ok i have a 91 f150 nite with a 351w...i just rebuilt it bored .030 over with new remanned e7te heads that i had the smog pump holes blocked off, comp cam,pushrods,lifter,springs, stock efi intake and throttle body and stock distibuter. i broke the cam in tonight and about half way through it started overheating. before i took the motor out it overheated but not as bad as tonght. heres what ive narrowed it down to but extra info helps


radiator cap junk?
water pump junk?
timing off?


now when i installed the heads the gaskets blocked off two holes in the back and two holes in the front i called a buddy and his where the same way and his runs 190 all day long....the water pump is the same one from before but before installing it i took it apart to change all the gaskets the blades were a bit rusty from sitting but still turned, on a second note mine has 3 tubes running off of it 1 for the radiator bottom hose and 1 for the heater core and 1 for the intake now im not sure if i have those two hooked up right...i got the bottom little tube hooked to the intake and the top little one hooked to the heater cor hose, i switched them around from the opposite way and it still overheats. my radiator caps sticker bubbles up when it starts to over heat(not sure if that matters) im going to try that first. also i just put straight water in instead of a 50/50 mix incase i had any leaks so dont know if that would matter. my timing is just a rough guesstament of a setting had no timing light so i dont know what its set at...also im new to fords and the little chip they have in the in the distributor wire so any directions with how to set it would be nice i think its something like take it out start the engine set the timng and then put it back in but not sure...if i can think of anything else ill post it and if i get it fixed ill let u know.


o and just so everyone can haave a laugh ive done it a hundred times but tonight was my first time being bit...5 minutes after it overheated i loosend the cap to releve the pressure with a towel over it, and when i tried clicking it back in it came off and burnt the **** outta me ill never do that again

 

Well i have a 1990 f250 with the 351w so its comparable......i had the same problem when i put the rebuilt engine in the truck, took about 5 mins as well. Turns out i made a mistake with the plug wires....check them all. Mine you couldnt tell they were wrong by the way it ran.....it was smooth. theres my two cents for you.

 

thanks i dont thinks thats it because i had timing a 180 degrees out last night when trying to start checked my wires three times and they were good took distributo back out and redid it all from the beginning and got it correct but i will for sure recheck them again tom... i got numbered wires

 

alright, well other than that in more random cases ive see the thermostat stick closed, or a water pump that sat not fail until the engine was rebuilt......or the plate behind the pump left out. in which case the pump would cavitate and not do a whole lot of anything

 

lol...ya i took my thermostat completely out and it still overheated...now on the water pump u may be on to something... i didnt leave the plate out but i did take it off the pump to put the new gasket on it it could be possible that i screwed something up by doing that....just so im not questioning it im going to get a new pump tom. and tear the front of the motor down again to replace it and put a new cap on and a 50/50 mix if that dont work im going to sit in my chair have a smoke and comence to pulling my hair out...this truck has been a pain in my ***...i got about 3000 in the motor now and when in the process of installing my t-case i notcied the input shaft bearing was roached so now i got a good running well half *** good running motor and no way to transfer power to the ground, a overheating problem, and a burnt throbbing hand....someone jus give me a gun

 

i know how that goes, when i put the engine back in mine we some how damaged the tranny main seal in the front......when we started for the first time......its dumped 7 quarts of tranny fluid on the ground in less than 2 mins. that plenum on the efi 5.8 makes it a b***h to take apart all over again...

 

dumb question....do you have a working fan for it, and were you driving down the road instead of letting it just idle when you have been encountering all this overheating?

 

ya i have a working fan and it was sitting in my garage while at about 2000 rpm breaking the cam in and i had a large fan infront of the truck blowing air through the radiaotr to similate moving down the road not to mention i live in central illinois and it was about 45-50 degrees outside last night so it had cool air coming in....i m thinking i have a bad water pump or an air lock inside it somewhere cause it was a completely dry engine

 

i would start with the water pump....i mean that would be the first thing to my mind since you said that you removed the t-stat and it still was messin up

 

when i put my cam in 95 f150 5.0L i bought the cam lifter and gasket set from sumitracing. with the gasket kit... mfg by Mr gasket i got 3 water pump gaskets none of them fit my truck. like urs i took the pump apart / removed the back plate to replace the gasket. i had gasket mat- so i made my own for the back plate. and with luck my fil had one to fit the block side.
check the gaskets and make sure ur flow tubes are not covered by extra gasket. let us know what ya find out.
before id go through the trouble of putting the thermostat back id check it in boiling water to make sure it opened. idk just some things id check.

 

hey its fixed... i put a new water pump on it today with a 50/50 mix of coolant and a new radiator cap...also set my timing at 10 degrees after top dead center i guess and it dont over heat and the throttle response is wickedly better....on my balancer i put a mark on the 10 btdc and it ran like a dog so then i put it at 10 degrees atc and it runs alot better...gona tinker with it a bit more tom and see if i can get some more out of it....ill post that clip tom chatterjj but it will be off my cell phone so i dont know how it will turn out

 

Theres something wrong with the timing. The base timing should be set at 10 btdc with the spout out , Did you hook the light to the #1 wire ?? , check the rubber on the balancer to make sure it didn't slip .....Lew

 

Looking at the balancer, did you set it to the 10° on the right or left of zero? The BTDC is to the right of zero when looking at the balancer from the front of the truck.

 

cool deal. glad ya gotter fixed.
when i made my vid- clip i had trouble with the sound it was fine on the comp- but after i loaded on youtube i had to edit out the sound. i think i got to close to the truck. cant wait to here it run.

 

im pretty sure i set it to 10 after the atc mark but not sure its hard to read i know it was ten though balancer may have slipped but it didnt have any power at all the first time i tried it and im pretty sure it was on 10 to the right of btdc ill check again tom but right now its running better than it has since ive got it running