351m help please?
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351m help please?
so I have a 351m in my 78 ford pickup and I need to fix a freeze plug in the end of one of the heads. The engine has 98,000 original miles on it, and still runs good, but while I have the heads off to put the new freeze plugs in them I would also like to swap in a different cam, and a edelbrock performer intake manifold to match the performer carb that I already have on the engine. my question is this will i have to do a full rebuild on the engine to be able to do the cam swap and the intake swap like I want to do? the engine has never been abused and I don't run the engine hard i would just like a little more pulling power.
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From: Ventura Ca
That is a sketchy situation. To be honest yes you should. Here is why, all the money you spend now could be wasted if something goes bad. Putting a new cam in you would need to change lifters, push rods, should check valve springs to ensure spec is right for cam, most likely change them. Then you have valves to look at. Now that the top end is nice and tight, your bottom end is in jeopardy. Could start pulling oil by the rings. Just my .02.
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okay thanks for the help. I guess i will just run the engine like it is then and see how long my temporary fix holds up then. maybe it will hold up until my odometer flips over to zero again. then I can decide what to do with the engine. also if I decide to swap in a new 351m crate engine will my truck still be considered a numbers matching truck?
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From: wyoming
let me think now!
would of been nice if you could of done a compression test first. if heads are good. One thing i would do on a partial build is install a new timing chain and not a $29.95 special. get a good double roller chain. install straight up. One of the things that really helps these engines is get rid of the factory chain or with the mileage you have is a stretched chain. good tight chain is good for some hrspwr/torque. this upgrade will be noticable compared to a old chain. if you do a cam upgrade look at something in the 255 duration to 260 duration max. compression is the reason, low with 351m.
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The cam that i was thinking of installing was the edelbrock performer plus cam that would match the performer series carb that i already have on the engine.
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okay thanks for the help. I guess i will just run the engine like it is then and see how long my temporary fix holds up then. maybe it will hold up until my odometer flips over to zero again. then I can decide what to do with the engine. also if I decide to swap in a new 351m crate engine will my truck still be considered a numbers matching truck?
As long as you keep a 351m, your engine will match the VIN code.
Now being an old fart, I am of the opinion that your truck, and others like it, are not and never will be "collectable" like the iconic 1956 model for example. Too many made, nothing earth shattering about them, and almost everyone wants to forget about engines like the 351M. I might be wrong.
That said, serving suggestion: Save your $5s and $10s and rebuild your motor as a 400, with 9.3 or 9.5 compression, a good cam, springs etc, and fresh everything. It will not burn any more gas than the 351m, and you will have double the horsepower and at least 50% more torque.
If you must keep the 351m, the cam change is probably the single biggest improvement to make.
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Ok thanks for the help my heads are still good. The freeze plug that rusted through was the one for the egr crossover tube that ford use to use but then just pluged off on the 351m. What parts would i need to build my engine as a 400 just the different crank?
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Crank and pistons. Not stock Ford 400 pistons--you still end up with 8-ish compression. Pistons and other info available here:
TMeyer, Inc. Precision Automotive Machining
Ford made these and other light & medium truck engines very low compression for durability reasons. Hours of WOT operation with heavy loads tend to build a lot of heat. Low compression = lower heat in the engine. Of course, it also means lower torque, lower horsepower and lower fuel economy.
TMeyer, Inc. Precision Automotive Machining
Ford made these and other light & medium truck engines very low compression for durability reasons. Hours of WOT operation with heavy loads tend to build a lot of heat. Low compression = lower heat in the engine. Of course, it also means lower torque, lower horsepower and lower fuel economy.
Laughing Gas
Joined: Jan 2006
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From: New-brunswick,Canada
I convert my 351m to 400. Bought a rebuilt crank at rock auto for 280 $ (6 years ago) it came with main bearing and connecting rod bearing. Then i oversize to 0.030 over and bought 9.5:1 piston at tim Meyer for 300$. The only difference between 351m and 400 is piston and crank.
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I convert my 351m to 400. Bought a rebuilt crank at rock auto for 280 $ (6 years ago) it came with main bearing and connecting rod bearing. Then i oversize to 0.030 over and bought 9.5:1 piston at tim Meyer for 300$. The only difference between 351m and 400 is piston and crank.
And what were your results?
Laughing Gas
Joined: Jan 2006
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From: New-brunswick,Canada
Yes i change intake performer 400 and 4 barrils carb 600 cfm from edelbrock new cam extrem energie 256 but might change for bigger one later on.with spring to match the cam. I also change for aussie fully rebuild heads with stainless steel valve.Double timing chain set straight up, oil pump......complete rebuild.Roller rocker, custom pushrods last year. Its a long term projet. Just missing distributor and dyno. Suppose to have arround 350hp and 470 tq.
Laughing Gas
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From: New-brunswick,Canada
Not from what i know. You can raise your compression with aussie heads. Small combution chamber like 4v heads and the same port(intake and exhaust) as the 2v heads but still dont have a good quench with 351m pistons. But i think it's cheaper to buy 400 crank and use stock heads with tim meyer piston to have 9.3:1 comp.