Making a 1.8L head into a 2.0L head - how much and how to do?
 

So I bought a 75 1.8L parts car so I could start assembling parts to bring my 1.7 up to 2.0. What exactly needs to be done to the head to bring it up to 2.0 specs and how much should it cost? I've seen Rimco's name mentioned for machine work, any other recommendations? Although I would like to build a "wild" race engine, 100HP should be enough for me and I would like to use as much of my 1.7 FI as possible (although I have a set of webers (40s) that came with the engine).

I am sure that I am over-simplifying this but basically if you are taking 1.8 heads and are putting them on an engine that has 1.8 or 2.0 sized cylinders, all you have to do is have the correct size valves and seats installed. I had mine done at Rimco and they did excellent work. They do not however do any porting or polishing. If you were going to be using the 1.8 heads on a 2.0 engine with D-jet you would have to modify the studs that the intake runners bolted to. The 1.8 has 4 studs and the 2.0 has 3, but since you said you were carbing this engine, just make sure your intake manifolds are the 4 bolt style.

GS

How exact a copy of the 2.0 head do you want it to be??

Differences include (but are not necessarily limited to) :
Different valve sizes (and seat sizes)
Different intake port size and/or shape
Different exhaust port size and/or shape
Different spark plug location
Different combustion chamber shape
Different number of intake studs

The valves and seats can be installed relatively easily. Most of the others require welding up some parts of the head and taking material off others.

The 1.8 heads are pretty good in stock form. If you put the 2.0-size valves in, they get a bit better. The rest probably isn't worth it IMHO--if you're going for more than just the valves, have someone knowledgeable flow the ports. Rimco won't do that (that I know of), but FAT Performance in Orange CA will. Rimco will do the seats for FAT, but FAT does the porting.

A big cam (and carbs) will definitely benefit from the bigger valves and porting.

--DD

More important to copy the performance...
 

Oh boy do I have alot of studying to do before I can follow all of the excellent advice I'm given. Dave, all I want to duplicate, actually, is the performance from an acceleration and reliability standpoint. Does a 1.8 head with 2.0 valves and seats need additional modification to produce a reliable, relatively efficient, engine that has the performance of a 2.0 with a stock 2.0 crank, rods and p&cs (besides boring out for the larger p&cs)?

Rich,

All you have to do to duplicate the performance of 2.0 head is install the right size valve seats, trim out in the intake and exhaust port areas where the larger seats were installed and put in the larger valves---thats all---if you are not going to use D-jet injection.

GS

Rich, If you are going to run it with stock FI or 40 IDF, I just built my 1.8 L heads back stock for the 2.0L I built (saved $$$). It runs great and I feel it will be reliable. The valve sizes are close and for street applications are sufficent. I put a mild scat cam in mine and gives it around 100 HP. Good luck! Duane

Supposedly thhe different spark plug location and different combustion chamber shape work together to produce a better burn in the 2.0 head. How much power is that worth? I don't know--but I think you could more than make up the difference by having the ports flowed.

The 1.8 heads have more "meat" to work with than the 2.0 heads, so there is a good chance they will be more reliable and won't crack in the exhaust ports like the 2.0 ones do.

--DD