Well, we have one more Buick in the driveway now. We brought home our 70GS last night. It has some issues, but it's basically what we expected. It's a very strong runner, I can't wait to get it to the strip to see what it does... allthough it will be very "hampered" by the one legged rear end and highway gears. Anyways... there's a few problems and I thought I'd get some questions on the table here... The carb is an 850 Demon. It idles so rich, it'll bring tears to your eyes if you stand behind it, and you can actually see the richness in the exhaust. Looks like smoke, smells like gas! I backed it out of the driveway so my back tires were in the street and romped it a little... it's ALL GO when the hammers down, but it idles terribly rich. I know nothing about the demon carb. It looks pretty much like a Holley, and I assume the needles adjust about the same. One at a time, I turned each one in all the way (the idle went up about 100 or so RPM) and then backed them out 1 1/2 turns. Didn't change a thing, so I turned them in a 1/2 turn. Still really rich. Where should they be set?? Second is the timing... It had very bad "hot start" problems last night, so I thought maybe the timing was advanced too far. I went to loosen the distributer bolt and found it was already VERY loose. I think the distributer moved on me. So I get my timing light on it and retard it to about 30 (total guess....I don't have a "dial back light") at idle. Thats as far back as I can turn it before it tries to kill the engine. But it still seems to "hot start" most of the time. I know I read somewhere here about measuring back so far on the damper and putting a mark and that will put you at the right timing. How far back do I measure, and what should the timing be set at? This thing idles terribly, like it either has a HUGE cam or something is wrong. I was told: Cam is a Lunati 501/501 235/245. (installed "straight up") 67 430 large port heads with swirl polished ss valves Intake - SP1 Carb 850 Demon Headers and 3" exhaust 2800/3200 torque converter Mallory Unalite distributer with what appears to be a stock chrome coil I would think this combo should idle pretty good. It idles very violently. Shakes the car and everything. Any ideas of what I should try first?? I'd at least like to get rid of that hot start crap. I'm afraid to drive it anywhere for fear that it won't start when I go to leave. Thanks in advance for any pointers! :beer
Congrats on the new car! I'd set the idle mixture with the help of a vacuum gauge, since your rpm went up as you turned the needles in. It sounds like you are idling on the primary jets to me. Maybe you should take a look at the throttle stops and the throttle travel, and maybe your return spring. If it is a GS 350 with a 455 in it, maybe you're having a throttle cable problem with the original 350 cable? Just a guess. I use my Skylark's old cable for the 350 with zero troubles on a 455, but I did have to custom fab a bracket holder for my intake. There are two different cables and I've never had a problem without having the correct 455 cable, but maybe yours is still for the 350 and you need the 455 cable for your engine as it's been built? Ask the previous owner if he knows what the initial advance should be for the engine with that distributor...when I got a new HEI, it came with a card that gave me specs and a listed initial advance of 13*, which seems almost right on, I have since determeined that it should be about 15*, but I'll forgive the 2* difference as being 'in the noise' so to speak, as they didn't know my exact engine build up. Stock is what, 8* initial, if I remember correctly? Does the starter have a heat sheild at all? It's a must. I'd also suggest investing in an Optima or similar battery. Not much more than a top of the line conventional battery, but you get 1000 amps from some of them. I have a SVT battery made for car stereo systems as my battery. With 1000 amps, the engine doesn't even consider not starting. In fact, when I store the car in the winter, I will disconect the hot wire from the distributor and crank the engine for 30 seconds to get oil moving before i re-hook up the hot lead and start the car. Even on the coldest days, the car starts right up even after that 30 second crank. The great thing about the Optima type battery is it can't leak. I'll never buy a conventional one again for my Buick, it was like 30 bucks more tha the best standard type battery.
Thanks Chris! I'll look at the carb. I'll have to buy a vacuum gauge. I know I used to have one, but I haven't seen it in a long time..... and I never did know how to use it. :gt: Would you mind describing a "step by step" as to what I should do with it when I get it? I think you're dead on about the battery. I unhooked the coil for sh1ts-n-giggles and tried to crank it. Same "hot start" syndrome. So it must not have anything to do with timing! I'll look for a heat shield, and swap batteries out of something else and see what it does then. I'll also see what I can find out about the distributor either from the seller, or straight from Mallory. Thanks again. :beer Oh... just for fun... I'm finding many wasp nests in the car. Most of them still inhabited. I've been stung once already. So far I've killed 9 wasps, destroyed 2 live nests (with eggs), a couple dead nests, and only been stung once...... I think I'm winning! :gt: ou:
TA offers a nice thick cad plated heat sheild that will fit with the headers- barely, but it does fit. Nice piece. The vacuum gauge should come with directions, but- in general, depending on how high you are above sea level- you want to see a nice steady needle at idle. I use an unused vacuum port on my Performer intake that I screwed an old fitting into. I capped it off with a vacuum cap. Makes a nice handy vacuum port when I tune. About 10-15" Hg should be what you want to see, at the least, with a pretty steady needle on the vacuum gauge. This is at idle, around 800 rpm. Any less than that amount of vacuum and you could have a variety of problems, but you can use the gauge to dignose that, the instructions should be more specific:grin: If you don't have that 'spare' port, I'm assuming that the full vacuum port on the carb is a good substitute? never done it that way myself. very basically- set your initial advance, and your idle speed with a good tach (also note on the tach if the idle speed jumps around- could be a sign of a wobbly distributor shaft or worn bushings in the distributor. Might be a reason it idles poorly). Check the vacuum, and note it. then cut the engine, seat the needles in the carb gently, and turn them out about 1 and 1/2 or 2 turns. Start it up and check vacuum. Turn one needle until you reach max vacuum, then reset idle speed. turn the other until you get max vacuum, then reset idle speed. Now turn both back in about a 1/4 turn. Check the timing again. Quick and dirty carb tuning for idle:grin: I live about 3 miles from the ocean as the proverbial crow flies. I get just below 19" Hg with a needle that quivers a bit, and personally I feel that's about the best you can expect in the way of the needle staying steady. I have a mild cam- the more aggressive the cam, the less vacuum you can expect at idle, of course. if you have power brakes- and i bet you do- and the brakes work fine you should have plenty of vacuum, though. If you rev the engine with the vacuum gauge on, you should see the needle twitch higher then fall off quickly and cleanly, then build back up just as fast as your idle falls. When you do this, check the tach too and see how quick it revs and falls off- really slowly and you might have a sticky advance weight? If playing with the mixture adjustment at idle has no effect on vacuum, you're off idle and on the primary circuit somehow- or- your seats are damaged. Since you're running really rich at idle, I'd suggest checking for fouled plugs before tuning. Hopefully a real pro can add loads to my descriptions and tips:TU:
Rick, As far as timing is concerned, if you make a second mark on the balancer, exactly 1 3/4" clockwise (facing the front of the engine), this corresponds to 30* of engine timing. Put the timing light on it, and rev the engine with the vacuum advance disconnected and plugged. Your new mark will move up towards the timing tab as your mechanical advance is working. At a certain RPM the mark will stop moving up. This is the RPM when your mechanical advance is all in. If you have stock springs in the distributor, this RPM point could be as high as 4600 RPM. You want all your advance in at or before 2500. The Crane adjustable vacuum advance comes with 3 sets of ideal springs. I bought the kit just for the springs, it's worth it IMHO. When your sure all the advance is in, just move the distributor until your new mark lines up with a number on the timing tab (while holding the engine at the RPM where the advance is all in) Ex. line the new mark up with the 2 on the tab, you have 32* total advance. Sounds like that Demon needs to be properly calibrated to the engine. I don't think playing with the idle mixture will do you any good. If it is going to be a street car, put a properly built Q-jet on it. If it's a track car, have the Demon calibrated and jetted to your combo. Good Luck.
cool! I'm so happy this discussion is fresh and posted. I am in the same boat as you Rick. It is Rick, right? anyways............ I have me a 455, auto tranny, and the motor has an sp-1, a 750 Holley double pumper, and the same cam...........a Lunati cam from Torque Tech.....it's 235/245 with a .491" lift on each side. Do you have bigger than stock rockers to give you a .501"? I'm using stock rockers. Same torque converter.....2800-3200 or so. Using an HEI and a MSD 6AL ignition. Mine is the same way. It revs great and sounds strong, but it has a somewhat "violent" idle and my eyes tear up like nothing else if it runs for more than a minute. Pulled the plugs and they were black and a little bit wet. The funny thing is when I turn an idle mixture screw in all the way, and not touch the other three, it idles a lot smoother. As soon as I turn it and loosen it, the idle gets all rumpity rump and it seems like the vacuum guage doesn't read to well. Is it alright to have a vacuum gauge that jumps around a lot, but within a couple degree increments? It doesn't jump all over the dial, but it jumps around between a few degrees. Is that just the characterisitcs of a big cam? Oh yeah...........that Lunati cam you have (I'm sure it's the same as mine) is the biggest cam you can buy from Torque Tech w/out needing notched pistons or a vacuum reserve for your brakes. Chris...........ever hear of guys timing their cars with a light to about 18* or so? It seems to idle the nicest there, but does that sound a bit too extreme? I'm somewhat of a novice when it comes to fine tuning a carb, and the fact that this cam is quite different than stock is making me confused on how the car should really sound at idle. Also, when using the timing light, you want the car in park, right? Or does it need to be in drive? If you don't have a timing light, do you turn the distributor until you get an optimal vacuum reading, or is that not the correct way? o No:
Thanks Chris I'll get a vacuum gauge tomorrow and see what I can screw up!! :gt: Larry 1 3/4" ... Thanks! I couldn't remember what the dimension was. The carb.... I don't have anything else to throw on ot to try it out. I've heard good things about the Demons, and I'd like to give it a shot. I'll start with the vacuum tips from Chris and see where to go from there. The distributor is a Mallory Unalite (Unilite?)No vacuum advance. Mechanical advance only. I assume there might still be adjustable/replacable springs in it though. I'll be looking into that too. It's small like a points unit, but it's electronic. It also has a Mallory tach with shift light and rev limiter all in one piece. Pretty neat little tach. It's mounted right where a factory tach would have been and it looks real nice there. (See attached pic) Kinda sounds like a slow "stutter box" when it's working. I set it at 2,000 and hammered it just to see. lol :gt: I just took it around the block for the first time about 5 minutes ago. Runs like a dog. It's cutting out big time now. But even missing and cutting...all it can do is smoke the right rear rubber. :Brow: musician... Have you had your car to the track yet? Curious as to what it runs.
You can set in it park. I check the rpm in drive, too, but I don't think it's needed. I have in the past, with a different HEI, had the timing up to around 18* initial, and the car loved to idle at that advance. It was smooth as buttah, if you can dig my Boston accent. but idle performance and driving performance aren't the same. I'd be concerned about detonation that far advanced on my buildup. Just because you can't hear knoch and ping, doesn't mean it's not there. however, i don't know the specifics on every engine buildup, so take that with a grain of salt. Jim W. could speak volumes about this... as for the vacuum, I can take an educated guess and foresee a situation where a big cam may make the needle behave the way you describe. In that case, I suppose a "steady" needle would be completely subjective to the properties of the cam. Since a big cam affects vacuum AND idle quality, I can easily beleive that it would also affect how steady the needle is. But like I say, Jim W. would pretty much be the Grandmaster Flash of all things Buickmotor. He'll probably chime in sometime soon. I'm hardly the super-tune guru. I'm a Craftsman, it says so on my tools:grin:
Rick- you may not see a very steady needle at idle on that vacuum gauge- I hadn't realised how aggressive your cam might be.
Well.... I used Larrys 1 3/4" and the timing was WAY advanced. (Hows about somewhere around 44+ :shock: Thus the hot start problem. I have it set at 32 (full advance) now and it idles and starts much better. I'll rip it around the block tomorrow and see if it still stutters too. Still makes ya cry when you walk around back though.:ball: Hopefully the vacuum gauge will help with that. :TU: Grant I've seen those kits before. I've always thought about getting them for a number of my GM cars with the "hot start syndrome" in the past... but never got around to actually ever doing it. Maybe it's because it looks so much like a Ford piece. :gt: ...next thing on my list for tonight... The shifter won't go into park or 1st gear. Kinda sucks. No.. it really sucks. :gt: He told me he used a Chevelle shifter cable and he never could get it adjusted right. I'll rip the console out and see what's going on..... Which reminds me.. get this... He drove the car ALOT with NO shifter cable at all. He'd fire it up in park, stick a wood block in front of the tire, reach underneath and pop it in drive, and jump in and go! Then he'd get where he was going, shut it off in drive, hop out, climb underneath and put it in park. As he was telling me this, I musta had a "your crazy" look on my face. He said "what? It has a 3200 stall torque converter in it... it's not going anywhere". LOL I still told him he was crazy! :laugh:
Maybe by being creative with the mounting location it won't be so noticable. That and a couple of cooked starters make that "ford part" make much more sense..ou: Rick, thanks for rescuing that GS from F'ed Up PO. Sounds like he should not be allowed to own/drive a vehicle, ESPECIALLY THIS ONE! Hopefully he didn't leave too many "booby traps" for you to have to fix. I hope you don't let the beast out in the public eye until she's presentable, safe to drive (and stop!), and reliable! Oh my God!!!! ou: :eek2: :jd: Time for a posi...:grin: :Brow: :beer Idle speed screw adjustment might be set open too far... or you might have wrong power valve for your vacuum reading, can't remember if Demon carbs have power valve or not. Does it have 4-corner idle??
I don't feel that I "rescued" this car from him. He was slowly working on it as time/money allowed. The guy was a real nice guy, and I don't think he left too many booby traps. He told me everything he should have, and answered everything I asked to the best of his abilities. As far as the driving without a shifter.... I still think it's crazy, but if I put myself in his shoes..... The car is done, ready to go, you can't find a cable, but your dying to drive it. Whatcha gonna do?? I probably would have bought a cheapie B&M or something for temporary use but..... :gt: Anyways.... I don't plan on hiding this car till it's done either. We buy cars because WE like them, and don't give a [insert your favorite swear here] what anyone else thinks about them. As soon as it's mechanically sound and dependable, we'll be putting miles on it just like all our other cars that are willing and able. :gt: It does have 4 needles. I messed with them a little tonight, but I'm not going to try anything with it again until I get a vacuum gauge tomorrow. Back to the shifter.... I took the console out and also looked under the car.. There's nothing to adjust. Apparently I need a different tranny bracket and/or cable. I'm guessing the tranny bracket. Anyone have a picture of atranny bracket for a 70GS with a TH400 trans? This one looks like a B&M aftermarket "generic" bracket. o No: Maybe I can buy a B&M cable so it will be adjustable?? But it seems that the geometry isn't right. The more I think about it, it HAS to be the bracket on the tranny shaft. The hole needs to be closer to the pivot point to get more "throw" from the shifter. (See'ins how I can't get into park OR 1st gear) o No: I think this is the most incoherant post I have ever typed. You deserve a gold star if you made it to the end and actually followed what I was saying. I think it's time for bed. :gt:
RICK, YOU COULD HAVE A BLOWN POWER VALVE WHICH WILL DUMP GAS AT IDLE. TRY REMOVING A MANIFOLD VACUMN LINE AT IDLE, IF RPM INCREASES AND SMOOTHES OUT, THE CARB IS DUMPING TOO MUCH FUEL. ALSO LOOK DOWN THE VENTURI'S AT IDLE(SAFETY GLASSES ON) AND SEE IF IT IS DUMPING GAS OUT THE MAINS. BLACK SOOTY SPARK PLUGS ARE ANOTHER INDICATION OF TOO MUCH GAS, GOOD LUCK
Well... After driving it to the place to get the "out of state inspection" done, and then getting temp tags, I ran to Autozone and got a vacuum guage and a new set of oil/temp/volt gauges and planned a long night of tuning with all the good advise in this thread..... But... My dad stopped by just after I got home. Well, one thing led to another and nothing got done but alot of big time BS'ing and a little garage cleaning. :gt: (I'm sure you've all been there) But on the bright side... I had to take him for a ride. His Hornet runs 13.20's and he's definately scared I'm going to clean him up. Changing the timing really helped. I can't punch it at any speed under about 35 without just frying the right rear, but I was able to stay "in and out of it" enough to show him what it's got. :Brow: NEED POSI :ball: Oh well.. tomorrows another day. Hopefully I'll be able to use all the good advise here then! :beer
Rick.. Sorry Buddy, I did not see this.. But here are a few things to consider, and I will touch on a couple other issues. 1... Big cam idling... you need 22-25* initial advance.. better option in my opinion than adding vac advance with manifold vacc.. Car starts easier, and runs better, avoids any "flatspots" from quick accelerations, in say second gear at 20 mph or so.. Total on that motor will prolly be around 34*, for the best power. Add 5-8* of ported vacuum advance to get something that resembles mileage. 2. What you have with the hot start problem is an issue with the battery cables. I sell a custom set for the 68-72's, made from HD 2 gauge red and black cables, with high quality cast copper lugs and battery ends.. a whole bunch beyond what you will find in the auto parts store.. we custom make them here, with parts thru the supplier that we get all our wiring products from. I have never had to run a mini-starter, extra heat shields, or Ford solenoids to get these 500+HP Iron headed GS's to spin over like there is no plugs in them.. even in Florida, during a 100* day, with the AC on, after the dreaded 5 minute hot soak. The Ford solenoid trick is designed to overcome symptoms of a cheap stater solenoid, coupled with not enough voltage available from the typical 4 gauge cables. I did the above two things to Bob Rennicks car a month or so ago, and easily solved the two issues he had with the car. And last, I bet that the power valves are either are set to low for the current vacuum level available, or they are leaking.. leak test is easy.. take the valve out, and use a tester, or just suck on the diaphram side of them, to see if they are sealed.. Only wildcard here is if the cam is in retarded, then that has to be corrected.. Your car should idle at 700 rpm in park, with at least 12-13" of vacuum. I have gotten 14 out of this combo in the past, maybe more, depending on what lobe center is on that cam. JW
Jim, in the last post you said: "Add 5-8* of ported vacuum advance to get something that resembles mileage." forgive the ignorance on my part, but how do you go about doing that? Is that with using an adjustable vacuum advance module? ~Mark
Vacuum advance I used a stock advance unit and made an aluminum plate that limits total vacuum advance to about 6 degrees. The plate fits in the distributor and is held down by the points mounting screw.
I moved my battery to the trunk, but did not want to use "cheap" 2ga or worse yet 4 ga kits that speed shops sell. My father gave me some 00-ga fine strand welding lead, which works FINE! OVERKILL!! I already had the "Furd" solenoid installed before, so I used it again. But mostly because I did not want 12' of HOT lead, I installed the solenoid in the trunk right next to the battery. The stock solenoid remains on the starter, and the terminals are bridged. Mark Hamilton of MAD Enterprises schooled me through my hot start problem waay back, and that was WITHOUT headers! The solenoid fix worked without fail for more than a decade now without one single problem since! Before, I was going thru starters like penny candy! That's my story, and I'm sticking to it. Good luck to all, whatever method you choose. :grin:
