setting up "351" firing order?

[gear_grinder]

hai

i recently rebuilt the engine in my 5.0 explorer and used an HO mustang/lincoln cam versus the stock truck cam (firing order 1-5-4-2-6-3-7-8). according to several databases i need to run a 351 type firing order (1-3-7-2-6-5-4-8). I have been plauged with misfires/stumble under low rpm loads (<2krpm) and slight backfires after the truck is shut off when at operating tempertaure.

Also should i be running a 180degree thermostat with this cam?

thanks!

 

[CDW6212R]

The firing order for those engines are all the same, 13726548. The other order is an old V8 order that went into the 80's but almost died off completely in the 90's. All of the roller engines are the 351 Cleveland order, 13726548. Set them back to stock and try it again, those coils are not easy to deal with those wires on, double check them.

 

[90ranajo]

The 5.0L HO firing order is 1-3-7-2-6-5-4-8 (with CCW distributor rotation), where as the older 260/289/302 (1984 and down) was 1-5-4-2-6-3-7-8 (with CW rotation)

 

[gear_grinder]

some people on SBFtech.com said i could be trailer hitching rather then the firing order, i'm going to go double check the wire placement regardless.

it did the slight backfiring after the truck was shut off befor i rebuilt the engine, thats why i'm leaning towards talking about headwork on SBFtech.com

 

[CDW6212R]

Double and triple check the coil wiring, that is not simple to put back on right without a diagram. Work on the miss before doing more work to it.

FYI, if head work is a thought, don't look at any heads with exhaust ports that are moved from stock. Your header choices are limited, and those other heads may not accept the headers.

 

[gear_grinder]

i was basicaly just thinking of rebuilding the GT40Ps, bronze valveguids, new springs, seats, locks, seals, posibly better valves, lapping the heads (and valves if i reuse stockers). and new set of lifters aswell as pushrods.

double checked the coil-ignition wiring per haynes manual. they were on right.

 

[CDW6212R]

Then look at plug wires first, those cause misfiring easily, they are very fragile.

Do an estimate for the heads, total cost. If you see it much over $500, I'd consider a TFS Twisted Wedge instead(complete from Jay Allen, plus a custom cam). That would mean another cam swap, plus setting up the valvetrain. Not cheap of course, but it would make a very noticeable gain. The headers and small intake would be an issue then too. Just more ideas, keep at it.

 

[gear_grinder]

plug wires are less then 4months old. napa premium grade at that. i have faith in their functionality

i'm moving more towards having the valvetrain setup wrong, i didnt check the lifter preload, etc... when i put it together with the HO cam and roller rockers. So that and new lifters (clatter on cold startup) are next on my agenda.

 

[CDW6212R]

I missed that, roller rockers create a new mess of problems. With OEM pedestal rockers, you bolt them on, poof done.

Roller rockers(adjustable) require checking both the preload and the geometry. Either being off can be very bad, but bad geometry can cause big trouble and be expensive to correct.

If you didn't have serious head work done, like milling the heads a lot, then most good rockers can be used with decent success on pedestals. There will be some noise, ignore any very minor noise.

The lifter preload should be no more than .030-.035, don't do it by common practice such as 3/4 turn past pushrod not spinning. That is too much, and not all studs have the same thread pitch. Always measure one lifter preload by thread counts to find how many turns it takes to get .030-.035 lifter crush. I've found that to be as little as 1/3 of a turn, the thread pitch decides that. The pushrods should be checked by moving them up and down until they no longer move, for zero lash, before applying the preload. Don't spin them, that doesn't work accurately. Lifters are very easy to compress .030, they will start to go down before the pushrod begins to "drag" as you spin it. So don't spin them, check the play UP/DOWN.

The geometry is critical in high performance applications, but you can do a very minor check that works well for near stock stuff. Find out what the max lift will be for intake and exhaust, and check one of each. Use a caliper or any device that can relatively closely measure half of the lift of each. Put a rocker on and turn the crank to compress those valve until the half lift is reached. At that half lift, or close, the rockers should be as close to perpendicular to the valves and pushrods. The angles to each is supposed to be the same at about half lift. This is the shade tree garage method which will be close enough for any basic almost stock engine build. All of that can be done in under an hour, including completing the rocker installs. Regards,

 

[gear_grinder]

yeah, i'm going to redo the valve trainsettup when i put new lifters in this summer, the valve train cant be off that far cuz it still runs fairly good.

i'm going to adjust them per tech arcive SBFtech

 

[CDW6212R]

That will work well. SBFtech is full of good people who want to make big Ford power.

 

[gear_grinder]

ya, their tech arcive has a pretty comprehensive thread on setting up valvetrain

http://sbftech.com/index.php/topic,318.0.html

 

[gear_grinder]

just to mention the explorer cam VS the HO cam, the HO cam should net a solid improvment over the stock cam acrosst the board.

explorer cam: .422/.448 lift and 256/266 advertised duration (I dont have the overlap for this one)

HO cam: 0.444"/0.444" lift and int/exh: 266°/266° advertised duration (Overlap: 36°)

This giving the engine more intake lift and duration to help increase volicity in the huge intake ports.

Unfortunatly, i think the gains will be <20hp because i'm too poor to buy some TMH

do you think they would sell a header kit?? i've got multiple welding classes under my belt at the local collage, so doing GMAW on it would be easy