 36 all in at 2300. I set my quadrejet at it's lowest idle possible with out stalling = 450-500 RPM. I then adjusted the Idle Mixture screws till I got a better smooth idle. I have them turned out 3 full turns from close. I advanced my idle to 700 in park, 600 in drive. But she still is a dog. I'm thinking of trying my buddy's New Holly next week to see if there's a difference. Unless somebody can help me out.

thegazman

Maybe you need a higher stall speed torque converter.

daanbc

You really think so? The cam is not that outrageous. I know a few here on the forum are running this cam. Maybe they can chime in and let me know if they replaced their stall converter. My heads are original.

STINGRAY1WORD

Is timing on make sure weights or springs are okay.

'75

Are you setting the timing with the vacuum advance unhooked and plugged at the carb? What is your initial timing?

BKbroiler

So other than standing start WOT, its running good? What does it shift at in Drive? Should be at least 5,500 to use that cam.
As for the off the line issue, if the Qjet is working, the Holley won't help. If you have a stock torque converter, thats going to be a killer. Probably combined with 3.08 gears, right? The converter is the biggest opportunity for improvement. Something around 2,500 stall would really wake it up. The looser converter would also make it more comfortable to have a higher idle speed which would safeguard your cam a little. Glad to hear its running good.
BTW - I have the XE262 cam in mine, with a 3,000 converter.

alconk

What gear you have in the back??

daanbc

3:08, it's time right with vac. Disconnected. Just a dog off line. Didn't think stall converter would be an issue with this cam. Thanks for all the replays. When I was hard on it today she shifted just like before I have a transpak. Second gear chirps a bit. Use to chirp and hit second harder.

dochorsepower

Need more info. What heads are you running, stock low compression? That 268 cam is pretty agressive and probably wants some decent compression. Also if you haven't recalibrated the Q-jet , it probably needs richer rods and jets. The stock Q-jet is an emmissions carb, but it has potential when modified. Like I said, need more info.
-Bill

myway76

What is the compression ratio? does it work well with this cam? Is it high enough for the duration of your cam? I see Bill Beat me to it! Great minds think alike!!!

daanbc

Stock heads. Don't want to tear into them now. My carb. is a 77 original to the vette. That year was the biggest rods that came with and made for Q-Jet. It may need to be re calibrated. But I'm no expert in dismantling these carbs. Like I said before my car was WAY quicker off the line with the old manifold. I could spin the tires all I wanted. Now -nothing-. I can't see how the cam would take that away. By the way I had it at the upper RPM's today a couple times and no floating as of yet. I asked Lars on his opinion and gave him all the info on my car. He suggested the cam and timing chain and lifters for me.

markids77

If you're certain of your tune up, and no vacuum leaks try this... "power brake" the thing a bit... hold the brake pedal to keep the car from moving and add throttle until you feel the car "load up" a bit, then floor the gas and release the brake at the same time. If this improves the car's acceleration I suspect a looser converter may be in order. If this technique causes the car to bog, or fails to improve the low end acceleration you have other issues.

daanbc

I have done this. It will not spin it's tires! Before I could smoke em.

Raphiki

Are you sure that when you put the distributor back in it wasn't off a tooth? Might want to recheck.

Vette5.5

77' was one of the lowest HP, lowest compression engine years, and usually wont take much cam, unless other work is done 1st. Mostly higher compression pistons, and better head flow. Actually the factory manifold may give you better off line torque than the after market job, for your engine combo right now. Keep in mind, larger cams move the power band up in the rpm range, and surely your problem, as nothing else in your stock configuration to support the added parts.

scottyp99

If your tune is not the problem, you may need a little more stall speed on the converter. There are tricks for beefing up the low-end, though, like 4-hole carb spacers. They are supposed to boost up the bottom end without too much sacrifice on top end. How much clearance do you have under the hood for something like this?

http://www.chevyhiperformance.com/te...e/viewall.html

http://www.carcraft.com/techarticles...que/index.html

I'm also thinking that the new cam has changed the way your engine breathes, and you may need some carb tuning.


Keep the shiny side up!
Scott

daanbc

Yeah my original manifold I had 2 inch spacer under the carb. My new manifold is the same hieght as my original with the 2 inch spacer. Figured I did'nt need it anymore. I will check again on the distrib. When I first installed it was a tooth/degree off. I lifted it up just a bit and got it over one. Maybe not enough HUH.

BKbroiler

Dave - You've GOT to be certain that your timing is set right. You said you have 36 deg at 2,300 rpm. If that's true then timing is not the issue. You can easily richen the secondary side of the Qjet by changing metering rods. Its a five minute process. Are you familiar with that?

daanbc

I am going to double and triple check my timing tomorrow. My next day off. As for the rods, I was under the impression that the 77 carbs. for the vette came with the biggest rods Q-Jet ever made. So that's why I never bothered with it. I have read "Lars" paper work on it. Like I said before, I can take a Holly apart with my eyes closed (there easy) but when it comes to this Q-JET, I'm in new territory.

silver79

Dave I have the same cam, I also have a 2800 stall torque converter and 3:55 gears backed by a 700r, I think that your tune in wrong. I thing hat it is on the rich side and that you should get it tuned on a Dyno. I had te same problem but an
Father the Dyno tune it is a lot stronger of the line and really roars after 3500 rpm to 6500 read line.