143 camshaft

[Bill W.]

I was given a old article today . It said there were three versions of the 143 cam used between 1965 and 1969. The 65 version had a 497 intake lift , a 503 ex lift 348 duration & 127 overlap . the 66 version had a 520 intake & ex lift 336 duration & a 108 overlap the 69 version had a 520 intake & exhaust lift a 302 ex duration .a 316 intake duration & 80 degree overlap. What is your opinion ? Does anybody have any restoration cam spec. sheets to compare ?

[Joe L.]

Re: 143 camshaft

I was given a old article today . It said there were three versions of the 143 cam used between 1965 and 1969. The 65 version had a 497 intake lift , a 503 ex lift 348 duration & 127 overlap . the 66 version had a 520 intake & ex lift 336 duration & a 108 overlap the 69 version had a 520 intake & exhaust lift a 302 ex duration .a 316 intake duration & 80 degree overlap. What is your opinion ? Does anybody have any restoration cam spec. sheets to compare ?

Bill-------


The specs for this camshaft never changed. If they had, the part number would have changed. There are numerous different conventions for describing camshaft specs. I expect the differences you describe are attributable to different conventions, not any real change in specifications.

[Duke W.]

Re: 143 camshaft

...what Joe said. I have carefully inspected Chevrolet drawing numbers 3863144 and the later 3904366. These are the drawing numbers of the finished ground camshafts. (The ...143 and ...362 are for an assembly of cam and indexing pin, which is what was sold over the counter. )

Lobe height in inches to five decimal places is listed every cam degree. Both cams use the same lobe on both the inlet and exhaust side and all are identical.

The ...144 blank is cast with a rough rear groove. A note on this drawing states that the blank for the ...366 may be used for a ...144 by machining a groove to the finished dimension on the ...144 drawing.

Any difference you see in "specs" from various sources is merely a matter of how the data is measured, and, unfortunately, this is usually not explained, which can result in confusion.

BTW this is an excellent cam for a high performance road engine. I tried, but could not improve the design, My only recommendation is to retard it 4 degrees on a 4.00" stroke and 6 degrees with a 4.25" stroke.

The lobe, on a slightly smaller base circle, is the inlet side lobe of the LT-1 cam.

My understanding is that the current Federal Mogul replacement CS165R does not have a rear journal groove, so one must be machining if used on a '65-'66 block along with the proper early "three hole" bearing.

Duke

[Bill W.]

Re: 143 camshaft

Duke , The person who wrote this article (I dont have the name) claims the cams used in production on the early 396s were not the same as the over the counter cams or those used in the 66 cars ???? The article is very old on yellowed paper .

[Joe L.]

Re: 143 camshaft

Duke , The person who wrote this article (I dont have the name) claims the cams used in production on the early 396s were not the same as the over the counter cams or those used in the 66 cars ???? The article is very old on yellowed paper .

Bill-------


Folks in the old days could be just as wrong as folks today. If the early L-78's used a camshaft with different specs, that cam would have had a different part number. I have no information that such a cam existed.