Does anyone know much about how well '60s era double(camel)hump Chevy heads would flow? I know they were used on some pretty stout engines(375hp 327, 370hp 350) so I was wondering with some mild port work if they'd flow well enough to use on an engine I'm trying to squeeze 425hp out of. I'll be doing the porting myself, though I will have a machine shop do the valve job. I'm trying to build this motor with swap meet parts as my budget is tight.

 

besides the lack of bolt holes in the end of the heads any aftermarket head would be abetter choice considering the cost of haveing them machined, screw in studs, enlarging the spring seats, etc.

 

Those heads were great..................back in the 60's!

Like Ede stated, your better off getting aftermarket heads. It's going to take a lot of work to get them to flow good and upgrade the parts. When all is said and done, you probably could have got a new set of heads and still had money left over.

 

They were fine along time ago. Some did actually come out with accessory holes, like the #186's. But they have small runners, like in the 157cc range, and have 62-64cc cumbustion chambers. Nice head, but by the time you have them built, it would be easier to buy a set of S/R Torquers.

 

Yeah if you want 400hp, then go with some S/R Torquers which are really cheap, can be ported a lot and are based on the similar design as the "492" casting but improved upon in many areas.

 

They were the best in their day; but that was before CNC casting, when there was no such thing as an aftermarket head. They are easily capable of 425 HP, but if you don't already own them in partially worked condition, you'll get there faster & cheaper by going aftermarket. Spring pockets, screw-in studs, larger valves, milling, port work, guide replacement,.... pretty soon you've got the same money in them that new ones cost, and you still have cast iron instead of aluminum. Not smart.

I should know, I'm driving around a set of 186 castings on this POS 265 HP 305 in my car right now for CA emissions reasons, and another set on the 400 that belongs in the car. Fortunately I didn't have to pay for most of what it costs to make them competitive.

You know it's funny, some of the same people who will tell you that the newer heads are better than the 60s iron, are the same people that will tell you all about their dad's cousin's boss' girlfriend's brother's roommate's showroom-stock 11 second 69 302 Z28 they heard tales about when they were in the cradle...

 

I can get a complete 327 with a steel crank and the aformentioned heads for $200-$300 at a swap meet. That itself is half what a set of torquers costs. I believe Powerhouse sells a tool that attaches to a drill to cut larger spring pockets for around $40, springs from a mechanical cam would run about $125, lifters for about $65, the cam itself is about $115. Most Camels came with 2.02/1.60 valves from the factory, though I'd still spend the $120 on Manley stainless replacements. I have a die grinder, but I'd have to spend $70 or so on a porting kit from Standard Abrasives. I'd probably have to have the crank turned down .010 or so, that's $150, balancing would be another $150. Boring it .030 over would be roughly another $150. A new set of forged rods from GMPP would set me back about $250, pistons from Fedural-Mogel would be about $325. New cam, rod, and main bearings from Clevite 77 would run me $60, rings for $100. When it's all said and done I'd have a scrappy little motor for around $2000 or I could just do a standard rebuilt for $400 and stab a new cam into that 327, churn out 375hp, and run down most of the 3rd Gens and 5.0s on the road for $500, $250 less than a set of Torquers.

I'm not disputing that aftermarket heads are superior to '60s era castings, I'm just saying that if you're smart, you can get a tough motor and not have to spend lots of cash.

 

Very few of the double-hump heads came with 2.02" valves from the factory. Every set I have ever had, with the exception of a few 292 castings, had 1.94" in them originally. And the 292 castings I have had didn't come in cars, they were over-the-counter parts. The only castings I am aware of that might have had 2.02"s and were installed in cars were 041s; I've never had an untouched set of those that I was aware of so I don't know for sure.

No double-hump heads that I know of ever coming on 327s had accessory bolt holes. Only the ones on 302s and 350s did. All of them came with pull-out studs and of course no guide plates; and they all had stamped sheet metal garbage rockers like everything else.

Odds are very high that a 327 with any kind of double-hump heads on it at a swap meet will be a small journal block, and the heads will be without bolt holes, so the accessories in one of these cars will be extremely difficult if not impossible to mount reliably. The bolt-hole-less kind are also without the "squish" or "quench" area under the plug, so they do very poorly on modern fuel. There are no decent SJ rods available any more that I know of. On the other hand, if it's a LJ block, you could stick a 350 crank in it, do exactly as you would do to a 327, and get that much more power out of it; but I doubt you'll find a combo like that at a swap meet since it never came in a vehicle.

My 2 remaining pairs of double-humps (186 casting) have bolt holes and "quench" provisions, so they can actually install into my car correctly and run on modern watered-down cat pee, with PS, A/C, etc. all working. They all have screw-in studs & guide plates, 1.45" spring pockets, drilled-out push rod holes, 400 steam holes, and port work; one set has stainless straight-stem valves (sorry, I cheaped out), one has undercut-stem ones; both have good springs & retainers; both sets are machined for Teflon guide seals, and both have bronze guide inserts. That's about $1000 of machine work and porting and hardware if you have to pay for it all. They run fairly strong, but nowhere near what a set of quality modern aftermarket CNC castings will run - and alot of the newer heads, Edelbrock Perf RPMs for example, cost less than $1000 outright, ready to run.

OBTW - the horsepower ratings on those old motors are a complete joke by modern standards; don't hallucinate for one instant that you're going to duplicate a stock one of those and come anywhere close to those numbers once the motor is in a chassis. They're about 20% overly optimistic, give or take, except for the ones that were deliberately fudged low. As an example, the "370 HP" 350 was absolutely identical in every way to the "290 HP" 302, except for the stroke, part number for part number. Cam, heads, carb, intake, exhaust, rods, all the same. Who's kidding whom?

You're right though, for cheap you can make a motor like that into a pretty strong-running piece, within its limitations. Just be carefully realistic, don't let your optimism send you down a path of wasted money on stuff that won't actually quite work without spending more than it would have cost to get there some other way.

 

AMEN to that!

 

Yeah the gross variety definitely is a joke when compared to the SAE net of nowadays. Don't the LT1 and 302 both use the Duntov 30-30 cam? I've also read other places that the 302 had a specific grind. There seems to be a lot of disagreeable information out there.

 

I wouldn't call 375hp out of a 327 too optimistic. Also, there are lots of rods availible for small journal small blocks.

 

The crank in all 327's is forged steel..stock. The double hump heads are a pain...unless you are good at fabricating brackets, be ready to replace alot of waterpumps, altanators and PS pumps. Getting the v-belt assembly to run true can take some time. My 327 Runs pretty strong with the mods listed. But by no means would I put $5-$700 in a set of heads with such limitations. From my research, most aftermarket heads outflow a worked set of camel humps, right out of the box.
Buy the motor...just get some heads that will feed the high revving 327 up to 7000+ rpm. just my opinion.

 

a machine shop can open up your spring seta better and cheaper than the 40 dollars for the powerhouse tool, and all of them that i've seen don't work that good. my machine shop charges 2 dollars a spring, for a total of 32 dollars. looks like you were fixing to take the path of wasted money right off jumping on the 40 dollar tool.

 

Not all 327 cranks are forged.

Up through 1967 they were forged. These were small-journal engines.

1968 and 1969 model year 327s had cast cranks. These two years are large-journal cranks. I've heard rumors of a truck large-journal forged 327 crank but have never seen one or talked to anyone that has either.

jms

 

I know they made the large journal cranks for those years, I was under the impression they also were forged...I could be wrong, I havent had any experience with the large journal crank...guess I'll have to look into that one. Do you know what vehicles they used the cast crank in?

 

I had a 68 Impala 327 (4 barrel, crap heads not double-humps) with a cast crank, so I know that's at least one place you could get one...

22, you're exactly right, that was the cam in question. A very hot-running cam for its day. I perfected my valve adjustment technique on motors with that cam in them.

This situation is a little like what you get into with the Vortec heads these days. The heads as they come are good; but they're not at all set up for true high performance applications, and while they can be made to perform very well, it's just not economically sensible to do that when you have so many aftermarket choices that will run better for less money.

 

During model years 1968 and 1969, all Chevy's that were available with a 327 had large-journal cast cranks.

1969 was a big change over year to the 350 engine but the 327 was still around, especially in the big-car line (Impala, Caprice).

jms

 

Are you completely sure about that? The books I had listed different valve lash adjustments for the 302 and LT-1 350. Also, 302 had 1.94" intake, straight-plug heads, while the LT-1 had the famous 2.02/1.60 angle plugs. (The 302 was probably over-carbed with that 780, though.)

I'll agree they did under-rate the 302 (heard it was to fool the insurance underwriters - kinda doubt that, though). Knew an Army guy who claims he saw a 302 out of the crate dyno 390 HP - okay, all GI's are liars, but 290 was probably somewhere in its low-RPMs - or else it was "net" .

 

The 302 small-block engines all had 2.02 intake/1.60 exhaust valve heads.

The 1970-1/2 LT-1 had the same size valves.

The 1967 302 was basically an L-79 327 with a 283 crank. Big valves, big compression, big carb, big cam, big intake, little stroke. They WERE very underated compared to other engines of their time. The '67 L-79 327 was rated 350 hp (the '66 was rated 360 hp). The 302 did not really lose 60 horses from 25 inches less displacement.

As far as I know, there were no "factory-stock" angle-plug heads until the aluminum L-98 Corvette heads in 1986.

All the earlier angle-plug heads were "over-the-counter".

jms

 

The 350, 365 and 375 horse 327's all used "461" heads with 2.02/1.60 valves. From what I understand all the 302's used the "461" heads with 2.02/1.60 heads while the LT-1 eventually progressed to the "492" which was also fitted with 2.02/1.60 valves. Around 1969, the "492"s were available as service replacement for the "461" heads on the 302s. There was an angle plug "492" but was only available over the counter.

Now to the cams.

I've had conflicting information but what I can piece together is that the 67 and early 68's used the Duntov 30-30 camshaft but there was a cam introduced in 68.

Duntov 30-30
Duration @ .050"
-(Int/Exh) 228/230
Advertised
-287/287
Lift
-(Int/Exh) .394"/.400"
LSA
-110*
Valve Lash
-(Int/Exh) .012"/.018"

Z28 302 Cam
Duration @ .050"
-(Int/Exh) 254/254
Advertised
-310/310
Lift
-(Int/Exh) .485"/.485"
LSA
-114*
Valve Lash
-(Int/Exh) .028"/.030"

So confusing......

 

I saw somewhere on a Z28 awhile back that they dyno'd it at 390hp also. I've seen estimates running in the 340-350 range, which is a lot more reasonable.

 

Not confusing at all.

The second cam was the stock 302/LT1 cam... .485"/.485", 310/310 @.006 but 324/324 according to GM; lash adjustment .030"/.030" according to GM, hence the "30-30" nickname... the first one was the "peanut cam" of its day, came in the base model Vette 327 (including the "fuelie" models) that got drilled by the 302 and LT1 cars. The best running GM cam back in those days though was the '754' cam, .026"/.028 lash IIRC.

That 30-30 cam will light up a short stroke, small journal, high compression motor. Runs terrible in a low compression, low octane, long stroke motor. It was inconsistent on the street in the LT1 but ran good at the track.

Those were the days.... it's scary not having to read magazine articles in order to know exactly how those historic parts worked... too bad Zora isn't with us any more to enjoy the LS1....

 

Yeah, but then some of the 302s had dual quads on them and some didn't. And two fours turning at 7000 rpms puts out a lot of hp

It gets so confusing

 

so what is the factory HP rating for a 327? I thought it ran around 270..Above stated 350-375...I dont think I have quite that with my mods....now I'm..

 

Which 327 do you want ratings for?

The engine was available from model year 1962 through 1969.

Sometimes Chevy changed the ratings on the exact same engine from one model year to the next.

Horsepower ratings ranged from the low 200 figure up to the upper 300s (375-horsepower fuel-injected).

Versions were available with two-barrel carbs, four-barrel carbs (Carter carbs, Holley carbs, Quadrajet carbs), fuel-injection, hydraulic or solid-lifter cams, cast-iron intakes, aluminum intakes, low-compression or hi-compression, single-point or dual point distributors along with transistorized distributors, crappy exhaust manifolds versus some pretty good ones, automatic tranny versions versus straight shift, etc., etc., etc.

The point is this: the 327 was a general purpose engine in the mid-1960s and could easily be "optioned" to whatever level you wanted, depending on your budget.

The 327 of the '60s was like the 305 of the '80s. Most anything that had V-8s had 'em but you could get better versions with careful selection.

jms