Another 489bbc question

[Roll'nSlo]

I'm working on building a 489 for my '66 c10. I'm not fond of boring any engine .060" if not needed. My question is with 781 heads rebuilt with stock size valves and running roughly 10:1 CR, how much HP does everyone think I can get? I know cam, intake and carb play part in it too. I haven't decided exactly what I'm going to use in those dept. either. I guess any direction or suggestions on them will be helpful too, thanks.

[Blue Rat]

Anywhere from 350-700 HP. Depends the rest of the combo. Really depends on your camshaft choice.

[Roll'nSlo]

Honestly want the biggest cam to get the most hp and torque. I have never been able to figure out which way to go on cams. It's going to be just a weekend play toy. Plan on running E85 as well.

[68c10owner]

Originally Posted by Roll'nSlo

running roughly 10:1 CR.

Originally Posted by Roll'nSlo

Plan on running E85 as well.

Its a waste to run 10:1 on E85. You mentioned you planned to run E85 so if that is still your plan then go with higher compression. Your mpg is going to be a lot less with E85 so you may as well get as much power from it as possible.

If your sticking with 10:1 then forget E85, its not needed.

[Roll'nSlo]

Actually may try to get higher CR as well. Would like to run a tunnel ram as well, but not if it's going to hurt me more than benefit. I've always messed with sbc.

[Super73]

Lets start with a couple simple questions as you are being way to vague.

How high are you willing to spin your motor?
How big of a converter are you willing to go with?
How steep of gears can you tolerate?

You say you want the biggest cam for max hp/tq but the bigger you go generally move peak tq higher up the rpm band to create more hp (hp=tq*rpm/5252). So the above 3 questions weigh in.

[Roll'nSlo]

Sorry about being vague, I usually build them to whatever I can afford. This time I really would like 600-700hp.
I'm willing to spin 6-7k or more if need be.
Converter I was wanting to keep it 2k stall or close to it.
On the gears I was thinking 4:11, would love 4:56 but that wouldn't be practical to drive on the street considering I live 35min from the closest town and it's small.

Have patience with me, this is the first true race engine I'm building.

[b454rat]

I wouldn't do 4.56s, you have a big block, not gonna be lacking in torque. I have 781 heads on my 454, mild cam, 10:1 comp, was told around 350-400 horse. This is in my 79 Malibu with a 4-speed, and 3.42 gears. Car gets around awesome. A 600+horse engine is quite a bit for the street, it's not gonna be crazy, but sure ain't gonna be mild.

[Roll'nSlo]

I was going to run a th350 behind it and probably 373 gears to start with. I have a mild sbc in my '63 now. You know speed is like crack, always want more. This will be my first big block, too.

[Ziegelsteinfaust]

My friend from back in the day had a 468 BBC, comp 268 cam, roller rockers, ideal headers for his engine, closed chamber O port heads, Weiand Stealth manifold, and full MSD ignition. I think the compression was just under 9-1, and the short block was a detailed rebuild. My guess was about 425hp, and 500 tq.

He put it in a 72 C10 swb, and settled on 3.08 gears. It would flat out run, and wasn't to bad on gas either when driven right.

If you never ran a big block before there is nothing like the torque they produce. I even thought of using a 455 Buick in my C20 before I went 4x4.

[Roll'nSlo]

Ok, here's a little more info on my plan. I was in a rush on my postings yesterday.

Build a 489 with my 781 heads. Hoping I can just keep stock sized valves; maybe port and polish them. Intake I'm wanting to run a tunnel ram with a 2x4 setup(unless that's a major headache). Cam I'm going to have to get help on. I always get confused with them on what is the best one to use. I would like to get the biggest one possible for 1) I love the nasty hard hitting lope and 2) I know it's easier to get more performance out of the engine as well. Piston I'm shooting for something 10-11:1 CR if possible to have that on E85. Headers I have a nice set of stainless I picked up. Only thing is I have to see if they'll work in my truck. RPM range is not a major concern but I don't want to spin it to anything over 7500 honestly.

Transmission is a th350 that I have on hand just going to need to get it rebuilt. Stall I'm not really wanting to go over a 2k stall but willing to take suggestions.

My other question is on the fuel line what's the best size to run for a setup like this?

[Blue Rat]

Too be in the 600-700 range feel like it is going to take bigger valves an Hyd. roller minimum. Probably more like a solid roller. The .050's needs to be in the mid 230's or 240 range. A custom cam would be nice.

[Roll'nSlo]

Originally Posted by Blue Rat

Too be in the 600-700 range feel like it is going to take bigger valves an Hyd. roller minimum. Probably more like a solid roller. The .050's needs to be in the mid 230's or 240 range. A custom cam would be nice.

I'm going roller as well, just forgot to put that in. Who do you suggest for a custom cam? Which is better timing gears or chain? Someone told me to go with gears.

[drag80]

i have iron 461 BBC, with ported 781 heads and a solid flat tappet cam, and a 850 carb. It made 510 horse and 565 ft-lbs at the flywheel.

[Super73]

I am sorry to say but I think that a 2k rpm converter paired with a 600-700hp BBC is going to be a turd out of the hole. My guess is the cam you will need to get you to your gos ls will move tq peak much higher in the rpm band.

Also, 600-700 n.a. is a pretty big nut to crack with out really thinking things out.

Being I know nothing about 781 heads, mind sharing what they flow? Hp is in the heads, don't skimp there.

[Captainfab]

Read thru this thread.

http://www.67-72chevytrucks.com/vboa...6+budget+build

This will give you an idea what it will take to get the power you are wanting.

[Roll'nSlo]

Being I know nothing about 781 heads, mind sharing what they flow? Hp is in the heads, don't skimp there.

I know nothing about flow or anything else until I get them in and have them reworked. Sorry

Talking bout cracking the nut w/o really thinking it out; that's why I started this thread to start tossing my ideas around.

[Roll'nSlo]

Capt I'll read the post and make notes as I go thru it. Thread that long will take me a while to read. Lol

Super73, I'm planning on driving/cruising with it as well as a lil racing. I see what you're saying tho. If I need a larger stall I can always get a larger one. I was just putting my thoughts out there as what I had in mind. I was hoping if my thoughts were wrong someone would correct me.

[68c10owner]

700hp isnt going to happen with stock valved 781`s. 600+hp is possible but will take a lot of work in the right hands to get the 781`s to work very well. Best bet is aftermarket heads. Brodix Race Rite ovals or AFR 265cc ovals or the 290cc ovals if you can swing it and will get 600-650hp out of the box on 10.5:1 using regular pump gas. If your planning E85 then go with 12:1 at least to take advantage of it. As for the cam talk to Chris Straub at http://www.straubtechnologies.com/ He will design you a camshaft for your exact combo but he is going to need to know some details. He`s very good though.

You will most likely have to step up to a th400 unless you can find someone who can build the th350 to handle the power but they arent cheap. And keep the gears no more than 3.73, let that stroke do its job.

[Blue Rat]

Those 781's will work. But they will need bigger valves an some work done to the ports. Here is a good web site with flow numbers. You could probably get a good set of aluminum heads that flow around 280-290 for a little more than the 40 year old castings that you are going to sink a hunk of money. (This my last edit) Stay with oval ports.

http://users.erols.com/srweiss/table...hevy_Big_Block

The camshaft needs to be on top of the game for something like this for sure. You really need to wait until the heads are done so you can give who ever the flow numbers an your other info about your truck. The camshaft needs to be designed around your truck parts list. You need to decide what the Compression ratio, converter, rear gears, headers, head flow numbers, intake an headers are going to be before calling whomever. If you go solid roller that is a whole new topic. We will save that if discussion for if you go that route.

I used http://www.straubtechnologies.com/ he is not cheap. Last time I ordered from him he used Bullet cams.

If you have not figured out by now. The tranny will have to be a good one. The 400 turbo will work, I would not use a 350 turbo behind this engine if you go the direction you are headed with the engine. A set of 3.73's would be nice too.

[68c10owner]

Originally Posted by Blue Rat

Those 781's will work. But they will need bigger valves an some work done to the ports. Here is a good web site with flow numbers. You could probably get a good set of aluminum heads that flow around 280-290 for a little more than the 40 year old castings that you are going to sink a hunk of money. (This my last edit) Stay with oval ports.

http://users.erols.com/srweiss/table...hevy_Big_Block

The camshaft needs to be on top of the game for something like this for sure. You really need to wait until the heads are done so you can give who ever the flow numbers an your other info about your truck. The camshaft needs to be designed around your truck parts list. You need to decide what the Compression ratio, converter, rear gears, headers, head flow numbers, intake an headers are going to be before calling whomever. If you go solid roller that is a whole new topic. We will save that if discussion for if you go that route.

I used http://www.straubtechnologies.com/ he is not cheap. Last time I ordered from him he used Bullet cams.

If you have not figured out by now. The tranny will have to be a good one. The 400 turbo will work, I would not use a 350 turbo behind this engine if you go the direction you are headed with the engine. A set of 3.73's would be nice too.

Aftermarket heads will flow in the 340cfm range. 280-290cfm from 781`s is pretty easy to get but you wont see 600+hp with those numbers. Out of the box Brodix 270cc oval port race rites flow in the 340cfm range and can be had for about $2000 ready to go depending on where you get them.

Pick your heads first, then your camshaft. Brodix and OEM heads will need about a 12 degree split because of the exhaust port. AFR heads can use a tighter split or even a single pattern cam because they have a better exhaust port. Compression isnt as important as matching the cam to the rpm range and what the heads flow.

[Blue Rat]

Yes they will flow more but I always go by the .400 valve lift figures.

http://www.brodix.com/heads/big-bloc...block-series26

[68c10owner]

Originally Posted by Blue Rat

Yes they will flow more but I always go by the .400 valve lift figures.

http://www.brodix.com/heads/big-bloc...block-series26

low lift figures are good, they show how well the head will perform but you still need to know what the max flow is and where. None of this is really important at the moment as the OP hasent gotten to this point.

[Roll'nSlo]

Originally Posted by 68c10owner

700hp isnt going to happen with stock valved 781`s. 600+hp is possible but will take a lot of work in the right hands to get the 781`s to work very well. Best bet is aftermarket heads. Brodix Race Rite ovals or AFR 265cc ovals or the 290cc ovals if you can swing it and will get 600-650hp out of the box on 10.5:1 using regular pump gas. If your planning E85 then go with 12:1 at least to take advantage of it. As for the cam talk to Chris Straub at http://www.straubtechnologies.com/ He will design you a camshaft for your exact combo but he is going to need to know some details. He`s very good though.

You will most likely have to step up to a th400 unless you can find someone who can build the th350 to handle the power but they arent cheap. And keep the gears no more than 3.73, let that stroke do its job.

I'm a little confused. Here you said 12:1 and now you're saying 10:1.

[mud.man.rj]

Nice thing about a big block is torque, so stick with the suggestion of 3.73 for gears, won't need to spin it up but will need more stall, at least around 2,500 to 2,700 and may even have to go up to 3,000 with a tunnel ram just to make it streetable, remember the stall actually moves the truck before it's listed stall speed. Tunnel ram will make it look cool but less streetable.