Paul67

The mystery of my engine continues…

I pulled the non date matching 840 heads off my 427/435, and noticed that I had 2 forged pistons and 6 cast, all were 2242-30.

So, I have decided to pull the engine to get to the bottom and built it from the bottom up, correctly.

However, as I was building up the courage to pull the block, I looked up the piston and mic the bores. That’s where the mystery starts/continues it mic’s at ~4.1 and some change, which is consistant with the 2242-30 pistons which are listed at 4.124 and are 396 NOT 427 pistons.

Some facts about the car, the block is a 3904351 casting NO DOUBT about it, the car was produced 9/13/66 per NCRS, the block casting date appears to be F 19 6 the F maybe an E. It doesn't appear to be resleeved, or at least I can't tell from the deck.

So, I’m opened to thoughts, were 351’s made less than 4.25? other??

What the heck am I dealing with here??

Thanks in advance.

JohnZ

I've never seen one. Have you checked the casting number characters with a screwdriver?

A-Snake

Very good idea! I will guess the last four digits were glued on. ;-)

Procrastination Racing

John's suggestion is just the first step. In the early '80s, I heard of all sorts of things to fake a car.

1. Epoxy on existing numbers
2. Grind old ones out, lay epoxy in a section, and cut numbers out of the epoxy
3. Ditto but use metal filings in the mix so that they don't have less magnet pull when checking with a magnet
4. Cut out casting numbers of the right block, if broken, and weld in the replacement block
5. Find similar numbered block and change the numbers you need


My first thought was #5. However, a quick check showed no 396 close, but a 366 in those years has 3904354 casting number. Cut the -4 to look like a 1 and you are in. I'm not sure if a 366 with a 4.00 bore can be bored to 4.094 or not, though. I'm also not sure if the 366 is a tall block. I think only the 427 truck blocks were tall blocks, which is a dead giveaway.



Once an original engine was an indicator it was a good car, most likely well cared for, and not driven into the ground. Then they became worth more, which meant that an incredible number of people began an art of faking original engines to cash in on the difference.

You may have just found one of them.

Procrastination Racing

I went over and read some of that. Thoughts are:

1. Seller may/may not have known. A lot of this stuff was done in the late '70s/early '80s and cars could have changed hands several times.

2. Poking and scraping on my car means one of two things - either you bought it or you get shot. I don't do destructive testing on anyone else's car, and they better not do it on mine.

So when it comes to glued on numbers, if you can't detect it with a magnet, camera, scope, your finger, or similar, then you have to decide on the gamble. I look at them very carefully, and error on the side of caution, myself. Usually something gives them away. For one, a 4 bolt main 4351 block should have the two large oil ports by the filter. Does this one?

3. A 435 hp and a 396 do not perform the same at all. The drive should be an indicator of something is wrong.

midyearvette

check that puppy for sleeves....just a thought
but all these guys are right about "bondo numbers"

A-Snake

They could use a 3902406 396 block and 'replace' the last 4 digits.

Paul67

Thanks for the input, even thou all the answers are not good outcomes.

I've scoped it again, check it with a magnet, and all looks good.

I'm thinking once I strip the paint, I'll find that the entire number sequence, including the casting screw heads at the beginning and end of the casting have be cut from a donorer block and welded on mine .

I'll try to post a picture this evening of the casting.

AND get ready for the next round of posting which should be more fun, which will be focused on what to do in terms of rebuilding this one or going with crate engine...

Stay tuned!!

Paul67

a quick question the 2 large ports by the oil filter referenced in thread early appear to be present, at least I think so, 1 has the pressure line and the other is plugged, OR should I be looking in a different spot?

A-Snake

The 396 block 3902406 was available in both 2 and 4 bolt mains.

AZDoug

We used to call those 396 motors. They were very common in midyear 427 cars, back in the 1970's.

Or, to quote my friend who bought and fixed up and sold a lot of corvettes; "F*&#, another G#@D$%&@ 396 motor!", after pulling a head.

Sounds like someone may have been playing with epoxy on the casting markings.

Doug

Paul67

TheGanzman

Looks like "fresh paint" just over the numbers...

Paul67

Actually the shiny paint is due to my windex'ing of the numbers to clean them off to expose as much as I could, the rest of the engine is the same just dusty, I'm guessing the engine has < 1,000 miles on the build.

PAmotorman

heat the area with a propane torch and burn off the paint and see what shows up. there have been number made from epoxy and iron filings,RTV and milled out a pocket and a insert from a blown block put in. when i posted this over in the NCRS site years ago you could hear the bodies falling. one guy emailed me his numbers blew off using a pressure washer

DansYellow66

Wow - if thats an epoxy job (or other shenanigans) they did a good job with the cosmetics. I can see why a bunch of people would stand around for days looking at the block and not suspect those numbers. I wish it would work out for you but it doesn't sound like it's going to.

Procrastination Racing

Here you are.


396 Oil Pad 2 bolt main

427 4 bolt main

427 2 bolt main

Notice the 4 bolt main has a very large hole. The front hole has a plug screwed in it and isn't that noticeable in this picture. These were used to connect an oil cooler or external oil filter to the block without an adapter, although you did have to change the check valve to get the flow to work.

The hole to the back and above is for the clutch Z-bar.

The 2 bolt main blocks have a small plug driven in.




I was going to call this a big red flag, but he explained why it is so clean.

I do notice two spots that look like glue or something has been smeared just past the end and the beginning.

jdk971

i always thought the p meant passenger block and the hiperf meant 4 bolt main. but
then again i am not a mechanic or try to play one. jim

Tom454

All of the 366 4 bolt main truck blocks I worked on were tall decks if my memory serves me.

Paul67

Notice the HiPerf mark