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Discussion Starter #1
First the car is a 1968 XR7, 390 2V, with a C-6 trans and 2-75 gears in the rear. I am a long way off on touching the engine but am wondering about possibly increasing performance. I will be keeping original heads and intake, also will be keeping factory 2 barrel and 2.75 rear. With this in mind is there much I could do or with my own restrictions am I better off just using factory specs when I do rebuild this engine?
 

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With your self-imposed restrictions you are left with changing the cam (not likely to improve performance without being able to change the fuel/air supply). What kind of performance are you looking for?
 

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The 390 usually responds well to exhaust mods.
If you would consider swapping the stock carb for a Holley 500cfm 2v, you'd see some gains and still keep it oriented with stock type equipment.

Local dirt track guys run headers and a holley 2v on their race cars with pretty good results.

I've seen a bunch of 390's have major seat of the pants increases with headers though. FE's are not my thing though. I'm just speaking of what I've seen other people do.
 

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Discussion Starter #5
Not really trying to do much just wondering if there were things I should consider. I am not by any means trying to make a race car or anything, and am staying with all stock appearance.
 

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I'd just stick to factory specs with yours Harvey since it's bound for showdom anyway. Nobody's gonna notice if you put a bit of a cam in it, but unless you make exhaust mods and get the intake side to take advantage of it your not gaining much ground. Once you freshen up the old valves and get new cam/lifters/guides in it, she'll feel pretty gutsy. That's no to say you could sweet talk an exhaust shop into making you a "stock looking" exhaust with improved flow (larger pipes, better mufflers) - could get you dinged if you are shooting for top honors at a judging event..
 

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Discussion Starter #7
Thanks I think these were the answers I was looking for. I just wasn't sure if there were internal upgrades I might want to consider and since the engine and tranny will be the last things for me to consider thought I would throw it out early. After all the reading I have done and asking around on here I believe the 390 could be a an all out screamer however one mod seems to require another and so on. For what I want I agree that stock specs will be best. Thanks I don't know about showdom though. Would like to think it would be one to look at though.
 

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I read where you will be keeping the 2.75 gear, but a gear around the 3.70 range would certainly HELP performance. IMO that would be one of the things to consider, I can't imagine this car being your highway LONG TRIP car, so it's not like the gear is going to RPM you to death. Couple the gear change to some PROVEN engine mods, well you should see some nice performance gains, IMO.

I wish you well,

Dale in Indy
 

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Harvey there's quite a bit you could do to improve the stock 390. But yes it would mean changing some parts. You could stroke it with a 3.98 to 4.25 crank and stroker kit. Install some Edelbrock heads, remove the Edelbrock name and paint them blue. Same with a Edel RPM intake. Barry R at Survival has done some really slick and trick things to aftermaket parts to make them appear stock. I saw where he removed the Edelbrock name and put a mold of the stock casting number into the RPM intake. With the stock aircleaner on there it's hard to see if you have a 2bbl or 4bbl. You really have to lean in and take a close look. You could also get some CJ exhaust manifolds and hog them out a bit. So yes while there's some compromises it would really wake up the 390. And alot of the changes are well hidden within a shock tower car. Some might even walk away scratching their heads?? LOL. And you can just hang on to your stock parts. If your 100% stuck on keeping the stock heads and 2v intake you can still stroke the 390, rework your heads (valves, port work) and intake (port match), new cam, port your GT exhaust manifolds. With some careful planning and advice from the pro builders and part choices there's always some gains that can be had. I would at least look into your options.
 
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