Vyktr

Good Morning folks. First post here on this for me. I found numbers matching 66 Holiday Coupe, all original and in good survivor shape. I have been cleaning and repairing all the minor issues to get it on the road. I have not 100% sure it is a high-compression 330, but it looks like it. I have only gotten this far cleaning, but from what I can see, it is a 330 High Compression, it has the Jetaway behind it, and the Quadrajet has been replaced.

Does anyone know for sure if this is the High-Compression motor?



CA car built in Fremont. Mostly surface "patina"



Right Head Stamping

Right Head read #3

Block

Sugar Bear

Borescope a cylinder and post a pic of the piston. It's the piston not the head on that engine for HC vs. LC

Nice find, good luck with it!
​​

Vyktr

I will do the motor and heads a match with the vin But it gives me the opportunity to use my bore scope

Sugar Bear

Try to get a picture showing the amount dish and the notches or "V" at the outer edge of the piston.

joe_padavano

ASSUMING the heads are original to that motor, the "G" suffix on the engine unit number indicates a high compression motor. As noted, only the size of the piston dish will tell for sure.

Vyktr

Here is one of the 8


cly 4

The notch looks V shaped to me I would say.

Sugar Bear

The notch looks like a V, if yes it's HC. Looks like mild detonation on the piston tops??? run premium fuel and check the timing.

A nice find...enjoy!!!

Vyktr

Thanks, man I just got it and am cleaning up the mechanicals. I will run good gas in it. The car has been sitting for quite a while

since I have to change the water pump. I am going to do the timing chain and such at the same time. I pulled it all apart on the front of the motor right after taking the bore scope pictures. I was going to do the cam, but it appears that the cam is interesting to source. So it's getting timing chain, intake, and some headers.

Thanks again.

Sugar Bear

When doing the timing chain line up #1 TDC on the
​​​COMPRESSION stroke, remove the front cover and take a picture. Reassemble the new gears and chain and take another picture. All necessary? No, save some second guessing and head scratching later? Yep.

Good luck!!!

edzolz

One of the best things you can do is get rid of that Holly carb and get a good rebuilt Q-jet and learn to tune it properly.

Vyktr

We all have our opinions; quite frankly, mine is not good on the Q-Jet. I have no issues tuning it; that particular carb was on it when I got it. It will stay carburated until I fab up a manifold for sequential multiport fuel injection at one point. But thank you again for your thoughts. I was having issues with how to make 100% sure I had the High-Compression 330. I did not find the post about the U and V notches being the only way to be 100% sure.

This one will be mostly stock unlike my 71

joe_padavano

The Chassis Service Manual clearly shows the different pistons. The depth of the dish is far more obvious than the notch.

Cutlass Fan

I may be mistaken but didn't the 66 come with a Rochester 4gc carb, I thought 67 was the first use of the Qjet on the 330.

66SportCoupe

The 330 got the Qjet for the first time in 1966.

Oldsmaniac

PS full tube headers will be difficult to find. I believe shorties are available.

lunaboy

The low comprsson 330 is a good engine because it runs well on todays pump gas; you can even use a two to four barrel carb adapter if desired or change the intake..
Seems like more 330 low compression engines from 64 -67 are still running and survived since the leaded fuels came along.

I like your 66 factory two tone paint. My 442 is the same color, with the black painted top not your white.