i've got a headache
- Thread starter SONNY
- Start date
Anything that puts any planned off XF head with less than 49 ccs chamber volume on an early XC, XD or XE, or TE/TF will cause trouble. Especially if you run it on peanut grade regular 91.
The later October 85XF heads run a dedicated emission and thick film ingition system according to the state of sale, fuel system, and transmission. On 91 octane, the XF ignitions peak advance of 40 degrees is way to high for the 9.15 to 9.35:1 compression the pre October carby 1985 engines had. All early XF's were designed around 98 octane leaded, and from October 1985, they were revised to cope with 91 octane, and the carb C/r ratio went down to the same 8.8:1 all EFI engines had.
According to Bill Santacionie who worked on these engines at SVC in the 80's, all XF Alloy Head II's are prone to pinking in stock form. The only plus is the bigger valves. The ones to avoid are the later XF high swirl, kidney shaped closed chamber items if your doing mods to the stock spec. You can use them, but you have to limit compression, and rework them to XD-XEspecs. (This means hogging out the cahmber from 49 cc to 53 to 56 cc, and remove the swirl ramps while still keeping the surface rough.) You could run 27.2 cc pistons, or do the dirty job, and just add the turbo 62.5thou spacer Mike Vine Turbos used to run. Later on, Mike resorted to having the heads chambers machined to lower the compression of his turbo engines from 8.8:1 to 7.6:1.
Detonation is the enemy of all Ford x-flows and Clevleland V8's. It is the hidden reason why people say these engines have cam and rod problems under extreme duty. Bill Santacionie had a hand in canted valve X-flow head developement starting from the Phase 3 and 4 era, and worked on the Quality Control 351 HO engines and before that, at Repco. Mick Webb and Kevin Bartlett aggree that detonation is the issue, and that rod and oiling issues were actually detonation issues which require very good detective skills to trace. The Phase 4 351 HO had the chambers reworked fromthe early Boss 302/351 spec used on the Phase 3. This had specific mods to reduce shrouding on the intake and had changes to lower compression to cope with detonation.
Long winded, but there you go. Use the XF head if you must, but modifiy it to get 8.8:1 compression, and remove the high swirl intake shrouding. Don't polish it, or it'll detonate even more!
The later October 85XF heads run a dedicated emission and thick film ingition system according to the state of sale, fuel system, and transmission. On 91 octane, the XF ignitions peak advance of 40 degrees is way to high for the 9.15 to 9.35:1 compression the pre October carby 1985 engines had. All early XF's were designed around 98 octane leaded, and from October 1985, they were revised to cope with 91 octane, and the carb C/r ratio went down to the same 8.8:1 all EFI engines had.
According to Bill Santacionie who worked on these engines at SVC in the 80's, all XF Alloy Head II's are prone to pinking in stock form. The only plus is the bigger valves. The ones to avoid are the later XF high swirl, kidney shaped closed chamber items if your doing mods to the stock spec. You can use them, but you have to limit compression, and rework them to XD-XEspecs. (This means hogging out the cahmber from 49 cc to 53 to 56 cc, and remove the swirl ramps while still keeping the surface rough.) You could run 27.2 cc pistons, or do the dirty job, and just add the turbo 62.5thou spacer Mike Vine Turbos used to run. Later on, Mike resorted to having the heads chambers machined to lower the compression of his turbo engines from 8.8:1 to 7.6:1.
Detonation is the enemy of all Ford x-flows and Clevleland V8's. It is the hidden reason why people say these engines have cam and rod problems under extreme duty. Bill Santacionie had a hand in canted valve X-flow head developement starting from the Phase 3 and 4 era, and worked on the Quality Control 351 HO engines and before that, at Repco. Mick Webb and Kevin Bartlett aggree that detonation is the issue, and that rod and oiling issues were actually detonation issues which require very good detective skills to trace. The Phase 4 351 HO had the chambers reworked fromthe early Boss 302/351 spec used on the Phase 3. This had specific mods to reduce shrouding on the intake and had changes to lower compression to cope with detonation.
Long winded, but there you go. Use the XF head if you must, but modifiy it to get 8.8:1 compression, and remove the high swirl intake shrouding. Don't polish it, or it'll detonate even more!
All blue and black early heads from 1976 to late 1980 were 302 Boss/ 302 2V style quench heads. They displace about 53 to 56 cc unplaned, and have small valve heads. Port diameter varied, as Ford finish machined the later XD casting differently.
Then came the silver XD / XE Alloy Head from 81 to 84. There were no changes even when the EFI notches got added into the intake ports in Jan 1983. The XE Alloy Head II was just the same as the EFI and XD Alloy head. These have small valve heads too.
The big valve 49 cc high swirl kidney head was XF carb and EFI. I don't know exactly what happened with the leaded and unleaded versions of the XF heads, but I think they are all the same in chamber size. The carby and EFI heads in 1986 were the same.
The casting numbers in the centre of the head with the rocker cover removed and the actual car they came from requires more sluth work than I have done. Every time new info comes along, I check off if what I have is bull pucky or legit. Often, I find I'm the bs merchant, but I only go on what I've seen.
Then came the silver XD / XE Alloy Head from 81 to 84. There were no changes even when the EFI notches got added into the intake ports in Jan 1983. The XE Alloy Head II was just the same as the EFI and XD Alloy head. These have small valve heads too.
The big valve 49 cc high swirl kidney head was XF carb and EFI. I don't know exactly what happened with the leaded and unleaded versions of the XF heads, but I think they are all the same in chamber size. The carby and EFI heads in 1986 were the same.
The casting numbers in the centre of the head with the rocker cover removed and the actual car they came from requires more sluth work than I have done. Every time new info comes along, I check off if what I have is bull pucky or legit. Often, I find I'm the bs merchant, but I only go on what I've seen.
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