I am building up a 350 for my 70 Nova.  The block came out of a 79 camaro, because the 327 I had was cracked.  I am using the double hump 1.94/1.50 64cc heads off the 327, I port matched the intake ports, ported and smoothed the intake and exaust passages, and did a 3 angle seat grind as well as valve grind (possibly getting new stainless valves).  the heads are getting shaved .010 and the block is going to be zero decked, with speedpro hyperuetectic flat tops the machine shop told us that we should be making about 10:0:1 compression.  Im using the stock 350 rods with stock 350 crank, a comp hydraulic bumpstick with 130/136 duration at .050, and 480/490 lift.  Putting in the recomended comp valvesprings.  This cams rev range was 1800-6200, im using 650 holley four barrel with vacuum secondaries on top of an edelbrock torker 2 single plane intake.  Ill be using stock rocker arms and pushrods for now until I get some money to blow.  I have a pair of hedman shorty headers which will be mated up to purple hornie 2 1/4 inch glasspacks and dual tubes dumping infront of the rear tires.  
      Im curious as to how much power I might make at the crankshaft and what kinda quarter mile times I might run.  Im most likely not gonna go to the trouble to get it dynoed, this is a backyard father son build, on a budget, not a six figure immaculate build with unlimited engine resources and funding.  Also I am building this car to compete with my dads 70 Nova SS396, im trying to figure out some cheap easy ways to make the car lighter, and hook up decently, because I know theres know way to beat him at the hp and torque game.  

Before going very much further it's necessary to know if this is a race only engine, street strip, or mostly street.

I have concerns for anything other than a race engine using leaded racing fuel. Old camel hump heads do not have hardened valve seats, as a result they will not last long with unleaded fuel.

Using the 327 heads on a 350 engine that's been zero decked with the flat top pistons and a tenth off the heads is going to produce way more than 10:1 compression. Between cast iron heads and available pump premium unleaded fuel, you'll have big time detonation problems.

Being short of time I don't have the cam specs. Your mention of 130 and 136 degrees is off by at least a 100 degrees, so what is this cam?

Why is the block being zero decked? And why .010 off the heads?

Bogie  

This is going to be a wicked street-strip motor (hopefully).  The block is getting zero decked for more and more even compression, and the heads are getting shaved for more compression.  Im sorry but I dont have the cam sheet here right now, Ill post the number up when I get to my dads tommorow night.  The goal im shooting for is 350 horse at the crank.  Im just repeating what the machine shops estimation of what the compression would be with the zero deck and head shave, im aiming for 10:1 or 10:5:1 compression, as much as possible on pump gas, my neighbour has a 350 in his rx-7 that hes always complaining about pinging all the time, hes running around 11:5:1 comp.  

het dude, you answered your own,your buds complaining yet you want the same problems???? crazy''''' you want 350 horse,you don't need 10.5 comp.or more.comb this mag and others it's linked to,your sure to find a combo[already proven]to get you to your goals cheap and easy....  

I'm concerned that between flat top pistons, milling the deck and milling the head that you're getting into way too much compression for street fuel. Also, and this is a BIG ALSO, old 327 heads are not designed to use unleaded fuel. You need to put on the brakes and do a cost estimate over the cost of rebuilding the 327 heads and what will be their relatively short life against the cost of new heads, be that Torquers or Vortecs or Fast Burns or whatever. This is where reality hits home; is that bites?. Already you're talking about refacing the existing valves. In the real world, a potent street strip engine doesn't reuse old valves, especially exhaust valves. Also the real world dictates mighty good guides and valve stems, especially when looking to a half inch of lift or more. Long lifts are really hard on stems and guides especially when racking up street miles. And knurling the guides is just peeing money away. So you now need to look at new exhaust valves and bronze alloy guide inserts. To keep the heads usable for more than a few months, you've got to look at hard seat inserts. All this costs a lot of money and you quickly find that a set of aftermarket heads is a lot less expensive. Or else you can drive this for 6 months and then scrap it. Plus you'll note I said nothing about stem seals.

Unfortunately, you've done what most people starting out do, many of the wrong things! Like porting a set of what's basically throw away heads and picking a bunch of components without building a foundation for them. Like a house, an engine is only as strong as its foundation. That means when cash strapped, money first buys a stout bottom end. you can always change cams, lifters, manifolds, rockers, etc. later. But the bottom end is a real pain to upgrade and usually if you cheap it out here buy the time you think about up grading, something's flying out the side of the block.

Not knowing what your cam is----is a big no-no. This is the heart of the engine. It drives the selection of all other components and specifications in terms of strength and durability as well as matching the heads, compression, spark plugs, valves, guides, ports, rockers, pushrods, timing set, ignition, carburetor, etc. All need to be chosen to work in concert with the cam. Compression is a huge issue in this selection and is a place I'm concerned about. 327 heads came in small chamber and large chamber types, regardless of humps, do you know which you've got and how big they are, there ought to be a casting number on them which will ID everything about them except valve size. Don't get excited about big valves if so equipped, big valves on obsolete ports is just big valves on obsolete ports; in this case combined with an obsolete combustion chamber as well.

Paper trail, an engine builder is not the same as an engine assembler. A builder keeps a detailed paper (audit) trail of the stuff that went into it and the results that came out of it. An assembler just bolts parts together.

The 350 needs a sizeable dish in the piston to keep the compression around 8 to one with large chamber heads. With small chamber heads and flat top pistons the 350 gets up around 11 to 1 pretty quickly and even with a long duration, mucho overlap cam today's premium pump gas on a carbureted, obsolete cast iron headed engine won't carry that without pinging. Plus, you're taking a .025 deck cut on the block and .010 off the heads, that's a lot at .035 combined, guess at least half a ratio. Hopefully, your mechanic/machinist informed you that the intake also has to be milled on the bottom and sides to compensate for these cuts. (More money plus the things hardly ever form a seal and leak oil forever. Plus you chance the distributor not setting on the manifold which then takes shims to position it assuming you didn't break it or the oil pump drive upon assembly before discoveing this. Not to mention that as you mill decks they get weaker and less able to hold high compression. And all this thin wall stuff like your block is pretty iffy without whacking a few thou off of things.

You're hauling a lot more weight than a 350 powered RX7, which is going to make your engine a lot more ping prone unless you jack the rear axle ratio up around at least 4.11. You'll love that on the street.

Getting 350 horsepower out of a 350 is almost a no brainer; it doesn't take astronomical compression nor cam timing to get there. A cam running 210 intake-215 exhaust degrees measured from .050 inch lift and a peak lift of .45 to .47 inch combined with a 9 or 9.5 compression will easily get there and maybe a little more. A little less cam like the old "929" with 200 on the intake and 210 on the exhaust will put 300 + a few ponies out of a 350 and will get to most of 350 horses by adding 1.6 roller rockers. There's more than one way to skin this cat, this builds a better low/mid torque profile at no expense on the top end.

Heads are as important as the cam, modern combustion chamber design, spark plug placement, and port layout such as the Vortec will deliver at least 40 more horsepower out of the box than the best ported double hump heads ever made. Time marches on and with it technology, the changes to these new heads is subtle but most effective. Plus they come ready for unleaded fuel. The cast iron versions will hold 9 or 10 to 1 compression without anything fancy to make them do it. If you go with aluminum fast burns, Vortecs being cast iron fast burns) you can push compression up to 11 to 1 on preimum unleaded because of aluminum's faster heat transfer. you can also take advantage of the heat transfer rate and up the operating temp to 200 degrees where a bit better mechanical effeciency can be found, especially with synthetic oils, there's another 5-7 percent more power hiding up there.

There's a lot of "modern" books out there by David Vizard, John Lingenfelter and others that covers all this stuff in huge detail, something that wasn't available when I was a kid, go cruise Amazon or Barnes and Noble and pick some of these up. CHP did a great book called "How to Build Small Block Chevy Engines for Maximum Performance", the opening feature takes you from a Mr. Goodwrench 350 of 210 horsepower thru evolutionary changes arriving at a 400 plus horsepower fire breather. It shows step by step the influence of carb and manifold changes, several heads, different cams, 1.5 to 1.6 rockers, compression changes, and the effects of porting. You can take your budget and wrap it around their parts till you get as much performance as you can afford. When I was a young guy, back before dinosaurs roamed the earth, the speed shop in my town had a huge banner that ran the entire length of the wall behind the counter which read; "Speed Costs Money. How Fast Can You Afford to Go?"

Until you get more experience don't read anything older than the mid 1990s. All that stuff that Smokey Yunick wrote is both too esoteric for the beginner and in many ways grossly out of date. Once you get a contemporary understanding of where new technology has taken us you can search Smokey’s writings with the proper jaundiced eye.

This isn’t easy stuff, if it was a 100 years later we wouldn’t still be searching for the ideal solution to engine design, we’d have it. But we don’t!

Best of luck, stay in touch; Bogie  

Well yes actually I do know what my cam is, and none of these decisions were made instanltly, this engine has been in the works for quite a long time and we have put alot of time and effort into the build, we have the input of a number of different people who know what they are doing.  i am aware of the valve seat issue, I discussed it with my auto teacher, and yes we are getting bronze valve guides put in, thats a given, and new stainless steel valves.  these are small chamber 64cc heads.  ALOT of thought and input went into this cam as well, this was the cam that fit all the reqs for the motor and what we are doing, compression wise, lift, duration, rev range, overlap, etc...  Unfortunately I cannot afford a new set of heads, its just not feasable right now, we are really strapped for cash, hovever much I would like a set of aluminum dart heads.  The main idea behind this build was a go big or go home approach, do everything possible within our means, you see ive got this compitition thing going on with dad, and im going to find a way to beat his bb monster some how.  There are ways of eliminating pinging, EGR, changing the A/F mixture, etc..  problems we will solve when we get to them.  

There are many suggestions to give here but the most important may be about about how you're handling this thread. I'd take this information Bogie is giving you with a little more respect and understanding. Im guessing from your post that you and I are near the same age. We're both still teenagers and we both have a lot to learn.   Bogie has been dealing with these builds for probably longer than we've been alive but he's taking the time to talk to you about this don't just tell him they're ways around these problems.  

Im sorry if I came off that way, but I dident mean any disrespect.  I was just inferring that my setup has been checked over by quite a few people who know what there doing (because I shure as *** dont   )  I think what we are going to do though is just get the block zero decked and scrap the head shaving idea, due to the fact that as bogie pointed out this would be a hefty amount of material removed and most likely, more compression than what I bargained for, especially because they are 64cc small chamber heads.  We have also decided to go to new stainless steel valves and resise the exaust to 1.60, bronze guides will be inserted as well.  

Hey again, the cam is a comp, number is CCA122463  

Gib, probably longer than your dad's been alive.

So what's happening in your world, I see your handle here and there in message boards and you’re giving pretty thoughtful opinions and advice? I'm going to steal the response to you (Gib) and speak to the originator of this Blog.

Mr. 70SS350, you seem to be doing pretty well with this project. Once you talk a little, it sounds like a lot of planning time has gone into your engine. Hopefully, you'll appreciate that when I reply, I have no way of knowing what your specific situation is. Landing on the heads, as I did, reflects the fact that rebuilding a set of double humps, or another old head for that matter, costs a major percentage of the cost for a new set of original design Vortecs; the new super part numbers having a super price tag attached to them. If you have friends in the automotive machine business or as it appears in your case the resourses of a school auto shop at your disposal the answer to rebuild or replace can be a significantly different equation. In a similar situation, because of the equipment and experience I have, I can do things in my shop that the average person just couldn't afford to achieve, such as my Franken-Mouse powered S-15. The engine is an 880 Vortec roller block with 95 Z-28, LT-1 heads, with a modifed GMPP 4 barrel intake to accept a set of TPI injectors, running off a modified TBI computer, with a Holley 4 barrel 4150 throttle plate modified to provide mounting for the IAC, throttle position sensor and form a base for a factory TBI air cleaner, the heads are modified to standard block first cooling with some external lines and shopmade thermostat/return housing. If I had to buy this motor, I couldn't afford it. But for a few bucks and a bit of machine time (OK quite a bit of machining time) it's just built from stuff left over from other projects that's been laying around the shop taking up space and collecting dust. Some years ago I put a 302 Ford into my 1980 Monza hatchback. It was a long week end, I had a Ford and a bunch of stuff lying around and a blown Iron Duke in my Monza and I just can't spend a weekend watching TV. So I got to work and in 3 days had a V8 powered Monza. Actually the reason the Iron Duke was lunched is because I breathed on it without putting a damper on the crank. While the "duke" would wipe the smile off many a 350 Camaro, in the end not having put a damper off a Chevy 6 cylinder on it left a lot of unresolved vibrations on the crank. This caused the snout to whip off center and that put enough twist on the #1 main to carve out the bearing, which lost oil pressure, that starved the #1 rod and it came out. Fun while it lasted. I mean, as anyone can tell you, the "duke" has problems with bad vibrations on the #1 main anyway, and doing things to increase power output and RPM range just makes the blow up event from a few years out to a couple weeks.

Both you and Gib, keep up the good work.

Bogie  

Thank you for the advice, and as it has worked out, the block wont be zero decked, due to some very nasty things my auto teacher told me could come of it.  Im just gonna keep learning and findint out stuff along the way, and hopefully my first build will be halfway decent.  I also have to make a serius apoligy to Bogie because I was being totally arrogant, and I really dont know what I was thinking.  Trust me, im not like that normally.  

I just wanted to stay on the safe side with my estimate of your age Bogie .I didn't think you'd been doing this for 65+ years so I didn't compare you to my dad . I just figured that the comparison to our life-span would get the point across.

I will be graduating from high school in a few months and will be heading off to South Dakota State for my bachelors in Mechanical Engineering next fall. I would love to go to another school with a more highly accredited M.E. program (plus one with a FSAE program ) but family issues have forced me to stay close to home.

Otherwise, there hasn't been anything else going on with me. Anything ground-breaking in Bogie's world?  

OK let’s not go nuts with apologies, I never took offense. I understand that young guys are willing to live with the foibles of a nasty engine on the street. The older you get the less you want to be bothered with a pinging, high ratty idling, torque less, short lived, screaming engine just to get to work and back in commuter traffic.

Of course you’re still learning, so am I, so is Gibb, so is your instructor and everybody else out here. That aspect just never ends. Like I said this isn't easy if it was you'd think after a 100 + years we'd have this engine science all worked out. But we don't. It's just the older you get the more "combat" stories you acquire. You see things that work and things that don't. Some things work in one place and not in another. You’re left to wonder why? You'll even see the pros get bit. A classic from back in the 1960s over at Ford. The idea of tunnel port heads worked really well on the FE block 427. Transferring this rocket science to the 302, it was a colossal failure. Why????

Yeah, I'm still concerned about where your compression would go with flattop pistons combined with 64-68 cc heads and the effects of deck and head milling, so I'm relieved to hear you backing off deck milling. I try, though not always successfully to minimize deck and head milling to no more than that required to make the mating surfaces flat. Especially with post 72 production; which suffer the effects of thin wall casting which can eat into your material strength margins pretty quickly. Angle milling the heads is an effective way around the strength of materials problem but introduces issues with milling the intake to fit; it may run out of material on the port side and require stuffing plates and or multiple gaskets all of which increase the possibility of miss register of the major parts and gasket leakage is encouraged. On the exhaust side the manifold or header gets rolled over in space and may cause clearance and mounting problems. Just keep in mind the whole thing is a set of compromises based on a set of engineering constraints a change in one place always causes problems somewhere else. Problems from thin decks are that as compression goes up so do gasket failures. And unless it’s a race motor that’s expected to be running on the edge, I just hate to pull a motor apart in my daily transportation just to chase stupid repairs. But that’s a personal preference. Mr. Franken Mouse in my S-15, for as bizarre as that combination of parts is, “knock on wood”, it runs every day with high reliability and it’s more than capable of blasting the doors off most anything on the street. But then you have to learn to control it and yourself and not get sucked up into doing dumb things just because you can. So often you just cool it in spite of so many frustrations from the incapable and incompetent or offers to race from the foolish or to prove something. Setting behind a very capable machine sometimes requires more of a milk-toast attitude than you ever thought yourself capable of.

Anyway go have fun, I’m getting too soap-boxish here.

Bogie  

Thanks for the age thing.

I'm glad to hear your off to universty. I think the important thing is to just get thru the BSME thing. Then as you get establihed in the work world or continue on straight to a post grad degree you can look into an MS or more at a university with more of a name if that's what you desire.

Just keep in mind that the drop out rate in college is pretty high, it's tough to hang in there especially when family issues are a concern.

Bogie  

I have a lot of empathy for SS350 street-strip. I bought a 68 Camaro with a shot 327 with small chamber heads and a 3 speed Saginaw. I had the 327 rebuilt with a 350 crank, KB 10:1 domed pistons, OE rods and iron rings, Elgin 214/224 cam with 280 degree advertised duration all balanced and blueprinted.It has a Quadrajet and open element air filter and standard 327 intake manifold. I retained the ramshorn type exhaust manifolds and installed a freeflow exhaust with crossover pipe. It runs strong on 93 octane lead replacement fuel at 4200 feet above sea level in Johannesburg South Africa where I live. (I envy you boys with the expertise and parts availability over there!) I am sure the elevation reduces the detonation problem I have as to which below. I installed a 4 speed Saginaw ( and have already stripped 3rd gear once when changing very hard at high revs which I simply had to do having a Subaru Impreza STI next door to me!) but the engine seems to run out of usable revs @ 5200/5300 rpm.

As I have said I have a detonation problem that is largely although not satisfactorily remedied by using Wynns octane booster as specified ie a bottle per 16 gallons.

My question is: will a set of headers, while improing flow, also address the detonation? If so will a high rise intake further assist in this and finally will all the above extend usable rpm?

Thanks for any advice.