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I have a scout 80, it has a 289 or a 302 in it . I want some nice torque, I do not think I want ot go bigger on the engine because I do not want the extra hp.
I want enough HP to move a 3000 pound scout mild lift with 31" tires and a T-19 nice but not overkill. I want ot put on a 4 barrel, high lift cam, headers, I will offf road this mildly in light mud, rocks, hills, woods around town to school and home. Is the holly 390 or 450 practical?
This will give you more torque over your stock equpiment and good gas milage.
The stock setup you have is rated @ 255lbs of torque @ 3500RPM, this setup will give you 290lbs of torque @ 3500 rpm.
No, actually 290 lbs of torque @ 3500rpm is a mild cam, most your big radical cams produce their max torque at around 5500-6500rpm's. Thats great if your drag racing. But when your 4 wheelin you want your torque right away to climb hills and get through the mud. You will start getting your torque right from the get go, it just max's out at 3500rpm. I don't know about getting 290lbs of torque @ 2000rpm? I'll check my book.If your not experienced in rebuilding motors, "porting and polishing" should be left to the pros that know how to do it. Theres a lot of things to consider when do this, i.e compression ratio's, CC chamber volumes, airflow, etc, etc.
Holly and Edelbrock are both good brands of carbs, and work relatively the same as far as adjustments go. If your gonna buy a intake/cam & lifters/carburator it should be a matched set that gives the right airflow, torque curve and compliments each other. The ones I listed for you are a combination kit that is designed to work together. Theres other combinations out there but they have different torque and HP ranges that would not suit your needs for 4 wheelin.
I'll check on that torque curve for you and see what I come up with.
Well #1, it depends on the year of your engine. My 69' 302 in my maverick stock 2v made 210hp/300lb.ft. If it is a mid 70's/early 80's 302, junk it, they're crap and made less torque and HP than a 289. Go to the junk yard and find an H.O. roller out of a 1988 or up mustang GT or Lincoln LSC, or find a pre-72' 302 and buy the long block. If your lucky yo may even find an explorer 5.0, they have better heads and camshafts than the H.O. but you have to use special headers. With the price of your cam kit, it is cheaper to buy a whole long block from the junk yard. Its cool to have the edelbrock Garb around your engine bay, but sometimes, as it looks in your case, its not worth the messing around, especially if you only want minimal power upgrades.
Well .520 is a huge amount of lift for a 302/289 cam and does not lend itself well to stock heads and valve springs, and somtimes piston/valve clearance issues can result. But most importantly the average cam that actually uses .520 lift is geared to the racing market making its prime power and torque figures in the 2000+ RPM range. Generally speaking these cams are not good for 4x4 work, and marginal for daily driving (expect 8mpg or so). Matching that kind of cam to stock heads and a 390 cfm carb is a pretty ill suited combo since the carb and heads will not be able to supply the airflow the engine will desire with that cam. Personally I am using a 250H comp grind in my 302 with an old cast iron 4bbl manifold from a 289 mustang with a 500 cfm edelbrock, it makes pretty respsectable torque and gets good economy. But I would have to agree with these guys going with a package deal is your best bet for a simple proven way to boost your torque. Or I might reccomend a long-block.
I would think about 9.5:1cr would be good for 91. .520 is way too much lift. New spring and probly screw in rocker studs might be needed. Low end is achived by short duration and medium lift. Polishing is not recomended on low end application because air flow thru the heads is slower at low rpms,(obviously) and doesn't keep the fuel in suspension. Irregularities in the head port with that.
If in fact you do have a 289, they stopped producing those in 1968 and went to the 302 full time. As a matter of fact the windsor plant was making the 289 and in 1969 started producing the 351 block out of that plant.
As far as heads go, (not including the 289 hipo)
1966- 289 200Hp 282lb torq @2600rpm 9.3:1 C/R
1967- 289 200Hp 288lb torq @2600rpm 8.7:1 C/R
1968- 289 195Hp 300lb torq @2600rpm 8.6:1 C/R
As far as the Holly and Edelbrock go, they are both the same price, you just get more CFM out of the Edelbrock. The Holly 390 is recommended for light vehicles, not sure how much you vehicle wieghs, but for the money I would go with the Edelbrock.