I need some advice from the masses. I have been working on our truck to pull our horse trailer and I have hit an issue. The truck is an 86 4x4 with the 351W and auto trans. The engine has been changed from stock with all pollution removed and bored 30 over. The cam is a towing cam and the carb is a Holley 600. The truck runs good but when we pull the trailer we have no power. On some of the local hills we can only do about 35 mph. The tranny doesn't slip that I can tell.
I wondering what to do next?
Can I swap in a 460 for more power?
Should I just get rid of it and get a diesel truck? I know its wrong for the forum but we did borrow a friends 98 Dodge Cummins and it had no problems.
If I am going to spend better than $2000 to put a fresh rebuild 460 (if it can be done?) am I better off getting something else?
The trailer is a two axle steel body trailer that is about 2800 lbs and by the time we add the horse 800 lbs and the assorted stuff another 300 lbs we are topping 4000 lbs.
What gears and tires is the truck running? Unless you have really high gears/big tires that truck should be able to pull that trailer without much fuss. What's your timing set at? You said all the emissions stuff is removed - does that include the EGR? Did you have your distributor re-curved?
First thought that comes to my mind is the ignition advance (old-style vacuum
advance on the distributor). You cannot merely remove an EGR valve and many
other emissions devices without tuning & adjusting the rest of the engine to
accommodate that.
Just our of curiosity, what tuning and adjustments would you do if you removed all the emissions gear? I had my smog pump on a 460 go bad, I just removed the pump and plugged the hoses, engine still seems to run fine (with vacumm removed from the EGR) with vacumm on the EGR she runs real crappy.
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Robert
--1980 F-150 Custom 302, 4sp OD
--1980 F-100 Ranger 300, 4sp OD
The EGR stuff was removed as well. The distributor is a Mallory Unilite with the standard vacuum advance. I can't remember what the timing is set to off the top of my head but I do know it is not 10 deg BTDC because of the towing cam. I am thinking of taking it to a performance specialist locally and having him check the jets in the carb to make sure it is not running lean and maybe check the timing as well.
I haven't the foggiest what gears are in it. When I get the chance I will clean the dirt off the diff tags and check it out. We have 32"s on 15" steel rims.
I thought it should pull better than it does but never having towed with any older truck like this I don't have a comparision point. All the other towing has been with newer mid 90 and up diesel trucks.
Just our of curiosity, what tuning and adjustments would you do if you removed all the emissions gear? I had my smog pump on a 460 go bad, I just removed the pump and plugged the hoses, engine still seems to run fine (with vacumm removed from the EGR) with vacumm on the EGR she runs real crappy.
The one with the largest single impact is the distributor's ignition timing
advance curve. The net effect of the EGR valve is to make the engine run
leaner under certain circumstances & conditions, and the advance curve is
calculated to accommodate that. Without the EGR, the engine is no longer
running with the same fuel/air ratio as it used to be, and you'll often encounter
pinging at low RPM under load.
The smog pump is inconsequential to the running of the engine, its only job is
to feed clean air to the cat(s) to promote a more through burning of unburned
exhaust gases.
There are many devices - vacuum amplifiers & delay valves & such - that serve
to, say, reduce hydrocarbon emissions at idle, or eliminate run-on, or eliminate
backfiring through the carb on deceleration, things of that nature. In my
opinion, many of those devices are in place to deal with and cover up the
symptoms caused by the detuning of the engines in order to meet emissions
standards imposed the the US government but that's just my opinion.
Regardless, it's really impressive what Detroit came up with to control the
behavior & operation of engines without computers running the show.
It sounds to me like your EGR valve might be all carboned up and sticking,
remaining open when it shouldn't be. Sometimes, they can be cleaned out (I've
used brake cleaner or carb cleaner or sumthin' like that) and made to operate
more freely but it's kind of a dirty job to undertake and there's no real
guarantee of success. I doubt you could make it worse, though.
Note, I'm talking about the valve itself, not merely the vacuum diaphragm
which actuates it.
The EGR is not supposed to operate at idle or when the engine is cold, they will
only do that if they're sticking (or otherwise misbehaving for some reason).
This will be the last I speak of this, as I don't want to hijack the thread, it's funny you say that about the EGR because I replaced it with no change. Also this system has no catalytic converters (even says so on the emissions sticker) so I don't see whay they would put an EGR on it in the first place.... not trying to argue with you at all ctubutis, what you say makes complete sense, I just thought it odd.
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Robert
--1980 F-150 Custom 302, 4sp OD
--1980 F-100 Ranger 300, 4sp OD
I am thinking of taking it to a performance specialist locally and having him check the jets in the carb to make sure it is not running lean
600 CFM carb may actually be too much. towing you're not looking for tons of power up top, you need solid torque in the middle. you may try dropping a carb size and running it that way. you'll see more intake velocity, which will better promote cylinder fill. checking your timing is equally important, but you don't need your truck tuned for max horsepower, you want it tuned for torque. your towing cam should have a medium lift with longer duration which will help build that torque. on a similar note, what intake are you running? if you're running a single plane you're shooting yourself in the foot.
Since you said your trans isn't slipping, i'm assuming you're running an automatic. you may consider a good shift kit. you'll raise your shift points which will help keep the truck from bogging down on those hills.
if it still doesn't work, my diesel is for sale in the marketplace (sorry, couldn't resist the plug...)
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If it ain't broke, you ain't worked it hard enough...
I don't think your problem is engine performance at all. But rather the problem is putting power to the ground. You said you have 32" tires. So they are oversize which is not good if you have a low numerical axle ratio. Then you say they are on 15" rims which tells me your truck is a 1/2 ton. A lot of 1/2 ton trucks were equipped with economical axle gearing and were never intended to be tow vehicles even though they were equipped with a V8.
So for instance if your axle ratio is a conservative 3.00, the oversize tires reduce the effective final drive ratio to 2.72. That is not good for towing. Even a 3.54 ratio sucks for towing with the 5.8 engine. Ask me, I know.
I stongly suggest first you find out your axle ratio. Because depending on what it is, a 460 with much more torque will certanly be better... but still not be the best combination.
FWIW, JMO 3.75 is the minimum axle ratio any pickup truck used for towing should be equipped with. If it's not a daily driver and used mostly for towing, then 4.10 or 4.30 would be my next best choice.
My dad was having trouble with his 351W at one time with the same symptoms your describing. He also was running a 600 holley. His problem was the power valves in the carb. Every time he put a load on it it would blow the power valve and the result is the truck seeming way under powered and add in the trailer and a steep grade and it just seemed flat out pitiful. We ended up putting a 600 eldelbrock on and that cured the problem. Just throwing this idea out here. i have an 85 bronco 351w built with a high torque low rpm cam(also with an eldelbrock)and it pulls like no bodys business.
__________________ 03' F250 7.3 FX4-6637,CCV mod,AIH delete,muffler delete,Petes cover,TC lock switch,Autometer gauges(boost, pyro, trans)hypertec max stage III,Trango tugger HD,Derale trans pan,2.5 lift and 33" BFG A/T's 85' Bronco XLT
I don't think your problem is engine performance at all. But rather the problem is putting power to the ground. You said you have 32" tires. So they are oversize which is not good if you have a low numerical axle ratio. Then you say they are on 15" rims which tells me your truck is a 1/2 ton. A lot of 1/2 ton trucks were equipped with economical axle gearing and were never intended to be tow vehicles even though they were equipped with a V8.
So for instance if your axle ratio is a conservative 3.00, the oversize tires reduce the effective final drive ratio to 2.72. That is not good for towing. Even a 3.54 ratio sucks for towing with the 5.8 engine. Ask me, I know.
I stongly suggest first you find out your axle ratio. Because depending on what it is, a 460 with much more torque will certanly be better... but still not be the best combination.
FWIW, JMO 3.75 is the minimum axle ratio any pickup truck used for towing should be equipped with. If it's not a daily driver and used mostly for towing, then 4.10 or 4.30 would be my next best choice.
Thats the answer! Now if you had the 300 6, the 3.55 gears and 33's tires would pull ok. Best to get 4.10 with those size tires.
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89 F250 2x4 302/AOD 4.10 gears ,now on road.
89 Bronco2 with dead A4LD again
84 F250 4x4 300/np435 3.55 gears. The BLUE MULE shut down due to cab cancer(looking for good cab)
95 E350 bus conversion 460/E4od 4.10 the new toy!
85 Plymouth Caravelle 2.5L someday to get the hairdryer treatment(turbo)
93 explorer now just a woods buggy
This will be the last I speak of this, as I don't want to hijack the thread
Me, too, as I also don't want to hijack this guy's thread.
Quote:
Originally Posted by 6fifty_f1fifty
it's funny you say that about the EGR because I replaced it with no change.
If the EGR valve is known to be good, then I guess I'd next be looking at the
vacuum control valves, solenoids & tubing that control it, tell it when to turn
on & off and to what degree. A factory Emissions Diagnostics Manual would
be a BIG help, they're probably still available from the various places on the
'net that sell manuals like that (as well as eBay).
But, if it's running well and isn't excessively polluting the environment and you
don't need to pass any state inspections & tests, it might be best to leave well
enough alone.
Quote:
Originally Posted by 6fifty_f1fifty
Also this system has no catalytic converters (even says so on the emissions sticker) so I don't see whay they would put an EGR on it in the first place
I think you're confusing the EGR with the AIR (aka smog) pump, the AIR pump
supplies fresh air to the cat(s) and is totally unrelated to the EGR.
I have a 1981 F350 and it doesn't have cats, either, and I had to wonder the
same thing as you (why is that pump there). Perhaps it was for mass
maufacturing efficiencies, perhaps to avoid government-required testing &
certification of another engine configuration, maybe something else, I really
don't know.
But, the EGR is to make the engine run leaner while warmed up and running at
cruising speeds, and the engine can run like crap at idle and low RPMs if that
valve is open when it shouldn't be.
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(sorry, couldn't resist the plug...)
