2.0 Heads on 1.8 case

03-23-1999, 06:22 PM

Quick question, can 2.0 heads bolt onto a 1.8 engine case without any mods?

Dave at Pelican Parts · Dave at Pelican Parts's Garage

No problems with the case. Don't know about the cylinders. Supposedly the 2.0 cylinders fit on the 1.8 heads, but I don't know about the other way around. There is only a 1mm difference in diameter (93mm vs. 94mm), but it is a difference.

--DD

JP Noonan · 03-24-1999, 01:23 PM

The 1.7L heads only fit 1.7L cylinders. 1.8L heads fit on 2.0L cylinders and visa-versa. So quick answer is yes, but the intake tubes won't fit. Maybe you can drill an extra hole for the third intake stud, but I think the 2.0L intake tubes are also larger so try and find the 2.0L tubes. With the 2.0L heads you get larger vavles and a better port design, you also get more frequent cranks in the head because of the sparkplug hole placement. Which reminds me, you also will need to either find 2.0L tinware or modify the 1.8/1.7 tin.

BTW the 1mm difference is in the bore not the outside of the cylinder. Also all type IV cylinders fit in any of the cases, the sigot hole as it is called, is the same.

PeterB · 03-31-1999, 02:31 PM

Note that in changing from 1.8 heads to 2.0 heads, you also create exhaust compatibility problems. If I recall correctly, the 1.8's use the four-bolt exhaust manifold/headers; the 2.0's have only three bolts.

JP Noonan · 03-31-1999, 05:16 PM

Ummmm, not that I'm aware of.

The INTAKE studs are different, 3 vs 4, but on the type-iv all the exhaust primaries are the same except for the late 80-83 2.0L bus motors which had a rectangular opening.

Unless you mean the muffler flange. the 70-73 1.7L and 74 1.8L have a "header" (four seperate tubes) type heat exchanger. The 73-74 2.0L have a very similar one but the tubes bend slightly at the muffler end on the 1.7-1.8L and the 2.0L go straight. The 75-76 2.0L and 1.8L have a more restrictive "manifold" type double back exhaust.

They all have 3 bolts connecting the H.E. to the mufler, but the pre-75 have two holes going in, the post 74 only have one.

(a side note: Using cheap calipers, the 1.8L SSI exchangers seem to have the same O.D. as the SSI 2.0L ones).