Help with header install

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markcp

Greasemonkey
Nov 1, 2007
106
18
Chillin014 said:
i just got my mufflers today and wow...routing an exhaust on this car is going to be fun....not.the popular route seems to be routing the pipes near the driveshaft until they clear the under-seat humps. ..but that doesnt give a whole lot more clearance. I'm running 2.5 inch pipes by the way. hopefully thats not too big.now i gotta head to autozone and see if they have any of the right curves to allow me to run these pipes.

Did you run a dual hump crossmemeber? I've got a great exhaust shop 3 miles away that will custom bend and weld my system once I'm ready for it. To some peoples dislikes, I went with Flowmaster 50 series delta for my mufflers. I had found a site that had sound clips that I could listen to. It helped me in my decision.
 

Chillin014

Master Mechanic
Thread starter
Nov 9, 2007
422
0
houston/richmond tx
85 Cutlass Brougham said:
If you have a computer carb, it is wise to replace it with a non computer variant if you do not runt the computer. I run the Quadrajet off of a 1979 350 powered Chevy van in mine which I modified for the full 800 cfm instead of the 600 cfm they have unmodified ( 5 minutes with a Dremel to cut down a stop on the secondary air valve). Use the later Quadrajet (75 and later I think...) which is a bolt on replacement for your carb but without the computer fittings. Try to get one off a Chevy 350 or maybe a 1980 Cadillac 368 and avoid ones from larger displacement engines. The idle feed restrictions will be too big and it will run rich at idle and part throttle. Also avoid ones with the straight in fuel fitting instead of the Chevy/Cadillac 90 degree inlet style. By all means though, avoid ones with electrical plugs on them ( choke excepted) as they will run bad without their computer attached! The later carbs have the ability to run the electric choke by simply swapping the coil. They also keep all of the same vacuum and throttle cable/TV cable hook ups as well. Quadrajets are by far the best street carb for a mild small block Chevy. They have great fuel economy and part throttle responsiveness, plus they keep their tune better than a Holley does. Stay away from Holleys if at all possible and learn how to make a Quadrajet run right and you will be much happier in the long run.

Also, if you have not done so already, get rid of the computer HEI distributor and replace it with a non computer one. I would get one from MSD as they make the best aftermarket HEI in my opinion. By the time you replace everything in a junkyard HEI with what they give you in their new one, you really aren't saving anything and your 30+ year old advance mechanism is likely shot and not going to hold a proper advance curve anyways. I have that problem with my 1978 HEI and will likely replace it with one from MSD in the near future. To see if you have a Computer or Non-computer HEI, check to be sure it has a vacuum advance can on the side of the distributor, on the passenger's side of the engine I think. If so, you have the right distributor. If not, and you have a 4 wire plug on it, you have the computer one and it will run like crap until you change to the right one.

BTW, if you live anywhere near where I live ( Tampa area of Florida) I would be willing to look at your car for free to help you get it sorted out. I'd just ask that you came to my house for me to do it. There are likely a lot of little things wrong and I could sort them faster in person than on the net.
800cfm might be too big for my motor (you would know better than I). But my friend has a 750 edelbrock I believe that we decided was too big so I stuck with my crapper. I have a Carter AFB that needs a rebuild but I'll probably just try to sell it online and stick with a quadrajet since you and others have said good things about it. Did you mean '75 and earlier?? Because Im thinking the carb on here is the one that came with the car which is 83 (that would be later than 75 like your saying). I might have to check on ebay or something, junkyards around here never seem to have many gbodies although I will have to check again for the cadillacs...theres just so many damn variations and mixed parts you can use I get confused.
I believe there's only a maximum of about 2 or 3 wires going into a harness that plugs into my distributor...it plugs in on the driver side of it. and yes it does have the vacuum advance.
i appreciate the help and offer but unfortunately I live in Texas. I'm in no huge rush to fix the car completely, its my project car. Once I get the carb straightened out, timing, and the exhaust right..I'm going to do some body work and such.

markcp - I did not get the dual hump cross member, I'm too broke for that right now. I did see someones set up on gbody forums where they used the stock crossmember and routed both header outlets pipes to the left side where the clearance is there...too much trouble for me however. I am looking at more parts on summit but something most likely WILL have to be done about the cross member. And I realize an exhaust shop could probably hook somethin up alot easier than I ...I just dont like other people working on my car..its a personal thing I guess.
 
Sep 1, 2006
6,687
0
Tampa Bay Area
That's the beauty of a Quadrajet-if you don't need 800 cfm, it will not flow 800 cfm. It has a spring loaded ( and tension-adjustable) air valve secondary door which is pulled open by engine vacuum that simultaneously pulls up on the secondary metering rods, thus the fuel matches the air. Engine load determines carb size. The Edelbrock uses a counter weight system for it's secondary air valve door and is not adjustable. I probably do not use the full 800 cfm when I hammer mine, but if I ever need it, it will be there for me to use. Oh, and I did mean 75 and later non computer Q-Jet. There are several variations and you want the newer one. Like I said, my carb is a 1979 model and has all the hookups for the power brakes, cruise control and TV cable which the early carbs do not have. The TV cable was not used on earlier transmissions and thus is not included on the older carbs.
 

Chillin014

Master Mechanic
Thread starter
Nov 9, 2007
422
0
houston/richmond tx
85 Cutlass Brougham said:
That's the beauty of a Quadrajet-if you don't need 800 cfm, it will not flow 800 cfm. It has a spring loaded ( and tension-adjustable) air valve secondary door which is pulled open by engine vacuum that simultaneously pulls up on the secondary metering rods, thus the fuel matches the air. Engine load determines carb size. The Edelbrock uses a counter weight system for it's secondary air valve door and is not adjustable. I probably do not use the full 800 cfm when I hammer mine, but if I ever need it, it will be there for me to use. Oh, and I did mean 75 and later non computer Q-Jet. There are several variations and you want the newer one. Like I said, my carb is a 1979 model and has all the hookups for the power brakes, cruise control and TV cable which the early carbs do not have. The TV cable was not used on earlier transmissions and thus is not included on the older carbs.
hmm I might search around for one on ebay in a bit to see if someone has one on there and i'll confirm with you.
Is the edelbrock and aftermarket set-ups simpler? or why do they have inferior/unnecessary qualities?
 
Sep 1, 2006
6,687
0
Tampa Bay Area
The Quadrajet offers more adjustability plus it's a spread bore while the Edelbrock and most Holleys are square bore. The spread bore carb offers a stronger vacuum signal to the booster venturis at idle and part throttle for better atomization during low speed operation. It has crisper throttle response off idle too. I had an Edelbrock 600 on my 355 before I swapped it to the Quadrajet on it right now. The Edelbrock is not too bad once it is dialed in ( mine was), but the Quadrajet offers better throttle response and fuel economy plus more adjustability. It is also shorter than the aftermarket carbs too, allowing for better hood clearance. I do not run an aftermarket air filter housing on mine for several reasons. First off is performance. The factory HO 305 Camaro dual snorkel housing I have (with 305 Monte Carlo lid) allows me to plumb in a ram air setup with cooler outside air as compared to the typical open element setup most people run. Next is clearance. The HEI distributor will not work with the typical 14 in open element air fliter unless you get an offset base or run a spacer on op of the carb which can cause hood clearance issues. Third is maintenance. The open element style gets dirty quickly, in as little as 3,000 miles in my experience. Fourth is cost. I got it for free after talking a buddy out of it in exchange for some work. Fifth, my car is a sleeper under the hood. I wanted a stock look because of all the optional ugliness the car has and chrome or polished aluminum parts just would not look good under all that crap.

Oh, and don't look to E-Bay for everything, especially stuff like this. Go to your local U pull it yard and bum around for a bit. See what's there and what you can use. 90% of my car came from the local junkyards and I tried to avoid new parts unless absolutely necessary. My carb was a fresh rebuild and I paid $25 for it. My intake was $15 and my HEI was $10. The starter and alternator were $10 each while my water pump was from the parts store at $15. I got my TH 200 4R trans for $35, rear axle for $50 and sway bars for $10 each. Oh, and I got my front seats for $10 each off a 35k mile car. You will be surprised at what you find at the junk yard-especially if you do not live in the rust belt.
 

Chillin014

Master Mechanic
Thread starter
Nov 9, 2007
422
0
houston/richmond tx
85 Cutlass Brougham said:
The Quadrajet offers more adjustability plus it's a spread bore while the Edelbrock and most Holleys are square bore. The spread bore carb offers a stronger vacuum signal to the booster venturis at idle and part throttle for better atomization during low speed operation. It has crisper throttle response off idle too. I had an Edelbrock 600 on my 355 before I swapped it to the Quadrajet on it right now. The Edelbrock is not too bad once it is dialed in ( mine was), but the Quadrajet offers better throttle response and fuel economy plus more adjustability. It is also shorter than the aftermarket carbs too, allowing for better hood clearance. I do not run an aftermarket air filter housing on mine for several reasons. First off is performance. The factory HO 305 Camaro dual snorkel housing I have (with 305 Monte Carlo lid) allows me to plumb in a ram air setup with cooler outside air as compared to the typical open element setup most people run. Next is clearance. The HEI distributor will not work with the typical 14 in open element air fliter unless you get an offset base or run a spacer on op of the carb which can cause hood clearance issues. Third is maintenance. The open element style gets dirty quickly, in as little as 3,000 miles in my experience. Fourth is cost. I got it for free after talking a buddy out of it in exchange for some work. Fifth, my car is a sleeper under the hood. I wanted a stock look because of all the optional ugliness the car has and chrome or polished aluminum parts just would not look good under all that crap.

Oh, and don't look to E-Bay for everything, especially stuff like this. Go to your local U pull it yard and bum around for a bit. See what's there and what you can use. 90% of my car came from the local junkyards and I tried to avoid new parts unless absolutely necessary. My carb was a fresh rebuild and I paid $25 for it. My intake was $15 and my HEI was $10. The starter and alternator were $10 each while my water pump was from the parts store at $15. I got my TH 200 4R trans for $35, rear axle for $50 and sway bars for $10 each. Oh, and I got my front seats for $10 each off a 35k mile car. You will be surprised at what you find at the junk yard-especially if you do not live in the rust belt.
ah. some of that is over my head. but I'll let you know when I find a carb and if your familiar with rebuilding them maybe you could direct me towards a rebuild kit or something. I am all for saving money I just haven't found the right places to look for american cars. I realize some parts are getting rare as the car is semi-old but some online prices are rediculous..like honestcharlies...wow.
 
Sep 1, 2006
6,687
0
Tampa Bay Area
Well, the cool thing is, these cars have tons of things that interchange from GM cars as far back as 1955-you just have to know where to look. Oddly, most magazines are no longer covering this stuff because it is considered too much of a common knowledge thing. As for the secondary air valve adjustment, this month's Car Craft shows how in the tech question section. Here are some pictures of my car's Non Computer HEI and Quadrajet setup. You can see the rusty silver vacuum advance can hanging off the bottom of the distributor which indicates a non computer version.
l_9f0896f4046e55e4f6219792f51ed811.jpg

This is the wiring harness for the A/C and the temp switch on the driver's side. The harness sitting on the header is the compressor plug and would not normally be there. You can also see the correct positioning of the throttle return spring and the TV cable. Also note the factory bracket that the temp wire is zip tied to. This keeps it from burning on the header. The chrome thing on the thermostat housing is a temperature gauge that lets me see what the actual engine temp is. It's my one bling item under the hood.
l_e8c5ca447cd149175387b68e360ba114.jpg
 

Chillin014

Master Mechanic
Thread starter
Nov 9, 2007
422
0
houston/richmond tx
i see i see. ty. My HEI distributor definitely has the vacuum but a small harness as well so i'm not sure what that would make mine.

your carb looks like mine except I have like no electrical connections connected due to them either missing or something tragic. lol.

Whats that? you say you have even a harness for your headers? Man...I thought these cars were supposed to be simple. :lol:
 
Sep 1, 2006
6,687
0
Tampa Bay Area
No, the harness sitting on top of the headers is not supposed to be there. The end of it is the plug that goes into the compressor clutch and will go back there once I get around to the A/C install. Were I to run the engine with it there it would be destroyed. The only 2 electrical connections on the carb are for the electrically heated choke and the A/C throttle kicker which compensates for the load of the compressor when it is on. Neither of these are critical to the functioning of the carb, but are there for driveability. You can hold down the gas to keep the engine running when cold, but the choke makes that unnecessary, and the throttle kicker prevents the engine from stalling but could be done away with if you bump the idle speed a few hundred RPM's. You can also run a different kind of choke heater that gets it's heat from the exhaust crossover in the manifold, but the electrical tends to be better in my opinion. The carb originally had the hot air choke but I converted it in the junkyard before I bought it so that I could run the electric choke instead.
 

Chillin014

Master Mechanic
Thread starter
Nov 9, 2007
422
0
houston/richmond tx
85 Cutlass Brougham said:
No, the harness sitting on top of the headers is not supposed to be there. The end of it is the plug that goes into the compressor clutch and will go back there once I get around to the A/C install. Were I to run the engine with it there it would be destroyed. The only 2 electrical connections on the carb are for the electrically heated choke and the A/C throttle kicker which compensates for the load of the compressor when it is on. Neither of these are critical to the functioning of the carb, but are there for driveability. You can hold down the gas to keep the engine running when cold, but the choke makes that unnecessary, and the throttle kicker prevents the engine from stalling but could be done away with if you bump the idle speed a few hundred RPM's. You can also run a different kind of choke heater that gets it's heat from the exhaust crossover in the manifold, but the electrical tends to be better in my opinion. The carb originally had the hot air choke but I converted it in the junkyard before I bought it so that I could run the electric choke instead.
i was just kidding man.
yea I've definitely got an idle problem, sometimes if I blip the throttle I can get it to idle low. but for the most part it idles fairly high. I wish I had a tachometer so I could see...I'll have to get the cluster with the tach in the future.
 
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