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TK
possibly a heater core issue, no coolant flow from engine , maybe remove both heater hoses and attach a water source to confirm no flow in & out could be sludge in the heater core, the fuel tank may be good inside but ugly outside, , I would soak the bolts for the tank straps , the fuel sending unit may be fragile so keep an eye on that
I am curious what gear set the rear has installed with a factory 3 speed
 

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not sure if you have used RA? I have sourced them before and had good luck, I also get discount codes(5%) every once in a while
 

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On the heater issue with the hoses being warm check to make sure there’s a thermostat in the housing. The hose coming off the head is the supply to the core. Just another suggestion to GPs suggestion
 

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1966 Pontiac Tempest Custom Coupe
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Discussion Starter #65
TK
possibly a heater core issue, no coolant flow from engine , maybe remove both heater hoses and attach a water source to confirm no flow in & out could be sludge in the heater core, the fuel tank may be good inside but ugly outside, if you decide to do the tank , I would soak the bolts for the tank straps & you may need new tank straps , the fuel sending unit may be fragile so keep an eye on that
I am curious what gear set the rear has installed with a factory 3 speed
Well, I was hoping I wouldn't hear heater core. After several years of no-heat winters in San Diego, I replaced the core in my Chevelle. Wasn't as experienced (nor the wisdom of how important the right tools are) at "bigger" (bigger than r&ring an alternator), so it took me all day to accomplish.

Agreed...I'm assuming it's okay inside, but it's so ugly, it's time. I ordered a new Spectra tank and new straps (with strap pads) a couple hours ago. I r&red the tank in my TR a couple years ago, so I know what I'm up against. Okay...I'll be very careful with the sending unit.

Very curious too about the diff gear. The high today is supposed to be 37 degrees. The forecast for Tuesday is 56, so haven't decided. Might happen today if I get too antsy. But I'll definitely let you know when I learn the gear ratio.
 

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Discussion Starter #66
not sure if you have used RA? I have sourced them before and had good luck, I also get discount codes(5%) every once in a while
I've used Rock Auto many times...great prices. I spaced it 5 am and went straight to eBay (see they also have the Spectra)...paid $20 more for the same tank before the 5% discount (I'm often emailed the discount code, but it expires...have Googled the current code so can always get it). I'll likely be using RA lots for this car though...will be ordering KYBs shortly through them (and possibly coil springs). But good tip/reminder...
 

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Discussion Starter #67 (Edited)
On the heater issue with the hoses being warm check to make sure there’s a thermostat in the housing. The hose coming off the head is the supply to the core. Just another suggestion to GPs suggestion
Was curious about whether it had a stat as well. Preliminary indication is that it does, as I saw no coolant circulating with the rad cap off just after cold start-up. That's not definitive (could be stuck closed), so I'll be doing a direct check soon.

Do you happen to know how the heater core in these is accessed? It required removing the wheel well in my Chevelle. I'm hoping some might be accessible through the passenger compartment's heater box. I'm sure I'll find a DIY vid on Youtube...
 

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Discussion Starter #68
Looks like I might be replacing the water pump soon as well. There's a small leak somewhere at or around it...looks like at the mating surface between it and the engine. Just enough to detect a bit of steam rising.

I see it's got a new radiator, so that's good.

That alternator trips me out...looks decades old, but obviously still working. Hard not to not justify replacing it as well.

Belts look okay, but I'll probably replace those as well soon.
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I know you said the cig lighter may not be working but this may work in the interim this is from Amazon of course if its just a blown fuse for the cig lighter
the alternator looks to have been replaced (stickers on the side) you can always confirm the stamping on the case
water pump not sure if there were different w/p for that year but you may want to measure the mating flange, if you do the water pump you are half way to the timing gear set, if the 70k is correct I would just bite the bullet and replace the timimg gear it will go soon if it is the the orig
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if the alternator is decades old it's probably rebuilt better(USA) vs the rebuild of today (off shore)
 

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non a/c car so I think you can get away without removing wheel well, I think the nuts holding the heater core cover in the engine compartment are 3/8, I think there was 2 nuts that are hard to reach , still better than removing the wheel well
 

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That's all great info...thank you Jim!

Neither Advance Auto or O'Reilly's had an oil filter in stock. Auto Zone (and NAPA) had it, so I got a Mobil One (M1-701, if memory serves) filter. Got that, Castrol 10W30 dino oil and zinc additive. Actually, the oil looks only medium brown, so while I normally change the oil immediately on any newly purchased vehicle, I'll wait a couple hundred miles and see how it looks. Also got Mobil One 75W90 "LS" gear oil. Waiting for Advance to have a diff cover gasket delivered later today (depending on the weather, might wait until it's warmer and the residual snow melts, just washed 'er!). Also got lead substitute (forget the brand).

I'm at about 5,700 ft elevation here in Colorado, so regular octane in this region is 85 octane. I filled it with mid-grade (87) a few days ago. Is 85 or 87 is okay with this (lower compression) motor? Normally, I wouldn't need to ask...I know when and when I don't need it (for my turbo cars or Z06; 11:1 CR), but just want to be sure there's not something I don't know with that Pontiac motor.Thanks again for the good info...
Great Car TK!
Another great oil to checkout with zinc in it alreadyIs Valvoline V-1 Racing Oil 10-30w
There was a discussion here that zinc worked best when it was added by the manufacturer into the oil But , prob it’s no biggie either way as long as it’s in there,
also ,Here was a discussion on adding the best rear spings, they may still avail on order thru
Summit or Franks Used Parts ,
also CC679F2D-F1F5-4FEB-B881-AD572F4DCE5D.png beats anything else hands down for loosing your parts up
I think The 15 inch wheels are really the way to go, mostNowadays I think have em, but purists still stick with 14’s
Guess it’s what yer into😀
 

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Was curious about whether it had a stat as well. Preliminary indication is that it does, as I saw no coolant circulating with the rad cap off just after cold start-up. That's not definitive (could be stuck closed), so I'll be doing a direct check soon.

Do you happen to know how the heater core in these is accessed? It required removing the wheel well in my Chevelle. I'm hoping some might be accessible through the passenger compartment's heater box. I'm sure I'll find a DIY vid on Youtube...
I did my heater core about 6 months ago and I did not remove my fender well on my 67 w/o ac. I used a extra long wrench (7/16 I believe) to access that nut from the top. Only would have took me about three hours but i started tightening and one stud was not thru the hole. So double check that before you start tightening up your bolts.
Resized_20210221_141233.jpg
 

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Discussion Starter #75
Get the PHS documents for your car which will tell you all the specs and options.

The rear gear with a 3-speed seems to generally be 3.23's. Use the 80-90 gear oil and if adding to the rear if flushing/changing, add a can of additive for the posi. I use Lucas brand gear oil.

The engine is a lower compression and should run OK on pump gas. Would not worry too much about octane/lead additives. However, this additive has been suggested to my by a Pontiac engine builder/shop. It is a lubricant and octane booster - and can add a little extra octane. Not too expensive and you might only want to use it every other fill up, or so. You can use it every fill up, of course.

Pontiac engines are known for torque and built for torque over HP. The 326 has a small bore, so it is not favorable in adding the larger 2.11" later valve heads - but not needed either. The 326HO was designed to compete against the Chevy Hi-Po 283 option back in 1964. You can keep your heads, add larger valves, I recall you can use the Chevy Hi-Po 2.02" intakes, and do the usual head mods to get a decent head. A good cam, dual exhaust, and I might add a later factory cast iron Q-jet intake and carb. Would make a nice, fun, street combo that won't break the bank at the gas pump, especially if gas prices continue to climb, and still smoke tires.

You are correct. The 2 doesn't show too clear in the photo, but the #s are definitely 42 and 13, which equals 3.23.
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Discussion Starter #76
You might try to loosen your fill plug before emptying your diff. Just in case your plug wont come out. Ask me how I know. Had to drill mine out, don't want you ruining your gasket.
I did presoak the fill plug with WD-40 Rust Release Penetrant spray. It came loose lickity split, which I think was more so because the fluid had definitely been changed prior to decades ago as I thought might be the case. The cover bolts also came of with ease (presoaked them as well), no muscle required. And the gear oil was only medium brown (molasses color). But...always nice to know specifically when it was last changed. So I'll be entering that service in a maintenance log.

Also changed the plugs...the ones in it weren't bad, but regardless, fresh ones it has (probably the easiest new plugs install I've ever done...classic car (with no a/c or power brake booster makes for exceedingly easy access!!!). Several plug wires weren't snapped on to the plugs. I had noticed earlier coolant leaking from where the upper radiator hose meets the radiator. It leaked a pretty good size puddle after a drive...a quick tightening of the hose clamp was all it took.
 
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Discussion Starter #77
Rock Auto has two different shocks, one for "w/heavy duty suspension" and one for "except heavy duty suspension". I just called KYB tech support, asking if it was just that one was stiffer or if they vary in size/fitment. The only thing she could say was restating in so many words that it depends on the specs of the vehicle.

The window sticker line item says "springs & shocks-ride & handling"...suggesting the possibility that it's what KYB refers to as the heavy duty suspension. But because it's not clear, I'm hoping someone can give some clarity on which suspension it has.

1966 PONTIAC TEMPEST 5.3L 326cid V8 Shock Absorber | RockAuto
 

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Rock Auto has two different shocks, one for "w/heavy duty suspension" and one for "except heavy duty suspension". I just called KYB tech support, asking if it was just that one was stiffer or if they vary in size/fitment. The only thing she could say was restating in so many words that it depends on the specs of the vehicle.

The window sticker line item says "springs & shocks-ride & handling"...suggesting the possibility that it's what KYB refers to as the heavy duty suspension. But because it's not clear, I'm hoping someone can give some clarity on which suspension it has.

1966 PONTIAC TEMPEST 5.3L 326cid V8 Shock Absorber | RockAuto
I would want the HD shocks regardless of brand or what the factory used. The ride and handling package for the GTO and I suppose Lemans & Tempest models, was simply the addition of HD shocks to the car.
 

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Discussion Starter #79
I would want the HD shocks regardless of brand or what the factory used. The ride and handling package for the GTO and I suppose Lemans & Tempest models, was simply the addition of HD shocks to the car.
Very good. HD it is.
 
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