1962 engine casting 3782870 height

[Jim G.]

I found a 3782870 327 block with a 1961 casting date. The height of the 3782870 numerals are 9/16" high. Does the height mean this is not a corvette block. The judging manual says the numbers must be 5/8" high. This is only 1/16" difference.

[Mike M.]

Re: 1962 engine casting 3782870 height

check the cast date--the year has to be a single digit for it to be a flint 870 block. also check for the presence of a pipe plug on the front face of the block at about 11 oclock if you are viewing the timoing chain area. also the stamping on the engine pad needs to have a F for its perfix if its a flint 870. flint cases were used to manufacture the corvette 327's while the tonowanda cases went into pass cars/trucks only.mike

[Jim G.]

Re: 1962 engine casting 3782870 height

The cast date is I 26 1, Sept 26, 1961. However the judging manual says the 3782870 must be 5/8" not 9/16". The stamping and pipe threads can easily be faked?
Is the 5/8" rule not accruate?

[Mike M.]

Re: 1962 engine casting 3782870 height

Jimmy: i'm aware of two cast # vertical digit heights, the tall height(used in 62,63, 64 and midway thru 1965). in mid 65, the 870 molds were changed and the smaller digit height came into being. my 61-2 judging manua(5th edition), doesn't call out an actual measured height. perhaps there is a newer 61-62 judging guide.anyway, 9/16 vs 5/8 measurements can be difficult to interprete with measuring devices. if your cast date is in 1961, i'd bet the farm you have the correct tall 870 cast # hieght. i have a mid-65 small digit 870 and its noticably shorter than all the tall 870 blocks in my 62 thru 64 vettes. taking a measurement when the block is in the car is at best a guess, even with a venier caliper. if in fact your 870 is a small digit casting, i'd take a real good look at the casting date, checking for Mr JB Weld . good luck,mike

[Michael H.]

Re: 1962 engine casting 3782870 height

Jimmy: i'm aware of two cast # vertical digit heights, the tall height(used in 62,63, 64 and midway thru 1965). in mid 65, the 870 molds were changed and the smaller digit height came into being. my 61-2 judging manua(5th edition), doesn't call out an actual measured height. perhaps there is a newer 61-62 judging guide.anyway, 9/16 vs 5/8 measurements can be difficult to interprete with measuring devices. if your cast date is in 1961, i'd bet the farm you have the correct tall 870 cast # hieght. i have a mid-65 small digit 870 and its noticably shorter than all the tall 870 blocks in my 62 thru 64 vettes. taking a measurement when the block is in the car is at best a guess, even with a venier caliper. if in fact your 870 is a small digit casting, i'd take a real good look at the casting date, checking for Mr JB Weld . good luck,mike

How about the length of the entire number package, Mike. Wouldn't the smaller characters result in a shorter package of 7 characters? I would guess it would but I've never actually measured the difference. If so, that would be an easy way to determine which size the characters are.

[Jim G.]

Re: 1962 engine casting 3782870 height

Mike,
Please look at pg 43 of the 5th edition just below para 2. ENGINE BLOCK. It refers to the 5/8" vs. 9/16. The block is out, it measures 9/16 with a digital caliper. The casting date is I261. What do you recommend? thanks.

[Joe C.]

Re: 1962 engine casting 3782870 height

A reliable way to check for a Flint block, is by the presence of the 1/8" NPT square plug into the front of the oil gallery. The plug is present in Flint blocks on the right side, near the head, in the vicinity of the stamp pad. It is NOT present on Tonowanda blocks. Not many counterfeiters will go to the trouble of adding this.

If you're permitted to scrape away the paint from the casting number, and especially the casting date areas, the presence of "foreign" casting material will tell the story.

If you know, for sure, that the heads belong to the block, then Tonowanda heads will have rough cast double humps, while Flint heads will have machined double humps.

Joe

[Mike M.]

Re: 1962 engine casting 3782870 height

How about the length of the entire number package, Mike. Wouldn't the smaller characters result in a shorter package of 7 characters? I would guess it would but I've never actually measured the difference. If so, that would be an easy way to determine which size the characters are.

never thought to measure the length of the 7 digit package. as i said earlier, the only short 870 block i have is in one of my 65 FI cars and not that easy for my old eyes to measure its length and compare it to the tall 7 digit length. my gut feeling is the lengths are equal tho.mike

[Mike M.]

Re: 1962 engine casting 3782870 height

Mike,
Please look at pg 43 of the 5th edition just below para 2. ENGINE BLOCK. It refers to the 5/8" vs. 9/16. The block is out, it measures 9/16 with a digital caliper. The casting date is I261. What do you recommend? thanks.

i missed the 9/16 vs 5/8 on p 43, but here again, the manual is comparing flint tall vs tonowanda 870's. i do have a 62 flint 870 here in the shop out of our 62 FI. i'll measure the heights and length and post later this evening. mike

[Mike M.]

Re: 1962 engine casting 3782870 height

i just measured the 870 cast # on a 63 870. its a B63 cast date. the 61-2 judging manual is apparantly incorrect as this 870- digit height is exactly 9/16" . its 7 digit pachage length is 2 53/64" . mike

[Loren L.]

Re: 1962 engine casting 3782870 height

Is there a reason why I261 CANNOT be "Sept 2, 1961" instead of "Sept 26, 1961?

[E S.]

Re: 1962 engine casting 3782870 height

Hi all-Interesting discussion- Am I reading that ALL Flint 870 blocks are corvette only?I can't really remember seeing any Tonowanda 870 blocks with a 62-65 casting date...

[Dick W.]

Re: 1962 engine casting 3782870 height

Is there a reason why I261 CANNOT be "Sept 2, 1961" instead of "Sept 26, 1961?

I'm gonna show my ignorance, but I believe that all Flint blocks if that era used a single digit year identifier.

[John H.]

Re: 1962 engine casting 3782870 height

Hi all-Interesting discussion- Am I reading that ALL Flint 870 blocks are corvette only?

EJ -

Nope - Flint made millions of 870 blocks, for passenger car, truck, and Corvette applications.

[John H.]

Re: 1962 engine casting 3782870 height

Is there a reason why I261 CANNOT be "Sept 2, 1961" instead of "Sept 26, 1961?

By just considering the number, no - it could be either. However, if it has the oil gallery plug at the front, that pegs it as a Flint block dated I 26 1, not a Tonawanda block dated I 2 61. Tonawanda blocks also usually have a "T" somewhere near the casting number.