head swaps

simon96 · rice boy Joined: 21 Oct 2001 Posts: 46

i read in the workshop that a 1600 on a 2000 will give 10.8:1 appx. and a 1600 on a 1800 will give appx. 9.8:1. is it safe to assume that an 1800 head on 2000 block will also give 9.8:1, will this prolong the life of my head gaskets or should i just go 1600 head? i also plan to go efi eventually, could i fit a surge tank and fuel pumps for efi and use them for a carby or doesn't it work. will i gain power from it?
thanks simon

Fastgem · tinkerer Joined: 04 Oct 2001 Posts: 166

the 1800 head has the same size combustion chamber as the 1600 so it wont really matter, just as long as it hasnt been shaved too much or the compression will be spastic (but this can alway be counteracted by a thicker head gasket). Best to have the block o-ringed though otherwise you may go through a couple of head gaskets. Might want to have the disy regraphed too and make sure it definitely doesnt detonate.

As for the fuel im fairly certain that if you connect up a efi fuel pump (about 40psi) to a carby then in technical terms you will fuck it. - they only need about 3-5psi To run. If the pressure is too high then once the float level drops to let more fuel in, it will be forced to stay open.

Mark · tinkerer Joined: 04 Oct 2001 Posts: 153

small note. you cant run a normal head gasket with orings, cos the orings chew holes in it. you have to run a copper gasket with orings.
other small note is you cant oring any overbored 2 litre block. not enough room between cylinders. Only oring standard 2 litre or smaller.
10.8:1 would only be acheived by shaving down the head alot. A standard 1600 head on a standard 2 litre block will give 10.1:1 . proven several times.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

I've gotta disagree with you here Mark,

O-rings are designed to bed into the fire ring of a composite gasket (the metal ring surrounding the cylinders). This is how they do their sealing. They also seal in the same way on a copper gasket, as the whole gasket is metal, but their placement isnt as critical.

I have been running O-rings in bored G200's for years, they are installed about 2.5mm from the edge of the cylinder, to allow for reboring of the engine. This will allow the maximum of a 1.5mm bore whilst still leaving a 1mm section of block material for securing.

And the compression resulting from the use of a 1600 head on a 2 litre bottom end depends on both the size of the combustion chambers and the size of the pistons. I have a couple of TD heads around the 40 and 42cc mark, one been shaved more than the other. I also have a TG pollution head with 51cc chambers, minimal shaving. These two 1600 heads will result in massive static compression ratio differences. A TX cylinder head has possibly a smaller combustion chamber again, resulting in over 12:1.

A 40cc chambered 1600 head on a standard 2 litre bottom end should yeild a 10.6:1 CR with a 1mm composite gasket.

Ben Wight

Mark · tinkerer Joined: 04 Oct 2001 Posts: 153

A standard 2 litre block has 7mm between cylinder 1 and 2, and 3 and 4.
Your orings are 1mm thick right? 2 orings, unless you run a figure 8 oring which arent as strong, will be 2mm. They have to be 2mm in from the edge of the cylinder to seal and generally you want a 1mm gap between the 2 orings. Thats your 7mm on a standard 2 litre block. You could possible do without the 1mm gap between the orings, but then your getting back to a figure 8 oring and theyre not as strong.
Apparently so i have been told from numerous engine reconditioners if they are less than 2mm from the cylinder edge they will burn in the combustion temperatures.
I run copper armature wire in mine, do you run stainless or copper?
I spose anything is better than no orings but for maximum strength ( i run an 11 second nos motor ) and best possible oring configuration a 2litre standard bore block is as big as you want to go.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

I just measured it then, there is 1 mm gap between the orings, with a total of 7 mm gap between cylinders on a standard bore engine. I am using 1 mm diameter stainless steel rings (MIG wire). This all means they are 2 mm from the bore. Mine are now 1.75 due to overbore. I have had them in for about 40000k's with no problems, and have had the head off several times with no resealing issues.

They really are a great investment for the price of installation, about $70 I think from memory. I have never blown a head gasket in my life, but unfortunately have cracked and melted 5 sets of ACL's.

I was curious as to what compression your engine has and what fueling/manifold setup?

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

I have to agree here as well, I have a 2ltr +40thou flat top pistons that were all individually zero'ed to the top of the block, and a tx head on top for induction NA twin 40mm Webers , I have to run a mixture of Avgas and PULP to stop pinging, a Monotouque head gasket lasts about 3 months of hard labour, a Felpro steel gasket lasted about 8 months, Also on my turbo engine I insisted on getting o'rings, I had it running for 4 months not a problem with a Monotorque headgasket, I pulled the head off for inspection and fitted a copper headgasket with 3Bond as sealant, and for the past 18 months and 18PSI I have not had to touch it, so I am about about to oring the NA 2ltr, and fit a copper headgasket so that I never have to touch it again, O rings are the way to go and can be used with any headgasket.
Felpro steel headgasket was for 4PlusPerformance about $70 and the copper from Ridgecrest about $120, I have been told that you can run a copper headgasket without o'rings but I haven't got to this yet, you guy's may be able to shed some light on this subject.