Wondering what distributor and timing curve I should look for with my 78 F150, with the 351M/C6/2.75 9" combo.

I removed all the smog gear, and the truck performs reasonably well, but it has issues with transition to power circuit, and some of this may be exacerbated by the curve not being quite what it needs. (emissions...)

Current carb: D7TE CVA C 8E 15
Dizzy: D7TE 12127 AMA 85 11

All I know, is if I'm cruising and go to 3/4 - WOT it can't take the fuel and sometimes backfires up the carb.

I've tinkered plenty with base timing, idle mixture, and accel pump rate.

I won't be surprised if I go with a reman carb and dizzy here, but I'm starting with the distributor and would appreciate any suggestions!! I'm interested in staying with stock DSII components, but am open to anything.

Thank you!

 

Other info:

Here's a thread when I purchased the truck:
https://www.ford-trucks.com/forums/8...questions.html

The issues mentioned in the thread have been resolved, excepting what I noted in the original post here.

Idle screws still 3-4 turns out for best vacuum, max vacuum is about 19-20", but no vacuum leaks.

Fairly certain the distributor should be replaced. It was seized in it's bore when I bought the truck, and sometimes the performance of the truck changes as if the centrifugal mechanism has deteriorated.

 

There was a thread not too long ago on the '73-'79 forum regarding what happens when EGR is removed. The general consensus seemed to be that the engine may have problems (such as pinging) due to the radical timing curve of the distributor and that the carb is tuned to run lean.

My truck (which has a 400) had the problem with pinging - the PO had removed the EGR but didn't do anything with the distributor or carb.

Following on a tip from this web site:
Duraspark_distributor_recurve_instructions_index

I replaced my distributor with one for a 460 (400 and 460 distributors are physically identical - I believe 351M's are also) - 460's of that era had EGR but the timing curve was different on the distributors - I couldn't find a recurve kit for it locally, so I dropped it in as-is and that, alone, took care of the pinging problem - engine runs fine. Carb is still running a bit lean though...

Hope this helps...

 

I think in my case, mine's only good for a core. I have recurved these before, with success - but I think I'm in the realm now of finding a unit with the curve I need. I'll read the link you posted for info concerning 460 curve... thanks

 

ahh yes, i've seen the 75 Elite reference before.

Well perhaps people have suggestions for a curve for this application with the following characteristics:

Truck is highway geared, so needs to maximize tourque. Highway RPM doesn't exceed 2500 rpm.

I don't carry much in it for loads, although it does see modest loads, and the occasional 1000 lbs.

Engine is stock, and will remain near to it.

I put a lot of miles on this, and it's mostly highway. The truck is eating fuel currently, getting about 12mpg no matter how i drive it. I know this engine should be good for at least 3 - 5 more mpg.

I don't have pinging issues. My issue is more a constantly rich condition, which is in part due to the carb (I will investigate jet sizes and power valve) and the timing curve not being optimal for the charge.

The engine is often in a lugging situation due to the gearing, and that makes it more critical for it to be able to handle the fuel properly under load.

Otherwise I like the gearing, and when this is working well, it holds 10" + of vacuum at 60mph, and is quite good on the highway. Tourque peak for the engine occurs at 60mph..

 

I just ordered Pertronix I3 Flamethrower as seen here: Pertronix Flame-Thrower Ignitor III Billet Distributors - JEGS

We'll see how it works. Something tells me I will want to alter the curve from the "performance" one it comes with, but it is easily adjustable apparently.