questions about Impco E-regulator

[Imperial73]

I am in a discussion with someone regarding the Impco E/EB/PE/...

According to some sources, the E is rated at 325hp, according to other 200hp. To my understanding, its 325hp?

What are the differences between the E, EB, PE,...? I thought that the PE was for CNG and the EB for LPG?

[franz]

Although many model E vaporizer covers list a 350 bhp rating, the Impco manual I have shows 200 hp for the PE and 300 hp for the model E. The PE is typically used for natural gas versions and USUALLY has the letter "V" in the name PEV, meaning its designed for vapor fuel service. The PE and the E have the heated grid while the PEV and the EV do not.

Many parts are interchangable and there is virtually no difference in the internal castings, only that the fuel inlet in the EV or PEV form can only flow so much through the small inlet opening.

Franz

[Imperial73]

Franz, thanks for your elaborate answer!

New question is, how do the (normal) E and L relate in rating? I assumed they both had the same maximum output rating.

[franz]

According to Impco literature I remember, both the model L and model E LPG vaporizers, when at full operating temperature of at least 180 degrees F, can feed 350 bhp. The OHG X-1 claimed the same 350 bhp but burst power levels of up to 500 bhp for 10 seconds. The danger was not fuel restriction but the limit of vaporization. The fuel was blowing past the primary vaporization area too fast to fully vaporizer, leading to rich and uncontrolled fuel mixtures.

Plan on 300 bhp when fully warmed for both the L and E. 300 bhp is not highway cruise speeds, but more like full throttle continuous load at max rated power. Few street engines can pull 300 bhp without significant modifications (your big block 440 engine would come close to it though, with a combination of vehicle weight, lots of torque, and about 4000 rpm).

Franz

[C3H8]

Franz is pretty well right on the money with his comments. The P stands for positive pressure. These regs put out 3" to 6" positive pressure WC. They are used strictly for NG.

The reason for the 200 VS 350 HP rating on an EB reg is the application. The reg is rated at 200HP for industrial engines. Industrial engines usually run at a fixed 1800 RPM and the water pump is geared different then automotive applications. The limited water supply means the reg is derated to 200HP. On vehicles the water pump can increase suction as the RPM is quite high at full throttle. This means more flow and heat for the reg so the HP rating is higher.

Lastly, personal opinion, I prefer the E over the L. The E has a water chamber the size of the reg. Heat transfer is great. The L has a U shaped tunnel through the reg and heat transfer on a cold engine is poor and wide open throttle is no where near as good as the E for heat transfer. In addition the L has a primary seat activated by tank pressure. The L seems to have more P seat problems than the E. We experienced a higher number of problems with the L's at our shop.

[Imperial73]

That is good to know! By intuition I already favored the E, but now you gave me some good reasons to justify my bias! Thanks!

[Steptoe]

I would only consider an L on say as 350ci if it is going to be limitted to very short bursts to 5000 rpms in say a passing manuver on the highway...if cruising for long periods 10 mins + above 4500 rpms go to an E.
The L leans out the E leans out at higher prms...I have an L and suits the use of the camaro very well for ME.

The limitations of the L we have confimed on the chassis dyno several times.

[Marc]

Hi Guys,
This is an old post that I am living through...

I think my model E vaporizer is leaking gas...

The car starts fine after 3-4 days in the garage. It also starts fine if I stop and restart.
But if I start then stop and leave it for 2 hours than start again it is bad, I cannot get it started directly and I sometime even have a backfire;
If I shut the egine off with the solenoid valve (emptyng the propoane until engine stalls) than in all situation it does start right!

I believe the mixture is enriched as vaporizer leaks in the large hose to the mixer. Then when I crank it this excess gas is released to the engine creating false starts.

I need either to buy a new one, or to rebuild my unit using a rebuild kit.
Both options are possible.
A new model E is ~120 euro more.
I am ready for a rebuilt, but I read on the instruction sheet :
36. Lightly pull the lever (5) up against the secondary
seat for measuring. Use a straight edge or the
IMPCO G2-2 gauge to check the lever height. The
secondary lever link pin should be approximately
1/32” (0.8mm) below the level of the body casting.
If the lever height is incorrect, continue to Step 37.
Once the lever height is correct, skip to Step 38.

This is the only difficulty I notice. I just don't understand what they mean.
Also I do not have a torque wrench for ~2 NM...

If I buy a new one I need to change the spring for pressure reference.
S2-23 Spring, Secondary Regulator (Orange), Option

Thanks for your insights.

[C3H8]

Sorry for the late reply. The lever height is directly related to the volume of gas it will pass at a given suction from the mixer. To set the secondary lever height correctly install the lever and secondary spring. Place a straight edge across the casting above the pin that hooks into the secondary diaphragm. The pin should be 1/32" below the straight edge. The adjustment is a lttle harder to explain but simply put there are three scenarios.

1. The pin is perfectly located 1/32" below the straight edge. (Fat chance . This happens seldom if ever).
2. The lever is more than 1/32" below the straight edge. In this case lift the lever with your finger and it will bend at the fulcrum point (the lower pin). The lever is reasonable pliable. Lift it until it is at the required 1/32".
3. The lever height is too high and the horizonal pin is pushing up on the straight edge. This is a little fussier and requires applying pressure on the secondary seat end while pushing down on the lever. Frequently it is best to just push a little too far and then lift on the lever to get the correct setting.

This setting is important. The mixers send a specified vacuum down the vapour supply line to the regulator. The secondary spring controls the distance the secondary valve opens based on that vacuum, however, if the lever height is incorrect the volume of fuel will be either too rich or too lean depending on the incorrect height.

The difference between and S2-23 orange spring and the regular blue spring is the negative pressure required to open the secondary seat. The blue spring requires -1.5" water column to open the secondary valve. The orange is weaker and opens at -.5" water column. In the past the orange was used for various reasons to richen fuel mixtures. One of those was when the EC1 emission device came on the market. Initially an orange spring was used to richen the mixtures and then vacuum was used to control the secondary diaphragm through a modified model E lid.

Orange springs were also used on industrial applications for various reasons. Keep in mind that an orange spring results in richer mixtures across the complete operation so cruise mixtures and power mixtures are richer. The power can be compensated for but the cruise cannot.

As for a torque wrench. The model E is completely assembled by screws. Obviously they can be tightened with a torque wrench. I would never suggest skipping this step but in reality I don't think I have ever seen anybody use a torque wrench on these screws. Use common sense and tighten the screws securely with a regular sized screwdriver, not one of the huge ones you sometimes see available.

[C3H8]

I should have added. Your hot start issue is probably the beginning of a primary seat failure. The seat eventually cuts itself into the base ring and can leak. The mixtures are probably very rich initially causing poor running. The other possibility is the primary seat barbell shaped spring steel that holds the primary seat open initially. Sometimes this spring steel wears a ridge into it where it sits on the casting. This ridge causes the primary seat to lock closed and prevents the flow of fuel. Inspect the underside of the old primary seat on each barbell end and look for a ridge when your rebuilding the reg. The primary seat failure or stuck barbell would both cause a lean condition accounting for the backfire on start up.

[Marc]

Hi!
Great you answered!
I was thinking my post was left without replies...

As I had not a reply this is what I did :
I opened the top and I add an extra 0.8 mm gasket on top. no other changes.
Problem is not solved.

Now I am considering to change the rubber seat indeed. I will also checking the lever clearance as you said.

I wonder where I can buy a rubber seat?? idea?

when you say to look for if spring steel wears a ridge , this is about the lever spring right? and it would lock the lever ?

Thanks.

[C3H8]

In this case I am talking about the primary seat spring. It is shaped like a barbell. It sits in a groove in the casting holding the primary seat open until fuel enters the regulator and pushes against the primary diaphragm. That is the triangle shaped diaphragm that operates the primary pin. There are cases where the barbell ends that sit in the groves of the casing wear a ridge into them. Eventually this ridge begins to stick on the edge of the casing and holds the primary seat closed and does not allow fuel to enter the regulator.

This barbell has a rubber composite seat glued to it to seal the primary opening. Typically it is part of the model E repair kit, however it is available separately if it can be located. It does not have a part number I can quote as most suppliers only carry the complete repair kit. The repair kit number is RKE-2. Look here and it is number 18 in the schematic. https://www.impcotechnologies.com/wp-co ... ctions.pdf

[gerrit11]

do you mean by: "primary seat barbell shaped spring steel" the pin that operates the primary valve?
and what if my secondairy spring has no color?

[C3H8]

Yes. The barbell shaped spring steel is the primary seat. It has a square thin piece of rubber on it that forms the seat. Typically this seat gets a groove worn it all the way to the steel leaving an imperfect seal.

How can you tell which spring you have in the model E. The only way is the colour. The model E's are typically all shipped with the blue -1.5" water column. The optional spring is a -5" water column. The original spring is dyed blue and unfortunately the dye does wear off leaving a fairly bright clean chrome looking surface. The orange spring also loses it's dye but typically it is fairly dark in colour when this happens. Placing a gasket under the spring is not the solution. PM me and I can send you detailed instructions on overhauling the model E.