Reply With QuoteDo we really need another thread for this?
Jim W made the suggestion in another thread that I share my engine build. It sounded like a good idea to me so I will do the best I can to share the experience.
Please keep in mind that this is NOT the "Ultimate Engine Build". If you want to read one of those stories buy a magazine where they build an engine with an unlimited budget, sterile shop, professional engine builder, etc.
My intention is to salvage as many parts from my original motor as possible.
L J
Do we really need another thread for this?
Do we really need another thread for this?
Yes Hammer, yes we do
Be good, Jim
Please don't read this. I wouldn't want to insult your intelegence by having you read the words of a mortal man.
L J
So L J,
here's where I am at.
I may have my unfired BBC, blower motor sold. It's more of a street motor really. B&M 420, 427 2 bolt main, iron heads, carbed.
I am now putting part's in it that exceed the base engine's build up. I started off at 7-800 Hp and now am over 900 Hp and in a boat, not a street rod. Going to alcohol.
Time to stop and regroup.
What I am thinking of building over the winter is.
496 tall deck with nice forged internals.11.5/1 cr., Alu. heads, AFR with a healthy (.700+) solid, roller lifter cam, on alcohol with a birdcatcher. To top it off, I would love to get a Whipple charger rather than the usual 8-71 or 10-71.
At Anna this spring, I was soooo impressed with Jacks alky jet. I know that was the way I wanted to go.
Be good, Jim
My intention was to use as many parts from my old engine as practicle. It was a 402 BBC with oval port heads, small rods, press fit pistons and a B&M 420 blower with 2 Edelbrock carbs.
The old engine dropped a value due to Reversion. Water hit my exhaust valve and made it brittle. It broke and tore up my head, block piston, rods, etc.
I got a donor engine, a Gen VI 454 425 HO (4 bolt mains, rectangle port heads, etc with a spun bearing. Since I had to replace the crank anyway my machinist, Rob Mahler, suggested I build a 496 stroker as the cost would be the same. I was all for it. We figured it would make about 700 HP by running 6 to 7 psi boost, etc.
The block was reconditioned (line hone, decked & bored .060 over, brass freeze plugs, etc.). The heads were given a competition valve job and the Crane springs and retainers from my old heads were installed and the head was decked. I needed to remove the stock springs because they were for a roller cam which would have been too stiff for my flat tappet cam and lifters.
Rob got all of the parts for me, kind of like a kit, so that they would be compatible. He has a lot better chance of picking the right stuff than I would sitting down with a catalog and buying a bunch of stuff.
The crank is an Eagle cast 4.25 stroke and the rods are Eagle I beams both of which are good up to 700 HP. The crank looks real nice. It has the large radius on the bearing surfaces and the oil hole are are chanfered real nice. The rods look much nicer than the stock rods and they have nice ARP cap screws instead of nuts and bolts. The pistons are forged SRP flat tops (.007 clearance). I found out, after much research, that no manufacturer makes a dish top piston for my 496 combination. You can get a dish piston for a 454 but not his deal. I really wanted to have 8 to 1 compression ratio but the flat tops got me about 8.6 to 1 with my 118cc combustion chambers which isn't too bad. My effective compression ration with 6 or 7 pounds of boost should still be in the range where I can still run 93 octane gas. I run my blower about 16% under driven which gives me the 6 or 7 psi boost.
The rings are Mahle - standard tension, Performance Rings (file fit). I fitted them to .024 end gap for the top ring and .028 for the 2nd ring as prescribed in the instructions that came with them (blower motor on gas).
The bearings are Clevite 77. The mains have .025" clearance (using plastiage). ARP studs are used with the main caps.
The cam is from my old motor. It is a Doug Herbert blower flat tappet hydraulic cam. I decided to not use the roller cam and lifters that were in the engine. A roller blower cam was another $450 and I was running close on money. I was also concerned that the 425 HO cam wasn't designed for marine use and it probably had too much overlap for a blower setup.
The bolt pattern for the old (Mark IV) cam is not compatable with the bolt pattern on a Gen 6 timing gear which used a single row timing chain. To change it to a double row chain I had to replace the timing cover with a after market billet aluminum one to make room for the double row chain.
Installing the full floating pistons on the rods was a bitch. They want 2 spiral locks on each end of the wrist pin. My fingers were sore after that deal.
That's where I am now. Tomorrrow I install the pistons and go at it from there. I will let you know how things go from here.
L J
The bearings are Clevite 77. The mains have .025" clearance (using plastiage).
L J
hmmm...... :2purples:
Lots of work, Lynn. If you can make the 700hp you will be spinning an A around 6k...
i want more..tell me more....like what kind of valves are in the head now...like actual measurement of the pistons(skirt, pin and pin90deg) and cyl measurements...like what the side clearances on the rods and thrust on the crank come out to be...like which lifters you are going to use on the used cam...like what headgasket and thickness you will use...like what method you use to torque the heads...oil system modifications or tests...valvetrain geometry setup and tests...and a picture is worth a thousand words.
I think it is great that you would take the time to expand the engine build for people like me who dont have much engine experience, but only book reading.
The mains have .025" clearance (using plastiage).
L J
I hope this is a typing error.
The bearings are Clevite 77. The mains have .025" clearance (using plastiage).
L J
Using some thick oil I guess.
:rollside: I figured it was to cool the pistons, to make up for the slightly higher compression ratio, and lube the cam better...but i would not go over .007 as there might be some knocking when the engine was not under a load, and at idle below 1500rpm he might brinell the bearings...an oil cooler would be manditory for this setup...50wt at 100F--120F would be about right.
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