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What is under my hood?

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Old Jul 13, 2015 | 02:21 AM
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Default What is under my hood?

I was hoping you guys might help another newbie out and share some wisdom. I've spent the last month up into the wee hours reading all of the great info on this forum (much of which is over my head).

I've gathered that the etiquette is to not combine multiple questions into one post so I will try to do that (or at least keep on the same topic).

A bit about the car first. I've had it for a month and it was bequeathed to me by a friend so I don't know a whole bunch about it other than he had it since the mid '90s. It is a 1981 with an automatic and A/C and is pretty much stock (as best I can tell) with the exception of the removal of the cat and conversion to true dual exhaust and some changes under the hood. I will add also that there are no emissions checks on vehicles in my jurisdiction - so that is not a concern of mine. I don't plan to show or race this vehicle - I just want a cruiser that has a bit of muscle (I'll add more muscle as we go I hope).

I know (from all my forum lurking) that the 1981 came with the computer controlled L81 engine as the only option. I have also surmised that most (or perhaps all) of the CCC and emissions controls have been removed. While the engine starts and runs OK, I feel there is likely room for improvement. I'd appreciate it if someone could have a look at these images of my carb and distributor and let me know what they are and if everything appears to be connected as it should be.

First the carb; I can tell from the number (17058228) that it is an M4MC Quadrajet from a 1978 L82 which must have been put on to replace the computer controlled M4ME. I see that some vacuum lines are plugged and I don't know what they are, why they are plugged and if they should be. I also have one line (the one with my hand on it in the 4th pic) that is not plugged but looks like it used to fit on the plugged "y" fitting right beside it.

Second is the distributor; I have no idea what model it is other than I can see a vacuum advance (meaning it must have been replaced when the ECU came out also) and it has HEI. I see three wires coming out of the base and also two small wiring harnesses on the driver's side. One of the harnesses has a short wire to a connector that goes nowhere (I'm holding the connector in my hand in the last image).

So guys, does this look about right and should it suit me going forward on this journey?

Much appreciated
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Last edited by StDomingos; Jul 13, 2015 at 02:36 AM.
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Old Jul 13, 2015 | 05:44 AM
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Here's some pics of a 78 system that may help.
Keep in mind you don't have an egr valve or A.I.R. pump. That's several hoses eliminated.
In my pic 2, the screwdriver is plugging the hose to the air cleaner.
In pic 3, the plug at carb front is temp, look to pic 4.

Wire at distributer appears to be for the tach. Does it go to that cylinder thing at the base of the tach? Does your tach work?




Last edited by KapsSA; Jul 13, 2015 at 05:47 AM.
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Old Jul 13, 2015 | 06:00 AM
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In your 2nd pic, the two orange arrows go to hard lines that go to the plate near the egr valve(see my pic3) You don't have that. You have electric choke.

Arrow in your 3rd pic is for hose going to egr valve which you don't have.
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Old Jul 14, 2015 | 03:09 AM
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Thanks for all that KapsSA - that helps a bunch. Everything seems to be where it should be then,

With regard to the distributor, that wire is not for the tach (I'm pretty sure) I have a yellow wire that goes to the tach filter beside the distributor and the tach in the dash works.

I have attached one other photo for your consideration that shows the driver's side of the distributor. It shows two wiring conectors. The mystery connector comes out of the black connector. Does that shed some more light?



wiring harness on driver's side.




Three wires at front bottom of distributor




Are the factory vacuum advance distributors all pretty much equal for the L48/L82 cars?
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