sbc H.P guess...

hey im building a 70's sbc and was wondering if anyone has built one similar to my specs and can shoot me a guess on the h.p ill be looking at.

its a 350 .60 over has stock stroke rods/crank,flat top 10.2.1 pistons,
-comp 280h cam (230 duration @ .50/ 480 gross valve lift)
-1.5 roller rockers,
-305 heads ported exhaust/ ported & polished intake ports, 1.96 intake valves and 1.4 exhaust.
-edelbrock performer rpm air gap intake manifold
-750 d.p demon (no choke,vaccum secondaries)

any help would be greatly appreciated...

thanks in advance

 

I'm guessing a little better then 300 hp

 

Careful with the 305 cylinder heads on a 350 with flat top pistons !!! >>>>.

 

ooh ooh why's that?

 

Compression Ratio !! Have you ccd them ?? >>>>.

 

Im pretty sure there 58 cc?

 

And what i know they were never shaved

 

you must be in the hole a lot, I would figure about 11:1 and be conservative.

 

Sorry guys its the first motor i put together... Thanks for the replies and do you think there would be a major problem with piston to valvr clearance?

 

Do you think this type of compression is ok for a daily driver On 93?

 

those heads are the bottle neck, not sure of hp guess on that combo usually see 350 2.02 heads with that set up and hp is around 350 maybe more with better ported heads.

 

So i think i see a cylinder head upgrade in my near future

 

if the heads were aluminum 11:1 would be easier but not as easy on cast heads, unless you want to retard your timing just to make it work, best thing would be to shoot for 9.5-10.0 to 1 with that cam and cast heads with todays unleaded

 

dart s/r cast heads......check em out

 

58cc on a true flat top 350 squeezes to about 12.25 to 1.
54cc 305 heads (both are pretty common) about 13 to 1.
These are rough figures- your squeeze may vary slightly.
If you plan to run it on the street you better know how to tune and jet properly.
With the set up you have, these heads leave about 40 hp laying on the table
compared to 64cc heads with 2.02 X 1.94 valves, not to mention the hassel
It's yo money dog-pay up and take yo choice.

Just my opinion- 305 heads do a pretty good job on 305's.

 

Any suggestion on what brand/ specs i should be looking for On heads?or any factory heads that will work?

 

Will look into them thanks

 

Thanks for helping me out it was really beating my head..i appreciate the helpni get here on the hamb alot...it has saved my ass a bunch of times

 

just checked there website they are now called dart iron eagle s/s heads $560 a pair from them i would check summit, see if they are cheaper......

 

Scoggins-Dicky Chevrolet sells new Vortec heads with the big valves and clearanced for up to .550 lift. Price dances around a bit. You can check on line for the going rate.
Most bang for the buck out there.

 

Yeah and if you use the 305 heads you'll get a lot of practice working on it !!! >>>>.

 

Lol i think ill take the easy way out and order some good heads to save the hassle..really liking the look and price of the dart iron eagle s/s heads so i guess ill look around for the best price and just order them....

 

Just checked my build sheet and there flat top 4 valve releif cut pistons... Do you guys think that may help my issue or shouldvi just stop matching fire with fire and get some heads?

 

I had something close to that in my 67 Camero many many many years ago....except I had the 2.02 FI heads (double camel hump).

300 HP? I really doubt it....close maybe....as noted above....heads are your problem....you really got to get those intake valves larger.....

 

Here's something I know. The way to make a 305 perform a whole lot better is to use 350 heads. I don't think it works the other way. Get some 350 heads with 2" valves and you will have a much stronger engine. Or if you have a little more cash the Vortec heads are even better.

 

48 chubby took the words out of my mouth.vortec are great heads mate has them on a 350 with around 400hp

 

I'd say at least 25

 

EQ Cast Vortec Heads are a great bang-for-the-buck.

Do a search on here as there have been a couple of lengthly threads on them lately.

You can check with Mike Rogers at Rogers Performance if you're interested.
http://www.rogersperformance.com/EQ.htm

I got my EQ heads from him a couple of years ago and I couldn't be happier with his
old-fashioned service and quality.

 

Put a set of stock Vortec heads on it with timing set correct you could probably see 375-390 on the dyno.

 

Maybe you already know this, but people are forgetting to mention that the Vortec heads will require a different intake, and valve covers too I believe. If you already have a good intake that you like, keep that in mind, because it adds to the expense.