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351m rebuild

Wanting to rebuild my 351m out of a 78 f100. What should I do for a performance upgrade? Making it a 400 worth it and if so how to do it? Already has edelbrok carb and intake with dual exhaust and headers.
 

DNFXDLI

The Token Canadian
Staff member
Go whole hog and make a 434 out of it :D

All kidding aside, a pair of closed chamber Aussie heads along with the correct pistons, cam etc. will make a real nice engine.

Check out Tim Meyer Inc...

http://www.tmeyerinc.com/400ford.html
 

DNFXDLI

The Token Canadian
Staff member
Would I need to bore the engine at all for that kit?

You'd need to check it first and I don't know if he has pistons in std. bore.

Typically once you pull your engine and measure things, normally an overbore is in order
 

DNFXDLI

The Token Canadian
Staff member
Would you have a hp guess for that upgrade?

If you read the post I linked....it gives you a dyno numbers tab.

388/460

Which is pretty damn good for what the $ is.
 

DNFXDLI

The Token Canadian
Staff member
Pretty good numbers! Thanks for the help

Anytime!...and you can make a great engine out of one of these boat anchors.
Shoot Tim and email or phone call, he is very helpful!
 
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So I got the engine build which is now a 400m. I cannot get the 78 f100 to idle properly. The fuel pressure is good, there is a new carb on it (edelbrock 600). It will idle high as then it will want to die. When I get it idling not too bad it pretty much stalls when I put it in gear and it misfires. Seems to smooth out when RPMs are up as it has lots of power it's just the idle. It also doesn't want to idle at all on factory timing setting, I have the timing as high as possible without pinging so that it will run. Any ideas?
 

DNFXDLI

The Token Canadian
Staff member
Have you checked your timing and are all the vacuum lines ok?....and just so you know, it will be a 400...no M on it smilieFordlogo :)
 

LEB Ben

Arrogant A-hole At-Large
34,919
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So I got the engine build which is now a 400m. I cannot get the 78 f100 to idle properly. The fuel pressure is good, there is a new carb on it (edelbrock 600). It will idle high as then it will want to die. When I get it idling not too bad it pretty much stalls when I put it in gear and it misfires. Seems to smooth out when RPMs are up as it has lots of power it's just the idle. It also doesn't want to idle at all on factory timing setting, I have the timing as high as possible without pinging so that it will run. Any ideas?

Timing should be around 12*. Stalling once in gear is usually a vacuum issue...unless you have a choke issue, which could also explain the back fire. What are your idle speeds set at??? On a warm engine, I like 650rpm in drive at idle. These numbers will obviously change depending on build, but give a starting point.
 
I can't find a vacuum leak anywhere. I've sprayed all over with wd 40 but no luck. I've tried different choke adjustments. It idles at just over 1000. Any lower and it stalls out. I replaced intake gaskets trying to fix a possible vacuum leak.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
I can't find a vacuum leak anywhere. I've sprayed all over with wd 40 but no luck. I've tried different choke adjustments. It idles at just over 1000. Any lower and it stalls out. I replaced intake gaskets trying to fix a possible vacuum leak.

1000 is too high at warm idle. I usually prefer starting fluid over wd40. Typical vacuum leak areas: intake manifold (I like using a valley pan with a crush seal just for this reason). Also, did you use the front and rear seals??? Those typically don't set well and spit out. Next would be booster and the check valve. After that, a half dozen or so lines that run the HVAC controls, trans modulator, reservoir, etc. However, with the exception of the intake, the other would have accompanying issues.

Have you got a timing light on this thing yet??? I've had similar symptoms when the timing chain jumps a tooth or two. It'll still run (like crap), but you get back fires and a lot of the symptoms you're describing.
 
I have a timing light and have been trying different timing degrees. I checked the timing chain and it was right on the mark. I just used silicone for the front and rear seals, otherwise I had oil leaks. I am going to try plugging off all vacuum lines at once an see what happens.
 

fatherdoug

Tonto Papadapolous
Do you have access to a vacuum gauge. What the needle does on the gauge will eliminate some possibilities. The way the needle behaves could indicate a problem, based on the directions that come with the gauge. I haven't used mine for a few years, so I don't remember the indications.
 

Big Jim F150

73-79 Ford Trucks Rock
You might try blocking off one vacuum line at time, and see if you can find the offending line, and it'll save you lots of confusion when trying to locate your problem. You might also want to check your vacuum advance on your distributor, the little chamber that's on the front or side of the distributor, and you might want to check the little vacuum line going to it. Did you have your distributor rebuilt when you rebuilt your engine? You might have a bad pickup wheel on your distributor, you might also want to check all your electrical connections as well, for you might have a bad or loose connection somewhere, or possibly a pinched wire somewhere. Hope you find this helpful to you .smilieFordlogo smilieFordlogo smilieFordlogo smilieFordlogo
 

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