I just installed my used 455 in my 71 Skylark. I am trying to dial it in for emissions testing. At idle it is getting hot and over boiling. The fan clutch is almost new, but it is off the 350. When the car is running hot the clutch still is not fully engaged. Got a clutch for a 1985 3\4 ton 454 Chevy truck, but the water pump shaft is to long. Are guys using a different pump or grinding down the shaft? It is an AC car with AC pulleys. TIA John
Well, I got the BBC fan clutch. Drilled it about a 1/2 inch deeper with a 5/8th drill bit. Made a difference, but did not fix the car. Added a Modine four row radiator part #365 and fixed the car. The four row actually fit better than the three row. Man the thing is huge. My only complaint is the BBC fan clutch is to noisy. I am going to try the 350 fan clutch and see what happens. John
Hey John, Are you running a shroud? That also will make a difference! Back in 1986 I had a GS350 that we put a 400 into. Because the shroud didn't swap over, and I was too eager to drive it, I went without. It ended up heating up a lot in a drivethru. Luckily we found a shroud that fit and never had a problem.
Yes. I am using a shroud off a 71 Electra. With the three row there was a 3/4 inch gap across the top. With the four row the shroud is flush with the core. John
How does your fan fit within the shroud? Is it all the way in, all the way out, somewhere in between? How's the fan's diameter? I went to a 19" on my 71 GS455. I think I could have even went to 20", but the 19 worked great for me.
The Electra shroud was made for a bigger fan (19.5"), not the 18" GS fan. Find a 7-blade, 19.5" fan and put in there. Oh and BTW, the super-duty clutch you have was also designed for the 19.5" 7-blade fan.
John, chances are if you're trying to set the car up to pass an emissions test, the carb is lean. I don't know if your engine is stock or not, but a carb. that is too small will cause overheating, not to mention leaning it out to pass that emissions test. Just food for thought, but when I switched from a 750 holley to a 950, my idle heating problems dissappeared. If you also retarded your timing too much it will aggrivate an existing heating problem. Just my .02 Good Luck. :TU: John
The fan is supposed to fit 50% in and 50% out of the shroud. With my 4 row my car runs too cool! From October to April I have to block the radiator with cardboard just to get it to 180*!
Drove the car 30 miles today. Ran about 180 at highway speeds. Fan clutch screeming the whole way. I have a 180 t-stat. I will probably go to a 160. At stops it creeps up 20 degrees. Comes right back down when cruising. Still have an air flow issue at idle. I am running a 19.5 seven blade fan that came off the 72 Riviera. The fan is 100% in the shroud. The shroud is 4.5 inches deep. Sound like I need a different shroud? Had an extra 72 Riviera Qjet. Had it rebuilt and went up two jet sizes. Will try the new carb tomorrow and save the other one for emissions. John
The one I had on my GS was an aftermarket heavy duty fan clutch/fan package. It sounded like a jet at startup, but once I hit the freeway and everything got up to temp, it quieted right down... the clutch allowed it to freewheel. You may not need a new shroud. Do you have some sort of spacer between the pulley and the fan? If you do, get a shorter one. If not, then you may want to consider some sort of changes to center the fan inside the shroud.
I'm missing something here. Why would you want the fan "centered" half-in, half-out? All the way inside the shroud is GREAT, in fact better, IMO. Look elsewhere, this is not the problem.
I messed aroung with the clutch fan setup , allways a pain. Went to electric fans and will never go back.
Back when I did the GS350/400 swap in high school I read about this. I think that by having the fan part way out of the shroud, it allows all the air to flow better, while creating a more efficient vacuum within the shroud. I can't think of a good analogy at this point though. Is it just me, or does it look like the distributor vacuum advance is sitting exposed? It's hard to tell from the picture. I just see an exposed nipple (don't get this confused with the Brittny/Esquire thread). :eek2:
Yeah, The vacuum advance does not work. Just went for a drive with the new carb and timing set at 16 degrees initial and 32 total. Ran a lot better. Temp seemed more stable, did not get as hot. It is hotter out today (90 degrees), but I only ran it for about 15 minutes around town. John
160* T-stat shouldn't lower your highest temp at all. Once the t-stat opens, it's open. I see 210*F with a 160* t-stat as my highest temp ever seen (not counting with the ehgine off, the gauge doesn't reflect accurate temp without flow) As it's been explained to me, the 160* T-stat is more for race applications. I think I made a big mistake installing mine. I see 160*F around town, and 200-210*F at about 80 mph on a hot, 90* F plus, summer day. Last night I was driving that fast for hours on end and never went above 180. it was about 55* last night here. If you have a 15psi radiator cap, your boil-over point is 247*F. 200, 220*F indicated should not cause you problems. This has been discussed a lot, and the best temp for the engine to see is around 190-200*F for efficiency and performance. The blades coming out of the shroud a bit should increase airflow. I have no pics of my engine on my new computer, and my old one had a nervous breakdown, so I can't post pics of mine, but I transplanted the engine and shroud out of a '73 Riviera, and the fan is exactly the way it was when stock, although I would say more like 1/3 of the fan sticks out of the shroud. Not only that, but with the fan sticking partway out of the shroud, I can replace the fan and /or fan clutch with the radiator and shroud in place easily. I just unbolt and remove. You don't seem to have a lot of clearance... I'd look at the following: temp gauge- electrical or mechanical? Electric ones, particularly stock type ones 30+ years old, suck. Mechanical ones are more accurate. Also don't forget that coolant must flow past the probe, and it's best to have it as close as possible to the t-stat. Overflow tank- if you just have a purge hose, you may be pulling air into your system. The water pump cannot pump air, if an air bubble makes it to the pump, and if an air bubble is in the radiator, it will cause a hot spot and also impede flow. The stock overflow does not just hold "extra" coolant, it actually has an important function, and was designed to work with the 455. It eleimates the chance that you will purge to atmospheric pressure and suck in air. The radiator will purge and draw from the overflow as standard operating procedure, in my experience with mild street 455s driven as daily drivers (since '91, rain or shine and sometimes snow) Also the overflow will allow any air bubbles a path to escape the system without a chance of drawing atmospheric pressure. radiator cap- the rad cap holds the system at higher than atmospheric pressure to increase the boil-over point. If it isn't working properly, you effectively lower your boil-over temp. It's a simple and cheap thing to replace. fan clutch and fan-why use the BBC clutch or fan at all? I've never had issue one with going to my local parts place and just asking for a fan clutch for a '73 Riviera, with a non thermostatic type fan clutch. I also agrree that the shroud should be the correct one for the fan diameter. ~edit- what kind of emissions test do you have to pass??
Carb might be too lean. Going thru this pain myself. Have heard that the 800 cfm QJet likes 75 or 76 jets, rods in the 44B, 45B, and 46B ballpark. If you're running 75 jets (2 sizes up from stock) and the stock 49B rod, you're too lean, especially at cruise. Especially if you have a low restriction exhaust on that car.
Had to pass an idle test in gear and a 35MPH cruise test. Car is still running hot. I am using the rally gauge as a guide, but getting temp readings using a raytek temp gun. Brand new rad cap with over flow tank. IT BOILS OVER AFTER IT IS SHUT OFF. Drove it this weekend and it got hot in traffic. Fan clutches really do not make a difference, so I think I will try a new blade that will put the blade out of the shroud. If I can keep it below 210 and not boil over I will call it good. John
John, I'm still concerned about the timing/fuel mixture. Especially with the vacuum advance disconnected. You stated that when you advanced the initial timing to 16*, it seemed to help. You might want to fix the vacuum advance and reconnect it. You had mentioned that it doesn't work, do you know why? Have you tried to fatten up the idle air/fuel mixture? Are both sides adjusted to the highest possible vacuum reading? How about the primary metering circuit (jets and rods)?
