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Post by sc397 on Apr 26, 2022 16:17:51 GMT -8
And they drove 45 miles per hour. I drove my 290 AMX with 3.54 gears to Cedar Point and back and got 20 mpg. at a average speed of 45.
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Post by spud on Apr 26, 2022 17:14:35 GMT -8
I dont think my 290 javelin did that good. Seemed like 16-17 was good for it. But then again it was probably the driver.
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Post by landbarge on Apr 26, 2022 17:58:33 GMT -8
The old Ford flatties has the little ass Stromberg 97's but the Ford version of the engine was only 239 cube as I recall. I'm kicking cobwebs around thinking back to my dad's old Ford when I was 6 or 8.
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Post by Captain Awesome on Apr 26, 2022 18:46:42 GMT -8
My 82 Shitvette Scooter got 44 highway. Automatic, 3.42 gears. Key was, do not go over 55 mph or it took a shit down into the high 30s. I removed the "computer controlled" carb and put one on from a 77 Monza Spyder, yanked the cat off, ran the exhaust out the side and bumped the "timming" up. But I was running larger than stock tires, which prolly hurt it. More drag.
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Post by sc397 on Apr 27, 2022 12:57:35 GMT -8
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Post by spud on Apr 27, 2022 15:24:27 GMT -8
Awe fuck. Does it come with a fortune cookie?
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Post by spud on May 2, 2022 20:27:50 GMT -8
So i wasted a bunch of my weekend tuning a 390 holley. It was used, so i rebuilt it, and had to fabricate a lever to bolt to the existing throttle lever, to work the torqueflite throttle linkage. Once i had it on and running the real head scratching started. It had problems. So in the end i found the main jets had been replaced with smaller ones, of course i didnt have any near as small as i needed. I also discovered the small carb on the 304 provided plenty of vacuum, so my power valve was opening late. Not sure about the vacuum secondary timing with all this going on. So i fired off an order to summit for tuning parts. Whats thr point in it? Gas milage. How does it run? Ok, it idles very smooth and has very good response. It has great low end power, but not so great high performance. It will improve when i get it tuned in. Then i can see if it really helps milage or is a waste of time. While sorting through a bunch of holley junk, I also discovered i have a 570 cfm holley street avenger carb. It looks like it is almost new, i forget where it came from. Its an 4160 carb with vacuum secondaries, two metering blocks and big center pivot floatbowls. You know a big 15 pound holley with little venturis. I find it odd holley would make such a carb. Interesting. I imagine i’ll spend forty bux or so and rebuild it and try it. Its been run and has set long enough for the accelerator pump to get stiff, and probable the power valve diaphram is pertrified too, so here we go. Another parts order to summit. Havent found a mower carb yet. Did find a pvc plastic elbow and a flat sheet… just enough plastic junk to make an adapter…
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Post by spud on May 24, 2022 17:44:44 GMT -8
Well tuning the 390 holley has been a challenge. I have made progress by going up to 52 mains and a big improvement going from a 6.5 power valve to a 9.5 power valve. Much better. Still fighting a problem with rich idling. I changed from ported vacuum source to full manifold vacuum advance, which has really changed the idle situation for the better, I think there might be some damage to the idle mixtute valve seats in the metering block, theres a difference in how many turns out to grt good idle from one side to the other. Got a flat spot off idle, something is off with the accelerator pump. Anyways i think this carb doesnt like itself. Thinking of giving up. Now if you like tuning and tweeking , like getting the most out of that, like good mileage , street drive your amc and such, i highly reccomend watching parts 1 and 2 “ THE ULTIMATE VACUUM ADVANCE TUNING GUIDE” on youtube. Wow what a brilliant approach to super tuning a distributer!!!! I’m in process on the proceedure and it has already got me some very encouraging results! Check it out i garantee you have never seen anything like it. If you think your CARB needs tuning, you might be right, but i can garantee your vacuum advance needs some work! And these guys have a great way to improve your tune!
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Post by Captain Awesome on May 24, 2022 17:49:26 GMT -8
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Post by Captain Awesome on May 24, 2022 17:49:59 GMT -8
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Post by spud on May 29, 2022 8:24:19 GMT -8
Thanks cappy. Well i did 210 highway miles yesterday. With my fancy wideband meter and vacuum gauge and new optimistic tuneup. I pumped up the tire pressures and checked alignment and with everything i’ve done to my carb and ignition curve, i got about 14.5 mpg. Thats right i made my milage much worse. And my super tuning lost power too. 🤣oh wtf. I should leave things alone. How did i fuck all my magic 16-17 mpg up ? Well it wasnt my 390 holley, i swapped the avs back on for testing the ignition changeup. I think The old ignition curve was ok (i guess).It was pretty drastically over advanced but i didnt know it. I have a habit of twisting in a little more advance arbitrarily to where it seems happy. I had like 18 degrees of static advance, 26degrees of cenrifugal advance, for 44 degrees total timing, without vacuum, and then 16 degrees of vacuum advance. It seemed to run fine with 60 total degrees of advance at idle, but i had no idea the timing was this far advanced because i didnt check it. I arbitrarily added 2 more degrees of vacuum advance and it started iding a bit rough. I drove it and it didnt feel as good. It didnt ping unless it lugged, and even then it was hard to hear. So thats when i got out the timing light, and found out the truth. I checked the damper for accuracy and its on target. Thats when i fucked it all up. I reset my static time to 8 degrees, which gave me 34 degrees of advance with the cetrifugal advance, then i put my old vacuum can back on, which has 16 degrees of advance, for a total advance figure of 50 degrees. And i figured it was good for a try. It idled smooth and ran ok, just less wide open power. And it was set to a curve i figured it SHOULD be. What a pig it is now. Guess i gotta rethink it all over. I’m thinking i need to cut down the centrifugal advance to maybe 22 degrees, increase the static to 14 degrees. And worry with the vacuum after i figure out what works best with the static and cetrifugal advance. It may be i need to play with this at the track. Who knows i might end up with over 40 degrees of static and centrifugal timing again. They say once you start messing with something sometimes it never ends
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Post by spud on Jun 6, 2022 5:18:16 GMT -8
Well i think i have tuned my distributer enough for a while. As it was i had too much total timing, and my centrifugal advance had like 28 degrees on top of the 14 degrees of initial timing, so thats 42 degrees in power mode( eek) add16 more vacuum degrees and that was 58 in cruise! Yaknow it didnt ping, guess the 304 isnt that sensitive in that respect. So i tweeked the delco with some msd limiting bushings so i now have 16 degrees of static ( 2 more than before, experimenting with idle and part throttle response) and 20 degrees centrifugal ( 8 less that before, to fit in 2 more static and limit degrees in power mode)for a total of 36. ( four less) with vacuum advance (16 degree, b26 delco can). I have 32 at idle, 52 cruise, which is all a pretty common chevy setup. I have the lightest springs on the centrifugal advance so its all in around 2300. The new curve is working ok. I still have some misfire at idle which bugs me, and I do think its the carbs fault, the holley did it too, I So i figure i’m going to try a msd box to get multiple sparks. The msd fires twice from idle to 3000 rpm. Drag is my old optical trigger is a no go with the msd box. So its christmas again! I ordered the cheap summit billet distributer ( with a simple mag pickup, not the ready to run unit) and a msd street fire box. And a set of ngk iridium plugs. Pretty cheap setup, the summit distributer is identical to msd, it and the streetfire box was the same money as a msd billet distributer alone. So i cheaped out which is fun. I love my old ignition but i’m going for a better tune. I’m also tweeking the avs-2 and have leaned it out in cruise mode pretty dramatically. Going for some more milage. Lets see how this all works out on my next road trip… Of course i will still try the other small holleys i have at some point. The avs2 is still my favorite. The holleys are more infinitly tuneable. just more adventures in tuning the 304.
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Post by spud on Jun 6, 2022 20:28:54 GMT -8
Well like i said once you start messing with something… i had an idea. Verify the tdc mark and pointer for accuracy with a piston stop. Actually it was very close. Then i had another idea. Degree the damper to 50 degrees. Which wasnt too hard using a timing tape from msd. Why all this hassle? Hey doublechecking. Doublechecking? Yeah cuz i suck at tuning. And i suck because of innacuracy. And i want to not suck at tuning. Well i have a dial back timing light, and. I was discussing my adventures in tuning with dennis at wells racing. He said watch out, those dial backs can be off… , i was appalled! How can my super hi tech 20 year old snap on timing light be off? Hogwash! so i used an old timing light with no electronics in it. Guess what? My dial back light is a piece of shit. When my new distributer gets here i gotta tune it all over again anyways. There appears to be a big difference in thinking, knowing, and reality. Hopefully i’m getting closer to a tune. I can say the car seems to like a little more initial ( static) timing. Off idle it was more responsive. I think i might havea little too much at idle with the vacuum advance though. It idles at 32. Once you start messing with something… i gotta stop randomly twisting the distributer looking for magic. Its not science if you cant measure what your doing. Accuracy is a big deal.
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Post by spud on Jun 7, 2022 18:03:21 GMT -8
Well i noticed how i turned a carb tuning thread into a ignition tuning thread. I guess it is what it is. Ok so heres my critique of the 230 dollar summit billet amc distributer. It is cleverly built to look very much like a msd billet distributer. However dont be fooled it is not the same. What is not so cool about it… NO instructions. I guess thats kind of sucks for someone who shouldnt be trying to tune one anyways but not much of an inconvenience for someone experienced with that kind of thing. Sucky #2- it only has four advance limit bushings. ( the msd has 6 different limit bushings) sucky #3- and this threw me, because the summit distributer comes with an adjustable vacuum advance, and i dont think thats a feature on the msd unit, at least not on the ones i have. So you figure a tweekable vacuum advance is a nice advantage right? Hell no. The vacuum advance is tunable to add or subtract amount of timing true, the reason it sucks is the spring is so stout it wont get full advance untill 25 inches of vacuum is achieved. And no engine idles with 25 inches of vacuum, so its unusable. Vacuum advance is a major fail . If you consider buying one just know you will be replacing the vacuum can. Sucky number 4- it doesnt come with gear lube , stickers, or as complete a parts kit as msd. I know weak but its still a cheap out. Anyways So far it works. I guess i will see how it does. I will keep my old setup in the trunk just in case it gives me chinese revenge. Keeping an eye on the gear. We all know about that. Don’t want it giving me chinese revenge either. Thought about just putting my old gear on the new distributer but decided to keep my old distributer intact just in case. All in all you can save a bunch of money over an msd distributer. Now here’s where i really really fucked the monkey- speedmaster sells a billet distributer that is about the same thing, for 80 stinkin bux. Thats dirt cheap considering the msd is about 400. I saved 170 bux over the msd with the summit chicom unit, but coulda save like 320 with the speedmaster chicom shit. Oh well Maybe next time i can try a speedmaster. I fuck up so you can learn how not to !!!🤣
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Post by 69Rebel on Jun 7, 2022 19:53:13 GMT -8
That $320 you saved will go along way towards buying new gaskets and bearings when the gear disintegrates and runs all that shit through your motor.
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