Hi! I have a problem. I dis***embled the engine Chevrolet 235. There is a broken piston rings. My mechanic friend said it happened on the high-octane gasoline. I use a gasoline with an octane number of 80. In Russia, the gasoline removed from the sales. Russia will not lower gasoline 92 octane. What should I do? Who knows how to convert engine to a higher octane gasoline? Who did this? I know, need to mill the head of the engine block. For how long?
Hmmmm, never thought about too much octane in a motor, usually the problem is not enough octane (detonation). The only problem I can see from running too much octane is money being wasted for a fuel you don't need. All octane does is it makes the fuel mixture burn instead of explode, so I can't see how that would affect any rings like you had. You could mill the head a little to take advantage of the extra octane, but if it were me I would just rebuild the motor with good quality rings and call it a day. I think your problem came from another source, maybe like carbon buildup, lugging the motor, or something like that. Maybe one of our more versed engine guys will have a different opinion, but that is all I can think of. BTW, I never considered that you guys in Russia played around with cars too. Don
Yes, Don. We also play in the car. Thanks for the advice. In Russia there are many people making machine. Most street racing, but there are also fans of Hot Roding.
"Ya ne gavareeu na ruskom", but my Fathers people came from Czechoslovakia and the only word I ever learned was "net". Don
Russia, like the rest of Europe, rates its gasoline using the Research Octane Number (RON). 92 RON gasoline is the equivalent of 87 octane gasoline in the US. http://en.wikipedia.org/wiki/Octane_rating A stock 235 should run on that. EDIT: "Russia and CIS countries: 80 RON (76 MON) is the minimum available, the standard is 92 RON and 95 RON. 98 RON is available on some stations but it's usually quite expensive compared to the lower octane rating fuels." 80 RON gasoline might be too low for automotive use, and is probably intended for farm or other motorized equipment. 92 RON gasoline is what I would use.
Langdon's is a good source: http://www.stoveboltengineco.com/ Remember, the 235 was installed in cars and trucks built before there were motorways and were geared low. They typically did not go faster than 50 mph or about 80 km/h. If you want to go faster, change to a rear axle gear ratio that is higher (numerically lower) to lower engine RPM at speed.
Langdon's are good people. Maybe try Summit or Jegs as well. Sounds to me like the problem is too low of octane, detonation occurs. Worst thing to do would be to mill the head. Replace the rings, retard the timing and go from there.
Okay, but how many mill the head? I do not know. I know in Russian car. This is done by us. How many mill the Chevy, I do not know?
No, do not mill the head. Milling the head makes the compression higher. Higher compression means you need higher octane. You are not going to make your 235 engine a high perfomance engine. Just rebuild it stock, or with a little bit more power ( dual carb intake, headers, mild camshaft), and be happy with it. The more power you try to make with it, the more likely it will break, and it will have a shorter life. Not good if you have trouble finding parts in your country.
I need to know where to buy quality parts, I can buy from sites in the online store. This is no problem. One inconvenient to wait long for your arrival.
The compression isn't that high on a 235 in the first place, bumping it up half a point or so with a mill I don't think is even going to make you need to go over that 92 RON rated gas. They were building highways when these came out and plenty of folks drove them at 55, 65, 75 mph when they were relatively new without killing them. Of course, if you broke one it was a lot easier to find parts then, too.
You can get quality parts on ebay, if you buy name brand parts. For rings. TRW, or Federal Mogul are good starts. For antique engine parts, Egge Machine, in Texas is good. Kanter is expensive, but can get parts no one else has. There are many, many more, though. You should try to find a Hemmings magazine somewhere. They have many dealers of antique parts, listed in it.
Rustem, You should only mill the head if it is warped (the mating surface is not straight or flat) and you should only take as much off of it as you need to to make it straight. Broken piston rings is normally a sign that the cylinder to piston clearance is wrong. in your case unless the engine was just recently bores out it is most likely that the engine is loose. The clearance between the cylinder wall and the piston is too much. Unless this is something that you normally do yourself have your machinist check the clearance. I your engine is too lose you will need to bore it and get larger pistons. If you need pistons I can help you find them along with rings or other parts that you may need to rebuild your engine. If you want more compression you should do that with higher compression pistons, unless I was racing in your situation I would not go above 9:1. You should be able to go just fine with the stock compression. If you donot underatdn what I am saying PM me or post what it is that you donot understand, if I don't see your post someone will that can explain it better or use words that are easier to understand.
You can run a cam with a larger overlap (closer lobe centers) and bleed off some of that compression to keep it down. But the low end may suffer depending on what gear ratio you're running in the rearend.
Thank you! George<SCRIPT type=text/javascript> vbmenu_register("postmenu_7279547", true); </SCRIPT> porkn******<SCRIPT type=text/javascript> vbmenu_register("postmenu_7279546", true); </SCRIPT> chopolds<SCRIPT type=text/javascript> vbmenu_register("postmenu_7279542", true); </SCRIPT> rustynewyorker<SCRIPT type=text/javascript> vbmenu_register("postmenu_7279541", true); </SCRIPT> Very useful information! I will copy the branch site itself. Thank you. I measured the compression and I have it 9-10. I got this engine from the U.S.. It could be repaired several times. I'll Gaugeable him the other day. This is the engine block 1962 and head 1956
If your mechanic told you that high octane gas broke the piston ring, maybe you should look for a new mechanic, rings break for many reasons high octane gas isn't one of them.
Broken piston rings are a sign of or due to one of the following: detonation due to either low octane or the timing being wrong. A sign of this would be pitting in the tops of the pistons and maybe erosion of the top edge of the piston. . The wear ridge in the cylinder not being cut out before new rings are installed. Improper installation. The ring gap being too small and not allowing for expansion. Excessive wear in the cylinder which allows too much cylinder taper. This would cause the rings to have to spread and contract on each piston stroke. There are probably some other reasons but those are the main ones. I've purchased several engine rering kits from Northern Auto Parts an online discount type auto parts vendor here in the US with good luck. They have a rering kit (no pistons) for a 235 http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=988 that includes rings, rod and main bearings and gaskets but a person may be able to find a better price.
In the original post, you said 80 octane. It would seem odd if you bought the fuel at a regular gas station and it was that low though...I think a lot more cars would suffer detonation issues. Could the octane rating of the fuel you're running be too low and detonation caused the rings to break? If that's what happened, then raising the compression would really hurt, not help.
Here are some places you might want to try for parts. http://www.jegs.com/ http://www.summitracing.com/?gclid=CJeKl6OVo60CFQhjhwod8Dbr8w http://www.egge.com/
Along with the other possable causes for broken rings, when it's cold over there do you use either starting fluid. To heavy of a shot of that stuff will break rings and ring lands.
My '37 Chevy (stock 6 cyl, 216 ci engine) had an octane selector device on it, as the gasoline octane varied from place to place and was quite a bit lower than today's gas (in the USA). All the octane selector did was to advance or retard the distributor to match the octane being used. If your engine pinged, you adjusted the selector as follows, taken from the shop manual: "The octane selector should be adjusted with the aid of an electric tachometer. Maximum engine performance will be obtained when the octane selector is set to the maximum revolutions per minute at a given throttle position under load. If an electric tachometer is not available, set the octane selector so the engine just starts to ping under full load acelleration with the throttle wide open." The octane selector could be advanced or retarded up to 10° from zero. Adjust your timing to suit your gas and the 235 should run without problems. Hope this helps. -Bob
TagMan<SCRIPT type=text/javascript> vbmenu_register("postmenu_7281287", true); </SCRIPT> Very interesting! Please be more about octane corrector! If it is not difficult to send the photo and where to buy. thank you
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