Hey guys, my 86 wagon has a 258 I recently took apart for a cam swap. Let me rewind. I bought this car from a friend last year. I completely rewired it as it had a fire under the hood at some point and almost everything was either totally unable to recognize or not even there at all. But I managed to make it run enough to feel comfortable with buying it. My friend's dad owned the car and recently passed. He drove it from ny to Mexico every few years. At some point he had work done to it, but we weren't sure what. What was obvious was the tri-y header and offy intake with a 4 bbl Holley. I had it running "ok" once servicing the axles and brakes. But it always had a lack of bottom end, top end, if it could get there, and didn't like to start, didn't like hills....at all! Just a mess. So I rebuilt the 390 Holley and it got better, but not great. Doing so I realized the car had a single plane intake. So I opted for a cam swap.
Fast forward a year. I finally got around to the cam. It's a k68-231-4 comp cams kit. When I pulled the head, I found .030" slugs and a nice looking head as far as valves go. Put it all together and wow, it's.......better? Ish! So then I made a financial mistake and bought the dual plane dual port offy intake, using the same 390 vac secondary carb but now with adjustable secondary springs. It's an honest improvement. The problem was at first, I didn't have enough throttle cable so I ran the carb backwards on the intake, big runners for primaries, small ones for secondaries. It did alright. Sure it was short term. Did ok on pull offs and low end but still not good enough. And it would not by any means run cold, w
Even with a manual choke, I'd have to wedge the choke plate totally shut. But it started fine warm. So I finally got a cable, and a spacer so the carb throttle bracket would clear the intake, and voila, wait what? Nothing got better. Almost worse. So, in any combination, the best vacuum I could pull at idle was about 16". The lowest idle I could get was about 900 or so, yes I checked 18 times for vac leaks!! I upgraded the duraspark to hei and adjustable advance which is unhooked bc it refuses to idle and if it doesn't it stumbles on Accel when it is hooked up. I've changed the plugs twice and wires, even tried "recurving" the distributor. The only way it's really happy is at about 16 degrees base timing. I can go back to four before it stalls but then I lose response, power and it stumbles way harder in turns and driveway/parking lot maneuvers.
So I have this awesome car, that sucks to drive and doesn't like to start when cold or pull down low and loves stalling and stumbling. But it's a cool car and I wanna fix it and daily drive it. I'm almost ready to buy a sniper Holley kit but ohh boy idk.....anybody have any ideas or experience with 4 bbl 258's???? I could really use your help!!!!
Are you still running a cat? Check your exhaust for restrictions. If you can't exhaust then you can't build a vacuum.
I got the car without a cat. It's all 2" into a turbo muffler. Not of the glass pack variety.
A hot cam usually needs more initial advance (16 degrees is not uncommon) and maybe about 34 degrees total with mechanical advance figured in (I have a Clifford-equipped Gremmie that needs that much). Hot cam also means less vacuum. Idling at 800 to 1000 rpm isn't that unusual either - altho I haven't yet looked up the specs on your cam.
It's more radical than a run of the mill eagle can but not crazy. The high idle doesn't bother me a whole lot but I can't run vac advance without base timing set at like 4 degrees when it's manifold vacuum. And if I hook it up ported I get a stumble shortly off idle . Almost as if the Accel pump isn't working but I verified that it is and if I adjust the advance I can make it better, but not better enough to go away. Are you using the vacuum advance on ur gremlin?
Nope; no vac advance at all on my Grem.
What are you running for an engine? I ran it unhooked but I hated seeing it unhooked and I thought maybe I could pull the advance back enough to let it idle down a bit and still have vacuum advance on port vacuum to help with low rpm load and recovery.
Its just a mildly-modified 232 (Clifford cam, header, intake, little Holley carb). Of course to run more initial advance (and no vac advance), you need to limit your mechanical advance some (to max around 32-34 degrees usually); or else ping city at max factory mechanical advance.
Well I adjusted timing to happiest idle after tuning the carb to happiest idle. I had already previously recurved the distributor for less timing advance and never even checked the timing with a gun(yet) I reinstalled the carb backwards on the dual plane/port manifold and idk what I did different but wow! I have to right all my adjustments down bc it's a new car now. It pulls back from idle in second gear almost stopped, it accels great when I drop the hammer and it cruises without throwing a tantrum. It's been a whole week without a backfire and I actually aim to check my fuel mileage this week! Lol my only complaint now is the choke needing to be completely slammed shut to run and she runs out of wind at about 75 or so, more than fast enough but with what I'm assuming is 3.54's I'd expect better top speed. Thing runs like1400 rpm in 5th at 50ish mph!
The choke flap needing to be totally closed is just weird! Maybe a huge vacuum leak or majorly messed up carb?
Are you running the EGR (exhaust gas recirculation) ? Could be stuck open or rusted out, giving you an internal vacuum leak. If choke is completely shut when running, its getting air from somewhere. My buddy had a bad idle all winter, changed carb, adjusted and readjusted, finally found loose intake manifold bolts.
It does sound like a carburetor or vacuum problem. Possibly the ethanol fuels we must use has damaged Corroded? the carb.
Quote from: 86erfixer on May 31, 2020, 12:22:50 PM
Well I adjusted timing to happiest idle after tuning the carb to happiest idle. I had already previously recurved the distributor for less timing advance and never even checked the timing with a gun(yet) I reinstalled the carb backwards on the dual plane/port manifold and idk what I did different but wow! I have to right all my adjustments down bc it's a new car now. It pulls back from idle in second gear almost stopped, it accels great when I drop the hammer and it cruises without throwing a tantrum. It's been a whole week without a backfire and I actually aim to check my fuel mileage this week! Lol my only complaint now is the choke needing to be completely slammed shut to run and she runs out of wind at about 75 or so, more than fast enough but with what I'm assuming is 3.54's I'd expect better top speed. Thing runs like1400 rpm in 5th at 50ish mph!
Only 4 cylinder Eagles had 3.54. You probably have 3.07's based on your RPM and speed if you have have stock size tires.
No emissions at all, other than pcv if you consider that emissions. I think my throttle shafts need new bushings as there is fuel staining on my new intake. It was also originally electric choke and is now manual, is there a port for pull off that needs to be blocked off? Other than cold op. It's been three weeks with no bugs until today, my lower ball joint let go at about 65.....I'm pretty much thanking the deceased p.o. for not wrecking!!!!