Hot Rod Forum banner

Looking to buy a used 454 BBC What to look for

13K views 12 replies 9 participants last post by  Carl 66 
#1 ·
Hi, As my 1970 Monte Carlo 402 engine has died I will be looking to buy a replacemt. Probably a 454 BBC used engine. What years would be good to install in my Monte. What years are better, what should i look for. What are the weak points of a 454. There is this guy that has 454 from a 1990 motor home. Engine is still in his camper and I have not heard it run yet but i will early next week. It has been setting for all most a year now. Any suggestions on checking out this engine would be appreciated. Thanks Old Bill From east central Illinois
 
#2 ·
the heads in a 1990 motorhome BBC are small port, low HP. you will actually de far better off doing a rebuild to original specs on the 1970 402,

buying a truck/motorhome BBC and performancemodding it puts you in the same pricerange as buying a gm-perfoemanceparts bbc.. (your old gen 4 heads wont fit so you are looking at new aftarmarket ones if you want the same power as you had in the 402) and i know which i would pick!
 
#5 ·
Many of the 72-85 454s found in cars and trucks used 049 heads which are a great start for mild street performance. They're a dime a dozen and flow about 239 cfm (28 in h2o) as cast. They have an uninspired open chamber, but so do most big block factory heads :)

Avoid rectangle port heads. They have way too much port volume for street. Avoid early truck heads as most of them are peanut ports and they are too small. They run out of breath at about 4300 rpm. 781, 049, and 290 castings are the ones that I remember off the top of my head. They're all very similar in flow, port size, and chamber size.

Other than that, there are two basic block designs; the low deck that was found in cars and most light trucks, and the tall deck usually found in gas dump trucks, 1-ton and higher. Avoid the tall deck. There is nothing really wrong with it (except that they were either 366 or 427 cubes) but it adds weight, intake width, and they aren't really good at fitting under low hoods sometimes. I have a 454 in a 73 impala wagon and I replaced it with a 454 from an 83 suburban. Not only were the heads 049 on both assemblies, they got the same cam and had the same basic power ratings. The intakes were different and of course the 83 had HEI, but they were remarkably similar. Otherwise, blocks were very similar. I wouldn't hesitate to use any 454 from the mid years as a foundation, but starting with one that has good heads will save you some headache down the road.
 
#8 ·
curtis73 said:
Many of the 72-85 454s found in cars and trucks used 049 heads which are a great start for mild street performance. They're a dime a dozen and flow about 239 cfm (28 in h2o) as cast. They have an uninspired open chamber, but so do most big block factory heads :)
I'm not trying to hijack this post or anything, but Hey Curtis73, I noticed that you quoted some flow numbers for the 049 heads. Do you by chance know where I can get the full spectrum of flow numbers for the intake and exhaust on the 781/049 heads in stock form?
 
#9 ·
You can take thses as you will. The numbers they got for the AFR heads were close to the the published numbers from AFR. They were off by a maximum of ~4% on the 180cc heads and ~2% on the 210cc heads. This was only at one point in the lift range, most of the flow numbers were pretty much right on for those heads. I only point this out in an attempt to validate these numbers.

049 flow numbers: scroll down a little bit
http://www.chevyhiperformance.com/techarticles/41598/index8.html

Adam
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top