How to ID a Mexico Head?

[IamScotticus]

I have a used Crossflow head with valve rims almost touching each other.  

Could it be a Mexico?

How can I tell?

[EdWills]

Hey Scott.  According to the sales blurb for the 1970 introduced Ford Escort Mexico, the engine was a more economical power plant than the one used for the London to Mexico Rally.. The Haynes Manual for the Ford Escort RS1600 and the Mexico 1600, notes that the valve sizes for the Road Escort Mexico are the same size as the 1600 Crossflow pre-uprated engine used in the 1600 Cortina GT and Lotus Seven Series 3..  Seeing as the uprated 711M engine with slightly larger valves was introduced by Ford at this time (used in the Lotus Seven Series 4 and later Formula Fords), fitted with the flat head and stronger block with meatier mains caps, it is possible that Haynes were publishing older specifications for the pre-uprated engine in their Mexico specs.

 

"A good example of a powerful but flexible use of a push-rod engine is given by the units used in the Works Escorts on the 1970 World Cup Rally. These engines were taken out to 1830 c.c. by boring and fitting a specially made long throw crankshaft.  The flat cylinder head, with very little work done to it, retained standard valves but compression ratio was upped slightly to 9.5:1 by fitting Mahle pistons.  Twin 45 DCOE Webers with 36 m.m. chokes were used and the camshaft was the Holbay R120 (my note: as used in the Lotus Holbay 7S Seven and available for the Series 4 as an extra).  Power from this set up was approximately 140 bhp at little over the normal rpm figure. These engines were built with reliability in mind as much as power - and they proved successful, as everyone knows." Quote from "Tuning Four Cylinder Fords by Paul Davies" - published by Cars and Car Conversions Speed Sport Motobooks.

 

So, I'm guessing that someone - perhaps other than Ford - has machined your head to take the maximum size of valves available. You may have to check that the area between the valves has sufficient metal as one tuning website notes that cracks can occur when the head is machined with the valve heads too close together.  If I can find this site, I will pass it on to you if you are interested.  Cheers,  Bill

[IamScotticus]

This head has had other sins committed on it.  It could make a pope blush.  Porting an exhautst through into a head bolt hole.  The fix I believe is to sleeve with a brass valve guide. 

Edited February 26, 2024 by IamScotticus

[EdWills]

15 hours ago, EdWills said:

Hey Scott.  According to the sales blurb for the 1970 introduced Ford Escort Mexico, the engine was a more economical power plant than the one used for the London to Mexico Rally.. The Haynes Manual for the Ford Escort RS1600 and the Mexico 1600, notes that the valve sizes for the Road Escort Mexico are the same size as the 1600 Crossflow pre-uprated engine used in the 1600 Cortina GT and Lotus Seven Series 3..  Seeing as the uprated 711M engine with slightly larger valves was introduced by Ford at this time (used in the Lotus Seven Series 4 and later Formula Fords), fitted with the flat head and stronger block with meatier mains caps, it is possible that Haynes were publishing older specifications for the pre-uprated engine in their Mexico specs.

 

"A good example of a powerful but flexible use of a push-rod engine is given by the units used in the Works Escorts on the 1970 World Cup Rally. These engines were taken out to 1830 c.c. by boring and fitting a specially made long throw crankshaft.  The flat cylinder head, with very little work done to it, retained standard valves but compression ratio was upped slightly to 9.5:1 by fitting Mahle pistons.  Twin 45 DCOE Webers with 36 m.m. chokes were used and the camshaft was the Holbay R120 (my note: as used in the Lotus Holbay 7S Seven and available for the Series 4 as an extra).  Power from this set up was approximately 140 bhp at little over the normal rpm figure. These engines were built with reliability in mind as much as power - and they proved successful, as everyone knows." Quote from "Tuning Four Cylinder Fords by Paul Davies" - published by Cars and Car Conversions Speed Sport Motobooks.

 

So, I'm guessing that someone - perhaps other than Ford - has machined your head to take the maximum size of valves available. You may have to check that the area between the valves has sufficient metal as one tuning website notes that cracks can occur when the head is machined with the valve heads too close together.  If I can find this site, I will pass it on to you if you are interested.  Cheers,  Bill

I should clarify my statement regarding Haynes's valve size specifications for the Ford Escort Mexico in their manual.  They are correct depending on the date of manufacture of the cars they were featuring. According to David Vizard in his handbook "Tuning Escorts and Capris", for Crossflow engines fitted up to August 1970, the valve sizes for the standard 1100 and 1300 were 1.41" diameter for the inlet, and 1.25" for the exhaust. The 1300 GT engine had inlets of 1.5", and 1.25" for the exhaust. The 1600 and 1600 GT engine had the same size valves as the 1300 GT.  After August 1970, Ford started using the uprated engine, and the valve sizes increased to 1.55" for the inlet and 1.34" for the exhaust on the 1600 and 1600 GT. This was when the flat head was used replacing the head with the slight recess and the bowl in piston with no valve cut-outs.  The uprated head required the pistons to have valve reliefs machined in the tops of the pistons.  David Vizard advised that the best head for modification was the 1100 c.c. flat head casting.  It had much more metal for enlarging the ports, as well as allowing for larger valves.  Way back, I purchased at auction a 711M oil pump engine originally from an oil company for $25.00, and the head was fitted with the flat head 1100 c.c. casting with small valves.  On a trip over the pond, I took it to Oselli Engineering in Oxford, and they installed hardened valve seats on the exhaust for unleaded fuel, bronze valve guides, and valves of 1.6" inlet, and 1.34" exhaust.  They called this stage 2+.  Note: 1.6 m.m. is considered the minimum space between valve edges to prevent cracking of the metal between the valves under hard driving including racing conditions.  In my case, I have a space of 1.725 m.m. between the inlet and exhaust valves on my cylinder head. (There is a formula for this if interested?) Cheers, Bill

[IamScotticus]

Good info.

Will look for the books.

Probably easier to find the books than the engines