I am in the process of restoring my 81 Dodge Mirada CMX. I plan on deep six-ing the Lean Burn System and replacing it with Mopar's Electronic Ignition kit. I also want to do some changes to the motor. I was thinking of a pair of Magnum heads from the local U-Pull-It yard, new intake and carb, and maybe a new cam shaft to boot. I also plan on Headman headers and a new exhaust. I want to add just a bit more power but what I am really after is a smooth running engine that is reliable and fuel efficient. The 318 gets 21MPG now but it runs like crap in the morning and when you get into it it boggs down and sems to be running to rich so you have to feather it and wait for it to come up to speed [that sucks big time] Any suggestions on a combo that will restore the power and keep it smooth would greatly be apprecisated. [when this car was running right, it was so smooth you had to look at the tach to make sure it was still running!]

 

If you want it nice and smooth running, then keep the cam stock or close to stock. If Hedman has ceramic coated headers the get them. For the rest of the exhaust, get a 2.5" mandrel bent dual aluminized system with an X-pipe. I highly recommend that you get a set of Flowmaster mufflers for both sound and power. You will need to have it custom made and will have to go to a speed shop to get a few madrel U and L bends for them to make it mandrel bent with and you will need to get the X-pipe there as well. With this set up you will notice big power gains as well as great sound. The Mopar Performance electronic ignition conversion will be a great way to add far better spark as well as eliminating the dreaded lean burn BS. A nice Edelbrock Performer intake manifold will free up it's breathing. Are you planning on going with a 2 bbl or a 4 bbl?

 

intake..edelbrock airgapis the best...but Nothing single plane.
i have a BG 750 mdp with a proform center, but thats more of a race carb.
i have flowtech headers, and theyve been great thus far...
and nothing rude meant to 71rr, but dont fall into the "mandrel bent" hole...another issue to consider, where do you live? alot of states dont allow true aftermarket dual exhaust anymore for emissions testing.

 

scatpackmopar. I suppose your familiar with the Magnum heads and the required changes you have to do to get them to work on your existing 318 LA block. If you could find a set of swirlport heads from the late 80's, sorry I can't recall the casting numbers, with the 1.88"/1.60" valves those are the way to go on a low buck 318. I would go with the old 340 cam MoPar P4452782. Pick a good dual plane, 4-bbl manifold froma stock 318/340, or an aluminium manifold like the Airgap. Good luck.

 

i have the above mentioned late 80s heads, 88 to be exact...360 swirl port, heavily ported, and theyve been great as well, compared to my stock 340 heads...

-and not trying to hijack, but miradas are classics now?? im honored![sm=thanx.gif]

 

Yeah, I think it was 88-89 that these heads were available.

Hey PAt.[sm=icon_blah.gif]

 

Thanks for the input. I think I will go with the Edelbrock Performer Intake and 600cfm carb and a pair of 88-89 heads from the junk yard. If that sounds about right?[The local U-Pull-It yard guarrantees their parts] The exhaust is a must cause the original one is almost totally gone. If I get stuck in the middle of all his I will let you guys know. I have to wait to get started until after I fix my 98 Dodge Avenger. after 129K miles it starts to act up on me....go figure!

 

ouch...a "cloud" car and a J body...you sure are glutton for punishment..

 

I really want to get an Intrepid but giving up 30-36MPG's is hard when I drive over 30K miles a year!

 

Yeah I guess so. It will take me around 4-5 years to get to 30K.