73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: klaussk on March 26, 2011, 06:45:33 pm
-
I'm trying to decide between attempting to rebuild the stock Rochester quadrajet or buying a new Holley 4160 600 cfm. Ive never rebuilt a carb and I'm afraid the quadrajet might kick my ass. haha
-
I'd get a Holley myself. But I know a little bit about how to tune them. I do agree though, a proper working q-jet is a fine carb to have. But I've never been able to make a non-properly working q-jet work properly, so i just scrap them and put a Holley on.
-
thats wat im thinking. i only have a very basic understanding of how a carb works. ive never rebuilt one and dont know how to tune them. but ive read that holleys are much easier to rebuild and tune. i think im gonna go with the holler 600. i might try to put a little bit of a smaller jet in it. i dont want to lose any gas mileage. all i gotta do now is get my wife to let me buy one hahaha.
-
Many people have rebuilt the quadrajet on here, they didn't really seem to have a problem.
You could go with the 4160 carb or an edelbrock 1406. You'll need an adapter to mount the carb to your intake assuming it's stock and only has the spreadbore flange. Do you have EGR? If so, you'll probably need another spacer to have the vacuum secondaries on that 4160 clear the EGR valve. Plus, I know on the 1406, you'll have to cut the fuel line and put a rubber a line from that to the carb (with a new inline fuel filter recommended). Looks the same way on summit's website for the 4160. What transmission do you have? You may have to get the linkage kit for the 700r4.
Another option, is summit's brand carb, http://www.summitracing.com/parts/SUM-M08600VS/
Still has the same probs as above, just a little bit cheaper, but the boosters seem to be of a decent variety.
You could also go with a holley 4175 carb. It's about $400 smackers though. It would fit a stock manifold without an adapter. You might still need a spacer to clear the EGR. The stock fuel line should fit it without modification. You may still need the 700r4 linkage kit if that's your transmission. It also comes with a dual stage powervalve which while not as as good as a rod and spring setup for power enrichment, it's still pretty good. Actually, I cannot confirm that it does come with a dual stage powervalve on holley's website.
You might just be better off rebuilding that quadrajet.
-
By the time you buy the new carb and any adapters and brackets, etc. to get it all hooked up you could buy a new direct replacement q-jet, or pay a local carb builder to rebuild yours, and I think you would be happier with it.
-
I have had 3 q-jets rebuilt by local reputable guys. 1st experience was good. After that Both guys were difficult to work with. The second time It took him almost a month and started poorly 2 months down the road. The second guy rebuilt the carb, said he would put it on his test engine etc. Would not run on the dyno and hold 2000 rpms to break in the cam. I bought a holley to run on the dyno and I am still waiting to get the q-jet back in running condition. after experiencing q-jets and now on my second holley, I will never go back again. The holley is designed to be easy to tune and I can actually do it. With the holley you get 3 springs that you can change to determine when your secondaries open(good for mpg). you can also use smaller jets in your primaries and larger jets in the secondaries to maximize mileage without sacraficing performance when you want it.
This is my experience with carbs.
You will get people on here with good and bad opinions on every brand of carb but for simplicity sake holley get my vote.
-
http://www.smicarburetor.com/products/sfID1/14/sfID2/9
-
well im still really undecided. but i am leaning towards the holley because i think it will be easier for me to tune on my own. and i dont know anyone in the area that can rebuild carbs. i do have the egr though which sucks in my opinion. ive heard that i can remove the egr valve and just bolt a plate on over the opening. im gonna look into direct replacements though. thank everyone
-
You run the risk of detonation if you remove the egr....not good for the engine, unless you plan on running better than regular 87 in it.
-
You run the risk of detonation if you remove the egr....not good for the engine, unless you plan on running better than regular 87 in it.
How does that happen? Is there something different about a sbc with and without egr (besides the egr itself)?
-
The EGR lowers combustion temps, which helps to prevent pinging. Burning a higher octane fuel can reduce the effects of running without the EGR, along with retarding the timing bit if need be, but on a stock motor you may not notice any difference at all removing the EGR.
-
My point was that sbc's didn't always have egr's. Other than minor things like timing possibly, I'm not aware of any changes that were made that would prohibit you from just running without one like they used to. That and all of the millions of people that disconnect them, block them off, or install a non-egr intake and I had never heard of a problem from it. That and I've disabled a few myself and never noticed any pinging.
-
They also ran Leaded fuel back in the days before EGR.
EGR allows us to run a little more timing, with lower grade fuels.
-
well ive finaly gave in today. i bought a new holley 4160 and edelbroke performer intake. im still in the prcess of putting the new stuff on. and i rented a timing light so i can get the timing perfect. i want to advance it a little bit and run premium in it .i have a msd coil and cap for it and nice napa plug wires and platinum plugs, so i got the spark to burn premium. anyone doin that. if so what kind of advance are you running
-
I blocked my EGR off because it made my engine missfire horribly when cold. I used a putty knife blade with silicone on it. Runs like a champ, stock everything but the cam, with timing agt 8 or 10° with 87 octane.
-
I blocked my EGR off because it made my engine missfire horribly when cold. I used a putty knife blade with silicone on it. Runs like a champ, stock everything but the cam, with timing agt 8 or 10° with 87 octane.
It probably wasn`t the EGR valve that was making it missfire when cold, but possibly the ported vacuum switch used to control it.
-
the kid i bought my truck off of said that my carb is an edelbrock rebuilt q-jet. i never messed with it, the thing works great. I've only looked at it enough to know thats its a q-jet.
-
ok im not sure exactly what was wrong with that post. but ill attempt to rephrase it. i dont understand how a bad EGR valve can make a truck run bad. But it can run fine without it.
-
Edit your post and rephrase that immediately.
-
I rephrased it for him and gave him 5 days to read the rules... Thanks for the report.
-
Edit your post and rephrase that immediately.
HUH?
-
That wasn't directed at you Jims86. Capt took care of it and we're back on topic now.
Question though, in the days of leaded gas and no EGR, what kind of compression ratio did those motors usually have compared to the later EGR models?
-
i have heard of some of the cars runnin as much as 11 to 1 back then i dont know for sure though. i know a guy that had a road runner with a 340 in it who said that he had rebuilt the engine back in the early 70s and when they took the lead out that he had to redo it becouse the compression was to high.
-
i have heard of some of the cars runnin as much as 11 to 1 back then i dont know for sure though. i know a guy that had a road runner with a 340 in it who said that he had rebuilt the engine back in the early 70s and when they took the lead out that he had to redo it becouse the compression was to high.
Yup, some as high as 11(maybe higher), some as low as 7.5