jnewby Posted December 6, 2005 Share Posted December 6, 2005 okay I have a small block 350 bored 60 over flattop pistons stock stroke stock rods cermic full lenght headers eldbrock 750 carb with proformer intake 305 heads and a 305 balencer I also have a complete stock 454 with oval heads any one have predicted power outputs? for right now I am still trying to complete the big block transplant iam also pretty close. thanks Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 7, 2005 Administrators Share Posted December 7, 2005 With the 305 balancer, the 350 should produce at least 1 meeeeeeelion Horsepower. The 454 should only produce 850,000 HP, unless you have an Edelbrock sticker on the rear window, then it will produce at least 1 meeelion horse power as well.... Quote Link to comment Share on other sites More sharing options...
Alf Posted December 7, 2005 Share Posted December 7, 2005 those 305 heads are going to KILL that engine, get other ones if at all posible. as for the 305 balancer, i thought the 305 was externally balanced, that would mean that the balancer will have a cast in weight on the balancer hub, but the 350 is internally balanced, they are not compatible. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted December 7, 2005 Share Posted December 7, 2005 The only early sbc that is externally balanced is the 400. 305 balancer is ok, doesn't add anything in the way of HP. 305 heads are for low end, up to about 3500 rpm or so, mostly torque motors and are pretty worthless IMO except when used for boat anchors. Some vortec's or even some 882 casting heads would be alot better choice IMO. The HP depends on cam selection, if it's stock, probably 200 to 250 at the flywheel depending on engine condition. Quote Link to comment Share on other sites More sharing options...
Michael Posted December 7, 2005 Share Posted December 7, 2005 Facetiousness aside, you’re going to find that both of your engine options will be relatively disappointing in horsepower. What’s the casting number on those big-block oval port heads? If the engine is from a 70’s truck, they are most likely 236-heads – which means about 220 hp at the crank. With that engine you still have a decent foundation for performance – but it will require considerable modification. BTW, please post more details about your BBC swap. Mine is “mostly†complete (after 6+ years, plus professional help), but if I were to do it all over again, the logical choice would have been a 350-based SBC. Quote Link to comment Share on other sites More sharing options...
dmyntti Posted December 7, 2005 Share Posted December 7, 2005 The 305 heads on a flat top 350 are going to produce some excessively high compression. For that to work you would need a cam with alot of overlap to bleed off some cylinder pressure. Unfortunately the valves in the 305 heads are small and can not perform well at high rpm where the big cam wants to make power. You should really swap out those 305 heads for something with appropriate valve sizing. Quote Link to comment Share on other sites More sharing options...
Trevor Posted December 7, 2005 Share Posted December 7, 2005 Put the 454 heads on the 350. Then port them with the complete engine in the car. I did this swap in my garage yesterday. with my wife......Morgan Fairchild. Yeah that's the ticket Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted December 7, 2005 Share Posted December 7, 2005 peanut port is of the devil 305 is of the devil Invest some money in cylinder heads. If you can afford it, buy some BB heads. If not, I agree with the idea of vortec heads. Quote Link to comment Share on other sites More sharing options...
jnewby Posted December 8, 2005 Author Share Posted December 8, 2005 funnie before reading this post I was already looking at vortec heads and manafold. so can you get those at a salavge yard they are the ones with four bolts in the center? right? I was told that they put the 305 heads on for proformance it had a 488/488 cam in it, but it caused a lot of problems like killing a starter evertime it back lashed. so we went to a mild cam and that killed alot of power. Quote Link to comment Share on other sites More sharing options...
jnewby Posted December 8, 2005 Author Share Posted December 8, 2005 As for the progess on the big block the motor is mounted in the car the th400 trans needs a crossmember the engine needs block hugger headers and I am modifing a ford pickup gas tank to fit also need a drive shaft and I need a job to pay for all of this. I also would have done the small block conversion, but someone once told me if it was easy then it wouldn't be cool. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted December 8, 2005 Share Posted December 8, 2005 The 305 heads are just generally regarded as bottom of the totem pole in regards to performance. A big cam is just a crutch for bad flowing heads. Look on mortec.com for casting #'s of the vortecs, just to be sure you get the right ones. The BBC is a good engine as long as you have regular oval port heads and not the peanut port heads. Both would take money and a job would be a plus, although I've considered panhandling on the street corner cause I hear those guys rake in the cash. Oh, well, it's winter now so I guess I missed my chance, maybe next year. For mild HP the SBC will make as much HP as you could possibly want IMO. The bbc will make more if you go insano and will fill the bill no matter what HP level you want, it's about choices and $$$. Cool, is really in your mind, it's not a tangible thing and it varies from person to person. One might think it's cool, another might not, and yet another might think your nuts. But that's my perspective. Quote Link to comment Share on other sites More sharing options...
jnewby Posted December 8, 2005 Author Share Posted December 8, 2005 the heads are oval port and everone that seen it has said it is cool. Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted December 10, 2005 Share Posted December 10, 2005 ...so can you get those at a salavge yard they are the ones with four bolts in the center? right? ... absolutely not, I have a pair of center bolt heads sitting in my attic and they are definitely NOT vortecs. I forget the casting #'s and years they came on but do your homework if you're going to a junkyard. A local machine shop here sells a set of worked vortec heads for $350 which I think is a pretty good deal (just an idea), they might even be cheaper now since all this ls* craze started. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 10, 2005 Administrators Share Posted December 10, 2005 Bang for the buck the Vortec CAN’T be beat!!! Port shape and size is excellent as cast to support in excess of a realistic 350-375 HP especially with the raised port floor and generous short side radius on the Intake. The chambers are, well, a work of art with the spark bolts closer to the center of the chamber, than any other SBC head I have seen. Below, this is the casting identification on the end of the Vortec heads. I just took these pics yesterday. I bought these for my father as he plans to use them on a very mild 383. He wanted me to massage them so I just performed a mild clean up in the bowls only. The chamber on the left is untouched as cast, the chamber on the right has the mild massaging done, below… Below, note that GM is shipping the new Vortec heads with high quality Viton Stem seals and also putting a 30 degree back cut on both the intake and exhaust valves. I perform a 30 degree back on the valves of EVERY cylinder head I do. GM saved me that step this time around FWIW, I also weighed the Vortec heads as a pair, fully assembled, without rockers, 90.4 lbs for the pair. I also weighed my Trick Flow Signature heads fully assembled without rockers, 58.6 lbs for the pair. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.