okay here we go got a 1970 Buick lesabre custom 4dr 455 just rebuilt the motor bored 30 over TA oil pump recipe and a TA stock type GM HEI distributor and a TA112 cam stock rebuilt 750cfm quadrajet my old distributor was a 1112110 (anyone know the specs on it) Okay well the problem is i have an open 2.73 rear end and a 4,380lb car so all these timing threads are saying run 30 to 36 total timing well that aint working for me. the TA hei has 22 degrees built in and its vacuum cannister has like another 22 er so and im getting pinging regardless of what grade of gas i use (91,92,93) estimated compression ratio is 9.6/9.7 er so. i started with 12 initial for a total of 34 and eventually backed the initial down to 6 which helped but didnt cure the issue. i then bought a hold off mechanism for the vacuum advance because i noticed that most of the pinging was at part throttle at highway speeds up hills and stuff like that....so then my initial was 6 my mechanical was 22 and my vacuum was 10 STILL PINGING WOT AND UNDER A LOAD UP HILLS AND WHAT NOT......i then bought a distributor recurve kit and put the heaviest springs they had on my TA HEI and ran 93 octane and almost completely stopped the pinging but still on occasion under WOT i get pinging. SO MY question is what do i do now from what i've read i cant limit the mechanical advance on an HEI distributor so is it okay if i just back the initial down to 0 and fiddle with different spring combo's tell i get it just right and maybe run a little more vacuum advance or well i lose all low end throttle response and all that other stuff that everyone says you get from running more initial......other than all this the car runs pretty great as a cruiser i use it as a daily driver and have no issues except when im trying to blow by some yuppy in a mustang lol thanks for any input guys
O and ive got a healthy 20hg vacuum at idle so no leaks to my knowledge......Could it be im running to lean or maybe my plug gap i bumped from stock .30 to .40 because of the high firing ignition idk man help me
You have a really heavy car, a tight lobe center small cam and too high a static compression ratio with that combo. Been there done that.,.. I could not do that with aluminum heads in an Electra with a small cam and highway gears. Too much load on the engine, especially at part throttle when all the vacuum and mechanical get dumped together. You have taken the right steps to eliminate most of the issues. Now here's the cure. Dump the HEI.. too much trouble to work with, unreliable, and weak spark energy at high rpm, unless you install an aftermarket coil kit/module. Many better distributors out there now, my recommendation is the MSD 8552. Make sure you read the directions.. and wire it right. The last one of those I sent out in an engine, to a "professional" shop, they could not get it wired right.. It must run with no ballast resistor. Use the proper MSD coil that is recommended. You will be able to work with that distrib much easier. Next.. There was a reason that mid 70's Electras, with tiny cams, had no static compression.. That was the only way they could avoid the pinging. But a bigger cam in.. When I fixed my issue, I put a 226/235 duration cam in it.. car absolutely loved it. No pinging, no detonation.. went to a 12" TH 350 converter, that worked great for the combo. JW
OK, first here are the specs for the 1112110 distributor attached below. Second, if you are using close to 10:1 compression with a small cam, the result is your dynamic compression is probably north of 8:1. Read more about Dynamic Compression Ratio. http://www.empirenet.com/pkelley2/DynamicCR.html Add a big heavy car, iron heads, and low numerical gearing, a quick mechanical advance curve, and it might ping at WOT no matter what pump gas you run. That Q-jet may need some tuning. You may be lean if it has stock jetting. I am kind of surprised you get a solid 20" of vacuum with the timing at TDC (0*). Most engines don't really like that, and it will probably run hot if you idle there in hot weather. Every combination is different, but I recommend you leave the vacuum advance disconnected and then set the total timing to 32*. I would not just assume that the 22* TA says that HEI has is there, but I would set the total timing and let the initial timing end up where it has to. Once you set the total timing to 32*, play with the springs and make some WOT runs from various speeds. Get the total in as soon as possible with no ping. Once you have that dialed in, then you can add the vacuum advance in and check for part throttle ping. You may have to limit the vacuum advance to 8* or even 6*. You want your cruise timing around 40-45* or so if you are at all concerned with MPG. I would confirm everything with a timing light and not assume what you have. Every combination is different. Happy tuning.
I run at 180* all day long with a 2 row brass rad. Never connected the vac advance. Also over 20mpg running 70 mph with 3.42 gears and NO overdrive. With no vac advance. But will admit every combo is different. You just have to try things to see what works.
wow thanks guys but damn geuss i shoulda maybe went with the TA212 or that other distributor so if have to buy a different distributor or cam then i will but for now really trying to avoid that but yea the jetting in the carb is stock and i know that the TA hei has 22 degrees of mechanical advance built in because when i power timed the car per the power timing thread on this forum i was at 32 with my initial at 10 and the vacuum advance unplugged. I am wondering since the info you provided me with on my stock distributor states that my initial should be at 4 (all my manuals and info for a 70 455 lesabre say 6 but idk) and the distributor has 14-18 built in and so does the vacuum advance that makes for 18-22 total mechanical timing and with vacuum between 32 and 40 so matching that would be a great starting point but in order to do that i would have to set my initial at like 0 so my total would be at the stock 18-22 is that okay to do should i try that or bigger carb jets or just change the cam or distributor or what..... again thanks guys
okay just looked at my fisher manual it says i should have 6 initial 30-34 total at 4,600 rpm and 14-18 from the vacuum advance so does it mean i should have 30-34 at 4600 including the vacuum advance or no if so then i could do that by running 2 initial plus 22 centrifugal plus 10 vacuum for a total of 34 if not that sucks what the heck am i supposed to do from there
and according to one of those always 100% accurate internet calculators my dynamic compression ratio is 8.2
fisher book also states this for 1970 buick 455 non stage 1 Distributor spark advance (crankshaft degrees @ 2500 rpm) total distributor advance 36-44 centrifugal advance only 22-26 this confuses me because i can get my total down to 36-44 by doing as i previously stated but not if they mean at 2500 rpm
First, once you change the distributor, all stock timing specs go out the window. The TA HEI will do just fine, 22* of mechanical advance is fine, and I am glad you verified it. Vacuum operates independently of mechanical advance. Vacuum advance only operates when there is vacuum. There is little to no vacuum at wide open throttle. The vacuum advance canister has a spring inside that opposes the vacuum pull. Vacuum must be high enough to overcome the spring to advance the timing. At wide throttle openings and at WOT, vacuum drops off and the spring in the canister wins out pulling whatever advance was there out. Total advance needs are different between WOT, and light load highway cruise. Buick engines make best wide open throttle power with timing between 30 and 34*. Some modified engines will want a bit more, but 30-34* works for most. At light load cruising, the engine will easily tolerate more advance, 40-45* will get you the best open road gas mileage. Not all combinations will tolerate that much, so you have to play with it until you get what your car runs best with. The stock engines frequently had stiff springs controlling the mechanical advance weights. Full mechanical advance did not occur until 4600 RPM. At lower RPM, like typical cruise RPM, only PART of the mechanical advance was in. The 14-18* of vacuum advance brought the total advance up around 40* for best mileage. Again, when you nail it, vacuum advance goes away, and the rest of the mechanical advance comes in by 4600 RPM. Bringing the mechanical advance in earlier (2500 or earlier), can improve low end power and performance. When you do that however, YOU MUST cut back on the amount of vacuum advance because now, ALL your mechanical advance is now in at typical cruise RPM, and the addition of 14-18* of vacuum advance gives you too much total cruise timing. Your original 1112110 distributor had a maximum mechanical advance of 14-18*. With an initial timing of 4*, do the math, at WOT, the most advance you could have would be 18-22*, far below the optimal 30-34*. I have no idea why Buick did that other than that's what they had to do to get emissions compliance that year. One thing is for sure, 22* makes a pig out of the engine. I would also say that your original Quadrajet is going to be seriously lean. You change one thing, you have to change others. I'd get the carburetor re-calibrated. As far as your dynamic compression, 7.5-8.4 is pump gas territory. The closer you get to 8.4, the more important it is to have everything optimized. Things like engine coolant and intake air temperatures become more important. Zero deck offers the most detonation resistance, but most aftermarket pistons end up .040 or more below the deck. You want your air/fuel ratio right on and not lean. With a DCR of 8.2, you are getting close to race gas range, the above factors come into play. Add into that low numerical gearing, tight torque converter, and heavy car, and it is no wonder you have your work cut out for you. I know you want a guaranteed recipe so you can just adjust and be done, but it just isn't that simple. If you want the best you can get, you have to test and tune. I wouldn't give up on your cam just yet. Hope that helps.
yea man thanks a ton i appreciate it i rebuilt her a few months back and i've been tweaking and tuning ever since but hell that's half the fun of this old boat anyways. since were on the topic of jetting and the only way i can get it to not ping at WOT is by running a total timing of like 24-28 should i just do that or go ahead and change the jets and if i change the jets what size should i go with and im assuming i would only be changing out the secondary side jets/metering rods correct?
No, get the carburetor right first. There are 2 guys on the board who can recalibrate your carburetor. It's way more than changing jets. Ken at Everyday Performance (techg8), http://www.v8buick.com/forumdisplay.php?172-Everyday-Performance-LLC Or Mark (carmantx), http://www.quadrajetpower.com/ If you want to do this yourself, then I suggest you buy this book by Cliff Ruggles, http://www.cliffshighperformance.com/buy_book_2.html There is way more to it.
