Need Big Block Chevy Help!!!!

[7d9_z28]

we have 3 engine categories on here but nothing for big blocks. so im here.

I just got a great deal on a 402 big block from a 72 camaro. i have a couple questions

1. i know theres a standard version and a hi performance version of these engines... mine says HI PERF on the back of the block behind the flexplate... is that how i know? if it is a hi performance block what does this mean? just that its a 4 bolt? (i havent looked yet so im unsure if its 2 or 4)

2. what exactly does my casting number tell me? it hasnt been to helpful so far.

im stuck guys! I need your help!

 

[BSL409]

Need the casting number of the back of the block, The head casting number, Also the numbers on the front pad

 

[Don Jacks]

Well,first off,the 72 engines were rather "weak tea"from a performance standpoint.They can be improved upon with things like bigger valves,more compression[stock was 8.5],a modern cam,headers,ect.Usually the "high perf"blocks had 4 bolt mains,and a steel crank,but you'll need to pull the pan to check.The heads are small valve,oval port,low performance type but this can easily be upgraded,depending on what kind of power level your looking for.Stock,It wont run much better than the 350 that came in your car.

 

[bobs409]

I think they all say hi perf on them except the trucks, they naturally have truck on them. Can be 2 or 4 bolt. From what I read, you can't trust numbers, you have to actually check to see what it has.

My 454 from a 74 Caprice has hi perf on it but it's a 2 bolt main. My other 454 is a 73 CE block and it too has hi perf but is a 4 bolt main. Both had cast cranks.

I think I'll change the 6's and small block forum to also cater to big blocks. We all know I'll get alot of use out of it!

 

[chevymusclecars]

You don't say what year engine but all of them I have seen say High Perf. The casting number doesn't always tell you if the engine is two or four bolt main but if you have a plug above the oil filter that is about 1 1/4 inch in diameter you have a four bolt main if not you have a two bolt.

Bill

 

[bobs409]

Moving this thread to the new 6 cylinder, small and big block forum.

 

[walkerheaders]

You don't say what year engine but all of them I have seen say High Perf. The casting number doesn't always tell you if the engine is two or four bolt main but if you have a plug above the oil filter that is about 1 1/4 inch in diameter you have a four bolt main if not you have a two bolt.

Bill

as usual Bill, you nailed it.
the 402-375 horse engines were a carry over from the 396-375 and 427-425. they had a provision for an oil cooler on the true hi-perf blocks.
usually, if you dont see the two giant thread plugs above the oil filter, its a 2 bolt block even though it may have hi-perf cast into the block.

trust me, you dont need 4 bolt mains on a BBC until you exceed 850 horses or spray a crapload of N20 thru it.

402's can be made to run.........belive me. I went 10.35 @135 in my 70 Elky with a 125 shot on it, square port closed chamber heads, a 400 turbo, 10 inch sliks and a 10 inch converter. no problem.

if you can get one.........get it.

 

[7d9_z28]

wow

i will check that all out.. its a block made in 71, but originally pulled from a 72 camaro. i dont plan to keep inside stock, but the outside will appear rather stock.

its casting number is vague cause it was a common one 3999290

@ don jacks the heads are not oval ports, theyre square (or rectangular, but not oval)

thanks guys, for the responses! you all have way too much knowledge, so thank you for passing some out!

 

[7d9_z28]

also

@ walkerheads i looked around and ebay wanted 500 bucks for a 402 block, and a mostly complete motor went for 1500 and up.. but i bought this 72 402 complete intake to pan and pulley to flywheel (minus distributor and carb) for 450bucks. rebuilt within the last 5 years (to stock, was pulled from original 72 camaro and put in a c10 pickup, thene almost into a pro touring 66 chevelle)

so after seeing the price of 450 bucks i figured even if it needed work it was well worth it!

 

[Don Jacks]

Sweet,The heads I was referring to was for a stock 402 as came in the 72 year car engines.With rectangular heads on it,someone has upgraded this engine which is awesome as well as the price you paid for this thing.Congrats and good luck.As Bob[walkerheaders] said,they can be made to run really well.