Newbie thinking about diving into a '65 GMC 1000

[Praxiss454]

Originally Posted by jtrichard

"the one in the lower right is likely in the proper position to help close the throttle linkage. That might be the only one he needs" AGREE 100% Marshy

I took off the extra spring and drove her around town, she did fine. Well, she was running a bit hot (between 230-250 according to my temperature gauge), and the idle once she was warm was a bit low. She spit out at least a couple of cups worth of coolant out of the overflow hose as well. Prior to the drive she was filled pretty much to the brim, which as I'm reading now was perhaps a bit too full.

Last night I also put in some new spark plugs set to the correct gap of 0.035".

[Praxiss454]

Originally Posted by Praxiss454

Well, she was running a bit hot (between 230-250 according to my temperature gauge)

I should add that it climbed to the 230 F range by the time I reached by destination a few miles away. I parked, and it was spitting coolant out of the overflow. After about 20 minutes I drove home and she didn't get above 215 or so.

[Praxiss454]

Used Prestone radiator clean/flush, and then also reverse flushed w a hose. There was no thermostat so I put in one of those too. Now she seems to stay around 210. On to the next thing.

[65 GMC]

Going back to when you first posted pictures of your truck. I noticed that it had the smaller 230/250 radiator mounted in the forward position where the larger 292/ v8 radiator should set. Is your truck still set up this way? If so that may be part of the overheating problem. The 230/250 radiator is narrower and it is more than likely letting air flow around the outside of the radiator than through it. What do the rest of you guys think?

[Praxiss454]

Originally Posted by 65 GMC

Going back to when you first posted pictures of your truck. I noticed that it had the smaller 230/250 radiator mounted in the forward position where the larger 292/ v8 radiator should set. Is your truck still set up this way? If so that may be part of the overheating problem. The 230/250 radiator is narrower and it is more than likely letting air flow around the outside of the radiator than through it. What do the rest of you guys think?

You are right, it is mounted in the forward position. I'm missing the radiator baffles, and I think (but am not sure) that I have a different fan and pulley. I'm sure the added distance and lack of baffles doesn't help the cooling situation. Do you think the radiator would fit in the rear position as-is? I'm not sure how I'd hold it in place even if there was sufficient clearance.

[TJ's Chevy]

If you can get a larger 292 or v8 radiator I would consider. I went aluminum dual core on my 64 GMC with a big block v8 and that thing Never gets above 190. The only time the temp gauge Finally hit Norm was when I was towing 10K on a hot day. lol

[Praxiss454]

Are the baffles significant in the cooling performance? Looks like I could grab a set for around $50 (which feels a bit pricey at first glance)

[65 GMC]

To put the radiator that you have back where it belongs. You would need a radiator shroud that bolts to the cowl panel between it and the radiator, and a upper radiator support for the smaller radiator along with a set of smaller rubber radiator cushions. Here are some photos of a GMC parts truck that I bought recently that was set up like yours was from the factory. Sorry but before you ask, No I'm not trying to sell these parts on the board. I'm just trying to show you how it was set up.

[65 GMC]

Here are some photos of the parts you need after they have been removed from the truck.

[Praxiss454]

Originally Posted by 65 GMC

Here are some photos of the parts you need after they have been removed from the truck.

Thanks for the pics, exactly what I was hoping someone would be able to show me. I think I have the items in the 2nd pic already, but not the first.

[Praxiss454]

Originally Posted by Praxiss454

Thanks for the pics, exactly what I was hoping someone would be able to show me. I think I have the items in the 2nd pic already, but not the first.

Hmm, maybe not quite exactly what I have, but close.

[Praxiss454]

Right now the question is, will the radiator have enough clearance to the 6-blade fan the PO installed. It looks larger than the stock 4 blade.

[jtrichard]

You might be better off getting a V8 radiator since you already have the mounts for it (and yours may be half plugged looks like over heating has been a problem for the PO also) ....The L6 parts you need may be hard to find.. As for the fan hard to see in pics but you may be-able to use a thinner spacer between the fan and water pump

[Praxiss454]

Originally Posted by jtrichard

You might be better off getting a V8 radiator since you already have the mounts for it (and yours may be half plugged looks like over heating has been a problem for the PO also) ....The L6 parts you need may be hard to find.. As for the fan hard to see in pics but you may be-able to use a thinner spacer between the fan and water pump

I hear you about the v8 rad but I would like to try to keep things stock (or take it back to stock) if possible. I have parts that look like everything shown in 1965s pictures except the baffles. Now that I have his example I'm going to more closely examine exactly what I have. If I can't stay stock I'll look for an era appropriate v8 rad.

My maintenance manual lists a handful of things to check for overheating and I'm still working my way through the list. Timing light is on the way, and I also need to adjust idle speed and mix.

[Praxiss454]

Here's a closer look at the radiator brackets and fan I do have. The radiator can rattle around as it stands now so these don't appear to be the I6 brackets.

[jtrichard]

Yes that's a V8 upper bracket the tanks are wider...At some point in the trucks life someone has put a V8 rad in there as you can see with the lower brackets (also wider than L6) you can NOT put the L6 rad in the correct place with the higher and slightly forward (lower) brackets in there

[Praxiss454]

Originally Posted by jtrichard

Yes that's a V8 upper bracket the tanks are wider...At some point in the trucks life someone has put a V8 rad in there as you can see with the lower brackets (also wider than L6) you can NOT put the L6 rad in the correct place with the higher and slightly forward (lower) brackets in there

You have a damn good eye jtrichard because I didn't even post the clearer pic of the lower brackets. The pic also shows I'd only have about 1/2" clearance between the fan and radiator if I did mount it in the lower spot.

My top bracket is differently shaped than what 65 GMC showed in his pic, as well.

[jtrichard]

WELL actually I am blind in my left eye but I do have 20/10 in my right

[Praxiss454]

Working my way through what my maintenance manual says regarding overheating. For anyone else's reference, here it is.

I've crossed off a, c, d, e, and f (I think). My new belt tension gauge just arrived, along with the timing light, so b and g are next. I slapped the gauge on there and the belt tension is around 50 lbs, which is much too loose, so when it cools off outside a bit I will adjust the tension correctly and move on to timing if I have time tonight.

I'm wondering if I can fashion a temporary upper radiator mount somehow until I can find a stock one for my radiator. This would allow me to at least try the correct lower position.

[Praxiss454]

Checked the timing, and it was about 12 degrees retarded. I set it to 4 degrees advanced, and holy hell what a huge difference.

Overheating issue appears to be resolved and the truck runs so much better now.

[TJ's Chevy]

Originally Posted by jtrichard

Yes that's a V8 upper bracket the tanks are wider...At some point in the trucks life someone has put a V8 rad in there as you can see with the lower brackets (also wider than L6) you can NOT put the L6 rad in the correct place with the higher and slightly forward (lower) brackets in there

Actually that is a V6 radiator bracket. The v6's came with a larger harrison rad than the v8's even did. You can tell by the taller top mount. Looks like a 305 V6 may have been there originally and someone swapped out for a 6, or just special ordered a larger radiator....

[Praxiss454]

Originally Posted by TJ's Chevy

Actually that is a V6 radiator bracket. The v6's came with a larger harrison rad than the v8's even did. You can tell by the taller top mount. Looks like a 305 V6 may have been there originally and someone swapped out for a 6, or just special ordered a larger radiator....

What other signs either there be of a v6? There isn't a fender badge or evidence of one that I have noticed.

[62stepside longbox]

Originally Posted by Praxiss454

What other signs either there be of a v6? There isn't a fender badge or evidence of one that I have noticed.

On a 65 if it had a v6 the emblem would be on the hood not the fender. Let's see a picture of the vin tag, gmc's could be special ordered with an inline six from 64 and up. If the vin on the tag has an "I" at the very beginning then it is an original straight six truck

[Praxiss454]

Originally Posted by 62stepside longbox

On a 65 if it had a v6 the emblem would be on the hood not the fender. Let's see a picture of the vin tag, gmc's could be special ordered with an inline six from 64 and up. If the vin on the tag has an "I" at the very beginning then it is an original straight six truck

Yes, it does have the "I".

[Praxiss454]

So I was trying to adjust the Rochester model b carb this evening prior to setting the timing, but my service manual stumped me. It's instructions were to:

1. Disconnect spark advance at distributor
and plug opening of tube.
2. Connect tachometer at coil.
3. Connect vacuum gauge to manifold.
4. With engine running (choke wide open) adjust
idle speed screw to bring idle speed to 450-500
rpm (Pow-R-Flo in drive, manual transmission in
neutral).
5. Adjust idle mixture screw to obtain highest
steady vacuum at idle speed.

I couldn't figure out where to connect a vacuum gauge. I assume this is NOT talking about the vacuum advance line from the carb to the distributor, because at idle that should not be pulling a vacuum.

Can anyone point me to exactly where I hook up the vacuum gauge?