87 XF compression upgrade??

[cisco 111]

The 87 XF had a low compression engine and was the first Falcon to get a computer.

 

I had one years ago and from memory the distributor did not have the electronic ignition module on the side of it and the timing was controlled by the computer module behind the passenger side kick plate. I believe this module compensated for different octane fuels and they would just about run on kerosene.

 

I took the head off for a decoke/valve job and noted that the lips in the bores were progressively more from cyl 1 to 6 which creates piston slap issues. I was told by a Ford specialist that it was because they did not run hot enough.

 

My question for the brains trust is if I rebuilt one of these engines with high or higher compression ratio pistons, would the computer module compensate the timing enough for the engine to run properly on 98 octane fuel??? I would be fitting a higher temp thermostat also.

[deankxf 20,294]

1 hour ago, cisco said:

The 87 XF had a low compression engine and was the first Falcon to get a computer.

carby model? 

unleaded 1986 that came in, an EST computer in the kick panel. it didn't control anything to do with fuel octane to My understanding. 

 

they'll run on 98 no issue, but if it's more of a stock engine you are planning on with fuel prices these days i'd keep it safe to run on 91 anyway. even a GOOD mild crossflow won't be as quick as most new hyundais etc. 

 

i don't know the compression ratios that came out stock, but i'd imagine they vary a lot between the different models (crossflows in XFs ran to 1993 with carby and same computer in the kick panel) 

i'd bump it up slightly from stock for a bit of improvement with very little risk of issues on 91, speak to the engine builder, they may just say the bigger bore and reco will be enough to make it spritely again. 

 

 

[cisco 111]

Thanks for your response. Yes it is a carby model. I don't own it yet but an original rust free 87 Fairmont with 220 on the clock at $5,000 has to be good buying.

If I get it I will pull the head off and if the bores are OK just give it a decoke, tidy the ports. valve grind, bash the ceramic out of the catalytic so  it can breathe and drive it. Maybe 10 or 20 thou off the head.

 

The one I had in the late 90s I took the family on a 4000k road trip Bundaberg, Dubbo, Lithgow, Sydney and back to Bundy and it drove a dream. Fingers crossed.

[deankxf 20,294]

1 hour ago, cisco said:

, bash the ceramic out of the catalytic so  it can breathe

I wouldn't bother doing that, it's not going to be a restriction that makes any noticeable difference. the cam and valve springs are the power limiters stock, 

 

the only reason i'd do it, is if i was sus that it was on it's way(rattling) and therefore it won't be a problem blocking the exhaust like i had twice in 20yrs (likely from going bush and hitting rocks with it)

 

you've probably heard the acronym KISS (keep it simple stupid) 
i prefer KISS (keep it STOCK stupid ) these days. 

[cisco 111]

A couple of handy pages with specs for xe and xf. 

 https://www.uniquecarsandparts.com.au/falcon_XE_technical_specifications 

 https://www.uniquecarsandparts.com.au/falcon_XF_technical_specifications

 

You will see the pre unleaded XFs had a 9.35:1 compression ratio and then 8.7:1 for unleaded and the XEs had 8.8:1. I would think 9.35:1 is an ideal compromise for performance and economy.

[deankxf 20,294]

1 hour ago, cisco said:

A couple of handy pages with specs for xe and xf. 

 https://www.uniquecarsandparts.com.au/falcon_XE_technical_specifications 

 https://www.uniquecarsandparts.com.au/falcon_XF_technical_specifications

 

You will see the pre unleaded XFs had a 9.35:1 compression ratio and then 8.7:1 for unleaded and the XEs had 8.8:1. I would think 9.35:1 is an ideal compromise for performance and economy.

yeah i'd assume 9.35 ish would be fine. 

interesting the efi which was quick by comparison had lower compression ratio than the carby ones. 

i'd just be saying to the engine builder, i want it to be happy on 91 with no issues. because paying for 98 or HAVING to use it can be a pain. 

[cisco 111]

The compression ratio in my XE went up a bit after 2 head removals over the years and just would not run without pinking unless I retarded the hell out of it. With that I have become accustomed to only using 98 octane fuel all the time. It actually uses less fuel on 98 but not quite enough to offset the cost. The added benefit of 98 is getting a cleaner burn.

[deankxf 20,294]

26 minutes ago, cisco said:

The compression ratio in my XE went up a bit after 2 head removals over the years and just would not run without pinking unless I retarded the hell out of it. With that I have become accustomed to only using 98 octane fuel all the time. It actually uses less fuel on 98 but not quite enough to offset the cost. The added benefit of 98 is getting a cleaner burn.

yeah back in the day i did notice i got better economy from 98 by about the difference in cost, but i believe it's tunable to run on 91 if needed still. 

what i think could be causing the pinking is sharp edges on the head chamber, or carbon. (or just advanced too much anyway)

91 rattled it's head off in My ute which i advanced the timing heaps for LPG, so i had 95 in the tank for that reason., 95 seems plenty good if you can get it. 

 

 

[cisco 111]

 Well dean the point may be moot in this case. Despite two enquiries I sent via Carsales on the 87 Fairmont without replies the car is now on hold. Had this happen before and it pisses me right off. Why do people list things for sale if they are not going to respond to enquiries???? Got me beat.

 

I remember the old Austin/Morris engines that had a heart shaped combustion chamber. The point of the heart would get red hot and sometimes you had to clutch stall the engine to stop the run on. The other issue with modern fuels is that they require VVT to extract the horsepower. Because of that my old school Ford man says if you are rebuilding an engine a standard cam is the best option if you are not building it for high performance.

 

My XE has a Dynotec CM251D cam shaft.The spec sheet says it has 214* duration @ .050"cam lift and 291* duration with SAE Valve timing .006"valve lift which is a little beyond me. The engine builder called it a "Tow and Go cam". The result for me is that idle is still smooth, is still tractible in traffic but has that bit extra grunt when you want it. Torque peaks at 3000 rpm and it will wind out to 4500 rpm easily. I think it will go to 5000 rpm if I want to flog it.

 

The diff is 2.77:1 and with the 4 speed single rail I put in it rpm at 100k is 2350-2400 and from memory economy is about 13 L/100 klm. My son made me promise the car to him so I am happy to keep driving it daily.

 

Some people have gotten the 200 crossflows really screaming them being a square engine or slightly over square when bored out. They are under rated I think.

[deankxf 20,294]

1 hour ago, cisco said:

Some people have gotten the 200 crossflows really screaming them being a square engine or slightly over square when bored out. They are under rated I think.

SLY250 (slydog's ute) goes to 7000rpm with a heap of mods (250 crossflow)

i had an XE panelvan many years ago with a big cam that was a pig until about 2500rpm then hauled to 5500rpm(would been better with a manual and 3.45 diff)

 

yeah annoying with car ads, try selling one, just as annoying. 

 

i like the "tow and go" type cams, the old days the "upgrade" to a stock engine was fitting the EFI spec cam, it's slightly bigger than stock. 
worn timing chains make a gutless issue also, i have had GOOD stock crossflows back in the day (20+ years ago) anything these days with 250,000kms ish is likely due for a freshen up, but they do rattle away for another 100,000 without much fuss and even beyond