Sarum

Yep I still have the major overheating problem with my '65 Cutlass. As the issue started after I replaced the distributor with one from Summit Racing (and installed a trick HEI module at the same time) I decided to check the engine's ignition timing and have attached a PDF containing the test results. Until very recently I had thought the ignition may be too far advanced but after reading some new info I am not so sure, hence this post.
1)Summit Racing's latest version Installation Instructions say that the distributor provides a maximum of 10 degrees of Mechanical Advance. https://www.summitracing.com/int/par...0006/overview/
2)Summit also also goes on to state that the new distributor’s Mechanical Advance provides 20 degrees total beginning with 6 degrees off idle progressing to full advance at approx. 1800RPM
3)The new distributor has a adjustable vacuum canister which is currently locked off.
4)The 2 previous sets of instructions for the distributor have also said that “The vacuum advance provides 10 degrees of advance”.This has been deleted from the latest version but as can be seen from the test results table I measured from 14 up to 19 degrees of vacuum advance with my Innova digital timing light so I am a bit confused about how I can test almost double what the distributor’s supposed to provide.
5)At the time of installation the new distributor was fitted with a Pertronix Flame Thrower 111 HEI Module D72000. Here is a link to it https://www.summitracing.com/int/par...2000/overview/ Another
customer advised to “check initial timing as the unit effects dwell”.I am of the opinion that all HEI modules effect dwell,that it is a part of what they do.
6) The thermostat has been replaced as has the water pump. The drive belt has correct tension to operate the pump and the hoses are not collapsing. The Derales fan controller and Derales electric fan are working normally although I have been switching the fan on manually while testing.
7) I had started thinking that I might well have a leaking head gasket and this is causing the overheating but there are no signs of any of the classic indicators eg bubbles in the radiator etc.
8) I took the car for a short run today and had the fan switched on manually the whole time and at 55-60mph cruise the temp was sitting at 200degreesF but as soon as the speed dropped the temp would start rising. Previous to this issue arrising I coud sit at the same 55-60mph cruise with fan switched off and the temp would be stable at around 150-180 degrees.This feels like a lack of coolant circulation to my way of thinking because if coolant was moving around the wind through the radiator was normally enough to reduce the coolant temp previously never mind the electric fan.
I think I will replace the thermostat again before testing for a head gasket leak with one of the kits you can buy that has a chemical that reacts to CO2 in the radiator coolant
Any ideas would be most welcome as I really want to use the car this summer.

Fun71

The timing numbers look good to me, so I have no idea why you are experiencing overheating issues.

Sarum

Hi Kenneth,
Thanks for your quick reply it's much appreciated. The only good thing about things going wrong with the Cutlass is that I learn something new! After reading an article on the very good 442.com website I am more comfortable with the timing results,Sounds like the majority of performance articles etc don't mention vacuum advance when talking timing,Actually if it wasn't for the overheating the car is going great as I also changed shift points on the trans recently.

oldcutlass

According to your chart, your distributor is providing 19* of mechanical and vacuum almost 20* and fluctuating a bit because its adjusted with the allen wrench to an internal higher spring pressure than you have vacuum available. First your initial is too low, in it self will cause the engine to run hotter. Disconnect and plug your vac adv and adjust your initial to 16/18. Leave vac adv plugged and take for a ride.

The Summit instructions must be a typo as for the amount of mech adv. Most HEI are set for 21*ish of mech advance.

olds 307 and 403

Add more initial timing as said, it will help. What is the compression ratio on this motor? That and camshaft as well as the octane available along with altitude determine what timing it will tolerate. What radiator is in the car? What amps do the Derale fans draw?

Sarum

Hi again Eric,
You might not remember but you have helped me previously hence the "again" I think some of the fluctuation is due to how difficult it is to get the desired RPM reading on the Innova timing tester's screen. Sometimes an analogue needle setup is much better to use than a digital screen.Re the Allen wrench used to adjust spring pressure I am assuming you are talking about the adjustable vacuum the dizzie has, correct? I am excited by what I have been reading so I am going to go and try and adjust the timing to 16-18 degrees initial and see what happens when I take it for a drive as you suggest.

coppercutlass

I dont think you have a timing issue. Look more into your radiator and fans. How big are your fans and how big is your radiator. I learned this a few years ago on CFM and area coverage . I had some be cool fans that where suppoused to be the cats azz. I ended up going back to the twin fans from a 95 impala ss. They pretty much cover my entire radiator. Went from having the same issues you had to Normal. I bought the fans thinking they where new and would be great. . I put my junkyard units back in lol.

olds 307 and 403

As said, what radiator and what model Derale fans do you have? Some of the Derale fans are US made, run big amps and move huge air, some not so good.

rustyroger

If all was well until you changed the distributor, then straight away started having issues, retrace your steps.
What else did you do?, did anything get disturbed by accident?.
If it runs fine at cruising speed but runs hot when you go more slowly I think a head gasket test is your next step.
Throwing big fans on won't help if it was ok before.
I think by coincidence a head gasket has failed the same time you changed the distributor.

Roger.

Sarum

As per the above I plugged the vacuum line to the distributor, reset the timing to 18 degrees at 735RPM and then took the car for a total of 4 test runs each with the vacuum line plugged. BTW the vacuum port I am currently using is a port on the front of the Edelbrock RPM intake manifold rather the manifold vacuum port on the carb.THe first thing I noticed with the higher initial timing is that the car now has better power low down,from a standing start or from when the car was being driven slowly.
From the first 3 runs I found that when the car was cruising at 50 to 60mph the engine temperature would drop down to somewhere in the 150 to 175 degrees F which would I would consider normal.This wasn't happening since this temp issue raised its head.
At slower speeds (up to 30mph) around town the gauge temperature would start climbing and would continue to do so until I could get the car up to highway speed. This is actually an improvement as since this temperature issue arose hitting highway speed and benefiting from the wind through the radiator wasn't enough to drop the heat to a lower temp range.
After completing the third run I jumped out of the car to open the gate and heard the relay click and the fan start to run. Checking the gauge it read 200 degrees which is not right as the controller had been set to run the fan at 185 degrees. I had checked and reset the fan start temperature recently so I then thought that maybe there could actually be 2 things causing the problem i.e timing and a fan issue.
On the fourth and final run I decided to switch the fan on manually to mimic "normal" i.e any time the temp gauge got up to 185 degrees. During these runs I kept checking that the fan was actually coming on by pulling over and switching the engine off so I could here the fan from inside the car.Every time I did this check the fan was running.
It was while driving at slow speed around town that the temperature started to move up to a higher range and despite switching the fan on it continued to rise but I could not drive any faster to drop the temp until I hit the highway. I thought that having the fan running and more air through the radiator at highway speed would drop the temperature but it was like I had reached a threshold and the temp would not drop.By the time I arrived back home the gauge was showing 250 degrees and the radiator dumped $10 worth of coolant on my driveway.Previously releasing coolant wasn't possible as the radiator had a cap installed that didn't have a pressure release mechanism.When the engine temp got high fluid would be released into a small alloy overflows tank via a small hose.This tank has a small pressure relief cap but it has never released any coolant in the 5 years I have owned the car.
I have a spare controller and relay so I am going to swap them out as it won't take long but I don't think it will fix things.
Eric, going back to timing do you think I should now retest as I have done previously noting results with and without vacuum advance at the different rpm's?
Also if you have an idea of what I should now do I would be very happy to hear it. Of course I could buy a kit and test the coolant to indicate a leaking head gasket etc but there are no indicators pointing that way and the engine seems better than ever power wise.

Vintage Chief

With the vacuum advance disconnected & plugged while reading vacuum (at idle or at least at a constant RPM). - does the vacuum gauge remain rock steady - unwavering & very steady; or, does the vacuum gauge bounce around up & down?

Sarum

As per Eric I have added more initial timing which has helped acceleration but the overheating issue remains.Oldsmobile say that the engine in my Cutlass has a 10.25:1 compression ratio from the factory but I have no idea what it is really is. As far as the engine goes it certainly sounds like it has a "performance" cam in it but if you remove the oil filler cap you can see there are is a baffle visible.I know that the factory valve/lifter setup is not adjustable, something that it would have to be with an aftermarket camshaft installed I would have thought but the engine certainly doen't have roller rockers etc.
I use 95 octane fuel in the car as that is the highest octane pump gas readily available in New Zealand.
The car has a large Griffin alloy radiator, the model that incorperates a trans cooler. There is also another transnission cooler mounted to the front of the Griffin trans cooler. I am not sure if the additional trans cooler is normal for these Griffin radiators or not.
I do not know what the fan draws in the way of current but I know that the controller has a maximum rating of 25 amps continuous.Unless I am missing something I am not sure that the fans current draw has relevance to my overheating issue but.I can see relevance on say a new installation where the fan can't draw sufficient power to cool the engine properly.

Sarum

I had previously installed a vacuum gauge in the car and another small fluid filled one mounted into a firewall mounted unit.Although the gauges provide different readings, I am guessing because the under hood one is fluid filled.Both gauges stay steady as long there is a constant low RPM.I even have another small fluid filled vacuum gauge mounted in the top of the aftermarket brake vacuum tank I installed not long after buying the car.

oldcutlass

Lets try hooking up the vacuum advance now to manifold vacuum. It would be the port that has vacuum at idle. You'll have to drop your idle speed down when you connect it. You have good temps at speed even with the fan off which leads me to believe you have an air flow problem at idle. Can you post some pictures of the front and back of the radiator - fans and trans cooler.

Vintage Chief

Instead of asking you questions, I'll just toss this out - there is some ability to assist in diagnostics which might provide insight in the direction you take:
(1) The vacuum reading should remain constant at idle and constant at any constant RPM;
(2) At idle, while reading your vacuum (In. Hg) rapidly accelerate the throttle and let go. You should see an immediate vacuum of zero In. Hg and a very rapid movement of ~5-10 In. Hg above the normal steady vacuum level and followed by a fast return to normal steady vacuum level;
(3) At idle, while reading your vacuum (In. Hg) - let's just say you have 20 In. Hg at idle - gradually increase the throttle to an RPM of 3000 RPM or 4000RPM. The vacuum should remain rock steady during this gradual increase in RPM - it should not waver from the initial idle vacuum.

If you get a drop in vacuum, a bouncing around of the vacuum gauge needle, or an increase in vacuum these sometimes can be a tell-tale sign of what direction you should be looking next.

coppercutlass

Personally from experience with stock and modified engines i have never experienced his type of overheating from timing. Unless it's retarded alot . you can have upwarfs of 36 initial and not have heat issues. I don't run a vacuum advance even on my mild 350 that's in my Pontiac. I would start looking at the cooling system. Just fwiw

Vintage Chief

Like coppercutlass, the times I've witnessed this aberrant type of overheating has been the result of the dwell being far too retarded PRIOR to setting the correct timing. That's why, IMO, on vehicles with breaker points, it's critical to set the sequence correctly: Dwell>Timing>Carburetor.
If the dwell is not set correctly, no amount of timing or carburetor adjustment will provide any help.
I just don't know much about the Pertronix Flame Thrower 111 HEI Module D72000 but I'd think it would have the dwell set properly. I mean, even with this type of module, you don't adjust dwell on-the-fly do you? Once dwell is set, it's set, right?

Fun71

You can use a fairly aggressive camshaft with the factory rockers. The W-30 MT cars had a .475" lift, 328ş duration cam from the factory, and from posts I have read the factory rockers are OK for up to .500" lift.

I agree with a factory / mild cam, but note that he said his sounds like a "performance" cam. The mild sounding 217 cam in my car gave a very bouncy idle vacuum until I recurved the distributor, gave it a lot of initial, and hooked the vacuum advance to manifold vacuum.


This is exactly what I was thinking.

Vintage Chief

I don't know. Running down the road 60-70mph w/ a dwell too retarded would allow a lot of the un-burned (actually, still burning hot) fuel to bleed right out the exhaust and be swept away. Even the additional air flow over the exhaust and cooling jacket would help to dissipate heat away.
When you get to the point of running slow - and, I'm talking about an engine that is running too hot as in it is too retarded, you aren't burning up the a/f in the cylinder efficiently and instead you have very hot incompletely burned a/f leaving the exhaust (again, it's actually still detonating because it didn't all detonate in the cylinder). You get this, IMO, from being too retarded. The exhaust is going to heat up, the manifold is going to heat up, the cooling system is going to heat up because it can't continue to absorb more and more heat. I agree, I think you have an air-flow problem - you don't have enough air moving across your exhaust, your block, your manifold, etc. to dissipate the heat because you're running retarded. At speed - you have no issue; at idle (slowly moving) you're building up heat but it isn't dissipating because you aren't moving at speed.

I'd check your HEI distributor and your coil. Aren't you supposed to use matched pairs of coil/distributor? I realize the HEI makes some adjustments to dwell, but it just seems to me, you're dwell is retarded and you're acting like a flame thrower at low speeds.

EDIT: My last statement is inconsistent with my logic. What I should have said was this - you're acting like a flame thrower at all speeds, but at low speeds you aren't dissipating the heat because you have no air flow - advance your dwell (e.g. check your HEI).

oldcutlass

There is no adjustment for dwell on an HEI.

coppercutlass

The module does control the dwell but it is non adjustable. When the module goes it goes. I have had coils that burned caps in less than 100 miles that caused no issues besides the burnt cap. Even my e/t's in the 1/4 mile where not affected. I would clean the charred terminals when i got to the track and run it lol.

Vintage Chief

I wasn't suggesting there was an adjustment (which there is not). I was only suggesting there is an issue with dwell on this setup.

(1) The issue first occurred when the distributor was changed out:
(2) The issue remains & IMO, the issue will continue to remain unless the HEI distributor is properly adjusted or the module replaced, etc.

I am not clear how throwing more diagnostics at the radiator (all of a sudden) and then the possibility a head gasket has mysteriously become an issue is helping. That's just my opinion.

But, this issue started with the installation of a Summit Racing distributor and a trick HEI module. Personally, I doubt a new distributor is going to mysteriously create a radiator or head gasket issue. JS

Was the vehicle running OK without a new distributor and trick HEI module? If so, install the old distributor and test it for overheating.

oldcutlass

This is not something that started recently, it started a few years ago.

Vintage Chief

Well, I'll say this as I did, in fact, read back through the posts.

(1) Initially when he had an OEM distributor & breaker points and had an overheating condition, I saw tons of suggestions to adjust the timing. Then he was making adjustments to the carburetor. In fact, the very first thing which was done was to have the carburetor rebuilt professionally and installed back onto the engine. Let's just think about this one minute. An engine in what condition? Dwell Angle off to the point it was already in a retarded state? After 47 posts regarding the initial overheating, not one suggestion was made to establish the Dwell Angle on an OEM distributor. Not one. The very first point of protocol on any engine running an OE distributor, breaker points & coil is to set the correct Dwell Angle. You do not move to timing an engine @ degrees of TDC, BTDC or ATDC until the Dwell Angle is established. You cannot tune an engine until the Dwell Angle is established. And, to do this properly, it is absolutely critical the distributor is inserted @ #1 TDC otherwise, you have no baseline from which to establish the Dwell Angle; next, the thread moved on to adjusting the carburetor - why would anyone adjust a carburetor if they first have not established Dwell and timing?;
(2) Next, on what appears to be (this thread reads like machete) several occasions, a couple different types of distributor was installed and yet a couple different types of HEI modules. Then, it was discovered the distributor was not inserted in the correct orientation with respect to (rotor alignment) of the Number One cylinder (not with respect to #1 @ TDC), but instead with respect to where the rotor was "found" to be located when the distributor was initially removed - and, then it was later found to be off a 'cog'. To be honest, there is no mention at all regarding TDC orientation of the Number One cylinder. It was assumed (based upon HEI installation instructions) that the OE distributor was being correctly installed (e.g. carefully mark the rotor so the new HEI distributor is installed in the same orientation). Of course, let's not be fooled here. This 'assumes' the OE distributor was in fact installed in the correct orientation with regard to Number One cylinder @ TDC. Call me an idiot, I don't care. I found more evidence it wasn't in the correct orientation than to say it was. Read on.
(3) You can flame me all you want, but I am suspicious about the direction this thread has taken with regard to the distributor and its proper installation. Regardless, if its running OE distributor, contacts, coil, MSD, or HEI I didn't find once where the distributor was aligned with #1 Cyl @ TDC, dropped the distributor into its proper position, then established Dwell Angle in the very first thread regarding Overheating with the OE distributor. I looked, I did not find any suggestion to establish #1 Cyl @ TDC, with the distributor in the correct position. I'm sorry, I may be a complete idiot, but am I completely missing something entirely? If the distributor is not installed/aligned correctly - there is absolutely no amount of timing and/or carburetor tweaking which can be done to further enhance diagnostics unless the distributor is spot-on installed in its correct orientation.
(4) Can I just go ahead and buy a new distributor and HEI module and drop it right in and Bob's Your Uncle, Betty's Your Aunt without first establishing the distributor is ALIGNED with #1 @ TDC? Someone, please anyone, please tell me I'm an idiot and say an HEI module and distributor are so advanced it doesn't matter if the distributor shaft is dropped into the oil pump cam shaft at any position - the HEI module is so sophisticated the Dwell Angle (time spent open/closed on breaker points, so what if it's an HEI) is going to happen correctly even if the distributor is oriented with #1 Cyl @ the bottom of the compression stroke?

This is probably going to sound as if I'm writing this is in haste and angst. Yet, when I read this historically documented thread: (1) no where was the initial Dwell Angle even suggested on the original issue when he had an OE distributor, breaker points & external coil [47 posts and not one mention of Dwell Angle]; (2) you don't throw timing adjustments to an improperly adjusted Dwell Angle - period, let alone; (3) you cannot adjust Dwell Angle correctly if #1 Cyl is not @ TDC; (4) after several HEI distributors/modules, it was found the rotor (not the distributor) was "off a cog"? - OK, whatever. What does that mean? Off a cog from what - TDC on #2, TDC on #3, half-way down the compression stroke of #1? Assuming, of course, the initial distributor was properly installed in alignment with #1 @ TDC. If it is NOT the case the distributor is sitting on #1 Cyl @ TDC how can you possibly install a sophisticated and advanced distributor/HEI module and expect to find the timing is not retarded or advanced? The HEI is 'assuming' #1 Cyl is @ TDC is that not correct? And, if it is NOT @ TDC what do you do next? Toss out some different initial settings, increase vacuum, look for head gaskets, fan pulleys, fan clutches, radiators, water pumps?

Done with my soapbox, pardon me for taking up your time.

I'll make one suggestion (instead of broadcasting my angst - which is most likely already upsetting many). Establish the distributor is inserted with #1 Cyl @ TDC, then, I'll shut up or convince me the HEI doesn't care whether the distributor is aligned with #1 Cyl @ TDC.

coppercutlass

The very fact he can get going down the road long enough tells me by very simple fact its not the distributor. He need to address his cooling system.

coppercutlass

Now the question is....... What did he hook up that hei to for the 12v. Source. Points distributors have a resistance wire that drops voltage once hot. HEI needs 12 all the time

Vintage Chief

Wrong. You can insert a distributor outside of #1 Cyl @ TC and still run down the road. But if not inserted properly, you can easily be retarded and run hot.

coppercutlass

Although you are correct. You would have driveability issues lack of power etc etc . so..... Yeah

coppercutlass

From the original posters' post it seems like the car is running well enough for him to make it down the road. Being off when stabbing the distributor would cause all kinds of tuning issues and driveability issues you would catch before even leaving the driveway.

oldcutlass

The engine does not care about the orientation of the distributor as long as its wired and timed correctly. The only time the orientation comes into play is if the proper timing cannot be achieved because there is interference by the firewall or the intake manifold. Then the orientation needs to be changed. There are 2 ways, 1 you can remove, rotate a tooth or so in the direction it needs to overcome the obstacle, and reinstall and reset the timing. Or you can move the wires right or left keeping the correct firing order an reset the timing. There is no such thing as being a tooth off and you can stab the distributor in either the #1 or #6 position depending on crank position of those 2 cylinders.

Vintage Chief

Again, it's a matter of I guess your perspective versus mine. You can insert a distributor outside of #1 Cyl @ TDC and still drive the vehicle down the road. It "seems like the car is running well" says nothing to me whatsoever. No, you would not necessarily have all kinds of tuning issue. I've seen vehicles so mucked owners have adjusted the timing to "compensate" (although they had no idea what they were doing) for bad Dwell Angle, en-rich or lean the carburetor to "compensate" for bad performance. Number one key is Dwell Angle - plain and very simple. And, Dwell cannot be established outside of #1 Cyl @ TDC. If you're off-beat just little, no big deal - engine runs just fine. Yet, be retarded and as I have said before you're tossing fuel into the exhaust which is still burning because it hasn't all burned in the cylinder and you're heating up.

coppercutlass

You can be about 7 teeth off which Is 180. If I remember correct .

coppercutlass

If its done right with a timing light you really cant be off you would see that

coppercutlass

You keep talking about dwell like he has points. He has an HEI. Which in an HEI its self adjusted through engine speed

Fun71

coppercutlass

@ chief Here is an article not supporting what you are saying. if the dwell was not working properly he would have a either a misfire at higher RPMs or if it stick and only has 10 degrees it would have bad low rpm driving qualities and pinging underload and a dead misfire which means he wouldn't make it out his driveway. I read this article sometime ago. Great refrence. https://www.hemmings.com/magazine/mu...I/1719426.html

Vintage Chief

I have read this article on several previous occasions. Thanks.

coppercutlass

Then …….. why so hung up on the dwell issue. Everyting you keep saying could be driven on would show driveability issues the kind one wouldn't pull out of the driveway and go kind of issues .

Fun71

coppercutlass

I also agree on the airflow/cooling system. Need to try better fans imo. I bought some killer fans once thinking I was stepping up my set up.... as I mentioned before I went back to my squad car fans.