Is it a 245HP or a 270HP? Help!

[Richard R.]

I could use some help trying to figure out whether my engine is 245HP or 270 HP. I just got it today (thinking I was getting a 245HP) but many of the parts point to 270 HP. I have checked the numbers against the NCRS judging manual and there are some conflicts.

Here's what I know.

It is a 1960 engine. The block identification stamping has the CT suffix code (I know this was a restamp). The block casting number is 3756519 The intake manifold has casting number 3739653 (implies 270 HP) The rear carb brass tag says 2613S (implies 270HP) the front carb brass tag says 2614S (implies 270HP) The distributor number is 1110891 (could be either 245 or 270) The heads are number 3884520 (replacement heads?)

Is there some other sure fire way that I can tell if it is 245 or 270 by, say looking under the valve covers? Any ideas?

Thank you for any input.

[dale pearman]

Re: Is it a 245HP or a 270HP? Help!

Why agonize over this question? 245+270 divided by 2 gives 257.5! You have a 257.5 Hp engine!

Regards, Varooom

[Jack H.]

Re: Is it a 245HP or a 270HP? Help!

Sounds like a real 'mixed bag' here. Might be more than one question to address: (1) what is the engine you've got and where did it come from if it's not your car's original (I know it's a restamp comment)? (2) what was the car's original configuration/how do you come to think that's true? and (3) what do you want to do with the car?

The CT stamp on engine pad points to 245 HP configuration IF it's a factory original motor. Hint: look at block casting date and verify you've got a Saginaw casting/Flint build motor (will have single digit for year + some other tiny variations) instead of a Tonawanda motor (not used in Corvette).

Next, the 520 heads are low performance power pack units (if I remember correctly) used for run-of-the-mill passenger car applications and '60 Corvette motor should be wearing 692 heads (short run on this casting and reasonably scarce items). From the outside (head end marking), the two should appear similar, but the inside and end marks are where the true Corvette 'action' is -- should be 692 castings with end 'hump' marks milled instead of left natural/bumpy as Tonawanda heads were constructed. Same goes for casting date (not seen on judging field due to valve covers) -- one digit year code for Saginaw/Flint and 2-digit year code for Tonawanda castings.

As far as the carbs go, brass tags are cheap and repops are easy to come by EXCEPT for the characteristic inspector's punch (pattern hole clipped through tag adjacent to date code that varied in style with time of build, shift, specific inspector, Etc.) If tags don't have an inspector's punch, you can reasonably conclude they're not the real McCoy item (though the underlying carb components could well be real and worth a reasonable amount). If there is some kind of inspector's punch, you need a 'pro' with Carter familiarity to verify the specific marks fall in line with known original norms of the era.

Also, it wouldn't be the first time, an engine got re-worked over time by prior owners using functional components that fit & worked.... Bottom line here, some thing(s) have been changed from known factory original configuration and the key questions are (1) by who, (2) when, (3) for what reasons, and (4) what do you want to do about it....

[Bill Clupper]

Re: Is it a 245HP or a 270HP? Help!

From what you've said, the real question is "what hsould it be", for in practicality, the only difference between the two engines was the 245 used a standard Hydraulic lifter cam (same as the on in the base engine) and the 270 used a mechanical (solid) lifter cam, same as used in the FI engine. Is the tach aroianal to the car, the redlines were different for the 245 and 270 horse versions. Does it have solid lifters? look at these areas and you'll find out what you need to know.

[Jack H.]

Or....

You'll find the chain of previous owner mysteries compounds itself along the way....

[Joe L.]

Re: Is it a 245HP or a 270HP? Help!

Richard----

Bill Clupper "hit the nail on the head"; the most easily performed way of determining if you have a 245 or 270 hp engine is checking to see if it has hydraulic or mechanical ("solid") lifters. Usually, you ought to be able to tell this by the sound,especially if one or more lifter have "loosened up". The tach redline is another piece of important evidence as to what the car originally was, assuming, as Bill, mentioned, it's original to the car.

Your 3884520 casting number cylinder heads are, of course, not original to your car, which, as Jack Humphrey mentioned, originally used 3774692 head castings. These heads were used during 1966 and 1967 for all 283 cid passenger car engines still in production during those years.

Interestingly, though, these heads were very similar. Both heads should have the "triangle-on-top-of-rectangle" end casting symbol. Both heads have nearly the same combustion chamber volumn, the "520" at 60.5 cc and the "692" at 59.7 cc. Also, both heads have the same 1.72/1.50 valve size common to ALL 283s except 1961 275/315 hp engines. The intake port configuration on these two cylinder heads was a little different, but not enough to make much of a difference performance-wise.

[Jimmy G.]

Re: Is it a 245HP or a 270HP? Help!

Question to be answered: 1. Tach Redline?? 2. Solid or hyd. lifters 3. Harmonic balancer ? Rear offset 270 hp only 4. Carb idle vents Square or angled ( see article in Restorer ) 5. Exhaust system crossover pipe??? Answer these and you may be able to tell.

[John H.]

Re: Is it a 245HP or a 270HP? Help!

If you have access to a borescope, pull a plug and take a look - 270's had domed pistons, 245's had flat-tops.

John

[dale pearman]

Re: Is it a 245HP or a 270HP? Help!

Hi Richard:

All of the advice you have received so far rests on the assumption that you are observing an UNMOLESTED original engine and unaltered tachometer installation. Such is clearly NOT the case. Using a bore scope to determine the shape of the pistons is not as reliable as tearing down the motor to determine if the pistons are original, replacement or aftermarket. If the CT code is a restamp as you say, then someone created this engine to be a 245 Hp. Most creations are the other way around. This fact is a pretty good indication that the car was originally a 245 Hp. If the red line on the tach supports a 245 Hp installation then I'd go with that determination.

Rebuilding an engine allows use of just about any component. Cams, lifters, pistons, cranks, oil pumps, etc. from any small block Chevy can be used. Perhaps a previous owner replaced a Holley carb and intake with swap meet components that would tend to make the car look more original. A dual WCFB set-up, even though a 270 Hp version, would be more "correct" in appearance than an aftermarket induction system.

Again, if you thought you had a 270 Hp engine and discovered 245 Hp components (clues), you should be biased toward the decision that in fact you do have a 245 Hp engine. This Hp alteration is the most common direction. To change from a 270 Hp to a 245 Hp is unusual but not out of the question. If your tachometer has a low red-line however and considering the other clues, my bet would be that in fact you do have a 245 Hp engine.

Hope this opinion helps, Varooom!

P.S. The 245 Hp car is much more fun to drive on the street versus the 270 Hp car because the torque starts at a lower RPM. You could more than likely win a drag race from stop light to stop light if competing with a 270 Hp.

[Doug Flaten]

Re: Is it a 245HP or a 270HP? Help!

Check the restorer index for dates of articles differentiating the 245 and the 270 HP carbs. There are subtle differences. The tags may have been slapped on a set of 245 carbs.

[Richard R.]

Still need help, here's some more info.

Thank you all for your responses. To clarify a few things; I bought the engine separate from the car. (my car came with a 350 HP. I believe the gentlman I bought the engine from had it made up by a professional by gathering together and stamping the block. So it is possible that either an error was made attaching the brass tags, or it was done intentionally to look like a 270.

I can go either way but I would like to know exactly what I have here. The engine is in very good shape, I just need to figure out how to proceed with it.

Can anyone tell me exactly what to look for on the carbs to tell if they are for a 270HP? And also, can you tell the horsepower by removing the valve cover? Since I beleive the engine was assemble from gathered parts I don't think looking at the pistons will be a reliable indicator.

And finally, what makes a 245 different from a 270? Besides different tachometer red lines, what are the other differences between 245 and 270?

Well, I'm now totally confused. Thank you again, in advance, for all your help. It seems like I'm always asking questions and not giving any answers (maybe I'll be qualified after this restoration is done).

Richard

[motorman]

Re: Still need help, here's some more info.

just check the valve lash. if it has valve lash then it has a solid lifter cam and 270 had a solid lifter cam. no lash means hyd.lifters and that is a 245 HP.