So after school I was looking for something semi cool to daily drive when a buddy informed me he was selling the 74 Malibu 4 door he had purchased from his aunt. Though not as cool as I had previously envisioned it is a 30k mile car with a L-65.
13.
So since my new job is 45 miles away I put on 90 miles a day. Though mpg isn't top of the list it is a concern. So after driving a few weeks to get a baseline of 13.3-13.4 I decided to do some modifications in an attempt to get the mpg better. First I used some of my advance springs to tailor the timing curve to be quite a bit quicker than the garage door springs the points dist came with from the factory. The closest I could get to the "all in by 2500" typically suggested was all in by 2800. The intial was set at 10 intial and 26 mech advance and 14 deg of vac. No real mileage gains but the power was much better.
Getting some tips from a old 2g post by Tuner, I bought a 74 version of the Doug Roe book that included modifications for the 2gc. I eliminated the APT and reduced the power valve restriction by .010 to .035, initially clipped the power valve 3 coils. Ran much crisper but seemed to gain a lean surge. I upped the jetting to 50s from 49s and the surge was better but not gone. Thinking I might be feeling the power valve fluttering I cut another coil off the power valve. Much worse. Finally I got off my lazy butt and welded in my O2 bung and hooked up my LM-2. The lean surge I felt was the carb going into the 20s. So I put in the 53 jets I had from a spare 2g and the air fuel was better but still into the 20s at high vac cruising. Finally I drilled out my original 49s to 55s. Now it cruises in the high 16s to the high 15s most of the time with it touching into the 18s in high vac cruising on a few cool mornings. Pulling hills it gets into the 15s and into the 14s starting about 6 in.hg then into the 12s. I feel this is really close to optimal from mpg.
How is the mpg now? Well after doing the initial mods during the lean surge time it gained 1.25 mpg to 14.5-14.75 mpg. Now after jetting? Back to 13.6 mpg.
I have added more initial timing to 12 intial, which added a lot of low end but no change in mpg.
The current car is a stock 30k 2bbl 350 with 993 heads, stock single exhaust, manifolds, single snorkel air cleaner, fresh tune up and a compression test showing 161-168psi. Stock th350 and 2.73 geared rear with 26.6" rear tires.
Though the ultimate goal is a 505 big block with a 5 speed, to get caught up on debt I am going to budget modify the stock 350.
I was given a set of 1 5/8 headers, performer intake, 85-86 truck q-jet, a new cam 214/224 112lca cam and a set of 3.23 gears . I have a posi with 3.08s left over from my h.s. camaro. I also plan on adding 12" front disks and s-10 rear disks along with a bigger front swap bar. I will add duals that will be too big at 3" but I am only doing exhaust once and there is already a 289 block 454 in my garage waiting on my budget to build.
Anyway, thinking mid 13s is pretty meh, am I going to really be disappointed in it next spring? Despite my carb being tuned to what I think is a great a/f for mpg and power, is the qjet just that much better that it will make a magic 4 mpg better?
Sorry for the long post as usual.
35mpg average over the last 8k miles at 80-85 mph average (plus the odd 120+). Fit a 550 to the old wagon 