Ted thats a nice car
Whats your heat shield made of cold rolled steel?

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85 d-100 HEI 2BBl
06 Toyota Corrola

It is .090 aluminum from the K&S rack at the hardware store. It is the stock sheet size. I drilled 3 holes and installed it with two of the thick gaskets. I did get two longer studs so I could use the extra thick gaskets. It works in two ways, one deflecting heat from the exhaust manifold, two wicking heat from the carb. The carb runs much cooler and never hot. It idles smoother and works much better especially on super hot days.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

thanks ted

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85 d-100 HEI 2BBl
06 Toyota Corrola

I put a heat shield under the carb and it didn't help much...Then today I had the hood up and shut it off while the electric fan was going and it dieseled. I started it back up and waited till the fan went off and stoped then. I shut it off agin and it didn't diesel. I should have said that my fan and hei get there power from the same fuse block so as the fan was still spinning it was making a little current that was making it diesel. I will change my wiring around a bit and see if that helps.
Thanks for all the advice

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85 d-100 HEI 2BBl
06 Toyota Corrola

How many miles on this engine?
What is the compression ratio?
How badly carboned up do you think the heads, valves and plugs might be?
What is the initial timing set at?

The reason I ask is that my old stock engine at about 300,000 miles was pretty carboned up from the low low compression and short commutes. It was timed per the stock setting which was zero degrees for a 74. When it got hot and I shut it off it would diesel like crazy.......

Then I learned about this website and cleaned out the engine, changed to 0-30W Mobil 1, got rid of the EGR and retimed the initial to 16 degrees and it ran great! No more dieseling!
At 450,000 I got a defective new oil filter which collapsed internally and starved the engine of oil at about 50 miles after an oil change and had to rebuild it. I am sure it would have hit 500,000 miles and would still be getting 22 mpg.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I have no way to be sure on the exact miles but I would guss 200,000.
The compression ratio is stock. There was a clean up cut taken.
I know the valves and head can't be too bad, I just had it off for a valve job less than 1,000 miles ago.
The initial timing is 8* set with the vacuum advance hose off and caped.

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85 d-100 HEI 2BBl
06 Toyota Corrola

So your still running a low compression motor (stock is around 7.4 to 7.6 regardless of the advertised rating), which I have found makes things worse. After decking the block and milling the head for 9.5 compression all my dieseling problems went away. I run a minimum of 10 degrees initial and 20 degrees mechanical and another 22 of vacuum advance. Running 87-89 octane fuel and did a distributor re-curve. I found my old distributor advance plate was sticking due to old dried out grease and one spring was stuck so I was only getting 10 degrees mechanical out of a 15R (30 degree) governor.

Why do you have your advance disconnected?
You need that extra advance right off idle or it will feel like a slug.

How hot is was your carb when it dieseled?
Mine runs luke warm with the aluminum deflector and fuel line mod with the electric fan.

How hot is it were you live?
Does it diesel all year round?
or is it temperature independent?

My dieseling problems were when my engine had stock compression and stock, zero degrees and or very low timing....and hot days after a long hard run especially with the Holley 1945 carb.

Dieseling can happen from a combination of too much heat, low octane fuel, low timing, low compression and boiling fuel.

My new 9.5 compression engine responds very crisp. Start ups and shut off are immediate no matter what the temp is out side.
In 90 to 100+ degree heat I prefer to run a 180 stat. In the winter I run a 205.
Where I live all the foothills the summers are super hot and the winters are in the low teens.
I do not run the EGR or a heat diverter, like the stock exhaust manifold.
Year round performance has been exceptional since I have made all the mods.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I should have said I put the hose back on after I got the timing set
It stopped dieseling but I'm not sure if it was the temp drop or a wiring change.
Before the heat shield it would get really hot 120*? Not sure. Now it gets luke warm.

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85 d-100 HEI 2BBl
06 Toyota Corrola

Wjajr, sorry to say it, but you may be wrong about the power valve for the Holley 2280. There actually is an adjustment screw, you'll find it under the small lid covering the vent valve.

Carlherrnstein, I have a 2280 without any pipe for a vent, and as far as I know, those with no pipe just vented to the inside of the carb. That may be a contributing factor for the dieseling problem if your carb has no external vent pipe. Also check your plugs, could they be overheating and thus creating a hot-spot?

See the film on servicing the Holley 2280 from Imperialclub.com's archives.

For those not familiar with the Imperialclub archives, look here.

Olaf.

An afterthought: If you have a high-quality relay for your electric fan - for example a Bosch relay, it has a small internal circuit including a diode, which will prevent backsurge from el. motors entering the main circuit.

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Aspenized

Correct.
Not correct.
Not necessarily. Bosch (and every other relay maker) makes many relays, some of which have a diode across the coil and some of which have a resistor across the coil and some of which have neither. It's not a higher/lower quality thing, it's a question of whether transient spike suppression is necessary; the answer depends on the application.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Well, yes, for the average buyer it is a quality/price question. The general purpose relays you buy over the counter in an auto parts store, are intended to be used for horns, fans, lights and so on. They all have a diode circuit, or none. All other types of relays are for special applications, their very existence is unknown to the general public. They will be marked as such special items, and will not be sold as general purpose relays.

I have two almost identical relays here, one Bosch, and one unmarked Chinese (or Thai, Burmese, Vietnamese or whatever), both sold side by side in a large chain of auto parts stores. The oriental model has all the depressions and ribs and markings of the Bosch relay, the only thing that differs visually, is the absence of the Bosch logo. The visual similarity is the reason I opened it, I smelled a rat. Internally in the oriental model - the plastic broke when opened - there is nothing at all but the absolute minimum of parts necessary to make the relay physically operate (for a while!). Clearly the result of a quality/price evaluation from the store management, and nothing that the customer is informed about. All Bosch relays sold here as general purpose relays have diode protection.
With boiling fuel there is.

Olaf

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Aspenized

Carlherrnstein, have you double checked that the vacuum pod on the distributor is connected to ported vacuum, and not manifold vacuum? With your initial set at 15°, you would normally have a pinging situation if that is the case, but it depends on how efficient the mechanical advance in the distributor is, and how much advance the pod gives. Manifold vacuum will advance your ignition at idle, just when you are going to shut off, and may in some cases cause dieseling.

Olaf.

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Aspenized

Wow, lots of odd opinions about dieseling.

Basically: Dieseling as it's called, is caused by there being enough compression after you turn off the ignition and the engine slows down, to ignite the mixture. It can be caused by hot bits of carbon in the cylinder, or something glowing red hot that's metal.

1. The farther open your throttle blades are, the more air is pulled into the cylinder and thus, more compression - more heat.

2. Retarded initial timing requires farther open throttle blades to idle at the speed you want. Advancing the timing allows you to close the throttle blades more.

3. Retarded timing means the air-fuel mix is still burning when the exhaust valve opens, heating the exhaust valves far more than they should be.

4. Richer idle mixtures are required for retarded timing. Richer mixtures (as long as "not too rich") ignite easier than lean.

5. Hot air pulled into the carb raises the temperature on the compression cycle, encouraging dieseling.

Engine too hot, or else there being tons of carbon stuck to the head or piston, glowing red hot will do the trick.

Moving the timing ahead relieves most of these, including decreasing the amount of heat absorbed into the head.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

Yep! One thing that can usually be counted on if you're looking for advice on a web forum is odd opinions — often issued in authoritative "take-it-from-me" tones of voice without warrant.

Yours is a nice rundown on factors influencing dieseling. The OP will want to check his timing and idle settings carefully. I would also ask what (exact) spark plugs are being used in this engine.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hi 65CrewCabPW, what you say is correct, but it also implies that the carburetor setting were done with a too retarded timing. Carlherrnstein clearly states that the timing is set at 15° initial, and if the ignition was adjusted after setting up the carburetor to run with very little or no advance, there would be a problem with running the carburetor at it's old settings. I may be totally wrong, but it leads me to believe the problem lies elsewhere.

Getting current to the ignition system from a running fan is absolutely plausible, and will easy be rectified with a good relay to turn the fan on and off, or with a diode mounted in the circuit. (a diode leads only in one direction).

Olaf.

Correction: Initial timing was later set to 8°, still dieseling.

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Aspenized