As long as the converter gutted itself out instead of plugging up, that worked fine. If it did plug, it could be removed and hollowed out. Many people did this. High octane no lead was not available for several years after 1975.

My 75 compression ratio in my L-48 is only 8.5:1
The 75 L-82 is 9:1 Nothing Spectacular by any means.

Oh yea those guys that only cruised around town and didn't open it up for a prolonged period did "muffle up" never saw one totally plug off just not flow so good and back pressure knock like crazy. Didn't realize super un-leaded was that late, but remember super leaded, well everthing leaded, disappeard quick when both "octanes" of un-leaded appeared everywhere. Took awhile for some stations to convert. Gotta remember when there was NO self service stations. Ahhh nastalgia of the old days . .

MIkey and his beast (winter project)

kstyer said: As long as the converter gutted itself out instead of plugging up, that worked fine. If it did plug, it could be removed and hollowed out. Many people did this. High octane no lead was not available for several years after 1975. My 75 compression ratio in my L-48 is only 8.5:1 The 75 L-82 is 9:1 Nothing Spectacular by any means.

did the drop in compression ratio have anything to do with switching from leaded to unleaded gas ??

i had always understood it was a contributing factor and with less compression comes less power..

i guess this is what i was trying to say in the above post..

The 77 I had was low compression and used a bit of oil, which the Dealer said was normal, but still ran well enough for the time of the "energy crunch", after all it was a vette and all the ladies wanted a ride up and down the drag.

MIkey and his beast (project)

Less compression was due to emissions, but not leaded gas. The lead and the compression are not really linked. Lead did affect octane, but octane was the derived by other chemicals, and the lead had no affect on performance. It did create lead poisioning to both people and converters. In later years it killed oxygen sensors as well.

And yes, less compression does much mean less power. Punch some numbers into the desktop dyno program and watch the drastic difference when changing nothing but compression.

But the compression drop was a seperate issue to help clean up other emissions. HC and CO, and for a large part, NOx.

|UPDATED|1/2/2005 9:50:47 PM (AZT)|/UPDATED|

But did the low octane unleaded of the early years influence the auto manufacturers to build only low compression motors or did the low compression motors influence the petroleum manufacturers to only supply low octane gas?
The Corvette Black Book states that in 1971 compression ratios were lowered to permit use of lower lead and no lead fuels.
Mike

The one or two brain cells that survived that era recalls advertising connecting low compression with EPA compliance for emissions AND mileage.
Maybe those cells are confused!!!!

MIkey and his beast (project)

mkapp7879 said: But did the low octane unleaded of the early years influence the auto manufacturers to build only low compression motors or did the low compression motors influence the petroleum manufacturers to only supply low octane gas? The Corvette Black Book states that in 1971 compression ratios were lowered to permit use of lower lead and no lead fuels. Mike

ahh yes... maybe that is where I heard that

which came first?? the chicken or the egg ??

The original no lead was low octane to take advantage of the fact more cars used low octane than high octane. Plus it was cheaper that way, and thus more likely to purchased by customers, and more accepted by those who did need to have it.

In the experimental theater, there was high octane no lead that worked fine, but it did not hit the market for years. It was quite a bit more pricy. The manufactures went with the program to make the feds happy, and encourage the public to buy cheaper fueled cars, instead of trying to sell cars the required that special expensive gas.

A lot of it was practicality, and a lot was promotion and advertising. All of it was to meet the Federal Standards.

|UPDATED|1/4/2005 7:40:23 PM (AZT)|/UPDATED|

Seems I recall some people putting mothballs (camphor) in their gas tanks to raise the octane. I never was brave enough to try it though.
Another trick I never tried; when all you could get was NoLead gas, some of the guys would put a gallon of diesel fuel in the tank. Never did understand that one!