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First BBC engine build: questions

3K views 6 replies 4 participants last post by  camarodriver67 
#1 ·
I have never built a motor I'm trying to get a parts list together to take to the guy that's going to build my bbc. This is going to be a Budget build. What I have already is a short block it's been bore to a 468 has new speed pro dome piston dh631cp.030 31412-06-c. I was told it has stock rods and crank.I guess here's my question what would ya recommend far as camshaft and heads like I said this is on budget build right now. I would like to have atleast 550hp if possible. This is going to be in my 68 Camaro . I want just a nice hot street car to Cruise to car shows and around town.
My car has not been on the road for 3 years now and it's killing me I know a lot people have waited longer but for now I just want get it up and going till I totally restored the car. I just bought a new house and don't see that happening for awhile.
 

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#2 · (Edited)
First BBC engine build: questions

Before you go buying a lot of parts what do you have for heads? The casting numbers are in the valley of the heads. You have the know what cc the chambers are to know what piston to buy for the correct compression ratio. You need to read an article like this to help you out. Building A Big Block Chevy Engine - Chevy High Performance Magazine. I 'll give you a little advice on the heads. The stock heads with the last three digits of 781 or 049 casting numbers are the best heads you can get. If your heads have 118 cc chambers these pistons would be the ones to get. I don't know what you have. I can't find the part numbers anywhere. I came up with H631cp-030 is a flat top speed pro piston for a 350 chevy.
 
#3 ·
Far as heads that's what I'm looking for to don't have any. I did find a set 049 but was not sure if they would work good with the dome pistons I already have?
If I bought the 049 what would be a good cam to go with the speed pro pistons? Here is pic of the pistons
 

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#4 ·
First BBC engine build: questions

No wonder I could not find the pistons. The part number is H693CP-030. Well if you can get the 049's make sure you know the size of the chambers before you buy them. 120cc or larger will help with those pistons. The factory rods will be fine but you will have to take them to a machine shop to have them reconditioned and new ARP bolts. Chevy made two size rod bolts 3/8 & 7/16. It would be nice to have the 7/16. Get a itemized recondition price. Don't go over the price of these rods. These are better for 500 Hp. https://www.summitracing.com/parts/SCA-26135716/?image=large. I would not put a hyd flat tappet cam in a big block chevy or any chevy for that matter. I would recommend this Lunati camshaft. https://www.summitracing.com/parts/lun-30110507/overview/make/chevrolet. To go with it Lunati lifters 70992-16 $102.97, Lunati valve springs 73121-16 $121.97, Lunati retainers 75748-16 $50.97, Lunati locks 75782-16 $50.97
 
#5 ·
If the 049s work for your application, spend the money on a basic port job. The porting can unlock 75 plus horse power, well worth the money. Get them flow tested after to match the cam to the flow and split duration numbers as required. Get the flow numbers and you can logically pick the correct cam. 9.7:1 compression ratio is about ideal for a street rat that s making way north of 500 hp.
 
#6 ·
Piston compression height 1.640, rod length 6.135, crank radius 2.000", so the stack measures out to 9.775. If we assume a 9.800" block deck height, that leaves a piston deck height of 0.025". If we use a Mr Gasket 1131G steel shim gasket @0.020" compressed thicknss, we get a squish/quench of 0.045". With a -22 cc piston (+0.030"), 0.020" shim gasket (5cc's), 118cc combustion chambers, 6 cc's in the piston deck height, I get 9.84:1 static compression ratio. A retro-fit hydraulic roller cam with 218 to 228 degrees duration @0.050" tappet lift should be about right. Take a look at the Crane 139611, for instance.
http://www.cranecams.com/120-125.pdf
 
#7 ·
First BBC engine build: questions

Marks68, I know you said you are building this engine on a budget but you need a set of heads. The most inexpensive heads that are decent heads are ProMaxx from Summit Racing or Speedmaster PCE281.2031 from Jeg's. Check the price on these aluminum heads. Speedmaster PCE281.2031: Big Block Chevy Aluminum Cylinder Heads CNC Ported 119cc / 320cc A/Plug Hydraulic Flat Tappet Complete Heads | JEGS These would be ideal with the pistons you have listed. The block decks will have to be milled to zero to use .039 thick head gaskets and a quench of .039 so you have the least worry about detonation. It is best to get the machine shop to square the decks to begin with. I know when I carried my 454 block to the shop, when the machinist measured the piston to deck height mine were all different. #1 cyl. was .017, #3 cyl was .016, #5 was .016, and #7 was .019. and 2,4,6,& 8 were off just as bad. He ended up milling the decks to .005 so I had to purchase .036 thick MLS head gaskets.
 
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