jackson

L81 has low compression from BOTH dished pistons AND large combustion chambers. Same reason ralphbh installed L98/ZZ4 heads w/ small 58cc chambers.

Suggest start by clearing a spot in your garage-shed for a motor buildup; locally find a core 350 sbc with iron Vortec heads. Look for 8th character in vin is "R" in about '96-2000 GM lite&medium pkp, van, suv. Spend a couple hundred on the junkyard L31 rebuildable core; rebuild it for less than $2K making honest 400fwhp ... install when you're done.

Or buy same roller vortec, dynoed, ready to go, from YearOne CT350PC1 for about $3K.

http://www.yearone.com/yodnn/tech/Te...7/Default.aspx
http://www.yearone.com/serverfiles/p...VF73496&trk=12

BB72

The L-81 actually has 624 castings. They're moderate performance light casting heads. You should be able to get decent HP with the right mods to this motor. It was rated at 190hp and 280 ft/lbs torque so increasing this without spending the all the $2000 on one set of heads shouldn't be too hard. There's more to performance and drivability than putting all the money in the motor. The guy only wants to spend $2000 not break the bank.

7T1vette

That's what I heard....

jb78L-82

I was just giving you options of which there are many. As I said, just an example and a comparison.

Dose11

If the ECM works...why should it be disconnected? Sorry if these are dumb questions. What is a good tried and true intake and carb

Thanks for understanding that 1) I am not expecting to have a super engine or super power for 2k and 2) for understanding that I obviously am either trying not to or can not spend a whole lot of money at this point
Umm what did you hear exactly?


J.

BB72

I had an 81 and I never liked the ecm control. There's more flexabilty without it I assume but if you would like to work within the capabilties of that system then you'll have to pick some heads about mods to your stock setup.

Dose11

I guess for me... I would like to be told(if it is working) if something is wrong...

Dose11

Is changing the gears something that I would want to do myself, or get someone to do it for me. I am trying to find a thread on how to change..but no luck as of yet

nate99

It takes quite a bit of precision. I've seen it done, and it is not rocket science, but I'd rather pay someone to do it than have to pay for another set of gears because I botched the job.

81pilot

[QUOTE=Dose11;1577763652]If the ECM works...why should it be disconnected? Sorry if these are dumb questions. What is a good tried and true intake and carb



No reason it SHOULD be disconnected if it is working well. I ripped mine out because I like to drive it. I looked at it this way: If it starts running poorly with the CCC system, you pull the codes (which are very ambiguous) and then you hope you can discern from the codes what the problem is, a sensor(many) or some issue with a carb that was only on the 81 (and Cali cars in 80 on the 305). If you have a timing issue it is not simple to put it where it gives the best performance, can be done but tricky. The CCC does a good job of locking the converter but you can wire a switch or buy a controller for B&M. I also read from certain guys that driveability and idle and start up are better with the computer, I call baloney on that.(disclosure) My computer I don't think, was working all that good I concede, it ran fine and idled ok but my mileage sucked. I assume it had a bad sensor and was running rich to compensate......however, My car now with a regular Qjet from a '79 L-82, regular HEI dist with vacuum advance starts on first twist, idles so smooth if you didn't hear the pipes you wouldn't know it is running. Carb and dist both set to Lar's specs. The 20MPG ain't bad either. So I guess if the CCC is working fine it is OK....until you need to work on it. I bought a low mileage Qjet that I barely had to touch and a new HEI dist both for under 200 bucks total. SO the short answer(too late) is do what you want, the performance and driveability is a wash on either. You get more ability to adjust and modify a lot simpler without the computer, but it depends on you. Oh and the engine compartment is a lot cleaner without all the smog crap, and all of those computer wires and superfluous lines and hoses associated with the computer.

Easy Mike

FWIW: the stock exhaust on the 81-82s (and 80 California cars) flow well and are some of the best GM ever made available. They are stainless steel and amount to factory short tube headers.

81pilot

Remember, it is a first generation computer, it does not tell you what the problem, is and how to fix it, it simply gives you its interpretation of what is going on. From there you need to try to figure out what is the issue, or which sensor is bad etc...

Dose11

Haha sounds like good advice

81pilot

Only the manifolds are stainless. the 2 into 1 into 2 exhaust is still restrictive. And the factory headers are very small and only marginally better flowing than cast iron ones. A good set of long tube headers and true dual 2.5 inch pipes are still a huge upgrade. In my opinion.

Dose11

Ahhh...so if engine light pops on...i pull the codes...I am still going to have to hunt around and try to figure out the issue????

or the other option

Pull all the crap...drive it...and when its not running right....try to figure out the issue???

Am I reading into this correctly...you guys tell me...but what it sounds like is that the Computer just monitors the system...and when theres a problem...it just says..."Hey theres a problem" but doesn't tell you what the problem is.

So you guys think Pull ALLLL computer stuff Emission crap, ecm, ccc, no prom.....

So then what is needed a new distributer??? and what else?

81pilot

The code will give you a ballpark, its a little better than an idiot light. Even the new computers that may tell you which sensor are just making that determination based on the inputs, and they are not always right. If you know how to interpret engine conditions and have dealt with computer codes before, its not as bad as I made it sound. But they still do not tell you where and what the problem is. You need to understand how the system works when it is operating properly, what it does when it senses a problem. What the default settings are when the computer has a problem etc...then the troubleshooting is lessened. All the computer control's is the carb, distributor and the lockup for the transmission, but it has a few sensors here and there to accomplish this...there are tons of threads on here about it and how to remove it.

BB72

If you eliminate the ecm you have to replace the original distributor with a similar HEI distributor that has vacuum advance. Your's doesn't have the VA and you will also need to replace the carb because you can't adjust it, maybe somebody knows an easy way around that. If you're trying for more HP, than you'll need a carb that you can tune to what your needs are. In my experience, it was really waking the motor up. Follow my first post and you'll be happy.

Dose11

Any specific ones that you can recommend Dist. , Carb, and Intake?

7T1vette

Well, you first said that you wanted the best performance upgrades for your '81, but had less than $2K to spend. Since you took issue with my response [a comment to others that would have you install a 'new crate motor'], maybe you misstated your intentions to begin with.

You have a decent engine/control system to start with..but, for all I care, pull all the good stuff off {because some ignorant folks are telling you to} and make it look and run like a piece of junk...

81pilot

OK once and for all, do you even own an 81? You say the same crap evertime someone asks about them and then to those of us no matter how much we try to say it is only our opinion you jump on here and call us names!!! I am not ignorant, I am very well schooled and I take offense to you suggesting otherwise! Frankly I get sick of it! He is a grown up, and nobody is telling him to do anything! My car runs so good is is scary!!!! So much so that I have not bought any parts for the one I am building because I am having a hard time justifying pulling it out! An engine looks WAY better without all the crap on it, thats a FACT. And as far as running like crap, well then your saying that ALL Vettes prior to 81 run like a piece of junk, yea thats good logic, everyone here should be offended! well your are are the biggest *** on this forum and frankly I am sick of it!