I recently had my 86' 351w reblt along with the transmission. Theres only 5000 mi. on it and it acts tired.
When I had it rebuilt, I was thinking dependability, not high performance and of course $$ was an issue. The engine runs great but I'm just not satisfied with the HP and MPG. they are just not there. I want the best of both worlds. My mechanic tells me that I'll never get any more power out of that 351 than I'm already getting now. I disagree. Can somebody give me some ideas on how to improve HP & MPG without boaring cylinders or remanufacturing cams?
I'd like to get the most out of this new engine. I'm thinking Intake and exhaust needs upgrading, any tips? Anyone?


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86' f-150 351w C6

 

Is that thing a 2 bbl now? What kinda mpg are you getting? ON a fresh stock rebuild (351w 4bbl), I put an intake (performer edelbrock), 600 cfm performer carb, didn't see much in the way of improved performance (I do like the carb though). This was through, dual exhaust no cats. I then put headers on, shorty style. It made a noticable difference no doubt about it. I let my wife drive it and she asked what I had done to it so it confirmed my thoughts. haha. You may try an electric fan setup, I have been using a single high performance perma cool fan ($80) for around 4 years now on another truck using the $15 thermal sensor to kick it on and have had no problems this far. The electric fan (or removal of stock clutch fan) will make the engine appear to run smoother. Headers, intake and an electric fan shouldn't hurt mpg in anyway, should increase mpg, if you can keep your foot out of it. Shoot for long tube headers if you can, they provide a little more on the bottom and help out on the top end as well, but don't hate yourself if you end up with shorties. Good luck hope this helps out some. I was getting 11mpg with poor tune new rebuilt motor with intake carb added only, through a c6 and 3.55:1 rear axle, 2wd, using the cheapest octane. I have yet to check my mpg with the engine tuned and headers installed. Hope this give you some hope. I also put a flex fan on it in the beginning. later

 

It's a 4bbl holley. I'm getting 9 if I'm lucky. I just put a K&N filter in. Not much difference that I can tell but my oil pressure suddenly droped 25%. I dont know if that has any thing to do with the filter or if I have bigger problems coming.
Where did you find your intake? I havn't been able to find one to fit a 351w 5.8l.
How are other headers better? what is there function?

Thanks for the feedback


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86' f-150 351 5.8l C6

 

Will my Holley 4bbl fit an Edlebrock intake? I have a new Edlebrock 4bbl stored but it wont fit my studs and the choke holes are smaller. It was given to me and told it would fit but it dont so I'm not sure what it fits. I believe it's a 600cfm but I dont know how to tell.

 

If it's a good solid engine that just does'nt seem to have the kick too it like you say I'd suggest a good tuning session.
Go th FordMuscle.com and read the tech article called Timing is everything and apply it too your engine.
A lot of times the mechanic will just drop in the distributor and set it at the factory specs and move on too the next car. Another thing, I wonder if the cam is set up retarded or straight up. I don't know if the newer engines were set up that way or not.
A Holley square bore carb will fit an Edelbrock intake. Maybe your Holley has a spread bore base plate.
Clint

 

summit and jegs sell the intake or you can search ebay. 71swissaqua nailed the carb fitment. a new air filter won't make your oil psi drop or affect it in any way. long tube headers build low end torque and shorties take a liitle torque off the off idle side not too bad though. it isn't the end of the world if you get either, but the long tube will work better in a truck application. later

 

Thanx for the info guys, Think I'll start w/ the exhaust system.