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I have a 89 351w that will idle fine and light driving and stay around 190-200. As soon as I lay the wood to it for say 30 seconds to a minute it will shoot up to 220 and if I don’t let out it will keep climbing quickly,
This motor came out a rolled truck and i dunno how long it ran that way, I had this motor in storage for 12 years, I tore it down and the mains were trashed, I put a reman crank and all new bearings in it
It has afr 185’s heads and a lunatti Bare bones cam, new timing chain and gears and oil pump, stock truck lower with bc bronco adapter to run stock mustang ho upper
Now this is where it gets iffy, stock must and throttle body and maf and computer and wiring harness and injectors. Brand new aluminum radiator with 3000cfm fan. Timing set at 16 degrees. Ran it at 12 with same results, 15/8 bbk shorty headers
I’ve battled this for 2 years and when it gets above 220 or so my headers will start to glow
Are my injectors too small or something in tuning or something possibly internal, I do seem to get small air bubbles in my coolant but I’ve changed head gaskets and they were fine, Possible crack in block?
Sorry for long post but trying get all my info out there.



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mustang computer is for 302 and 19LB injectors

you should have timing set at 10deg spout out

is that the overheat cause, maybe, probably not

have you verified no air in cooling system, does the system and rad cap hold near 16psig?

if you lower the rad level 1/3rd and see coolant tubes, does the coolant flow look good and increase with rpm?

are you running a serpentine belt system which requires a reverse rotation water pump?
 

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Discussion Starter #3
mustang computer is for 302 and 19LB injectors

you should have timing set at 10deg spout out

is that the overheat cause, maybe, probably not

have you verified no air in cooling system, does the system and rad cap hold near 16psig?

if you lower the rad level 1/3rd and see coolant tubes, does the coolant flow look good and increase with rpm?

are you running a serpentine belt system which requires a reverse rotation water pump?
Yes serpentine belt with correct pump and flow seems to be good, I’ve put 2 new pumps on it.
I’ve used a burp funnel and even cut the center out the tstat and tried that, I’ve put 3-4 different Tstats in it.
To be honest it doesn’t build a lot of radiator pressure, I put a tester on it and it holds pressure fine, I’ve tried several caps at different psi too but nothing helps.


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Discussion Starter #4
Also motor runs great and has never boiled over even at 240. Manual temp sensor
And once it gets hot it will not cool down under 210-220


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what does the system hold?

what does the rad cap hold?

actual psig numbers from the tool

the system has to build pressure, or you have a leak or air in system

fill the system so rad is 1/2 to 2/3rds full, get it nice and hot, stat opens and see if flow increases with rpm, it has to shoot out

you do have the bypass hose on stat housing, right?
 

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Discussion Starter #7
Bypass is on and heater hose is capped
Think I pumped it up to 20 psi and it held for probably 20 mins on a cold engine.


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Discussion Starter #8
the glowing red headers tell me the timing is retarded, this will cause it to run hot.
I have ran the timing all over the place and nothing seems to help. This has been a long battle and I’m very frustrated with this engine


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Discussion Starter #10
Have cats? Running lean?
No cats. 2.5 inch exhaust and flowmaster Fx mufflers and plugs do not look like it’s running lean. And I know I probably catch hell but I’m running this in open loop as well


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I have ran the timing all over the place and nothing seems to help. This has been a long battle and I’m very frustrated with this engine


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timing is set in ecm, what tuner are you using?
 

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Could be going lean, you still running the stock #19 injectors and stock fuel pump, too small for a 49ci more and way better heads then stock?
 

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No tuner just stock ecm


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so do you understand that the ecm is for a `302, not 351, right?

spark is calculated in ecm, and guess what, the major factor is load

so y
when you say you have tried adjusting spark, you were in fact not, just messing the total spark right the hell up
 

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Discussion Starter #15
so do you understand that the ecm is for a `302, not 351, right?

spark is calculated in ecm, and guess what, the major factor is load

so y
when you say you have tried adjusting spark, you were in fact not, just messing the total spark right the hell up
They have the same firing order so where’s the problem. I’m no expert but it runs great just gets hot. What computer should I be running then


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none of the load calculations will be accurate unless you are able to adjust the tune. at a minimum you want to change the displacement to 351. next up you need to get some o2 sensors in there and get it running in closed loop
 

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since we know spark is hooped

lets address the fueling

you say you have it open loop, i assume there are no 02 sensors plugged in

those OL tables based on load for a 302, so what is going to happen?
 

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They have the same firing order so where’s the problem. I’m no expert but it runs great just gets hot. What computer should I be running then


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BASE SPARK TIMING, who ever said anything about firing order?

maybe you should run the computer that came with that engine.
 

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Discussion Starter #19 (Edited)
Well I don’t have that computer so is is it as easy as going to a junkyard and grabbing one and swapping it in ? Or can I get a tune burnt into a chip for my current computer ? I do appreciate the help. Sorry if I sound clueless but this was first time I’ve done this type swap and I went off what someone told me would work and I want this thing running correctly
Edit. After thing about it those years were speed density so that computer won’t work and I’d imagine a maf computer for a 351 probably won’t work with my harness but I’m not sure

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Besides the above issues, also check for a spun balancer. Make sure where the TDC is marked on the balancer is actually TDC.
 
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