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steve25 · 10-18-2021, 06:10 AM

Here's another question .
Has anyone ever seen a factory replacement block for a 389 that had the 3 freeze plugs per side?

67 was a bit of a crazy year for the factory with the change over/ overlap of motors!

Mike Davis · 09:01 AM

Quote:

Originally Posted by steve25

Here's another question .
Has anyone ever seen a factory replacement block for a 389 that had the 3 freeze plugs per side?

67 was a bit of a crazy year for the factory with the change over/ overlap of motors!

There was a 66 389 SR block on ebay last year that had the 3 freeze plugs. It was unused and had the pistons with it. Was cast is mid 68 I believe.

Here is a thread I started on one I found.

https://forums.maxperformanceinc.com...d.php?t=836287

I have a 421 SR block that has 3 freeze plugs. Basically just a 1967 4 bolt 428 with a 4.090 bore.
Casting number was ground off but never restamped.

tekuhn · 10-18-2021, 09:00 PM

@Rocky, I don't mind sharing the details on the SR block that I own. It is an NOS #9799915A which is the 1970 Ram Air IV part number. It was cast on January 6, 1973. It was fitted with cam bearings, cam retainer, galley plugs, freeze plugs, head dowels, timing cover dowels, 4-bolt main caps, and pistons with pins and rings. There are all 5 mouting pads machined, drilled, and tapped. There is no large year cast near the distributor hole. The factory wire-tag with matching SR number was still attached, and the whole assembly had been dipped in Cosmoline to preserve it. The entire part number was wiped or ground off and then restamped since the '73 part number would have been completely different.

Interestingly, the pistons appear to me to be cast. I assume perhaps they used these for replacement of both RA-III and RA-IV engines and equipped them with either cast or forged pistons accordingly. That would make sense since most if not all '70 RA-III engines had 4-bolt main caps (unlike '69).

The block is still un-used, so please let me know if you need any more pictures or information.

tekuhn · 10-18-2021, 09:06 PM

A few more pictures:

steve25 · 10-19-2021, 06:15 AM

This piston thing needs more investigation!

Are we to assume that all RA4 fitted replacement blocks destin for warranty for the 1970 model year got built with cast Pistons , or after that intial run of warranty fitted short blocks built with the forged Pistons ran out, that from then on ( like by 1973) all factory fitted RA4 blocks where just intended for over the counter sales ( since warranties would be over) and thus built with the standard cast Pistons?

Rocky Rotella · 10-19-2021, 05:42 PM

tekuhn, thank you so much! That's very helpful!

Steve, Pontiac had three separate service replacement applications for the 1970 model year.

479877- all 400 except Ram Air (presumably with 2-bolt caps)
479878- Ram Air III (four-bolt caps with cast pistons)
479879- Ram Air IV (four-bolt caps and forged pistons)

We can surmise that tekuhn's above is a 479878 assembly as it has 4-bolt caps and cast pistons. Since the 9799915 casting would have been used with cast and forged pistons, I've often wondered if the "A" denotes lesser/wider wall clearance for piston use? And since tekuhn's is cast A063 (which is shared by many 9799915 SR blocks I've documented), it certainly started life as a typical 481988 block that was fitted with 40bolt caps during machining and stamped accordingly for the 1970 application.

tekuhn · 06:11 PM

It does beg the question, if they were going to distinguish 4-bolt blocks for cast pistons by adding the "A", why not just stamp it as 9799914 which was the Ram Air III casting number?

Rocky Rotella · 10-19-2021, 10:11 PM

Quote:

Originally Posted by tekuhn

It does beg the question, if they were going to distinguish 4-bolt blocks for cast pistons by adding the "A", why not just stamp it as 9799914 which was the Ram Air III casting number?

That's a good question. I should have explained. I have yet to come across an SR 9799914 block. That doesn't suggest that Pontiac didn't produce one, however.

I have data on (10) 9799915 SR blocks in my files. Of those (6) were cast A063 and it's only those that are stamped "A" or "B". The other cast dates were partial cast/stamped 9799915 or fully stamped 9799915.

For those cast A063 that are/were NOS, those stamped with an "A" were tagged 479878 and included cast pistons. Those stamped with a "B" were tagged with 479879 and had forged pistons.

Has anyone came across a 9799914 SR block? And if so, what was its cast date?

Rocky Rotella · 10-19-2021, 10:17 PM

A quick search revealed this 9799914 block, which was equipped with 2-bolt caps.

http://forums.maxperformanceinc.com/...03#post6000803

Apparently Pontiac used "9799914" in SR applications for 2-bolt applications (479877).

tekuhn · 10-20-2021, 08:57 AM

Quote:

Originally Posted by Rocky Rotella

A quick search revealed this 9799914 block, which was equipped with 2-bolt caps.

http://forums.maxperformanceinc.com/...03#post6000803

Apparently Pontiac used "9799914" in SR applications for 2-bolt applications (479877).

Lots of interesting information, thank you.

Rocky Rotella · 10-20-2021, 10:26 AM

tekuhn,

Would it be possible for you to take a close up of the tag? And can you take some pics of the main caps? I'm interested in the partial part numbers on them.

tekuhn · 11:11 AM

Quote:

Originally Posted by Rocky Rotella

tekuhn,

Would it be possible for you to take a close up of the tag? And can you take some pics of the main caps? I'm interested in the partial part numbers on them.

Here you go. I had never noticed the Assembly # written on it. There's also writing below that which I can't read. Looks like "1970" then something I can't figure out. Other observations: There is an 8 written above the underline in "SR_". Past Model is selected and also the holes in both parts of the tag seem to have been made with a specially shaped hole punch.

Tag:

tekuhn · 10-20-2021, 11:04 AM

Pictures of the caps:

Rocky Rotella · 10-20-2021, 12:14 PM

Thank you for the additional photos!

It's good to see the 479878 part number on the tag. That's what I guessed we'd see, which also explains the cast pistons.

Those are the main caps I expected to see as well. An interesting point worth noting is that all five caps were cast as a single unit, rough machined, cut apart, installed on the block and finished machined. That makes them a custom fit for that exact block and prevents installation into/onto another block without effort.

tekuhn · 10-20-2021, 12:39 PM

The first picture I sent of the tag was just a photograph taken with my phone. I decided to see if it would be clearer if I scanned it. I scanned it in color first and then greyscale and adjusted the brightness and contrast and I think the additional writing on the bottom of the tag becomes clear..... " 1970 Ram III".

tekuhn · 10-20-2021, 01:03 PM

I'm not sure how I feel about this information. I thought I was buying a RA-IV SR block. It has the correct RA-IV block part number with an A added, yet it's clear it was intended for replacement of a RA-III with 4-bolt main caps. There is no difference in the block, only the pistons that were fitted to it. Does this information diminish the value of the block somewhat? Is a "B" block worth more than an "A" block if they were in identical condition? Could someone restoring a '70 RA-IV vehicle use this block and it be considered correct? With what I now know, I would have to say no.

I realize this is all subjective, and I didn't buy the block as an investment. I bought it to pair with a set of 614 heads for a '70 Judge I was building. After I bought the WY RA-V crate engine for the Judge, I stopped any plans to build the RA-IV. I no longer have the Judge or the RA-V engine.

TRADERMIKE 2012 · 10-20-2021, 04:25 PM

Quote:

Originally Posted by TRADERMIKE 2012

Mikes Question is: In creating a 389-400 ci Replacement Block "Did the Pontiac Factory use one of the original 1968 Plugs to form a Cast in the manufacturing of this 1970 Replacement Block in this Post, so that the completed Cast is both new and as original as it could be?" I ask this because I see 68 Cast into the top of the Block near the Dist. hole and the cast date depict's 1970.

Note: as I read on in the assignment, I found that pertaining to the Service Replacement Blocks "He was told that the factory ran off some SR Block replacements for 1965 and 1966 389 ci Engines in 1968. This Man is selling this particular Engine for $1800 and sold it for less.

TRADERMIKE 2012 · 05:14 PM

Quote:

Originally Posted by tekuhn

A few more pictures:

Mike has a question? In Post # 44, I am looking at the Edge view of the Crank INSTALLED IN THE SHORT BLOCK "Why is it off center?" It looks like there are half-moon parts that surround the Crank, kind of like an Oil Pump in a Transmission.