High or Low Compression

[grslightng02]

I just pulled a 1.9 L motor from a 1969 GT. I'm guessing it's the High Compression motor. Are there any ways of identifying that this is actually the high compression motor(without tearing the motor apart), and not a low compression engine that was swapped?

Also if I wanted to maximize power by boring the motor out to a 2.2 or 2.4 would the high compression parts make any difference?

[namba209]

The easiest way to check for a high compression engine is to bring a piston up to TDC and see it it is a "dished" or flat top piston. That's the only difference between the two engiknes. So if you bore out the engine, you'll have to replace the pistons. The other indication on some early high comnpression engines is the change from a 3 bearing cam and solid lifters, with a 10 bolt head, to a 4 bearing cam and hydraulic lifters, and a 12 bolt head, but all low compression engines had the 4 bearing cam set up. HTH.

[grslightng02]

Excellent thanks for the info.

Neil

[GTJIM]

From a study done some time ago it looks like the earlier HI-comp motors have an Engine Number with a * stamped at each end of the number on the engine pad. Lo-comp ones have a * at one end only.

Hi-comp *19S ######*

Lo-comp *19S ###### or 19S ######*

[2 Fast 4 U]

In Europe we have the folowing codes:
High compression [S] engines:

*19S 123456*
16S-123456

Low compression [N] engines:

19*123456
16*123456

[namba209]

That's all true for the original engine configuration, but, after all the years gone by since new, there could have been changes made and may not reflect the block cast markings.

[wrench459]

Originally Posted by grslightng02 Also if I wanted to maximize power by boring the motor out to a 2.2 or 2.4 would the high compression parts make any difference?

Todays late model cars are running over 10:1 c/r on pump 87 gas.
I dont know any performance guys wanting a low compression engine.
Oh the supercharges my Bad!

[OriginalOpelGTOwner]

I just checked my 1971 Opel GT engine serial number. Mine has the 2 *,s. Reads like *19S 123456 *. My opel was manufactered January, 1971. Based on the notes above is it really possible I may have high compression pistons? Next time I pull the plugs I will check the top of the pistons to see if they are NOT dished out. Interesting....