I am looking at a 66 427/425hp. I believe the car is a 427 because of the things I checked, But I am wondering if this car was not origionaly a 390hp? Other than the intake, carb and 80lb oil gauge what can I check to see that this is really a 425 and not a 390? Help before I may spend a lot of extra money. Thanks Bill
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Re: 66 Corvette 425HP??
Bill,
The tach red line......can you tell if the guage cluster has been out or not? If you can get the Gage Cluster numbers off the white sticker on the back of the cluster you can compare with other 425 HP owners.....does not mean cluster was not changed but it can be an indication. Good luck with this..... -
Re: 66 Corvette 425HP??
stamp pad????Comment
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Re: 66 Corvette 425HP??
Bill,
As someone said "Stamp pad". On the engine stamp pad the suffix should be either IP (427/425/special cam/mech lifters/4 speed) or IK (same but with M22 4 speed). However, I understand there are unlisted codes IT (heavy duty 425)and IU (alum heads). On my 66 427/390 the suffix is IL. If you think the numbers have been messed around with, look for another car.
A couple of specification / history sites that help ID a car.
http://www.corvette.net/tech.htm
Good luck
JimComment
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Re: 66 Corvette 425HP?? Previously 390 HP??
I want to confirm that this was not origionaly a 390 and the engine was changed to a 425 HP and restamped. I looked at the broach lines they look good and engine numbers say 425hp. Is there anything different on the car, other than the tach and oil gauge?Comment
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Re: 66 Corvette 425HP?? Previously 390 HP??
L-72's had Trans. Ign., L-36 did not.Comment
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Re: 66 Corvette 425HP??
With respect to Kurt's posting, you should be able to tell from the engine compartment wiring harness(es) if it originally had Transister Ignition, even if it has since been removed.Comment
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Determine by what is there and shouldn't be.
With the 390 hp, you could easily have items that should not be on the 425 hp, and vice versa. For example, if it is a transistor igntion, then holes where the coil ballast resistor mounted should not be there.
I can't remember, but I believe that would mean only one small wire on the solenoid. Without looking it up, I don't know it the 425 hp solenoid is different and would not have a switched 12 volts to the coil as a result (outside small bolt goes to coil, inside to ign sw purple wire).
The only transmission was the 2.20 close ratio four speed, so check nothing else was in.
As such, there should not have been an automatic installed nor the cooler with it.
Check for power steering, the mounting locations, the plugs in the steering arms, and so on.
Alternator bracket with the PS is different than the non-PS car.
The 425 hp block would have the large oil line plugs above the oil filter for external connection, but the 390 won't. You didn't mention them but the heads are different. So is the distributor. Many often leave an existing distributor and those were frequently changed.
Of course, in a really high-dollar restoration, these things could all be changed or covered, so you will still have an amount of uncertainty.
A lot simply has to be gut feeling, with the owner and yourself. For all the fuss here in the past on restamped blocks and broach marks, an unstamped block could be stamped and then the broach marks are correct.Comment
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the TI uses a full 12 volts from the starter
while cranking the engine so the extra terminal on the solenoid is usedComment
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But doesn't the TI use the full 12 v
all the time? Hence, no need for the resistor and so the supply at the firewall is 12v, and doesn't have to be bypassed by the switched 12 from the solenoid?Comment
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Re: But doesn't the TI use the full 12 v
Mike,
The TI system still uses resistance wire in the harness instead of a balast resistor on the IP. It cranks on 12V just like a conventional point ign system, then runs on the reduced value through the resistor wire. The engine harness is almost exactly the same as a non TI harness and attaches to the solenoid terminals the same way.
I have a nice diagram here somewhere and can send if interested. (if I can fibd it)
MichaelComment
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the 12 volt power lead is a resistance wire
the big white wire is a resistance wire feeding the systemComment
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TI uses Two resistive wires.
I went back to the diagrams and found they run a resistance wire from the ign switch to the amplifier to supply it and they run a resistance wire from the amplifier to the coil.
I also double-checked and found the GM capacitance discharge system used no resistance wires and I was probably thinking about that.
Need to double-check those things before writing.Comment
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Re: 66 Corvette 425HP??
Doesn't the 390 hp have 80 lb oil pressure also? Mine does and I'm pretty sure it is original (in fact I'm damn sure) and it is original engine and as far as I know it is 390 hp.
SteveComment
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Re: 66 Corvette 425HP??
Jim,
I also own a 66 427/390. Have you removed the instrument cluster? On the back of the cluster, there is what has been referred to as the "broadcast code" sticker. Rick Snow has referred to it as the "gage cluster numbers off the white sticker on the back of the cluster." What are the numbers and letters on your sticker.
HectorComment
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