Quote:
Originally Posted by maydaymike
Thanks for the HEI link. I've been looking at the various less expensive HEI dizzys, but have been a little reluctant to pull the trigger without any feedback. I have an Offy manifold with a 390 Holley coming from Ebay that I'll be fooling with in the near future. I plan to use the Langdons cast headers with it. I watched Tom's video about the 3 bbl mod on the Chevelle. Might look into that too if I'm not happy with the 390.
I did a little trip this morning. I wanted to get an Idea of what I can expect for gas mileage. Cruising 2 lanes at 50-60 MPH, I used 8.260 gallons for 135 odometer miles. Google maps showed 138 miles for my route, so close enough. I'm pretty happy with 16.3-16.7 mpg with a bone stock 250 complete with points and rochester 1 bbl.
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That is Excellent mileage! The HEI will even help a tad more. My rebuilt 292 with a 5 speed tko600 should be seeing around 18, but it has been hopped up. Mileage Might go down a bit with the 390, but you can play with jetting to see if you can make things better. Tom has a lot of experience with the 390 as well. I've been using edelbrock.
EDIT: I only ran that HEI on mine for a few hundred miles. If yours Does happen to go out you can upgrade it to a DUI cap and coil I believe.