1964 327/365 HP hot idle temp problem solved

[Tim D.]

Thanks to Duke Williams, I have Finally gotten to the bottom of why my full restoration 1964 convertible 327/365 SP Hi Perf engine with 4,500 miles has AlwaysThen, I stumbled onto the magic problem/solution in this post between Duke and another member that I previously mentioned!This correct orientation allowed me to get more initial timing advance since the VAC can was no longer hitting the intake manifold.

Duke saw my post on my fuel pump issue and we began communicating about this heat issue. He coached me through removing and reinstalling my distributor. He also walked me through many procedures such as confirming my 236-16 VAC can was performing up to specs and confirming the 2" rule he talks about in his San Diego presentation. We established baseline specs on my engine's "current" settings BEFORE we altered anything. I believe at the time my engine was only producing about 13" of vacuum which seemed low. Then he guided me through shimming my distributor drive gear up to specs to reduce spark chatter, installing lighter distributor advance springs (I now have "gold" springs/Mr. Gasket #928G advance curve kit) and completely dialing in my timing advance map curve. I think my initial timing is now 15* and I know my engine is producing more vacuum than before. The Dwell is set at 30* I think my new baseline is as follows but I may have some facts incorrect

[Ed S.]

Re: 1964 327/365 HP hot idle temp problem solved

Thanks for passing this great tip on and for being persistent until you resolved the problem. I also have a 64 L76 - it seems to run fine but with a 50 year old machine you never know when some component is going to go south or just fall out of adjustment. I like to copy threads like yours to a word (or PDF) document and file them in my "personal" tech library for future reference. That said, can you post a link to any articles or postings by Duke on this or other relevant topics. Thanks again

Ed

[Leif A.]

Re: 1964 327/365 HP hot idle temp problem solved

Tim,

Great follow-up post and nice kudos to Duke and John who always have the answers to our overheating/tuning issues...if only we'd listen

Ed,

Just put "hot idle issue" in the search line and you will find more posts than you will be able to read in a day (including one of my own).

Leif

[Duke W.]

Re: 1964 327/365 HP hot idle temp problem solved

Perhaps Duke will chime in on the more technical info/data. I think my new baseline is as follows but I may have some facts incorrect:

Centrifugal Advance start @ 900, 24 @ 3200 (max)

Vac. adv. ( 0* @5"hg - 16* @ 9"hg )
Initial adv. 15
Total WOT adv. 39* @ 3200 RPM
Total idle adv. 31* @ 750 RPM
Total cruise adv. 55* @3200 RPM
Idle: 750 RPM @ 15" hg
Idle screw setting: one turn out from seat


Tim

The "Idle screw setting" refers to the idle mixture screws on the sides of the Holley's primary metering block.

The original centrifugal didn't start until 1300 and wasn't all in until about 4000. This certainly contributed to idle/low speed hot running along with the fact that insufficient initial timing was available due to the gear being on backwards.

The manifold on my 340 HP SWC still has a couple of small gouges on it due to the VAC being jammed up against it back in 1966 when my distributor suffered from the same assembly error. None of the "experts" had a clue, but I finally had a Eureka moment about the third time I removed the distributor and finally saw the dimple.

There is nothing that I am aware of in any service documentation that explains proper dimple indexing, which is why I assembled it improperly despite careful attention to the shop manual. What really surprised me was that none of the "experts" I talked to knew anything about this. At that point (as a 20-year old ME undergrad) I realized that I was, from now on, going to be my own expert (and I'm still working on it) and take any advice with a grain of salt

Reinstalling the distributor, even without moving the drive gear, can sometimes be a problem due to the oil pump drive not meshing, which requires tweaking the shaft slot with a special tool - a paint mixing stick. If you have to rotate the drive gear then it will definitely need tweaking and can sometimes take several attempts before getting the distributor to engage the pump drive, gear, and seat properly.

I had Tim begin upon distributor removal by indexing the engine at about 14 BTC on the #1 compression stroke rather than TDC as recommended by the "experts". Tim was hesitant about this, but I said: "Trust me. I'll explain when you are ready to drop it back in."

Upon installation I told Tim to check the orientiation of the pump drive shaft slot, then hold the distributor above the hole with the rotor tip pointing straight forward, then rotate the bottom of the distributor 90 degrees forward, observe the pump drive pin orientation, compare to the pump drive shaft, and tweak the pump drive shaft an appropriate amount so the drive pin at the bottom of the distributor will engage.

Tim has a good eye because it dropped right in.

Now on to where to slight snug the distributor hold down bolt to get initial timing in the proper ball park so the engine will start. If you ever worked on a sixties vintage Honda motorcycle you probably know how to "static time", but most guys don't seem to understand the concept. I instructed Tim to rotate the distributor so the VAC was against the coil bracket, then slowly rotate the VAC forward and watch the points. The instant they began to open, STOP, and tweak it back until they close.

The spark fires when the points open and with the crank set at about 14 deg. BTC, guess where the spark will fire when you crank it - at least within a degree or two. No guesswork required.

Tim also checked with an ohmmeter (coil negative post to ground, which will measure zero with the points closed and infinite the instant they open), but his eyeball was as good as the meter.

Of course the engine started right up. Then time checked the start/stop points of the centrifugal, and set the total WOT advance at 39 at 3500 - 300 revs above the stop point of the centrifugal advance and secured the distributor hold down bolt. Then he checked initial below the 900 RPM centrifugal start point, connected the VAC, checked total cruise advance at 3500 and total idle advance at 750. All the numbers were exactly as expected. The final step was the idle speed/mixture adjustment procedure. The engine was assembled with a L-79 cam, which is why the idle behavior is typical L-79.

The engine was also assembled with "flattop" pistons and a .035" head gasket, so assuming nominal deck height the CR is about 9.5:1, depending on the volume of the piston valve clearance notches.

Relatively high overlap and large clearance volume due to low compression means lots of exhaust gas dilution at idle and low load which slows combustion propagation, so the engine likes lots of advance under all conditions. If he can find some lighter springs I'm sure the engine would like a more aggressive centrifugal curve.

In the meantime he can run detonation tests on midgrade and if it passes, regular unleaded. He's giving away some torque/power and fuel economy with the low compression, but there's no point paying for premium if the engine doesn't need it.

Duke