1968 engine casting number issue

[Dale & Abigail Patches]

we purchased a 1968 corvette to be used as a driver .. upon investigating the numbers we noticed that almost all the numbers indicated a 1968 427/400 HP car with manual trans .. all of which are correct .. except the engine block casting number which is 3935439 (this relates to a 435 or L 88 car) yet the casting dates fits exactly .

the pad reads T0506IM .. 18S419291 .. the block casting dates is D118 .. the body build date is J15, the distributor, carbs etc etc all match for the build date and a 400 HP car .. could GM have used a block that was to be used in a 435 HP car for a 400 HP car .. or did someone go through all those issues to put a wrong block into a 400 HP car or is this a true 435 HP car and not a 400 HP car at all .. with no documentation we are at a stand still .. either way the car is going to be enjoyed but it would be nice knowing what we have

ANY IDEAS FROM ANYONE ??

[Jack H.]

Re: 1968 engine casting number issue

Hum, as I read the '68-69 JG book, I don't see the problem. Book says there were two 427 engine casting numbers used in '68.

3916321, a carry-over from '67 production that was used on early cars
3935439, the main production casting that extended into mid-69 production

Also, the text of the JG in this area states a running change in placement of the casting date. Early cars (up to about VIN 20,000) had the cast date placed RH side of the cylinder case (behind the passenger side exhaust manifold) which agrees with '65-67 placement. Later cars had the cast date moved to the RH side of the rear apron (where bellhousing bolts on) like traditional small blocks are dated. Your car's VIN is right at the change point cusp....

[Dale & Abigail Patches]

Re: 1968 engine casting number issue

Thanks for the response .. what is your reference source ?? would love to add it to my library

[John H.]

Re: 1968 engine casting number issue

Dale -

The #435 block was used for all four 427 engines (L36, L68, L71, L88) in "late" cars; the #321 block had the same usage on "early" cars. Yours is fine.

[John H.]

Re: 1968 engine casting number issue

Dale -

I don't have a '68 TM&JG - info is from the NCRS 1968-1982 Corvette Specifications Guide, Vol. 2, Third Edition, Winter 2000 (available from the NCRS On-Line Store).