Ok, I think I've posted about a million times to this board with strange od-ball problems my engine is having, and this is yet another one. My engine is a somewhat tired bone stock 72 455. About a week or 2 ago, she started doing this weird thing where I'd notice on accelerating from stoplights, she'd stutter and pop and occaisionally backfire for a little bit, and then it'd smooth out and run great. The longer I was stopped at the light, the worse and longer the stuttering and popping would last. and once I drive for a minute or 2, it smooths out, and I had come to a stop and floor it and she runs great, so long as I dont stay stopped for more than 20-30 seconds. My dads convinced its running too hot (it has been like 90's ehre all week, and i have a black car) and when it starts to heat up at lights it starts detonating, but it doesnt SOUND like detonation or pinging, it sounds like its about to stall. I am assuming an ignition problem???o No: Maybe fuel delivery (carb, pump, etc.)??? I had a timing gun on the motor about a month ago, changed plugs, wires, cap and rotor, and retimed it, ran great after I did that, but now its falling to crap. I already checked that my distributor is nice and tight (wondered if i hadnt secured it well if it had walked loose, but that wasn't the case). I don't wanna worry too much about it because in about a month, maybe month and a half, i'll finally have enough money to start the buildup on my new engine (68 big port heads, sp1, .030 over, probably ta 413 cam) :laugh: As a result I dont wanna sink too much money into this engine if i can avoid it. Oh, and in case you were wondering, my ignition is stock, except that I have the pertronix ignitor module in place of the points, i have no idea how long ago it was installed, it was on when i bought the car. Any help would be appreciated, thanks you guys!!
easy things to check would be things like make sure the advance weights in your distributor aren't sticking- they should snap closed with a click, check if you have a cracked spark plug, damaged plug wire, cracked cap, check timing again and see if the timing mark is jumping around (worn distributor bushings), check your fuel filter. Could be boiling your fuel in the bowl, or you could have a bit of grit blocking yor needle and seat, check for vacuum leaks, check the engine ground strap
Ummm Backfire usually makes me think of spark 1st. I'd suggest sending the distb to the ignitionman for an HEI conversion. For $200 you will end up with the ignition you need (whether or not you rebuild one day). The upgrade of the ignition will be well worth it. :Smarty:
Check to see if the rivet holding the contact on the rotor is loose. This happened to me once (non buick).
Re: Ummm What is the benefit of having IMan do the $200 conversion over getting ahold of a stock HEI distributor? Is there a technical and/or performance advantage, or is it solely to keep the "stock look"? Or are the HEI's really hard to find? And please don't take that question the wrong way. I am just curious. I have a stock HEI on the 455 I just dropped in my convertible. (Thats what the engine had on it when I bought it) I haven't fired it up yet, and have no experience with anything other than points on my Buick engines. I'm just trying to learn. :TU:
Rick, The ignitionman's HEI conversion uses the stock distributor and this is important to some guys so they have a stock look. I think Dave will tell you the main advantage to his system is you don't use the coil in the cap set up of a stock HEI. The stock HEI coils are epoxy filled and tend to run hot, and this can sometimes hurt high RPM operation. I have never experienced this, but it sounds reasonable to me. If you have an HEI, you can use a separate coil by buying the MSD kit that lets you do so. I had Dave convert a spare stock distributor to an MSD magnetic trigger. I am using the MSD Digital 6+ ignition and I love it. Dave does some excellent work and he really goes through the distributor and redoes everything as well as curving it to your specs.
That's it in a nut-shell Dave's system ($175 for conversion and the $28 Accel coil), is more reliable with a hotter spark than factory. Then you will not have to go thru what Corey is going thru. :TU: If Corey gets the conversion, and later decides to go with the other engine, he will already have the ignition for it. He can't lose, unless he keeps trying to get that Puktronics to work right.:Brow:
Thanks for the info Larry and Dan. I think I'll be looking up IMan when it comes time to put together an ignition for the race car. (The race engine happens to have a point distributor in it right now) Yuk. :gt: :TU: Sorry to steer the thread off track a little, but curiosity got the best of me.
Flaboy, I had the exact same thing happen to my 430, it was fixed by replacing the vacuum advance unit (which was shot...)
can you buy just the vacuum advance unit, or does this neccesitate a whole new distributor? and if you cna buy just the vacuum advance unit, what should i get? (i assume there are units with different rates of advance???) Thanks for the help so far guys, hopefully by next weekend I'll feel well enough to get to my car some.... probably not, but a guy can hope. lemme tell ya, "chronic debilitating previously undiagnosed medical phenomona" (as my doctors call it) is not a fun thing to go through. Thanks again for all the help !!!
spit and sputter First dose this happen when the weather is cooler if not i might rule out the dist. at look at the carb fuel level to see if you are not boiling the gas in the carb when you sit at the light.You mention that when you come to a stop and go wright agian you don,t have this problem thats why i rule out the dist. and look at the carb fuel delvery first.
FlaBoy, I just bought the vacuum unit. I got the stock one, but there are different types out there, some are variable etc.. To see if yours is shot there are two tests you could do.. 1: Connect a vac hose to it and try sucking on it.. you should get resistance, if you don't, it's shot. (Mine gave no resistance at all, the diaphragm was probably dried up and cracked) 2. With the car running, connect a known good vacuum source to the vac-advance unit, the idle speed should speed up or at least change.. if nothing happens then it's probably shot. I got gm part# 1116163 for my Riv, don't know if it is the same part for other Buicks, probably is for cars about the same age...
First place I'd look is the Pertronix unit. I had similar trouble with mine and swapped in an old loaner HEI. Guess what, instant fix!. I then sent the original to th IMan and had him do the samll body HEI conversion. He does A-1 work! Many people have had trouble with Pertronix units. That is where I would start. Put a new quality set of points back in and go from there. Make sure you use the factory wiring since I believe it a ballist resistor. Some one please correct me if I am wrong! Good luck! Brian
hows the fuel? are you geting enuff fuel?vapor lock?i have seen a similar problem but it was upon acceloration.and load and ended up being valves . but yous sounds like a heat soak or weak fuel system andy
