Tom M'Guinn

Any recommendations for the best ring compressors to use on the 944, particularly with an o-ringed block?

mark944turbo

http://www.sjdiscounttools.com/kd850.html

I use this style after trying 3 others, I find it best for adjustability and ease of use.

Jon Moeller

Tom,
I found the units from Summit to be fool-proof. And I think I'm a pretty effective fool.
Summit Compressor

Just get the correct size for your application.
-Jon

Ski

I like this one from Snap On, you can even see through some of the openings to see how everything is seated. If you use this one, better to save the head stud installation till after piston install.

Tom M'Guinn

Bret -- I actually have a very similar version, but the edges overlap and look like they'd overlap the o-ring in the cylinder tops.

Jon -- sadly they don't have one in the right size range for me... They have a fixed size version that is about .0015 inches (1.5 thousands) too big. Close enough?

Chris White

These are the ones to use, I have a couple of them to cover the whole 100mm to 108mm range.

Daniel Dudley

Don't forget to make sure you have a decent chamfer at the top of the cylinder. I think this is as crucial as the type of compressor.

Tom M'Guinn

They don't seem to sell an adjustable version to fit a 104.5mm (4.114 inch) bore. Closest they sell is a fixed diameter version at 4.115 inches, which will probably work (in light of the chamfer mentioned above).

Chris White

My adjustable one seems to work fine, I will check the sizing on it.

Tom M'Guinn

It's odd. The description of those compressors at Summit says they have almost an inch of adjustability, yet the specs show very narrow min-max ranges (e.g. 4.00 to 4.090).

Tom M'Guinn

Well, as it turns out, I assembled a small collection of compressors...

No. 1 is a pain, literally. It has razor sharp edges and was difficult to expand and contract without cutting my hands...

No. 2 is the best (made by ARP, sold by Summit). It has all the benefits No. 3, but also can be tightened and loosened, which is critical when the piston gets stuck in the sleeve. By far the easiest to use for me...

No. 3 is great (sold by Summit), but each sleeve works only for exactly one size of piston. Also, with a sleeve the same size as the bore, the pistons liked to get hung up in the sleeve, which is why I preferred No 2 above. With number 2, you can loosen the sleeve a bit, straighten the piston, and keep going. With No. 3, you have to work to get the piston unstuck and then start over.

No. 4 is good for most motors, but with an o-ringed block, the sleeve sits on top of the o-rings and can nick them.

just thought this might help someone down the road...

marcoturbo

I entirely agree about #1 compressor. Very unpleasant to use.

hosrom_951

Good info on different products Tom

chris951

I'll second that #1 is unpleasant. My old roommate and I were building an engine for his nissan 240 and we were trying to get the piston in and my roommate cut the **** out of his finger with that damn compressor!

Chris White

#2 is the way to go. No question about it.