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1971 Ford 302 Low End Power Adders?
hi. I have a 1971 ski nautique with a 1971 ford 302 small block in it.
what I’m looking to do is get more power out of the engine. I know for a fact that its not a boss 302, cause of the round freeze plugs, and it’s a 2 bolt main.
I’d like to get about 400 horsepower out of it. or at least in the ballpark. but I want it all on the low end, so I can pull about anything out of the water.
I’ve thought about boring it out to a 347, but I’d have to pull the motor. which I’ve done before. . . .. and don’t ever want to do it again.
so here are the limitations. I cant touch the exhaust, cause it a marine exhaust. so headers and mufflers are a no. the carb is also a marine carb. it’s a holly 650 cfm 4 barrel with electric choke. those are the 2 things I cant touch. other then that I can do anything I want. oh and one more thing. it’s a reverse rotation motor. meaning if a standard 302 rotates clockwise mine rotates counter clockwise. so I don’t know if its possible to put a cam in it.
oh one more thing when I say 400 horsepower I mean at the crank. unlike a car there is very little drag for the drive train. all that’s behind the engine is a hydraulic tranny, and a prop shaft.
I was thinking about getting a edlebrock performer intake, heads, and possibly cam (if it will work). but I don’t know how much low end power that will make. oh also the motor already has 351 heads on it. i'm pretty sure there 351 clevland heads, not windsor.
my budget is about $2,000 or close to it.
any thoughts, suggestions, links, or anything else would be very helpful.
thanks
i dont think 400 horsepower is too much. you can buy a new nautique with a 502 big block, with 425 horsepower.
yeah the heads must be windsor. thats my bad.
prop size is something i'm going to play with, but thats anther issue. the reason i know its a revearse rotation motor is cause ALL ski nautiques are. as to why they do it, i have no idea.
NOS is out of the question. its just something i dont want to do.
from what you guys have said, it sounds like my only option is to pull the motor (d*mnit) and bore it out to a 347. from what your telling me i doubt i'll get to 400 horsepower if i dont.
thanks so far
4 Answers
- popeyethesadistLv 51 decade agoFavorite Answer
supercharger is your only option to get near that given your limitations. You more than likely do NOT have Cleveland heads as they are for high revving engines not ski boats.(like previousposter said, they are not "bolt on" either) You also probably already have a R.V./marine cam which provides the most punch out of the hole. You don't get more top w/o giving up bottom w/o going bigger in displacement. My suggestion....Play with prop size. I got just what I was looking for in an offshore go fast by going less pitch bigger circumference props. Also aluminum performed better in my case by being lighter. I gained 5 MPH w/o touching any thing mechanical. Find a shop willing to let you try-to-buy. They also make dual pitch props for out of the hole and top end speed. HP is good but not the only way to skin these cats. (BTW I hear you about not wanting to yank engines, sheesh. It's a bigger pain than a car. ) Also reverse rotation is not a big deal. cam makers grind for it. Just reverse firing order. And if you don't have twin engines, what makes you think it's reverse rotation? And why would it be unless you had changed to a left (port side) gear-box?Yes a 502 will easily get 425. But a 302? Yes 400 is very possible but you lose sooo much bottom that it really makes boat appl. tougher esp. skiing. It's why they use bigblocks so much on boats. But really, why build for HP on a ski boat? Torque is what's needed, not top speed.
- ChrisLv 51 decade ago
351W heads are the only ones that really are swappable to the 302. The 351C heads require extensive drilling and lining up of oiling holes.
You wont be able to get close to 400hp on the marine 302 cause the carb is limiting your air/fuel intake and not having headers also.
If you install a pair of aluminum heads, like the GT-40 ones or Edelbrock assembled, a Stealth or Edelbrock RPM air gap intake, with a nice matching cam, I can see you reaching about 300-320hp max.
You will need some help to reach the 400 limit, like a supercharger and the other parts mentioned.
- TexasLv 71 decade ago
is height an issue? This is on the back of a ski boat eh?
For better torque you want long intake runners about 18" runner length high rise manifold.
400hp sounds like a pretty impressive (perhaps too high?) target. As a practical matter for a ski boat what you want is positive steady smooth power coming out of the hole. A hot cam may deliver more top end but make it more ratty and rough on the low end.
Take care and don't go too rad.
Source(s): Read this bit on 351 Cleveland Head on 302, if thats what you got you need a custom manifold (or presumably already have a custom manifold)... http://tomsmustangbarn.tripod.com/sbossbuild.htm - 1 decade ago
i would change the heads to a set of gt -40 heads then i would throw a lil bit of nos on it like a 100 shot or so just start out small and work ur way up also a good cam swap will make the biggest difference or another option u can run a small single carb blower wich would be he best and safest way
