New here with some questions

Hello All,

I'm new here and have a 4AC in an 85 Nova. As a person who does NOT support the new car industry, I have this one as a gas saver and "go to" car when I need something that works. I bought this car about 3 1/2 years ago for $400.00 and have put about 8000 miles on it. Though its not much to look at and my son hates it, I want to get the engine a little perkier.

My off the top of my head mechanic skills are few but I have the patience to read and follwo instructions. I have a few questions about where to start on improving performance. Right now with things that won't keep me down for more than a weekend.

I recently started the car back up after about a year off sitting in the yard. No smke but a rough idle that was the result of a disconnected vacum hose. The distributor, coil and wires were replaced before parking the car . Here are some questions

1) I intend to check the compression today but am curious if there is anything else I should look at closely before putting some time and money into the engine.

2) There seems to be a slight hesitation when tapping the gas pedal. I know nothing about adjusting or rebuilding the stock carb. (My Carb rebuild experience is limited to a welding machine carb). Id like to get rid of that hesitation and possible get a little more performance . I have seen quite a bit in various forums about Weber Carbs being added. Is this something a novice can do and with the sideways mounted engine, will the air cleaner fit?

3) Looking in the haynes manual, it appears a camshaft replacement seems pretty straightforward and easy. Is this something that could boost performance alone or other components be replaced in conjunction ? I have a friend from Memphis who works at a performance parts manufacturer that said he could get me a pretty good deal on parts. He just wasn't sure if they had anything for that engine.

4) Can the stock intake and exhast manifolds be modified/improved upon by hand/milling machine? I have access to a mill and am pretty skilled with hand grinding/polishing (non engine stuff).

5) The car uses little to no oil except when it is full. After it gets about a quart low, it stops. Any ideas?


I appreciate any information that can be provided. I have had a recent renewed interest in getting a little more involved in my own car repair and for some reason I love driving my rusted out Nova. My son thinks its a piece of junk so I'd love to get it where he will have a problem keeping up with me accelerating to the speed limit. (He has a 96 neon With an automatic). My logic may be bad but the car has been long since paid for, has made me over $4000.00 in travel pay on trips as long as 8 hours from home. And the oil on the dipstick looks as clean as the day I put it in. Spending some time and money just "for fun" is justified in my mind.

Have a good day

gerald

Welcome to the forum.

1. Even if it needs some work, it generally doesn't cost much to redo one of these engines.

2. The Weber is not too hard to put in. If you are a welder and can do some machine work a proper install should not be a big deal. You can machine a better adapter than the unit that is
commercially available. You do need to be able to adjust the carb and do some rejetting though. You might be able to adapt the stock air filter, but you can buy one for the Weber as well. I
have a write up on the doing the install in the Reference section.

3. It is easy to do swap the cam out. You can't buy a new performance cam, someone like Schneider Cams can regrind a stock cam for you though. Comp Cams won't have one if thats where
your friend works. You can't buy hardly anything in the way of performance parts for these engines. Doinga performance cam probably won't help your fuel mileage though.

4. You can certainly do a bit of improving on the inlet manifold. I don't know about the exhaust manifold but you might be able to as well.

5. Does it leak oil, or consume it? If there is a leak at the oil pan flange ( or somewhere low on the engine), the oil level could get to the point where it is low enough that it can't reach the hole.

Is the car stick or automatic? If it is an automatic, converting it to stick would do you some good. Automatics have more parasitic losses than a stick, so an automatic car is usually slower and gets worse gas mileage. If you can get the parts out of a junkyard it can be fairly inexpensive to do.

1) Thats what I figured. Other than the looks of the car, a rebuilt engine gets me something that I can depend on and fix myself.

2) I imagine it comes with instructions but your writeup will probably be a great help.

3) I am willing to give up some MPG if I can get a little performance out of it. My son is determined its junk. He wants to drive it off a cliff. If I could perk it up some it may get his interest up in working on his own car.

4) On the inlet side, is it just the connection to the head or are there some internal contours that can be improved? I can weld up any outside areas that need more meat if needed.

5) I believe it leaks it but I only get a few drops when its parked. But its always wet underneath. I replaced the pan gasket about a month before it was parked last time. It seems wettest by the flywheel.


It is a 5 speed and I like driving it. It does slip out of 5th if you don't hold it in. I had my son try to follow me on a back road the other day and I left him till I hit about 40.

Thanks for the info. I'm headed to a junkyard now to look for spares.

2) I don't think it actually comes with much in the way of instructions. There is one thing wrong with my write up that I keep meaning to change. You need to check your fuel pressure, it might be too much for the Weber.

4) I don't think that there is much good in grinding on the head side of the manifold (other than a gradual chamfer at the very end). The runners are the same diameter for a long way, it would be hard to make them bigger all the way through with out cutting the manifold in half, griding it, and then welding it back together. Most of the grinding that will do you some good will be on the carb side. I have a write up about the inlet manifold in the reference section as well.

Hi Gerald, I drive a AE82 which is mechanically very similar to your nova and shares the same chassis. I see that you are interested in putting in a aftermarket carb such as a Weber. I have a Weber 38 DGES in my car, the engine is mounted on longitudinal, and the Weber fits. However, my Weber came with its own air filter, so I had to scrap my stock air cleaner assembly. It took about a day to install the Weber, and another day just to tune the Weber. With the Weber my fuel economy suffers, but power is improved noticibly, throttle response is also improved significantly.

EvolutionGTS, Thanks for the info. I was curious what other models I could get partss off. I made a trip to a auto salvage yard today searching for parts but didn't have much luck.

I checked the mileage on mine on the highway today and got about 33MPG so something seems a bit off from what I was getting before. I hooked a manual vacuum pump to the two lines on the diaphram of the advance unit and the ignition didn't advance any.

I noticed metal around a front engine mount a bit rusted so there may be some needed chassis work too.

I'm thinking the carb and maybe a header is the easiest route to a little more power. I'm thinking a tune up may be in order 1st. I picked up a dash mounted tach to set the idle speed and will see if the timing is still good.

Any suggestions from anyone on the best service manual to get ? I thought about a chiltons but wondered if a factory service manual was a better way to go.

I did a quick check to see if all of the cylinders were showing the same compression at idle and they were all around 90 PSI. I imagine the pressure comes up some with the throttle open and engine no running but I was just curious if they were the same and was in a hurry. The car cranked up just reaching through the window on 3 cylinders each time so I was pleased. Noticed my fuel filter a little reddish brown so t may be causing some problems too.

One thing I frgot to mention, when I 1st bough the car and it would use/loose the quart of oil so fast, I used chainsaw bar and chain oil. Made at least 2 trips to Baton Rouge and back with that stuff. At that time I was in the drive it till it dies mode. But its grown on me!

if your good at welding and have access to a mill, or other machines, you should make your own headers and intake manifolds.... you'll notice power the diffrence

It's probably not too hard to design and make a header / exhaust manifold that works better than stock, but it's riskier to design a new common plenum inlet manifold. You might make something and have it work fine, but there is also a good chance that the you could make something that has mixture distribution problems, IE some cylinders will run leaner than others. You have to jet the carb so that the leanest cylinders are at the appropriate fuel air ratio so as not to cause engine damage, which means that rest of the cylinders run rich. It's just something to keep in mind. I personally would not want to take something like this on.

Isolated runner carb manifolds (like for two Weber side drafts) or fuel injection manifolds like the one I had made are not as susceptible to this sort of thing, so you don't have to know very much to design them. Either option is more expensive and complicated than the single downdraft Weber.

90psi thats a little low there.

87AE-82 wrote:

90psi thats a little low there.

I did it with the engine running at idle so I'm not sure if having the throttle open just turning over the starter without the ignition would bring it up.

To get a proper result you need to hold the throttle wide open. You also need to watch how time time the engine turns over to get full pressure.

Hello.

Oil that leaks under the bell housing usually means that there is a leaky gallery plug. Or worse a rear main seal. If your compression is 90lbs wet, then your prolly going to end up ripping the motor out and rebuilding/replacing. Slipping out of gear is a problem too.

Luckily 4ac engines and transmissions are a dime a dozen. I wouldn't bother rebuilding them when for a fraction of that cost you could just go to a wrecker and replace em both. That all changes of course when you want real HP out of it..

As for headers, there is a fair amount of math thats involved to get the right plen length and tube Dia based on many factors. (chamber cc, bore, stroke, V.E.R., carb CFM, etc etc etc) Most people can get away with just equal tube length headers. In the past I've built them with very limited success. I've been thinking about trying again, but its a pain in the ass.

[quote="pipewelder_1999"]

87AE-82 wrote:

I did it with the engine running at idle so I'm not sure if having the throttle open just turning over the starter without the ignition would bring it up.

To get an accurate reading:

remove all four plugs, and if the engine is cold pour about tablespoon of 10/40 down the plug holes. insert a long thin rod down the carb throat to hold the plates open.

Screw on the compression tester and hit the starter and watch the compression gauge "bump" upwards 5 times. record pressure. repeat for all four cylinders.

Take your highest reading and multiply by .75

The answer is your lowest allowable compression reading for proper power balance.