View Full Version : Darkside(BBC) head question....3993820


BIGBADBOWTIE
05-18-2006, 11:40:53 AM
I know the 049 and 781 oval heads are the ones to have BUT I have a chance to buy a set of 3993820 o-ports that have been opened up a little. They have 2.19./1.88 valves, lunati solid roller double springs to 700.

I can get these heads,with a BIG lunati roller (.700) with lunati lifters(new) for 500 bucks.The cam would have to go for a milder solid roller.

My question is..... are these heads any good for any REAL hp?

Thanks
slowly making my way in to darkness.......;-)

Urban Samurai
05-18-2006, 12:02:46 PM
according to http://www.mortec.com/bbc.htm these heads are pretty good. They will give you more power than the stock rect port heads. Real hp is relative. What do you consider real hp?

theflash
05-18-2006, 12:21:12 PM
I'd have the heads cc'd to be sure of the chamber volume.

BIGBADBOWTIE
05-18-2006, 12:25:18 PM
550 HP N/A would be acceptable. I can't comment on the port work other than the fact that they have been. The guy Im buying from bought the heads over 5 years ago from a local racer. He had them freshend and they have set bagged ever since.

theflash
05-18-2006, 12:51:46 PM
550 HP N/A would be acceptable. I can't comment on the port work other than the fact they they have been. The guy Im buying from bought the heads over 5 years ago from a local racer. He had them freshend and they have set bagged ever since.

Acceptable? That's a fairly tall order.

Urban Samurai
05-18-2006, 01:25:11 PM
550 hp on those heads is a bit much... May be possible with bigger valves and extensive flow work. I think if you want that much you would be best going for an aftermarket. I myself have been looking at new heads and want to keep a lot of low end torque, therefore have decided on the afr 305 cc CNC heads. For the money these heads out flow most larger heads. It is a rect port, however, I am keeping my oval intake and porting it to match the head. This is a great way to increase velocity and low end torque.

BIGBADBOWTIE
05-18-2006, 01:40:03 PM
Thanks for the info....I don't know very much about the BBC side of chevy thats why I asked. I know of some fast cars with O port heads but they had some pretty extensive port work done.

It looks like these heads came off of the LS5 BBC.

Ill more than likely pass on these heads and will be doing some more research. :-)

This is an 049 casting oval port headed solid roller 468 on pump gas.
http://www.rochesterstreetsyndicate.com/videos/scott_at_cfr.wmv (http://www.rochesterstreetsyndicate.com/videos/scott_at_cfr.wmv)
Its a full weight car as well with only a fiberglass hood.

Urban Samurai
05-18-2006, 02:06:26 PM
Hey bowtie, check out this web site http://www.chevyhiperformance.com/techarticles/41598/ This is where I did most of my research on heads. It does not have all the available heads, however, will give you a good understanding of what is what. Let me know what you decide on.

By the way that camaro in the link is a bad azzzzzzz.

BIGBADBOWTIE
05-18-2006, 02:21:42 PM
Scotts car is SUPER nice. It looks just as a nice as it runs. Interior is MINT as well as the gold paint. 10.80s on grunt is awesome. Im just tired of having to spray my ride to keep up ;-).

Thanks for the link.....Ill check it out.

cody
05-18-2006, 03:09:10 PM
wow BIGBADBOWTIE any idea on the specs of the cam?the solid roller i have for my BBC is:

255/265 dur. @ .50
lobecenter 110
lift 630-650 with 1.7 rocker

i too have a pair of 049s that ive had cleaned up at the machine shop that im gonna do an extensive amount of port work to,but i was intending on building a 489,but that 468 sure is getting the job done......kicking @$$ on pump gas

BIGBADBOWTIE
05-18-2006, 03:51:07 PM
He sent me specs on it...just a little street cam. Should be easy on valvetrain parts. ;)

.700/.700 lift 1.7 rocker 274/280 @ .050 on a 108lsa

Maliboost
05-18-2006, 04:34:06 PM
my 427 runs 10.0's @ ~3580 Lbs, on the jug
anyone have a HP to ET calculator handy to figure out how much HP its making?

Bob

Grumpy 427
05-18-2006, 04:46:39 PM
well 2 things i have learned this year. My engine builder was good enough to give me an education on his flow bench. The stock type BBC head will only flow so much air due to the location of the exhaust port. Anything with raised ports will flow better and allow the motor to reach higher RPM's Most oval port heads are done by 6500 RPM.

BIGBADBOWTIE
05-18-2006, 10:17:23 PM
here is one calculator bob....

http://www.race-cars.net/calculators/et_calculator.html

says you are making over 700 at the wheels....

procharged 79
05-19-2006, 06:00:53 AM
well 2 things i have learned this year. My engine builder was good enough to give me an education on his flow bench. The stock type BBC head will only flow so much air due to the location of the exhaust port. Anything with raised ports will flow better and allow the motor to reach higher RPM's Most oval port heads are done by 6500 RPM.

Good point Grump, and I fully concurr with what your builder said. Having said that, everyone needs to capitalize on the flow potential of the stock oval ports below the 6500 RPM, in other words don't slide a cam in it that makes power from 4000-7500, use a good dual plane intake and small headers.

I personally have used the 820 heads and they are a very good head considering stock oval ports. I cc'd the chambers and they came in at 113 cc's. I installed the bigger valves (I question if they were really needed), cleaned up the ports, bowls, chambers, and good valve job. I put them on a +.030 427 with a comp XS 274 solid cam and 10:25 Compression. Dropped it in a 3600 pound 72 Chevelle and right off the trailer ran 11.90's on motor.

Rob

Maliboost
05-19-2006, 01:19:35 PM
here is one calculator bob....

http://www.race-cars.net/calculators/et_calculator.html

says you are making over 700 at the wheels....

thanks amigo. that sounds a little generous, but it would mean that the motor makes about 500 (200 Shot). IMO, Pretty good for a Hyd flat tappet, with an unported set of GM heads. as Grumpy said, dont rev them to the sky & get that load in @ low RPM's & it will run like stink.

I know you guys think Im high, but the key to running nitrous motors is to get it in there as low a rpm as you can AND "letter eat". the valves are open for a longer period of time the slower the engine is spinning. chew on it for a while. it really does make sense. fast valve action with big rocker ratio's help this, Low lift flow numbers are where its @!!!!

Bob

ZS10
05-19-2006, 07:52:37 PM
My 427 dynoed at 463 with stock valve 781 heads, 9.5:1 and a comp 280 cam. I'm sure another 90hp could be had with some work, and a bigger cam/valves.

+1 on the low revs concept.