I have a 235 with 500 miles on the rebuild of bottom end and 300 miles on top end rebuild. New pistons the works, the rings are Crome. Break in oil was used for the first 500 miles Just changed the oil to a straight 30 w and the other day decided to run a compression test. The book states 130 psi min. I came up with #1 100 psi. # 2. 100. #3. 90. # 4 90. # 5 90. #. 6. 90. Truck runs good. Could have more power but runs good. I have heard that Crome rings can take a long time to seat. Could this be the issue for the low pressure. I does not burn or use a lot of oil For the first 300 it used a quart but not much since and it does not seem to have a lot of blow by coming out the crankcase tube. So do I have an issue or do I need to wait longer for the Crome rings to seat fully. Any help in this matter would be greatly appreciated. The top end rebuild was every thing including new rockers. This engine has a 1959 block with a 1954 head. Thanks again for any help.
Poor compression Skiter Find out what 235 engine you have ( 105 hp, 115 hp 0r 136 hp) ? Your fresh overhauled engine shows much to low compression. After 500 miles these New piston rings should have been seated. As you stated 130 PSI and moore when engine is hot is rather commen. Did you installed New valves/seats aswell ? Have you checked how the engine valves open and Close . Maybe some adjustment is needed here ? If you wanna check your compression again follow the firing order .Check the liabillety of the compression meter! Engine spesifications in prod. year. http://www.secondchancegarage.com/public/468.cfm Hope this is of some help . Martinius.
Don't want to miss something obvious like being sure the throttle was blocked open when you did the testing.
While low, those numbers are very consistent. That's a good thing. And you said it runs well. Put the gage away -- drive it and enjoy.
What I would do... What I would do is double and triple check the full route of checking the valves...make sure they are where they should be....they need to be right on. Next, make sure your compression tester is working right...check another modern good engine to make sure it is working properly. And finally, make sure you are checking it the right way...I forget details, but years ago...I had been doing it wrong. My numbers were kinda like yours until I did all of the above. rod
Thank you Come to find out I was doing the test wrong. Thanks for all the help really. Ended up with 140/137/142/143/138/136. D. 145/145/148/144/141/140 w. Looks good to me. It also ended up being the 115 hp engine. And yes I did replace all valves and spring. Thanks again everybody
Did not pull all plugs I pulled the plugs one at a time and did not open the carb wide , and the engine was not warm . Second time around engine warm, carb wide open and pulled all the plugs before starting test. Thanks again to you all for steering me in the right direction.
Routine Compression Test I hope you've adjusted the valves again by now and know to keep cranking the engine until the gauge stops rising..... Those current #'s look good . FWIW , correctly done , pistons rings bed in in the first 60 seconds of initial operation , doesn't matter what typ of rings are used , lots of whacky old wive's tales still around . Chrome rings are great .
I think this is the answer to at least one of my questions, but thought I'd float it by the group to see if there's a consensus. When a Stovebolt is bored and honed, is it best to use Chrome or Cast rings? (I assume Chrome, and Patrick's has them listed in many common oversizes for a reasonable price. Or is there another recommended source or brand?) I am not finding a source for moly rings for a 261 (3.75" or common overbore with the 261 groove sizes). Does anyone know of one, or should I just go with Chrome? I've also heard choose Cast when replacing rings without machining, only breaking glaze with a ball hone. Sound right? Thanks y'all.
Piston Rings Actually Chrome rings will probably be what you want , there are ' gapless ' rings you can get , they increase compression and reduce blowby significantly . If they don't stock them you'll have to mail them one piston and they'll make you up a set , IIRC it's Red Line Performance in Van Nuys , Ca. that sells them , well worth the effort if you can wait the few weeks . I no longer glaze break / hone any cylinders unless they have longitudal marks in the cylinders as the proper 60 second bedding it obviates the need .
Pat gets most of his internal engine parts from Egge Machine. I would go directly to Egge & eliminate the middle man mark up. http://www.egge.com/about.shtml http://www.egge.com/site/?d=48&dt=1&SubCategoryId=22 .
I never removed all the plugs nor open the throttle and this is what i got on mine after 800 miles after a full rebuild.
Talked with Patrick's today. The rings they carry are from Egge, but are cast (not chrome). Also not finding a source for the gapless rings for a 261. Nate, are you sure that was Red Line in Van Nuys? There are several different "Red Line"s, and none of them are advertising gapless rings....
Both gapless & chrome rings are avail. from our wholesale sources but..... We wouldn't want to be accused of creating a "Grey Market" on them.
HA! Touche'.. I talked with the folks at Total Seal. For the 3/32 top and middle grooves on a 261 piston, they can do gapless top chrome rings in 3.750 (STD), 3.760 (+.010), or 3.780 (+.030); with Napier seconds and standard tension oil rings for "only" $264 for a set of 6.
Gapless Piston Rings Total Seal is the brand , I am pretty sure I bought mine @ Red Line Performance , maybe it was Top Line Performance ? . Danged if I can remember , I was looking at a box of them Saturday but no receipt . Be SURE to read and follow the assembly and bedding in directions ! this is critical and it takes a HUGE leap of faith to do , I have been doing it this way for decades and the improved compression and longer life is amazing .
Sorry ! I was cleaning up to - day and found the info : Top End Performance 4752 Varna Av. North Hollywood , Ca. 91605 www.topendperformance.com
