Those with Modified Engines and Original Carb

[Sensei]

First I want to re-address my answer to Barry08 about anyone using my carb. I did not mention that I have been using one on my 350-400 hp car for several years now. I learned to work on these things (E4MEs) because I had one and no one else seemed to know (or want to know) anything about them.

I drive the car every day (it is my primary vehicle), I get around 18 mpg city, 23 highway. As far as performance, here's a quick story my daughter told me:

My wife drives a 2007 4WD Suburban. I borrowed it recently and she was driving the Vette. She was driving my daughter somewhere and was about to pull out into traffic from a side road (sitting with the front wheels turned). I guess with her truck, she is just used to putting the pedal to the floor, but that is not a good idea in my car. My daughter told me "Mom hit the gas and before we knew what happened, the car spun around in a complete circle (270 degrees) and we were facing the oncomming traffic."

My wife really does not like to drive my car.


As far as metering rods/ jets: I am not aware of any rods or jets for these carbs except what came stock and all of the E4MEs I have rebuilt (probably a dozen+) have used the exact same ones no mater what kind of engine they were on. But this is not a problem because they are around 72-73s if I remember correctly (I'm not looking right now) and the double stepped rods go from nothing to quite large. This set up will flow a lot of fuel, but the computer can still rein it in for economy. The mods for the primaries are mainly in the idle fuel and air delivery (which effects performance throughout rpm range). For secondaries, the E4ME uses standard Q-jet rods, so you just pick the best ones for the application.

 

[damoroso]

Sensei,

From the story, it sounds like you certainly have great throttle response in your car!

Thanks for the information, I'll be working this carb for this engine, like you I belive it's a very good piece of engineering and very capable.

Thanks again.

 

[alexdrastico]

Hi Sensei, i'm Sandro from Italy and i own a 1981 Corvette and i'm very happy to know that is possible to increase the power of my car keeping the original E4ME and is ECM.My car have 46K and it is a matching number and i would like to increase the power on it, is better to change the engine with a new crate or keep the original L 81 with some modifications?What you think about it?My aim is 300 HP.

Greetings

Sandro

 

[KANE]

...My daughter told me "Mom hit the gas and before we knew what happened, the car spun around in a complete circle (270 degrees) and we were facing the oncomming traffic."

My wife really does not like to drive my car...

Great story! I hope she didn't take off too many years of her life with a scare like that.

My wife stopped driving my modified Vettes years ago for the exact same reasons.

When I was looking into getting a Trans Am, she suggested I second generation. I asked her if she'd drive it and she said she wouldn't. She doesn't drive a stick... so when I found the '95 she said she wouldn't drive it anyway- so don't base a decision on her thoughts.

 

[Sensei]

is better to change the engine with a new crate or keep the original L 81 with some modifications?What you think about it?My aim is 300 HP.

That's all a mater of opinion. Some people will say to put the original engine aside to preserve it and use a crate motor. In a lot of cases, it is cheaper that way, and certainly easier. Being in Italy, that may be the way to go.

I have no place (or desire) to keep a V8 engine lying around. I also don't think the numbers matching engine will ever be that important on an '81. Finally, what made me go with modifying the original engine instead of using with a crate engine was the desire to build it myself the way I wanted it.

Either way, 300 hp is very doable.

God bless, Sensei

 

[GerryLP]

Chris,

Before returning the L81 to the Vette, I used a 1968 Camaro "302" block (punched to 0.040" over and 3.48 stroke crankshaft), with Eldelbrock heads (Performer), 268 cam, holley carb, single plane intake, and headers, and I got it running with a best time of 14.600 seconds at 5,000 feet of altitude in the local track (and the rule of thumb around here is that the same motor should do nearly one second faster at sea level), but later, when I built my L81, I made sure that it was a true (measured -not advertised) 9.5:1 CR, and with a quench of 0.045", same 268 cam, and a balanced/blue-printed motor (353, I only went 0.020" over on the cylinders and of course pistons) with the Q-Jet E4ME.

I wonder If I should try one of your carbs to see if I see an improvement, or if I don't, I am willing to bet that what might be holding it back are the cylinder heads.

The displacement between the old track motor (357.5) and the L81 (353.36) is approximately slightly over 4.0 cubic inches, but the CR ratio on the old track motor was 9.21:1 as opposed to the L81's 9.49:1. The Cranking pressures are higher on the L81, so I know that it should have room to do better....but again, I have this sneaky suspicion that the head differences played a bigger role on the old track motor.

What do you think?

GerryLP:cool

 

[Sensei]

Gerry, there are of course a lot of variables between the engines. From what I understand, with two engines of the same displacement, the one with more stroke will produce more power.

As far as the heads, of all people, you know that the quality of the L81 head leaves a lot to be desired. With the fact that the head was never designed for performance anyway, I would say it is a weak link.

That said, with your CR and cam, I would think you should be able to gain a bit with some carb modifications.

God bless, Sensei

 

[alexdrastico]

Hi Sensei
I'm agree with you for to modify my L81, but tell me something what i have to change for to improve horsepower!I have bought a new E4ME and a 2 on 2 stainless steel complete exhaust because i want to change the original catalytic converter, what do you think?

Greetings, Sandro.

 

[Sensei]

Here is my opinion for best HP mods in order:

#1: Good free flowing exhaust system. Best bang for the buck.

#2: Heads and cam. The camshaft is your engine's brain, the heads are where HP is made and there have been a lot of advances in head technology since 1981.

#3: Stroke it! There is no replacement for displacement. While a stock set up may last longer and be a better choice for daily driving, a big inch small block is the way to go for serious performance.

God bless, Sensei

 

[GerryLP]

.... With the fact that the head was never designed for performance anyway, I would say it is a weak link.

That said, with your CR and cam, I would think you should be able to gain a bit with some carb modifications.

God bless, Sensei

So, can you run by me the cost again? Did I understand in this thread that approximately $180 dollars should get me a modified Q-Jet? I would still want to retain my original Q-Jet untouched...


GerryLP:cool

 

[Sensei]

Gerry, the original carb I posted about building is now long gone. It was a core someone gave me and all of it's parts (choke thermostat, pulloff, TPS, M/C solenoid) were there and working properly, so I had very little overhead with it. I also rebuilt another member's core for his performance engine, but to date, neither has their vehicle on the road. I'm hoping one or both will post results on this thread soon, as that was the entire point.

If you would like me to build one for you, I can do it for that price if you can supply a complete rebuildable core with all components working properly. Be aware, choke thermostats are usually bad and other components may be as well. If I have to buy these parts, that is not included. I could also look around for a core here, but you would have to cover the cost.

Gerry, you know, after the ordeal we went through on those heads that I am honest and will treat you right. If interested, PM me.

God bless, Sensei

 

[GerryLP]

Gerry, you know, after the ordeal we went through on those heads that I am honest and will treat you right. If interested, PM me.

Chris,

I recall perfectly fine that you are a stand-up person and I already know that you will be extremely fair on this transaction. I just got to see if I find an electronically-controlled Q-Jet to modify.

Since you brought it up, I will tell everyone the story behind the heads you mentioned....A couple of years ago, or maybe closer to 3, I was on my rebuild mode for my L81 engine. The shop I took my engine for the machining/servicing of the engine parts (Edward's Engines) has an outstanding reputation in Albuquerque, and for that, one gets to pay a 20% higher premium on the same services any other machine shop would charge, but the quality of work shows. Anyway, Edward's Engines told me that the original heads were cracked (something very common with 624 heads caused by higher exhaust temperatures and the lightening of the heads during production/casting). So I embarked on a cylinder head search to at least get as close to the production dates as I could with the replacement heads. I must' ve spent nearly $400 dollars in shipping charges getting the heads that some of our CAC members had offered me including Lanny and Sensei. I also had bought some heads in eBay as well that turned-out to be cracked as well. So by the time I was dealing with Chris, I was ready to offer to pay for the inspection of his original heads before shipping them to me, so in turn I could save the shipping cost and disappointment later since it had proven to be likely to find the cylinder heads cracked. So, Chris takes them to a buddy of his, and they told him that the cylinder heads were good, except that later it comes out in the wash that they did not used die penetrant or some other method to check them (they just had eye-ball'ed them). So of course , I get them here and found one head cracked, and when I spoke with Chris he found it hard to believe, but offered to talk to his buddy, and of course he found out what I already told you earlier in here, so then a day later, Chris calls me and offered me a full refund!!! I thought, "what an honest and stand-up guy Chris is!", so given that one head came out ok, I countered offered that he could refund me for the cost on one cylinder head, and he did.

That's how I know that Chris will help anyone here with this carburetor modifications. This is my testimonial on Chris' honesty and all around good person nature.

GerryLP :cool

 

[81Batmobile]

Gerry, Cris,

I picked up one of Cris's rebuilds a couple of weeks back. If you are following other threads I also just got my rear end leveled out, the car that is. I'm going to put Cris's rebuilt card on my Vette this weekend. I'm putting it on my stock L81 just for reference, I have a stroker motor in the process of being assembled. I started down the road with the PROCOMP alluminum heads but have changed my mind since they have raised intake runners meaning only a couple of intake manifolds will work with them and I don't plan on making huge HP numbers. I also want to stay as close to the original look as I can.

I'll post the results of my Rochester experience soon.

If interested in the PROCOMPs let me know, they have never been bolted to an engine. They flow big numbers but they require an aftermarket intake manifold.

Drive 'em like you stole 'em!!!!
r/Ron

Chris,

I recall perfectly fine that you are a stand-up person and I already know that you will be extremely fair on this transaction. I just got to see if I find an electronically-controlled Q-Jet to modify.

Since you brought it up, I will tell everyone the story behind the heads you mentioned....A couple of years ago, or maybe closer to 3, I was on my rebuild mode for my L81 engine. The shop I took my engine for the machining/servicing of the engine parts (Edward's Engines) has an outstanding reputation in Albuquerque, and for that one gets to pay a 20% higher premium on the same services any other machine shop woul charge, but the quality of work shows. Anyway, Edward's Engines told me that the original heads were cracked (something very common with 624 heads caused by higher exhaust temperatures and the lightening of the heads during production/casting). So I embarked on a cylinder head search to at least get as close to the production dates as I cool with the replacement heads. I must' ve spent nearly $400 dollars in shipping charges getting the heads that some of our CAC members had offered me including Lanny and Sensei. I also had bought some heads in eBay as well that turned-out to be cracked as well. So by the time I was dealing with Chris, I was ready to offer to pay for the inspection of his original heads before shipping them to me, so in turn I coul save the shipping cost and disappointment later of likely to find the cylinder heads cracked. So, Chris tajes them to a buddy of his, and they told him that the cylinder heads were good, except that later it comes out in the wash that they did not used die penetrant or some other method to check them (they just had eye-ball'ed them). So of course , I get them here and found one head cracked, and when I spoke with Chris he found it hard to believe, but offered to talk to his buddy, and of course he found out what I already told you readers earlier, so then a day later, Chris calls me and offered me a full refund!!! I thought, " what an honest and stand-up guy Chris is!", so given that one heAd came out ok, I countered offered that he could refund me for the cost on one cylinder head, and he did.

That's how I know that Chris will help anyone here with this carburetor modifications. This is my testimonial on Chris' honesty and all around good person nature.

GerryLP

 

[81Batmobile]

Cris, I have installed the Rochester you rebuilt for me and all I have to say is , "WOW!!!" Those tires talked to me when I got on it and hit second. It has that unmistakeable roar when those secondaries open up. And this is sitting on top of my tired L-81, I can't wait to get it on top of my stroker motor. This carb will easily feed a 450-500 HP bowtie masterpiece. I'll update everyone when I get the motor back from the dyno. I'm going to try and talk them into making a couple of pulls with the old carb too.

Great work, Cris, you are the MASTER!!!

thanks,
r/Ron

 

[22229stingray81]

I'd be VERY interested in seeing those dyno numbers.

-Tatortot

 

[GerryLP]

So Chris,

I am curious about the regular adjustments made to the E4ME.

If and when I get a Q-Jet and you get to modify it, then would I still need to adjust the air valve with the Dwell gage (or any other adjustments)? Or would I just receive the carb as-is from you and it will be ready to roll?

The reason I also ask is that I am at 5,000' of altitude...

GerryLP:cool

p.s. Maybe you can achieve different levels of performance on the Q-Jet modifications and market them as, "Green Belt, Brown belt, and Black Belt" modifications...lol

 

[Sensei]

... would I still need to adjust the air valve with the Dwell gage (or any other adjustments)? Or would I just receive the carb as-is from you and it will be ready to roll?

The reason I also ask is that I am at 5,000' of altitude...

I put all the carbs I build on my car and adjust/ test them before sending them out, so it should work as is (GM adjusted them all at the same location). That said, It would not hurt to check/ fine tune the idle air bleed and mixture screws on your car if you know how.

p.s. Maybe you can achieve different levels of performance on the Q-Jet modifications and market them as, "Green Belt, Brown belt, and Black Belt" modifications...lol

I like that!

 

[GerryLP]

Chris,

I have been meaning to tell you that I found an L81 Carb (by P/N), and that I wanted to send it to you for the mods. It would probably need to be gone-over with a rebuild, since it "appears" to be semi-virgin...:L...you know, the idle jet plugs have been cut, and the air valve cover is gone, but the choke housing still has the rivets on the housing.

How's your Christmas schedule?

GerryLP:cool

 

[Sensei]

How's your Christmas schedule?

GerryLP:cool

Busy, just like the rest of the year :L.

Send it to me and I'll get it done but it will take a few weeks.

God bless, Sensei

 

[motorman]

sounds great BUT will it still pass smog inspection ???