Hi Guys-I'm talking with a fellow about his NOM '64 coupe (for sale) who says the tach has 5000 yellow line and a 5300 orange (red?) markings on it. He also says the oil gage has 80 as max on it. Do these markings indicate the original HP? Also where would I find info like this on C2's? Thanks.
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Re: C2 tach & gage markings
My '64 Convertible with the original 327/300 engine has the same gauges - 5K yellow line with a 5.3K red line and 80 PSI oil gauge. I believe the 327/250 HP cars had the same gauges.
A good source for this type of information (as well as lots of other stuff) is Noland Adam's Restoration Guide, Vol. 2. Volume 2 covers C2s. -
Re: C2 tach & gage markings
A 5300 RPM redline tach indicates a base 250 HP engine or the optional 300 HP L-75. Another good source of detailed information that you seek is the NCRS Judging Guide.
DukeComment
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Re: C2 tach & gage markings
Tony:
For 1965, only the SHP engines used the 80psi press gauge. All others, including the L79 (350HP)which used the high redline tach, used the 60psi gauge. I find it hard to believe that it was any different in 1964. Check the 1964 TIM&JG, the answer will be there. Post what you find, I'm sure many of us would be interested.
JoeComment
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Re: C2 tach & gage markings
Funny,
I was just going to post the same question. I have a 63 coupe with a yellow line at 50 and redline at 53. The Oil gauge is 60. Since someone replaced the block with a 350, I have been trying to determine the correct HP to put back into the car. I assume from what everyone is saying, we are leaning toward the 250HP with these readings?
Thanks for the info btw.
DaveComment
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Duke knows!!!!
You'll find the '63-64 JG book lists 80# oil and 5500 RPM gauges as correct for both 250 and 300 HP Corvettes EXCEPT for early '63 cars where ALL engine configurations used 60# oil pressure gauges....Comment
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Re: Duke knows!!!!
:-)
My VIN#30837S111272 indicated almost right in the middle..... not a big help I guess..... oh well have to keep trying I guess.
ThanksComment
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Duke just reads the JG and AIM change record
Okay, here is the deal for '63. Late in production GM changed the bypass spring on the oil pump to increase SHP/FI oil pressure from nominally 45 to 60 psi. Base and HP engines (250/300 HP) retained the early spring and 45 psi.
Concurrent with the change in oil pressure on SHP/FI engines, a companion change replaced the 60 psi gage with a 80 psi gage, but the JG says that this is not consistent with engine option, and either gage is acceptable with any engine after sequence number 16000. Now, it is my believe that the correct configuration would be 80 psi gage with SHP/FI engines and 60 psi gage with base/HP engines, but it could be there were substitutions due to component shortages,which leads to inconsistency in the observed record.
Now, here's where things get tricky, Jack. According to the JG ALL '64 engies have an 80 psi gage! This was new to me when I read it.
Later in production we all believe that only the SHP/FI engines carried a 80 psi gage while medium performance engines continued with the 45 psi relief spring and a 60 PSI gage.
The bottom line for you, Tony, is that NCRS says an 80 psi gage is CORRECT for all '64s and if you had a 60 PSI gage, regardless of installed engine/tach redline, you would likely receive a deduction.
DukeComment
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Re: C2 tach & gage markings
David:
Your original motor would be either standard (250HP), or L75 (300HP).The SHP motors for 1963 (340 Duntov cammed, and 360 fuelie), used the hi rev tach, with the 80 psi gauge.
JoeComment
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Re: C2 tach & gage markings
Duke,
Let's see if we can muddy the waters some more. I have a 1965 365 hp with the 6500 rpm redline. The water temp gage reads to 250. I was told by one of the instrument rebuild vendors that in 65 many people experienced high water temp readings, and feared overheating problems. The solution was, Chevrolet authorized and/or supplied replacements that read 250. The JG says all were 240 for 65, so I am interested in feedback on this. I am sure mine is a replacement, as is the 60 lb oil pressure gage which I have just sent out to have converted to 80 lbs. I am interested to hear if anyone else has heard or seen this.
Thanks in advance for yor response.
George
Member # 36809Comment
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Re: C2 tach & gage markings
Untouched original temp gauge in my April build L78 is 240F with NO color coding on it and she's a spitting image of the GM promo shot shown on page 256 of Noland Adams' Vol 2 book. Don't know about cars running hot/gauges reading too high because mine rarely goes above 180F. Oil pressure is 80 lb as was used with all solid lifter engines in '65.
The 240F temp gauge is a 1-year only item ('65) as earlier mid-year gauges used the stylized 'bent' needle pointer. In '66, the temp face was changed to make 250F the upper limit gradicule with the last 10 degree swing accented with a yellow/red warning band.
Original '65, non-colored, 240F temp gauges are somewhat hard to come by (short lived run) as service spares commonly encountered were the later '66/67 250F gauge with colored warning accent (one part fits all -- '65-67).Comment
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Re: C2 tach & gage markings
George - unfortunately my experience and observations at this level of detail are limited to '63 models, but I hope other '65 owners can chime in.
I don't have anything worthwhile to offer on the temp gage issue, but as far as I know, the engineering change that increased the oil pressure on '63 SHP/FI engines (which included the 80 psi gage) carried through to 365/375HP engines through '65, but I'm not sure if it included the 350HP engine - SHP with hydraulic lifters in parts catalog lingo.
My question for you is: Does your oil pressure run closer to 55-60 or 40-45 psi? My bet is that it runs near 60.
DukeComment
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Re: C2 tach & gage markings
Jack,
Mine has the exact 250 degree gage you are talking about as was used in 66. I have no doubt it was replaced. I was interested in the story about GM dealers replacing them due to high readings, not sure if that was a common issue. Mine also seem to hang right at 180, thankfully no overheating issues.
Thanks,
GeorgeComment
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Re: C2 tach & gage markings
Duke,
Thanks for your response, I am sure my gage was replaced. On the oil pressure, mine too is always running at 55 to 60 lbs. I was a little nervous with it until I read that the car should have an 80 lb gage. In my younger days I was one of those guys who added a washer to the oil pump spring to increase the oil pressure. I have sent the gage out for recalibrating and screening to make it right.
Thank you,
GeorgeComment
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Re: C2 tach & gage markings
Well-that Q stirred up the bees!!
Thanks for all the info guys-it helps. I'm gonna buy a judging manual shortly.
TonyComment
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