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327 head valve size and cam question.

6K views 44 replies 12 participants last post by  64nailhead 
#1 ·
Hi Guys


I'm rebuilding a 327 for my 1956 chevy truck 3100.


I want to rebuild the engine myself, I was a diesel mechanic last century so I have some skills, but none in head cam/tec stuff.


I've done a lot of browsing, reading but not quite got the stuff I need.


Ive got a Small journal 327, std bore needs a rebuild (no I don't want a crate engine thanks all the same). edelbrock rpm intake, HEI dizzy, no headers or carb yet.
th350 trans, 2x 10 bolt diff's - 2.7 open and 3.4 posi, plan to run 265-70-15.


The problem I'm having is the type of heads available in New Zealand is limited, and importing them is expensive, try 2 times the cost in the states.


I have found some heads $1270 for a set, but come with 2.02 intake 180cc, 1.6 exhaust 70cc and 64cc chamber, are these too big for my combo? or can I make these work with the right cam, carb, exhaust or rear end gearing choice?


Oh I better mention fuel is $2 per litre or $7.75 per gallon.


Cheers Chris
 
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#4 ·
Isn't there a foundry in Australia or New Zealand casting chevrolet heads? Are they still prone to the importation problems? I'd recommend the 3.42 rear gear, your TH350, a 68.5cm tire (that should be 27 inches), a stock torque converter, and a camshaft like the comp cams 260H (12-206-2). Id prefer a roller cam, but I understand your importation problems.
 
#5 ·
Heads and other chevy stuff hard to find down there, you say!!
Not when I was last there.
Swap meet in Pukekohe had more chevy performance stuff than I've ever seen up here at a meet.
You gotta look around, everything you need is right there in NZ.

And you need to get yourself educated.
Find a book like this.
Or any others to do with rebuilding or hotrodding sbc's.
https://books.google.ca/books?id=G2...ce=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
 
#14 ·
Heads and other chevy stuff hard to find down there, you say!!
Not when I was last there.
Swap meet in Pukekohe had more chevy performance stuff than I've ever seen up here at a meet.
You gotta look around, everything you need is right there in NZ.

And you need to get yourself educated.
Find a book like this.
Or any others to do with rebuilding or hotrodding sbc's.
https://books.google.ca/books?id=G2...ce=gbs_ge_summary_r&cad=0#v=onepage&q&f=false


How about - "How to Rebuild the Small-Block Chevrolet by Larry Schreib" is it any good?


I hear what you're saying about the swap meets, Kumeu swap meet is in Feb and Pukekohoe is March, I guess I want to get started now.
With the drop in the NZ dollar every thing is up by %20. A lot of importers are sold out.


Cheers Chris
 
#6 ·
when building the engine you start with the heads. If you have a particular performance you want(not a random horse power figure you pull out of your,,,head) Then we do some math.

example: I want my 1965 Acadian to be a fun street car that I can drive on weekends and to work once in awhile.
I want a standard but I will not spend extra for a 5 speed overdrive,so Im using a Muncie wide ratio(2.54 first gear)
I will use 4.1:1 rear gear if I drag race(or set gear ratio to intended use of the car)
I know how to adjust valves.
I want a mild but a little bump in the idle(just because Im cool)

first find heads,cast iron or aluminum?
9 1/2:1 for cast, 9 3/4:1 aluminum
The heads need to flow 240 cfm on the intake side with intake runners 190 CCs or less
Edelbrock performer rpm intake and a 750 double pumper
Camshaft would be an Isky Z-25 solid flat tappet with pressure lubed lifters.
headers would be long tube with 1 3/4 primaries or 1 5/8 primaries if the tubes are equal length and 30 " or more long(no shorties)
3 inch exhaust system with X pipe

27 inch rear tire,shifting and cruising at 3,000 rpm,nets speeds in gears of24/31/40/59 mph
this little engine will pull hard past 6400 rpm and would require lots of fun shifting,,,,

with the truck; if you have taller tires you could choose the gear that best suits you driving?
 
#7 ·
The heads sound about rite,as far as size goes for a "hot 327".More importantly tho,are these iron OEM (need casting #)heads,or,aftermarket aluminum.Chamber design also is important.You need more info to get a good answer,such as the piston type/volume,piston to deck hgt,etc.,so that,compression ratio can be calculated to match all the parts.
 
#13 ·
when building the engine you start with the heads. If you have a particular performance you want(not a random horse power figure you pull out of your,,,head) Then we do some math.

example: I want my 1965 Acadian to be a fun street car that I can drive on weekends and to work once in awhile.
I want a standard but I will not spend extra for a 5 speed overdrive,so Im using a Muncie wide ratio(2.54 first gear)
I will use 4.1:1 rear gear if I drag race(or set gear ratio to intended use of the car)
I know how to adjust valves.
I want a mild but a little bump in the idle(just because Im cool)

first find heads,cast iron or aluminum?
9 1/2:1 for cast, 9 3/4:1 aluminum
The heads need to flow 240 cfm on the intake side with intake runners 190 CCs or less
Edelbrock performer rpm intake and a 750 double pumper
Camshaft would be an Isky Z-25 solid flat tappet with pressure lubed lifters.
headers would be long tube with 1 3/4 primaries or 1 5/8 primaries if the tubes are equal length and 30 " or more long(no shorties)
3 inch exhaust system with X pipe

27 inch rear tire,shifting and cruising at 3,000 rpm,nets speeds in gears of24/31/40/59 mph
this little engine will pull hard past 6400 rpm and would require lots of fun shifting,,,,

with the truck; if you have taller tires you could choose the gear that best suits you driving?

"hot 327" sounds great. Shall I rename this thread to "327 hotness"?
Ok I'm in I want 327 hotness. But is it possible with these heads.


Pistons I haven't bought any yet but I've priced some seal power flat-tops at $450.


Engine machinist wants to balance the crank with new piston's and is looking at decking the block to get 0.040" piston to deck height (quench).

Head specs below-


S/B Chevy 327, 350, 400
Cylinder head Material A356.0 Aluminum T6
Combustion Chamber Volume 64cc
Exhaust Runner Volume 70 cc
Intake Runner Volume 200cc or 180cc
Spark Plug Style Straight
Intake Valve Diameter (in) 2.02
Exhaust Valve Diameter (in) 1.60
Valve Material Stainless steel valves
Valve Tip Hardness Above 48 HBC
Spring Install Height (in) 1.85" @ 100lbs
Maximum Valve Spring Lift (in) 0.575 @ 300lbs
Outside Diameter of Outer Spring (in) 1.47
Number of Springs per valve Dual
Lock Style 7 Degree
Valve Stem Seal Style Vition seal
Rocker Arm Nut Thread Size (in) 7/16
Guide plate Pushrod Size (in) 5/16
Valve Cover Mounting Style Perimeter Bolt
Valve Angle 23 Degree
Valve Steam 8.67mm
Valve Guide Material Manganese bronze
Intake 5 angles
Valve Seat Machine Style Exhaust 2 angle plus arc
Valve Seat Material Power Metallurgy
Valve Seat Max Pressure 96 HRB(35 HRC if required)
Steam Holes Drilled No/ if required
Oiling Style Through pushrod

Flow Chart cfm@H20

0.2 0.3 0.4 0.5 0.6
2.020
Intake 125 183 231 254 262
1.600
Intake 103 145 165 172 177
 

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#11 ·
Valve size isn't the problem, it's the 180cc intake port volume that is the problem....port is too big for a mild 327, it would need to be revved up to get enough airspeed in the big lazy port for the engine to breathe decent. Makes it sluggish and doggy at lower rpm's.

You'll want to be looking for 160-170cc Intake port volume heads.
 
#12 ·
Ah I see, so smaller volume/size will increases the air speed.


I've been talking to a couple of engine machine shops, One guy was trying to find some Vortec heads, with not a lot of success, and the other was an old school machinist, and is going to look through his stock of older heads.
 
#15 ·
There are several books like that. Get a couple. At least you'll have some know-how when the machinist starts talking.
Maybe you could get lucky and someone from the up here could bring you down a pair of heads. I did that sorta thing. Took some 9 inch axle bearings down once for my buddy in Upper Hutt!
Good luck with your build!!
 
#18 ·
You need to think about what rpm range you are going to be driving this car at. Start with your rear gears and tire size then transmission converter. Converters have some slip so you can figure on adding a few rpm depending on the stall of the converter. You can calculate what your rpm will be at average speed you will be driving. Then look at your cam that you are going to use. Match the intake off that. Then your valves. Your low-end throttle response will suffer with too big of ports/valves. I would not recommend aftermarket heads unless you stick with a "Stage I" or Stage II at best. Most tout large flow rates and say nothing about velocity thru the rpm range. You can over do velocity but it is what makes your volumetric efficiency higher. NASCAR engines can reach up to 115% without a pump due to VE. Bigger is not your friend on the street. I would pickup some abrasives and do a light port matching and smoothing of the ports at best. Most flow increase is done with valve angles the rest is reduction of turbulence and depressions (low spots) in the port. Short side radius is also important (the part the bottom of your finger hits going from the valve to the port opening. That you just want to have a smooth transition. Just stay away from any carbide bits for your first go at porting.
 
#20 ·
Rear gears , tire size and transmission will reflect the rpm range your engine will run at on average. Cam, valves, intake and port flow/velocity should be calculated for that rpm range. NASCAR pretty much runs in the 7-8000 rpm range constantly. They change the rear gears to keep the car within a speed range depending on the track they are on. There rpm does not differ. They can go to big ports, large lift cams and big valves that will support the 7-8000 rpm. I doubt many street cars should see that.
 
#21 ·
Heavy,I agree with some of your post.The rear gear set/transmission combo should match the combo of the vehicle usage. The transmission has a selection of multible gear ratios,ie,some standards have 7 gears and 8 speed autos are becoming common in new cars. You do not "need to change rear gears for bigger cams or valves,just select the correct gear for the driving at hand. Adding a steep rear gear is not a cure all for cams or valves. Transmissions and diffs are for the cars needs.

BTW Nascar engines run way over 8,000 rpm
 
#22 ·
But I guess if you want to run in second gear so you can keep your car liking the big cam, large valves, oversized carb, you can do that. They started using the CVT to keep the engine in the tq and hp range to optimize power and efficacy. VVT to widen the tq and hp range. That is what I am talking about is making a car that is fast, responsive and engineered for its purpose. If it isn't going to go over 100 mph, why put 3.23 in the rear only to put a trans that has a granny gear so you can increase your 0-60 times?
Getting more air in at lower lift is more important than maximizing flow at highest lift. By then, your piston is already on is way back home. Cam profile can help offset inefficiencies in port design, so you want to see where the head lacks. 5.7 Hemis lack exhaust flow. 5.3 chevys lack on intake. That of course can be helped by grinding a huge rocker stud boss out of the port.

Here are the numbers I came up with. 9000 max and getting out of the torque range. 7-8000 looks like the sweat spot. I drove one of
Kasey Kane's old cars on the Kansas Speedway. It was pretty fun.

NASCAR Sprint CupNASCAR Nationwide SeriesNASCAR K&N Pro SeriesNASCAR Canadian Tire SeriesNASCAR Whelen Modified/Whelen Southern Modified850 @ 9000 RPM750 @ 8400 RPM625 @ 8000 RPM550 @ 8000 RPM625 @ 8000 RPM12:0112:0112:0110:0112:01550 ft./lb.@ 7500 RPM535 ft./lb.@ 6500 RPM425 ft/lb@ 7000 RPM450 ft/lb@ 6500 RPM500 ft/lb@ 6500 RPM
 
#23 ·
I am a firm believer in old school as well, but using new world strategy with lots of quench movement; I would look for a contemporary cam that comes close to the 350h.p. 65-70 327 350c.i. factory hydraulic lifter engine and 110' lobe separation, aluminum heads in the 160 to 170c.c. ports, and a good 180 degree intake and 650 cfm max carb. (again for torque)
The gearing can easily be the 3.42 posi, (standard rear ratio in the old days for a stick) and 26-28" tall tires. Our freeway speeds would be at 2- 2300 rpm at 60 mph with a TH350. Compression should be about 9.7 to 10 to 1 and total timing about 27-28' with mechanical, and mayne restrict the vacuum advance to 34'(?); quench should be fine with just the head gasket giving you .040" or so - the piston should be at ( +/ - ) about .005" up or down to give the intake charge some real movement, not .040" down; (down a half point in compression with that). The engine will just labor with that and be sluggish I think. The 4.030" bore, 3.25" stroke, a 64cc chambers and a set of flat top pistons with the 2 or 4 valve reliefs in them should give you about +2 to 5 c.c. extra room and keep the compression down to about 9.7 to 10 to 1.
Someone said a good wide ratio 4 speed would be fun and I agree, it would not be as much $$ as the newer 5 and 6 speed sticks as well. If you got or want an auto, a good 700R4 would be fine and that overdrive would give you better mileage as well.
You should get about 300 to 325h.p. at the flywheel and about 310 to 325 lb/ft of torque, but you should have about 250 lb/ft at 2500 rpm, lotsa grunt for most any type of street, but might run out of steam about 6 to 6200 rpm;.
Please note that this is a PERSONAL OPINION, and not necessarily the opinion of the group, which probably has much more information than I, as well as only 1, (one), build I did at 327c.i. from 15 years ago. Good luck and have fun!!
Oh yes, and read those books first; I am hoping they will come real close to what I said.
 
#24 ·
For 300hp, I would go to the junk yard, pull a 5.3 (327) with the whole engine compartment wiring harness with the ecm and drop it in for about $300 - $500 and have good fuel mileage and not have to run premium. 1999 - 2002 GM trucks that still have the cable throttle body. If you can't find one that early, you can get the TB on ebay for about $100. Reflash the ecm with a tuner and be getting over 300hp at the flywheel. Take the time to grind the boss out of the intake ports ( there will be a small hole going to the stud, just use sealant on those bolts) and you will get around 325hp. I would replace the cam bearings (cam bearings are an issue with the LS), HV oil pump (to fix the cam bearing issue) and if you want to put in a better bump stick , 350hp or more would be easy. It would probably be cheaper than trying to get something old to that level. I am in the process of building a ecm to replace stock that is totally tunable, not a plug and pray. No, not a megasquirt. We are designing it and going to keep the price less than the $1000 - 2500 others go for and to use stock or upgraded parts on LS and 5.7 and up Hemis. This is what I am doing in my 68 C20 to replace the old 327.
 
#27 ·
NASCAR Sprint Cup NASCAR Nationwide Series NASCAR K&N Pro Series NASCAR Canadian Tire Series NASCAR Whelen Modified/Whelen Southern Modified 850 @ 9000 RPM 750 @ 8400 RPM 625 @ 8000 RPM 550 @ 8000 RPM 625 @ 8000 RPM 550 ft./lb.@ 7500 RPM 535 ft./lb.@ 6500 RPM 425 ft/lb@ 7000 RPM 450 ft/lb@ 6500 RPM 500 ft/lb@ 6500 RPM


This is from NASCAR. Just because the rev limiter is set that high, does not mean they run them there. They will stay together, sure, but if it above the peak torque and HP, why? They are not formula one. The acceleration coming out of the turn is pretty good, but there is not a huge amount of time between when you have someone in your way or your backing off for the next turn. Our speedway is one of the longest and not that I looked at the gauges around 170 with a turn coming up in seconds, but from the sound, I was not over 8000. I had it floored coming out of the turn. And no, I did not take the turns like your grandmother. I didn't get lose, but I did impress the trainer. As I explained to him, I have had my car to 160 more than a few times on the way to work. Actually, driving past the speedway. It did make the 58 mile drive shorter! They might get to 9000 during qualifying on large tracks. But no one is in there way and it is just a few laps.
 
#29 ·
You can buy a 5.3 from the yard if you pull it for $300 -$500. I got mine for just under $300 with the harness, ecm, PS, Alternator, AC, belts, complete. Well, someone already got to the throttle body, like I said, I got one from eBay for $100. All other things mentioned are more... But compared to spending crap loads on an old 327, I think it is comparable if you do the research and you get a car that starts in the winter and better mileage. Now sure if you get winter on the other side, but... We get plenty here. After I pulled it apart, the cam bearings were dead. Mains and rods showed almost no wear and no ridge on the cylinders. I cleaned it, replaced the cam bearings, gaskets, porting the heads, doing a valve job ( I have a Winona, and can surface the heads on my blockmaster). Although, the heads are in spec. So, $250 on gaskets and $30 on bearings. The oil pump will cost about $200 and it is ready for my truck. So, I will have about $780 in it, Just over $1000 if I had to have the machining done. Wiring will add some more, but Just for some aluminum heads, your looking at $1200 for the old 327. then add pistons, bearings, rings, intake, all that other stuff... That leaves me room for a healthy cam and springs. If I want higher compression, I would buy some 4.8 flat tops, but I think I will pull at least 325hp the way it is. That is just a little more than my Dodge Neon at 300hp.
 
#31 ·
You're previous post made it sound as if he could swap,be up & running for $300 to $500.
Also,there are more costs associated with that swap than you list.What transmission are you using?The vehicle you are swapping into plays a big role as well.After you start weighing up electronic speedos,didital gauges,etc & their installation,it adds up quik in time & money,especially in another country.
IMO,swapping in a used bone stock 5.3 is not gonna perform any better than well built Old School 327.It may be more efficient,but,that would be it.The 5.3,if using the yr models you listed,is over 15 yrs old & has how many miles vs a fresh built 327 with good heads & a modern ground cam.
The 6.0 would be worth it,but,not the 5.3.I iknow the 5.3 can be upgraded to make a lot more power than the 327,but,cost for doing that are not even comparable.
 
#30 ·
or build a stock 300 hp 327 and use a megasquirt system,same results and no messing with exhaust system that is already established or custom headers if you need power. A lot less personal labour. In a modern car the LS is the best choice.In a custom older pick up a rat is the best choice.For a cheap replace,ent engine in an old car a gen 1 is the best choice.
Pick your poison
 
#33 ·
The LS will respond better to the upgrades,but,cost a lot more doing so.It is said that a cam swap for 5.3 can get you in the 400 HP range.To get a 327 to that level,it wouldn't be considered very streetable to most,requiring some fairly extreme parts & work.
I guess I should have worded that better.
I just haven't jumped on the LS bandwagon yet.LOL.They are great engines,but,so are the SBC's & with minor upgrades,the SBC can run just as well as the LS engines.
 
#35 ·
I agree Vinnie.I'm not a big fan of the 5.3 myself.If I were gonna do anything with an LS,it would be the 6.0,or,larger.
A lot of the glamour of the LS comes from the CNP ignition,EFI,etc.Without all of that,there's not a lot more to them.The bottomends may be stronger & hold up better.IDK.
 
#36 ·
I guess I like the challenge... Also, the injection system for an old motor will set you back big $$. Unless you are going to fab your own, but doesn't that nullify the much simpler exhaust rework? Just saying... I have no issue with megasquirt other than it does use a lot of outdated hardware.
 
#37 ·
Hi guy sorry for not replying sooner I've had a mountain work to get through.

Great tec I'm loving it, I'm really keen to find out how to combine heads cams compression ratios and gearing to produce a combo which all works well together.
I've just ordered "How to Build Max Performance Chevy Small Blocks by David Vizard" and "Chevy 302 & 327 Musclecar & Hi-Po Engines".

I've thought long and hard about the LS swap but decided to rebuild a small block, I've got a 4x4 buggy running an LS1, and I love the power, the thing weighs 1100kg and pulls hard.

But what I'm really keen on is building an old school hot rod, It's properly old tec and out of date to you guys but for me its new, and its been a few years since I've rebuilt an engine.

I want to use the truck for club runs, cruzin at the beach hop and the Americana festival here in Taranaki (pronounce the a - ah and the i - ee and roll you r's), and having a go at the local drags, so huge hp isn't the goal but building an engine which ticks the old school hot rod boxes is what I'm after.
I've heard older guys in the local club talk about fueile heads, L79 cams 600 holleys, It sound like a history lesson I'm soaking it all up.
But I don't want to ditch the new stuff at all just try to make a good combo.

I've been talking to a couple of builder about what heads they have so I'll let you all know, and maybe we could discuss the pros and cons of each?

Thanks heeps for all you suggestions, please keep it coming.

Cheers Chris.
 

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