A friend of mine has tried a couple and says the best one he has used is the Snap-on. He said that it has a great picture that come in clear and bright, bright being the key word in dark areas. He said that the screen picture on the other ones in the dark was poor. I thought he said it was around $600.00 but well worth it with a lifetime guarantee.

Just be aware of the diameter of the scope cable, be sure to get one small enough diameter to fit into the spark plug hole. I got one really inexpensively and it is "just this much" too big. Next size down diameter wise 3 X price.

Rigid CA-300 about $450, that is what we use at my work and they work great I will be getting one for home also.

Snap on makes a few good ones around 400 bucks I think they have one that can actually send pictures wirelessly also save photos and has a bright light on the end which is important btw they have a one year only warranty on electronics

+1 on warranty.....snap on is not the snap on I started wasting tens of thousands of bucks on 30 yrs ago...

Thanks for the advice.

Just looked into some of the models mentioned. The Ridgid has some decent features including the ability to capture and store pics and video, but it has a 17mm head which looks huge in the video. 1yr warranty and a was $450ish. The $375 Snap on looks pretty basic has a 8mm head and a slight improvement in resolution with a 2yr warranty. The Harbor Freight unit with the fixed head is under $100 and actually gets pretty decent reviews. It has the best resolution and a 90day warranty that you can extend. They don't list the head size but it was noted it will not fit into a 14mm plug hole. It was also reported that it couldn't be used to view closer than 1in. because of the focus. I'm worried about that 1 inch issue. What size is the plug hole on a big block?