Rochester 4 bbl carb

[Guest]

I have an 86 supreme brougham, with a stock 305 in it.

The dizzy seems to have a built-in coil on it (on the top). Could someone tell me what kind it is and if it is good enough for performance?

What impact will increasing the gap of the spark plug have on my car's performance?

The carb I have is a Rochester 4 bbl. My mechanic told me that it was a poor carb. What are my options for replacement? I need to get max performance from my car, and want to learn how to do it. Does anyone know which carb to go for and from where I can get a used one? Is there someone selling any of that stuff?

In another post, I was told by an experienced person that my engine is computer controlled, and that I need a different performance chip for my car. Where can I get it from?

[Sgt Art]

Dizzy? I'm guessing you mean distributor, I've just never heard it called that. It's the standard GM HEI distributor and if in proper working order, will provide adequate ignition for your 305 engine. Gapping the plugs out further than what than mfgr specs will probably cause pinging and will not give any gain in power.

The Quadrajet is a good carb if it is in proper working condition. However, if it's worn out, it's probably time for a rebuild. You could try this yourself, but if you've never taken one apart and done this, I don't recommend it unless you have a replacement. Is your carb computer controlled? Are there two wired connectors attaching to it? One connector is the throttle position sensor and the other controls the mixture rod also known as the dancing stick. When you turn the key to the "on" position, you should hear a constant ticking, that's the stick dancing. Back to the distributor. Does it use a vacuum type advance, or is there a four wire connector going to it? If the carb and dist both have wire connectors, then your fuel mix and advance are both computer controlled, I'm betting they are.

The chips....ah I've tried them and never felt all that HP I was supposed to get. In the end, I decided to go back to a vacuum advance distributor with a regular four barrel carb. I live in a state that so far does not inspect emissions. If they decide to, I'm screwed.

There's not a lot you can do with that 305. You'll find in the long run, it's cheaper to swap out to a 350 or 403 Olds engine if you want more power.

[Guest]

Thanks for such an excellent resposne, Sgt. I really was able to learn from you.

Now since I am in Toronto, Canada, I do not have the kind of facilities people in US would have, when it comes to swapping engines. I was informed by another person on this forum that the 305 has a lot of performance parts made for it, and this is the engine for which there are maximum number and types of performance parts made. I am of the opinion that I might have to go for an HO engine in some months or a year, but till then, I want to put in parts that will give me more power with this 305 and then when I get a better engine, they wil work with that as well. What do you suggest? I am not changing my distributor (yes, it is called 'dizzy' in the circles of classic beetle lovers. I used to have one, and am still an ardent lover of the classic beetle), because it is an HEI. But should I just swap the carb and get a similar rebuilt on or should I go for a webber or edelbrock?

I have converted my stock exhaust to duals with resonators on both sides. I guess that has improved my top end, although the low end has suffered somewhat.

Would advancing the timing a few degrees help in power bost?

[Sgt Art]

Is this a 305 Chevy engine in your car? For some reason I was thinking you had a 307 Olds which is a totally different animal. As I'm sure your aware, GM made engines in each division with the same Cubic Inches but are all different. Example a 350 Chevy and a 350 Olds are not at all alike. If you're dealing with a Chevy, yes, there are more performance parts available than with small Olds. The biggest problem with 305 Chevies are the heads. They're pretty restrictive. Cylinder heads are where the HP is made and the best thing to do here would be replacing the ones you've got. That's a big job, but you'll see some differences for sure. I've read many articles about that in Hot Rod and other magazines, just can't think of any casting numbers. Dual exhausts are a good idea, but will only really work in conjunction with better flowing heads and a cam that will compliment them. See where we're going here? Basically, with that engine, you're looking at a rebuild to see any real HP gains. A small block Chevy is the mouse that roared and has great potential with almost unlimited parts availability. Get some hot rod type mags to read up and find one that would work for you. Follow the "receipe" as they lay it out. The biggest mistake guys make when hot rodding, is they just start throwing a bunch of performance parts together without knowing how they will work. Wrong cam, or carb combo gives rotten performance.

[Guest]

thanks a lot, sgt.

I have learnt my lesson. I guess the best thing to do is to see my budget and decide whether I should go for a rebuild or a bigger engine. WHta are my options for a bigger more powerful engine? Is there any place that would supply these engines at a low price? I am even willing to go for a used one, if that is what it comes to.

As far as the carb is concerned, I have to wait every morning for about 10 minutes before I can drive it full throttle. If I drive out immediatelyu after starting it, it does not catch on speed. It hesitates, and then sometimes dies out, or goes really slow. I cant push the throttle. And then if I wait for about 10 minutes for the engine temp to climb up, then it seems ok. Is it the carb or something else? I also want to advance the timing, but cant seem to find how to loosen the distributor (dizzy <img src="http://www.aaca.org/ubbthreads/images/graemlins/smile.gif" alt="" />).

thanks for your kind help, sgt.

[Sgt Art]

Sounds like the choke pull off is kaput. It's a small vacuum diaphram that's mounted on the front upper right side of the carb. Check it by applying vacuum (suck on the sucker) and see if it moves the linkage any. If not, replace it. It's a cheap part easy to get at any parts store. You'll see a short rubber vacuum line from it to the front of the carb (about an inch long) that's the vacuum source. I think it's held on with two screws. The pull off allows you to have the choke closed while the engine is cold and will crack the choke open when you start to accellerate and not bog the engine down. It's a common problem.

Before I rebuilt a 305 Chevy, I'd scour the junk yards for a running 350 Chevy. Then build it up depending on what you want to do. If you want a balls out (that's not a vulgar term it refers to the brass weights used on old time governors for steam engines that worked with centrifugal force) then do as I said earlier. Find a receipe in Hot Rod, or Car Craft or whatever and follow it to the letter. Assemble your parts (it ain't cheap basic small block Chev rebuild kit is going to be over $500) have your block machined (if you need to have it bored, the machinist needs your new pistons .030 to .040 is standard) have the big end of the rods reconned etc. All this can lead upwards of $1,000 PDQ. More on an Olds, Chevy will be the cheapest. Another option is to buy a crate long block from a Chev dealer. Depending on which one you want, it's going to be anywhere from $1,200 to $3,000. No free ride I'm afraid. I just spent over $600 for a set of Olds big block heads (cost plus machining). The cheapest way is to buy a running engine from a reputable (as in refund or replace is the engine is junk) salvage yard. I've seen them going for about $600. THe risk here is, you don't know for sure what your getting. The 455 Olds I bought was represented as running. I guess it was if you consider it could run on 7 cylinders. It had a broken push rod due to a failed lifter on no. 8 cylinder. So, if you go that route, buy a gasket kit and tear down and inspect. It would be advisable while doing that, replace the cam, lifters, timing chain and sprockets,rod&main bearings and oil pump. That won't cost too much - it's a poor man's rebuild. Remember, cleaniness is next Penske-ness. Clean the crud out of it.

What I'm saying is there is no cheap easy way to get HP