70/71/72 402

Tim

Well Known Member
Supporting Member 4
#1
This may be out of the wheelhouse here but I have a chance to buy a 402. I can’t seem to find the proper identity of each year for casting numbers. It seems vague at best. He says it’s out of a 71 but based on date code might be the late 70 version. Any ideas?
 

1964SuperStocker

Well Known Member
Supporting Member 2
#3
When it comes to those engines, the heads bolted on the block are all that matters. Not sure how original the owner is claiming the thing is but the only thing I would be doing is opening the valve covers to know which heads it has. That old and it could be anything and people bolt large round port heads on Peanut ports all of the time. Peanut port, round port, square port... All of that matters if you are considering it for power of any kind. My jet boat 454 was a 320 hp tiny peanut port, open chamber, low performance baby when I got it. Now it has square port, closed chamber heads with 2.30" intake valves. Higher compression and massive flow numbers. What is your plans for it?
 

Tim

Well Known Member
Supporting Member 4
#5
Mike, I’m not sure he’ll let me take the intake off. Says it’s rebuilt with 10,000 miles on the rebuild. Was there a difference in block numbers for each year 70/71/72? Or were they all the same with different heads
 

1964SuperStocker

Well Known Member
Supporting Member 2
#6
Mike, I’m not sure he’ll let me take the intake off. Says it’s rebuilt with 10,000 miles on the rebuild. Was there a difference in block numbers for each year 70/71/72? Or were they all the same with different heads
Is it an #854 or is it #290 casting block? 290 block was a 240hp with a 2 barrel I believe for 72 only. 854 could be 240hp up to 375hp. Your heads could be nearly anything. I wouldn't buy a motor without knowing the head casting numbers. Unless you don't mind its a 240hp, then its cool to snag anything that runs.
 

Tim

Well Known Member
Supporting Member 4
#7
Is it an #854 or is it #290 casting block? 290 block was a 240hp with a 2 barrel I believe for 72 only. 854 could be 240hp up to 375hp. Your heads could be nearly anything. I wouldn't buy a motor without knowing the head casting numbers. Unless you don't mind its a 240hp, then its cool to snag anything that runs.
I’m going to go look at it. I’m not sold on it yet but the price go my attention. $1500 Can fully dressed with manifolds and a turbo 400 behind it. Both redone 10,000 miles ago. I’m concerned about the potential cracks in the lifter galley. I don’t know these engines well
 

1958 delivery

Well Known Member
Supporting Member 2
#8
If it's built and has run it probably is trouble free. The 402 had that reputation. I use to build nothing but big blocks years(many years ago) ago. Mostly into correct Corvette stuff, a good friend and Corvette shop owner is the one that had mentioned it to me. I never went after 402's but occasionally a 4 bolt would pop up at a good price and he warned me about them, sure enough probably 40-50% of the few I bought would be cracked, and he did say I told you so. We'd salvage the 4 bolt caps:doh
 

1958 delivery

Well Known Member
Supporting Member 2
#9
854 and 290 are the only casting numbers which is also the casting number for the 1969 396's. Either can be a 2 or 4 bolt. Both numbers were used for low performance and high performance applications. The 4 bolts were the only used on hiperf (square port heads) I would feel safer with the older blocks late 69 early 70.
 

1964SuperStocker

Well Known Member
Supporting Member 2
#11
Tell the guy you want to check compression and bring your own tester. Get the plugs out and have him turn it over. Only takes a few minutes and you will know how good the motor is. If its in the car/truck and you can take it for a drive and it will turn the tires over, then its good enough for me.
 

Tim

Well Known Member
Supporting Member 4
#12
Based on what I’ve looked up the 854 block is the 396 based block and should be 4 bolt but could be 2 based on HP. The 290 block is the lower HP one they used in trucks and cars but not found in performance cars like chevelles and are 2 bolt.(from what I read) this could be a late 69 or early 70 block but I’ll go look and see what the date code is.
 

Tim

Well Known Member
Supporting Member 4
#13
Tell the guy you want to check compression and bring your own tester. Get the plugs out and have him turn it over. Only takes a few minutes and you will know how good the motor is. If its in the car/truck and you can take it for a drive and it will turn the tires over, then its good enough for me.
Randy, it’s out of what it was in. I need the valve cover off and check the block numbers. I’ll pull a plug but if all else is good it’s a tear down and do it my way project anyway. Unless it’s coming from someone I know I’d take the heads and pan off at least to loook.
 

Tim

Well Known Member
Supporting Member 4
#14
Turns out the motor is out of a 71 high Sierra C10 4X4 loaded with a trailer package. I haven’t seen it and don’t have the block number because the guy is gone away for a week or so. I do know who’s truck it was prior to him having it and it should be the high hp L78. I’ll know more when he gets back. It was fogged and put away for storage a number of years ago. We have some friends in common and he’s an old car guy so if the block is an 854 it’s good and he will let me take the valve covers off to have a look.
 

Tim

Well Known Member
Supporting Member 4
#16
No high hp in trucks, hi perf is with square port heads and 4 bolt main.
That’s why I need to see the block. He says when it was bought new it was a 350hp. That would make it 854 block. But.....I’ll know when I see it. I’m assuming the hp was controlled but the heads and pistons for all 402’s?
 

64ss409

Well Known Member
Supporting Member 9
#17
Turns out the motor is out of a 71 high Sierra C10 4X4 loaded with a trailer package. I haven’t seen it and don’t have the block number because the guy is gone away for a week or so. I do know who’s truck it was prior to him having it and it should be the high hp L78. I’ll know more when he gets back. It was fogged and put away for storage a number of years ago. We have some friends in common and he’s an old car guy so if the block is an 854 it’s good and he will let me take the valve covers off to have a look.
C10 is 2 wheel drive. No bbc's in '71 1/2 ton 4x4's from the factory. 4x4's were K10's. But the bbc in a K10 is a fairly easy install. I've done 3.
 

64ss409

Well Known Member
Supporting Member 9
#18
That’s why I need to see the block. He says when it was bought new it was a 350hp. That would make it 854 block. But.....I’ll know when I see it. I’m assuming the hp was controlled but the heads and pistons for all 402’s?
In 71 they went to an open chamber head and different pistons.
 

1958 delivery

Well Known Member
Supporting Member 2
#19
No high perf in any truck, ever. That's like saying you could get 690's in a truck never happened. However someone could have built anything.
The only factory 402 in 1971 was a 300 horsepower 4 bbl
 

Tim

Well Known Member
Supporting Member 4
#20
C10 is 2 wheel drive. No bbc's in '71 1/2 ton 4x4's from the factory. 4x4's were K10's. But the bbc in a K10 is a fairly easy install. I've done 3.
And this is why I ask questions, I don’t think now this guys knows what he has. I certainly don’t know any of this other than what he said but obviously isn’t right. It may Well be a bbc in a 4x4 but done at sometime after the fact and be a car engine transplant.
 
Top