I wouldn't be surprised if the water pump impeller is half gone. Seems like the only time the coolant circulates decently is when the RPM is way up. BTW, did you ever check your total timing, not the initial (that is useless), I need the timing at cruise RPM. Also, while vacuum advance can cause engine ping in some cases, it can also cool the engine down by advancing timing under light load. If your mechanical advance is stuck, and you are running at a constant 8*, that would heat the engine up. It would also make the engine down on power (I think you would have noticed that though)
Nope, didn't think to check total timing, I'll do that tomorrow. The advance moved freely but I'll check it. I don't have a tach either so I won't know when it's kicking in. There's no adjustment on the vacuum advance, is there? I'll just plug it in again and see what happens. I unplugged it when I had no idea what was going on with the engine. I figured it was one less thing to worry about. What do you think about MSD boxes? That would eliminate any mechanical irregularities. I remember years ago screwing around with spring weights to try to get the "perfect" advance. What a PIA.
You don't need a tach. The timing should advance smoothly as you open the throttle and race the engine. You can easily see that with a light. No, there is no adjustment on the vacuum advance, but you can make a limiter plate for it. You should also verify that the vacuum advance works. You can also easily verify that with a light. The vacuum advance will make the engine run cooler unless you already have too much total advance. Another thing you can check. An MSD box won't help you unless you get one that is programmable. You'll have to lock out the distributor advance before you can use one. PIA? That's called tuning That's part of the fun. Read my Power Timing Thread, http://www.v8buick.com/index.php?threads/power-timing-your-buick-v8.63475/
I wanted to update everyone, I think the overheating problem is solved. The Champion radiator is working great and Derale dual-fan, 4000 cfm, are keeping her cool at stop lights and while idling. We'll see when the HOT weather comes... I want to thank everyone for their input, especially Larry 70GS and BuicksStage1. I'm off to enjoy the ride! Have a good weekend!
hey wildcat 68 I read about your situation and have the following to share I stuffed a 75 455 in a 1955 buick roadmaster and had problems with lo speed cruising ,idling I switched to Spal (puller) elec fan and added a griffin radiator bit still experienced lo speed overheating at fairground cruises etc checked timing and all other avenues then after having to change a water pump I looked at it after removal and saw small vanes that were short on impeller and didn't go to the edge and noticed area between suction and discharge was common and wondered if there was something better than part store crap so I got on the web and found a water pump from TA Performance after talking to the guys they shared same troubles with their cars and their company did the work and came up with what I think is a great piece! it is recast in aluminum with thick flanges and a separation between suction and discharge cavities to reduce cavitation and this thing has a actual bearing on the shaft this thing is made tough so I bit the bullet and bought one yeah it was $200 bucks bit very well designed and has turned out to be the ticket for me I can idle around fairgrounds all day and maintain good temp im very happy and the guys at TA Performance are great and very knowledgeable and enjoy buicks of their own call them , talk to me or whatever Good luck!! I forgot to say that part of the new redesign is an all aluminuw (closed) impeller which is definitely part of the low speed performance !
Can someone explain why the timing specs are different between the 455 and Stage1. If the motor is turning 4600rpm zero vacuum. 455 has 40* and Stage1 has 34* Thanks!
What you are looking at is the manufacturing tolerances of the day. You have a range given for medium and maximum mechanical advance. Since it is the size of the slot that determines the maximum mechanical advance, and it is the spring tension that determines medium mechanical advance, the actual advance could be anywhere in that range. Today we have microprocessor controlled ignition, much more precise. The best way to determine what a particular engine wants for timing is to run it at the track, or on a chassis dyno. 30-36* seems to be what most Buick engines want. I have found my aluminum heads seem to like even higher totals. The trap speeds go up with more timing. Paul Cassidy told me his wagon motor likes 40*. Not sure if he is pulling timing at the top end of the track.
After viewing the pics, I think the overheating was caused by the bright blue wire cladding. Seriously, I'm glad to read that the repairs you elected made the difference. You can enjoy cruising now!
Wild Guess: Less timing on the Stage 1 due to higher compression than the other 455 variants, which might result in detonation. There are two distinct limits to total timing advance: 1. The engine goes into detonation with the fuel used or recommended. 2. The engine stops increasing power production with more advance without detonation present. In the case of #1, using more detonation-resistant fuel, or perhaps a richer mixture or colder inlet temperature (anything that suppresses detonation) may allow additional timing advance and more power. A person looking for more power has to be careful WHY the engine wants a certain maximum spark advance. An engine that "wants" excessive spark advance may have high-octane fuel being burned in a crappy, slow-burning combustion chamber. The slow-burning chamber needs a lot of time to get the burn going. An engine that doesn't "want" a lot of advance may have poor fuel in a crappy, slow-burning combustion chamber--the spark advance is limited by detonation. By comparison, a good, fast-burning chamber will tend to allow lower octane fuel than a slow-burning chamber while still making as much or more power. The spark advance AND detonation AND octane level can be minimized with a good chamber.
Looks like there's still a range there, so maybe using all of the total wasn't intended except that it falls within range. The extra might be simply because the initial is slightly higher along with the way the stamped advance parts turned out. I can picture the service spec being slightly tweaked vs. coming up with different distr. parts already made ahead of time and the possibility of a service tech backing off too much initial timing resulting in a poor driving vehicle. Anyone really racing competitively would be using a timing light and adjusting things anyways.
Yup, that's what I meant when I said that I shifted the numbers. I was looking for a pattern. I have no idea how it was running either. I'm hoping that once I get the new radiator in (and hopefully it'll be O.K.), that will solve my overheating problems. I'm terrible at the formatting but here are some pics of the shroud, pulleys water jacket inside the intake and inside the neck of the radiator. View attachment 354624 View attachment 354625 View attachment 354628 View attachment 354626 View attachment 354629 View attachment 354630 View attachment 354627 [/QUOTE] I was looking for a thread and came across this one, I see its a couple years later but it looks like I dropped the ball on you and didn't respond back to you after you took those pictures. Those pulleys you have are a big problem, those are small ID crank pulley and large ID W/P pulley set up are "Under Drive pulleys" You need to find Large ID triple crank pulley and small ID W/P pulley so it speeds up the flow at idle.
