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View Full Version : TIII Ring gaps for 2.5L TIII Venolias



iTurbo
10-10-2015, 06:23 PM
I'm assembling a 2.5L TIII with Venolia pistons that is bored .020" over. I'm in in the process of measuring ring gaps and have found a few rings that are out of spec according to the '91 FSM.

This engine was previously assembled by a local machine shop, but I tore it all apart (0 miles/no startup), to check everything out now that I actually know how to build an engine myself...

A couple of the "top ring" gaps are measuring a gap of .030". I'm measuring the gaps by pressing the ring down the bores (with a piston so they are square in the bore) about 5/8" from the bottom in accordance with the FSM. Looking at the ring I can tell that the machine shop file fit these somewhat as there are filing marks on one end.

Do I need to buy a new set of rings and set them myself? I'm concerned that the .030" gap is too large but maybe that is OK with the forged Venolias.

The last TIII I built was a 2.2L with stock TIII pistons and everything checked out perfect with the FSM and that engine is still rocking. Seems like the top/bottom ring gaps should be more like .017-.020"......not .030" like I am seeing with this one.

I would really appreciate some quick help with this because I'm on vacation for the next two weeks and am now stumped. I have many engines to build so the holdup sucks.

iTurbo
10-10-2015, 10:03 PM
Well, I guess it doesn't really matter. Who in there right mind would want a .030" ring gap on any ring? Going to buy another set and do them myself. So frustrated. These ring gaps are all over the place. I checked twice just to be sure. They even filed the oil control ring gaps too big.

rx2mazda
10-11-2015, 12:14 AM
Well, I guess it doesn't really matter. Who in there right mind would want a .030" ring gap on any ring? Going to buy another set and do them myself. So frustrated. These ring gaps are all over the place. I checked twice just to be sure. They even filed the oil control ring gaps too big.

From Venolia Tech section......

Ring Clearance: Side Clearance .003 - .004 ring gap. .004 - .005 per inch of bore.
RING CLEARANCE: Side Clearance .003 to .004 ring gap: .004 to .005 per inch of bore.


RING CLEARANCE: Side Clearance .003 to .004 ring gap: .004 to .005 per inch of bore.

Ondonti
10-11-2015, 04:06 AM
Dont worry about the oil rings. Random gaps on the others sounds like an old worn out factory motor.

Force Fed Mopar
10-11-2015, 09:03 AM
I just did a 2.2 TIII w/ Wiseco pistons, I set them at .020 and .022, slightly on the large side maybe but he's shooting for over 400hp so wanted a little cushion. Remember the top ring will expand slightly more as it sees more heat.

Pat
10-11-2015, 10:14 AM
I typically run them loose, bit not quite that loose. Current street/strip motor is .020/.022 and it's fine. Built a race motor for Barry and we tried very loose with .024/.026 and it sealed up nicely.

Shadow
10-11-2015, 10:28 AM
I have never gone more than .020 on the top ring and bottom .022-.024

iTurbo
10-11-2015, 10:44 AM
Thanks guys. I forgot if I these Venolias take the E453K or E640K ring package. Might have to call Cindy on that one.

iTurbo
10-11-2015, 06:48 PM
Dont worry about the oil rings. Random gaps on the others sounds like an old worn out factory motor.

This is something I have wondered a lot about lately. Just how critical are the oil ring gaps? I see the specs and a service limit for them in the FSM, but until this motor I've been lucky enough not to have to touch them as they have been correct right out of the box. I was surprised that the machine shop had filed them and they were sort of all over the place too.

It's really tricky just trying to measure the gap as the oil rings are so thin that they tend to move around easily with the slightest pressure of the feeler gauges.

glhs727
10-11-2015, 09:49 PM
Our Venolia's take the E453K

iTurbo
10-11-2015, 09:57 PM
Thanks Cindy!!

iTurbo
10-17-2015, 01:38 AM
What kind of tool are you guys using to file rings to fit?

I guess I got lucky on my first two motors....all the rings measured great right out of the box....but this one.....015" seems a bit tight with the new E453K ring package.

Ondonti
10-17-2015, 04:44 AM
What kind of tool are you guys using to file rings to fit?

I guess I got lucky on my first two motors....all the rings measured great right out of the box....but this one.....015" seems a bit tight with the new E453K ring package.

Summit hand crank ring file.

iTurbo
10-17-2015, 04:52 AM
OK here's what I got. This is with a brand new set of untouched Sealed Power E453K +.020" rings. After trying as hard as I could to get the most accurate measurements with feeler gauges and using the method outlined in the '91 FSM. I used a flashlight and kept the feeler gauge as close to perpendicular to the ring as possible.I used a piston to press the rings into the bore to get them square near the bottom and started all over again if the feeler gauges pushed them out of square...I feel like I attained a good 'feel' for it believe me I got really good at flicking back and forth between feeler gauges getting the best measurement.

Top to bottom

#1: .015
.019
.028
.028

#2: .015
.020
.028
.028

#3: .015
.021
.028
.030

#4: .014
.020
.028
.028


These are the gaps with no filing. I'm thinking installing these rings "as-is" with no filing. For a motor that will probably make no more than 300 WHP. Thoughts? It seems a bit tight but....I'm amazed at the close manufacturing tolerances with these. This will be my 3rd engine build (all 2.2L) with untouched out-of-the-box Sealed Power rings.

EDIT: I'd post pics but....yeah right.

going4speed
10-17-2015, 10:02 AM
14 thou for a top ring seems awful small. In a non turbo might be fine but I would not be comfortable in a turbo motor with that tight a gap. I prefer between 18 and 20 for a street motor.

Shadow
10-17-2015, 11:23 AM
If you're seriously not going to make more than 300WHP and on relatively low boost, I think you will be fine with those gaps ;)

iTurbo
10-17-2015, 05:28 PM
Just building a fun street car here. It will, in all honestly, be just fine at 250 HP with a Buick GN (Super 70) turbo at 15-16 psi. I have enough irons in the fire! 91 octane only.

Force Fed Mopar
10-17-2015, 06:08 PM
Summit hand crank ring file.

Same here.

Ondonti
10-18-2015, 06:25 AM
If you're seriously not going to make more than 300WHP and on relatively low boost, I think you will be fine with those gaps ;)

I don't forsee things going perfectly. I haven't seen him carrying the charmed life banner. Shooting for the small end of the OEM ring gap spec for more than twice the OEM WHP is how you find weapons of mass destruction.

iTurbo
10-18-2015, 02:02 PM
No charmed life here for sure, but on the last TIII motor I built, the top/bottom rings were in the .017-.019 range if I remember right. It's still going strong despite being upgraded since then with 50-trim TO4E, big intercooler etc, and ~25 psi boost.

And looking for 250 WHP isn't twice OEM WHP. If it breaks I will post all about it and eat crow.