427 BB Chevy project.

Looking for ideas on building this 427. What I have is a good 454 block, Eagle H-beam rods, good steel crank out of a 69 396. I have the large oval port semi-open chamber heads off of a 69 396 also. I know I will need to get 427 pistons. Also have 1 3/4" primary headers and 3" exhaust with Flowmaster mufflers. I have not built a big block in over 15 years. Anything I should change? What type of cam, intake, and carb. This is going to be a street/strip engine, in a "TRUE" 1970 Chevelle SS with Muncie close ratio 4 speed and 12 bolt rear axle with 4.10 gears, and a Moroso Brute posi unit. 295/50/15 BFG DOT slicks rear tires. Thoughts???? Thanks guys.

Shawn


Register now (free) or login to remove ads

Well the first thing I can put out there is the 396 crank will probably have to have heavy metal added to it to balance the heavy 427 pistons.Try to find a 427 crank if you can. I got my steel 427 crank off e-bay for $100 and it had to be lightened for my 396 pistons.Mallory is expensive.Pump gas motor?

Your not helping yourself with the heavy H-beam rods either, just making it even harder ($$$) to balance. Since you are going to have money into the crank, you might be better off selling it and getting a 4.25" stroke crank and building a 496. 70 more cubic inches is hard to argue with for about the same amount of money, and put together well a 496 will destroy the 427 power-wise.

Maybe I would be better off just building my 396? $ wise anyway? So that still did not answer any questions on my heads, cam, etc...

Pump gas motor?

4.11 gear and 4 spd. then use 10:1 cr, stock oval port heads are ok, 292H compcam, performer rpm intake, 850 cfm carb.

I don't recommend flowmasters. too loud and they don't flow that well.

I would build a 454 or 496. Why build a small engine?

you need to find out the head volume so you can get the right pistons.

Actually, I have never seen a balance problem with a 396 crank or even a 366 crank in a 427. A good balance guy can cure it simply. Also the rods are not a problem. Guys have used the heavier stock 7/16 dimple rods for decades.

The 69 heads are probably around 96 cc's. Use a piston with a .100" dome or so and you will have right at 10-1 compression. The 390 hp. Stockers from that era used such a setup.

Big blocks like a lot of lift. Cams bigger than 284 are the way to go if you have convertor/stick shift for them. Performer RPM or an air gap. 750 carb. Electronic ign. As big an exhaust system as possible. Double roller chain and a standard volume oil pump. If you must fool with the oil system. Put a tiny air bleeder hole in one of the front oil galley plugs and boost the pump pressure a bit, with a shim under the relief spring.

Like c454 pointed out for head volume get the casting numbers to see which ones you have. As for the 396 crank, I have run with those with 427 pistons and have never needed mallory metal to balance them. (Maybe one of the engine shop gents that visit this board can give their experience). On the rods I run with standard chevy rods that are reconditioned with arp bolts. I see on the eagle site http://www.eaglerod.com/ they list there sir I beam rod sir6135 at 830 grams and the crs61353d H beam @ 780 grams. After seeing some dyno results the 1 3/4" header would work good i don't think I would go over 1 7/8" because it is on the smaller end of the big block's.

Like Bob stated you are not going to have any balance problems with that combo.If shop doing the work knows what they are doing.

IMO, it sounds to me like your going more for a performance build????

If your not married to those old out dated cast iron heads , I would spring for a set of Edelbrock aluminum heads, get the compression around 10.5:1, it will run on 93 octane that way, and run a small solid roller cam, 244@.05 and as much lift as you can get. Vc jr intake and a 850ish carb.

That above combo in a heavy chevelle is a proven high 10 second ride.


Keith

I was told by several people that in some engines, the 366, 396, and 427 used the same crank, and rods. Only difference was that the 427 piston had the wrist pin location moved down on the piston for the shorter stroke crank. As far as why I am building this engine, is because these parts are setting in my shop. I have a good standard 454 block, and standard 396, block. Steel 396 crank, balancer, and manual flywheel. I wanted to use the 454 block to build the 427 for the cubes. I have two sets of iron gm heads, one has larger chambers than the other. The are both large oval port. I have a new in the box Holley 650 HP street carb that I will have to sell and pick up a larger carb. I have the 1 3/4" headers in the car, along with 3" exhaust and 3" flowmasters. Now I am confused about the balance of this crank from what people have said earlier.????? Is it true that a 427 uses a different balance? Or are they the same crank??? Thanks

Shawn

They are all the same basic crank. Each usage is balanced a bit differently because of the piston/rod weights. Even a 427 with cast pistons and 3/8 bolt rods would be balanced differently than, say, a 427 Forged piston, dimple rod assembly. I had assumed you had this stuff available and there is no problem putting a budget motor together. Thats why I said to use a 750 type carb. Lots of old 3310 Holleys out there dirt cheap and perform well with your type combo. I have built lots of these style streetable combos for the locals.
As any engine builder will tell you. Horsepower is in the heads. But if you gotta use what you have. Go with the 96 cc. heads with a little compression. Lots of valve lift!!

Thanks, I picked up a newly machined .010/ .010 427 crank and resized truck rods with arp bolts, for $200. Also comes with balancer and manual flywheel. Good deal? As far as carb, once I sell the new 650 HP street Holley, then I will probably pick up a new 750 or 850 HP street Holley. As far as heads, I have a set of GM Phase 6 aluminum bowtie heads with 2.05/1.6 stainless valves that I plan to sell or trade for some better big block heads. Both parts are listed in the classifides on this web site. And my 64 Nova is also listed for sale on here as well. Thanks guys

Shawn

The crank, and rod set up I bought yesterday came with a set of trw L2300 pistons installed on the rods. It looks like two pistons were damaged. What happened was the ring lands broke on one piston, and somehow broke a valve, then another valve dropped and got the top of another piston. It was in a drag boat. Very low hours. But, I think that I could just get two pistons and new rings and re use these pistons? I can't find the specs on the pistons anywhere either. If I could find them I would know weather to use them with the heads.

I will have to check my old TRW catalog. I know that L-2307 are 454 and L-2308 are 427 Both BIG dome 13-1 compression.