Ok, so I don't have enough fan to keep my engine cool while sitting in traffic, or cruising down the hwy at 4200 rpm on a 85-90 degree day.

Anyone know the largest fan I can run that will fit inside the shroud?

Thanks!

 

Do you have a tape measure? Measure your fan, then measure the gap between the blades and shroud (at the tightest point). Multiply that number by 2 (you have gaps on both sides), and add a little less than that to your existing fan diameter so you still have a little clearance left. Be sure to allow for enough engine flex while it's under a load so that the blade won't whack the shroud. I'm wondering though, if it isn't a fan issue, but something else? Cruising down the highway, you shouldn't even need a fan. I have a single electric fan, and only switch it on while in traffic. I do have an aftermarket aluminum radiator though, so if you're running a stock radiator, that's apples and oranges. But still, a stock radiator, if that's what you have, could be your problem. Especially an old, possibly restricted, less efficient one. One other thing, is your ignition timing set right? Too far one way or the other (retarded more so than advanced) can make the engine run too hot.

 

cruising down the highway at 4200 rpm!

 

At that rpm, with my diameter tires and 4.10 gears, I'd be going 81 mph. I guess he must like to fly down the highway.

 

ha ha!

Well, I know I'm running lean @ 4200 rpm... just haven't richened it up yet. Hey, it's on my list!

But yeah, I have 372 rear end with a 350 tranny. Tires are a 255/15/60. It was way, way worse years ago when I had the 4:11 rear end with the 235's. I'd be buzzing down the freeway at 5,000 rpm with ear plugs and old ladies would comfortably putz right by me in their small compact's, windows rolled up in their comfy air conditioned cars no doubt listening to gospel

Anyway, I jumped on the expressway recently and tried to keep up with traffic. My speedometer doesn't work, but I was tacking 4200 rpm. I ended up slowing down and just following the big rigs and everything was fine. Again, I think it was because I need to put some bigger secondary jets in.

Just to open a can of worms, when I bought the carb, I was told it was an 850. When I went to rebuild it, I found out it was only a 650.

As a base, I put the carb back to stock with the exception of the power valve. I know it's running lean because it pings above 6,000 rpm where before with the bigger jets it was fine.

Anyway, I'm more concerned with sitting in traffic. I have to drive the car almost 50 miles to a car show next week and I know I'm going to be in bumper to bumper traffic. This means I need to find a bigger fan tomorrow or early next week. Because I have a stock radiator and shroud, I was just thinking somebody might know the biggest fan they could get in there without any issues.

Thanks everyone!

 

67-68 Camaro Covan Instrument Panel with Autometer Gauges

Speaking of Speedo's not working. This is the exact instrument panel and speedo that I have and my speedo is not working either. It gets up to 20 and doesn't go any higher. I hope it is just the plastic gear that goes into the tranny otherwise I don't know what it could be and I dread having to take it out and trace the wiring. LOL, and speaking of rear end gearing, I drove mine out on the street for the first time yesterday since purchase and at a little over 2K rpm's I was doing maybe 40-45 so I know I have at least 4.11 gears. I'll be chaning that out to 3.73 asap.

 

are you using a flex fan? those seem to really pull the air in our old street rods. i still have the old 4 blade on my 68 for now. and i heat up a little. i have a good original corvette 5 blade clutch fan i just need to put on.

 

Seems to me if the engine is overheating at highway speed, it is more than a fan problem, you should look into a better radiator. Do you still have a thermostat in the system? If not you should put one in. Coolant flowing too fast does not have enough time to absorb or reject all the heat coming from the engine, and one of the functions of the stat is to slow down coolant flow.

 

Hey Camaroboy,
When I bought the car 11 or 12 years ago it came with some plastic after market fan. I'm going to take a wild guess and say that it's maybe 15 inches? It's pretty small and I've got a lot of room left for a bigger fan.
Somebody else told me about a clutch fan also, but honestly I think I'm just going to try and find a straight fan this weekend from the speed shop if possible.

Fastb,
Nice cluster! I'm hoping one day I can get one of those!
I'm thinking that my spedometer is around 20-25 mph fast. I just need to figure out the right gear for the tranny. It's a pretty easy fix. Just another thing on my list LOL!

Aside from that, I'm not sure why your speedo is doing what it's doing. I'd check the cable first and make sure that it's both plugged in all the way and if so, unplug it and make sure the cable ends are in good shape and they aren't stripped out. Aside from that, I wouldn't' think it would be your new speedo gauge unless it was making noise. I seem to recall that our older gauges had a gear in the gauge itself as well as the gear in the tranny.

 

Yes I have the thermostat in. I learned that lesson back in the early 80's

At highway speeds, I'm with you. At that point it's not about the fan. I'm pretty sure it's not my timing, or if my timing is off it's not off that far. Tell me what you think.

I have a 650 Holley that I just rebuilt. Before I rebuilt it, it ran strong through 7,000 rpm. No knocking or pinging etc. When I rebuilt it, I put in smaller jets both primary and secondary to put the carb back to stock configuration.

The primaries that come stock are 67's and the secondaries are 73s. I want to say (my memory isn't the best here) that the primaries I took out were 69's and the secondaries were 78's. As you can see, the factory jets are much, much smaller.

I don't have the power I had before the rebuild, and now, when I start bumping 6,000 rpm the engine pings. Keep in mind, I haven't adjusted the timing after rebuilding the carb, but I shouldn't have to.

Also, I want to say that I can hear the secondaries open up around 3,000 rpm while just cruising.

Anyway, I'm thinking that I'm just running lean @ 4200 rpm which is contributing to the over heating at highway speeds. I think I can play with the timing a bit, maybe even put in a lighter set of springs on the distributor but I'm fairly confident I'm really close where it's currently timed. I dunno... one thing at a time. Thoughts?