292 engine upgrades questions

[RichardJ]

>> HEI Modules will burn out if not given their full 12 volts.<<

That is not, I repeat, not true.

About 15 years ago I installed an HEI with coil-in-cap. When I added the AC, I changed it to the '75 inline six type with the externally mounted coil. I wanted the extra clearance so that the compressor could be a little lower.
Both distributors for all these 15 years have been running with the original ballast resistor installed. Voltage measured at the Bat input to the coil is only a little more than 2.0 volts lower than actual battery voltage. 14.5 volts at the battery will provide an actual 12.0 volts at the distributor.

[GRX]

>> HEI Modules will burn out if not given their full 12 volts.<<

>> That is not, I repeat, not true.<<

http://www.classicinlines.com/HEIdizzy.asp

Contrary to what some will also say, low voltage, as in still using the resistor or a resistor wire, will not kill an HEI module,. It will make the overall spark weaker exponentially as volts are reduced. After a certain level of volt input lowering, the module will simply stop working from lack of volts, and the system will simply not idle. Once again, low volts will not harm an HEI module, it'll just stop making spark when it gets to the point it can no longer run on what isn't there. Add volts, it will come back alive again.

['68OrangeSunshine]

OK, what burns HEI Modules out then, high heat?

[Shaky]

Originally Posted by RichardJ

>> HEI Modules will burn out if not given their full 12 volts.<<

That is not, I repeat, not true.

About 15 years ago I installed an HEI with coil-in-cap. When I added the AC, I changed it to the '75 inline six type with the externally mounted coil. I wanted the extra clearance so that the compressor could be a little lower.
Both distributors for all these 15 years have been running with the original ballast resistor installed. Voltage measured at the Bat input to the coil is only a little more than 2.0 volts lower than actual battery voltage. 14.5 volts at the battery will provide an actual 12.0 volts at the distributor.

As stated above - it will reduce the performance of your coil.

I had a '70 Bel Air with original points. It would cut out completely at high rpm. After much diagnosis it was found that the resistor wire had degraded. It would provide 7v to the coil at lower rpm but spike to 12v at higher rpm.

Maybe your resistor wire is degraded and feeding the HEI acceptably. I dunno.

I solved my problem by putting in an HEI and running a dedicated 12v wire to the coil.

[Shaky]

Originally Posted by '68OrangeSunshine

OK, what burns HEI Modules out then, high heat?

I had a SBC that went through modules all the time. Tried all different brands. I always theorized it was heat related (only happened in summer, would kill the motor but restart after cooling) but didn't know for sure. New module would fix it for a while. It wasn't fuel related.

I've never had a module problem on an inline HEI.

[hamjet]

Originally Posted by '68OrangeSunshine

OK, what burns HEI Modules out then, high heat?

I believe it is heat. there is a dialectric paste, or grease you put between the module and the distributor that creates a heat sink for the module. when the grease breaks down or dries up you loose the heat sink and it over heats and fails.

[GRX]

In my eyes, mistaken use of Dielectric grease for thermal transfer has caused overheating of many a coil. Most coils will come with a pack of thermal paste which is not the same thing. I go one step further and use premium thermal paste made for computer processor heat sinks.

[hamjet]

Originally Posted by GRX

In my eyes, mistaken use of Dielectric grease for thermal transfer has caused overheating of many a coil. Most coils will come with a pack of thermal paste which is not the same thing. I go one step further and use premium thermal paste made for computer processor heat sinks.

You are correct, its not Dielectric grease, wrong words...

[LockDoc]

Originally Posted by GRX

In my eyes, mistaken use of Dielectric grease for thermal transfer has caused overheating of many a coil. Most coils will come with a pack of thermal paste which is not the same thing. I go one step further and use premium thermal paste made for computer processor heat sinks.

Arctic Silver or Arctic Silver5 is what I use. On my computer processors AND my HEI modules.

LockDoc

['68OrangeSunshine]

Originally Posted by GRX

In my eyes, mistaken use of Dielectric grease for thermal transfer has caused overheating of many a coil. Most coils will come with a pack of thermal paste which is not the same thing. I go one step further and use premium thermal paste made for computer processor heat sinks.

Good to know.
I killed one HEI Delco distributor by greasing the works, counterweights and under module with White Lithium grease. The lithium hardened and jammed the counterweights. I never thought about overheating the module, too.

[swamp rat]

Originally Posted by '68OrangeSunshine

The most important detail about the HEI install is that you feed it full-time 12VDC. The Points distributor system has a Yellow 20 ga. wire going to the Coil Pos (+) terminal. This end, plus its other side, the Yellow 20 on the Starter, are connected to the Resistor wire Orange/Purple/White from the bulkhead connector. You will need to run a new line [I like Red] 10- or 12- ga. from "Ign.Unfused" on the Fuse terminal in the cab thru the firewall and right to the (+) coil lead in the cap of the HEI. The old line with the resistor wire will provide 12 volts initially, at start up, but as it heats up will increase its resistance; dropping voltage to 7-9 VDC, so the points don't burn up. HEI Modules will ... not function optimally... if not given their full 12 volts.
So you need a fresh wire. You can keep the old yellow wire in place, just tape it off, if you ever want to go back to points. Keep the other end Yellow lead on the Starter, that's still necessary.

Thank you for that!

[Daner]

Here is the thread I used when I installed my HEI. I bought mine from Langdons. http://www.langdonsstovebolt.com

http://67-72chevytrucks.com/vboard/s...d.php?t=148346

Lots of great threads out there to read on tune ups and anything else you need to do. The thread search is your friend. A Haynes repair manual is a great resource as well.

[slomotion]

Esahic, all of the info you've been getting is good, straight stuff from guys who know what they're talking about, but before you go changing up a lot of parts, re-read SS Tim's post #3. You need to know what condition your engine is in before you make any substantial changes. You need a baseline to start with to know what needs to be done first. Do a compression test and write down the numbers. (This is your cylinder and ring condition) Check your oil pressure with a known good gauge. (A general condition of bearings, although not all-inclusive.) Do a leak-down test. (Ring and valve condition.)
If these tests come out within the specs you're good to go with the modifications, but if your foundation isn't sound you'd be much farther ahead putting your $$ into bringing the basic engine up to the best condition possible. These are tough engines, and last a long time, so your chances of having a good one are on your side, but you need the baseline now so you can document which modifications over time- (HEI, headers, 4bbl, etc. etc.) made the biggest difference in performance. You're in a pretty exclusive club! Sixes are cool!

[Shaky]

The post above is good advice. No sense spending time on a engine that's too far gone...

[esahic]

Thats some great advice SLOMOTION. I was ready to order new parts, but now I am going to check the oil pressure, compression and leak down test, before I spend money on it.

Now I need to start doing some research on how to do all these test. Can't wait, should be fun.

[SCHRUMGMC]

I've been following this thread for some time

I put a petronix ignition kit in my Delco Remy distributor, in my 270. I'm not 100% sure I notice any difference other than it being more reliable

I can't ever get my truck to run right, I have a Rochester B 1 barrel and its always given me problems and I am going to go with the original Zenith for my engine soon

[EARNHARDT#3]

Originally Posted by SCHRUMGMC

I've been following this thread for some time

I put a petronix ignition kit in my Delco Remy distributor, in my 270. I'm not 100% sure I notice any difference other than it being more reliable

I can't ever get my truck to run right, I have a Rochester B 1 barrel and its always given me problems and I am going to go with the original Zenith for my engine soon

I kept thinking my problems were all because of my Rochester B as well. I was wrong. Bad points, bad vacuum advance, timing off, intake leaking and so on. But ever issue that arose I thought it was that little carb. Never was.

[SCHRUMGMC]

The Rochester leaks though even after a rebuild. I've even tightened down the bolts, The Rochester B's are made for 235's, and its currently on my 270 GMC engine, which should be a Zenith and I am certain to buy one soon

My timing is off still, it would run without the choke but suddenly just cut out. So I just keep the choke out. I just recently replaced the vacuum advance as well, it was the original one

[slomotion]

Thank you Esahic. A couple of searches on "youtube" should net you a few good tutorials on anything you want to know. I wouldn't take all of the info in one video to be the gospel though, watch three or four from different techs on the same subject then you'll have a good understanding of how to go about these different tests. Check with your local parts store for the equipment too. Several of them will loan you the gauges and test equipment (with a deposit,) in hopes that you'll purchase whatever you need from them.
Quite a while ago I was given An HEI distributor for my 292 and I thanked the man telling him I'd install it when I had to do some major rework on my stock distributor. That was two or three years ago and I haven't had to do anything to my points/condenser dist. yet.
As for the big 1 bbl carbs, they do what they can, but they're not the ideal configuration. The trouble is the engineers tried to come up with a compromise carb that would do everything from idle to highway RPM with a single unit. A good compromise is a small 4 bbl carb for all-round driving because with the secondary's closed you still have good vacuum through the smaller primary's for low RPM/town driving, but also have the secondary's for highway and higher RPM driving. The 4bbl is a better mileage getting carb, but what you pay for the 4 bbl and associated manifold kind of nullifies any gain in the pocket book from better mileage.