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327 build help

15K views 50 replies 10 participants last post by  hhchassis 
#1 ·
Hi,
I'm looking at rebuilding a 327 and could use some help on part selection, the car is as following:

CAR:
1965 Corvette (to far gone from original to go that restoration route)
M21 4 speed
4:11 12 bolt posi rear end
Weight 3200#

Engine:
327 l79
original block .030 over
heads double hump with 1.94 valves (not original or correct)
2.5 in ram horn exhaust manifolds
zz4 intake
eldebrock 600 cfm carb

Goals:
weekend driver, no racing intentions, I'm more interested in driving winding roads but would like some off the line performance.
325-350 hp
350 minimum torque (I do understand that this is a 327 and not a 383)
$ 2500 to $ 3000 budget (hopefully including machine work)

Intend to keep:
Block
crank
Rods (if feasible)
carb
intake
2.5 in ram horn manifolds

Intend to replace:
Cam
heads
pistons
and other required items for a rebuild

I am pretty set on keeping this block as long as it checks outs and would like recommendations for heads and cam replacement. I am willing to consider aluminum or cast iron heads, weight is not a real concern to me, also what kind of intake flow values should i be looking at for the heads? (I have looked though previous posts and have a basic understanding of high vs low flowing heads, so thinking on the lower end, just not quite sure what target should be.)
I plan on lowering the compression of the engine to be pump gas friendly (91 max octane in California). I'm assuming that this would be accomplished through different pistons. (present pistons are the 11:1 comp. l79 327 sbc). If my goals are unrealistic please let me know and your help is appreciated.
 
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#2 ·
327 build

i to am doing a 327.useing 10.5 trw pistons and a melling mtc-1 cam,1500-4500 rpm range,thinking of useing tbi heads because of unleaded gas.my friend who is very experianced at engine building says they work great.i have an 82 cutlas calaise with air ,cruise etc
 
#3 ·
I think if I were in your shoes, I'd do some Vortec heads and probably a Vortec Performer intake, with flat top pistons: 9.7 to 10.5 compression (depending on deck height and specific piston part number), will run on on pump gas, GREAT lower end torque and hp on up to 5500 rpm, (slightly more or less, depending on intake and cam choice). :cool:
 
#4 ·
Swap out the rods with the scat small journal I beam rods.

Properly prepared vortec heads would work well or there are plenty of
aftermarket choices. Runner and chamber volume are critical. Intake runner
volume in the 170 - 180 cc range. Set up the piston to head clearance near
0.040", use combustion chamber volume to achieve the desired compression
ratio.

Camshaft selection will depend on the intended RPM range.
 
#5 ·
i'd sell what you have and buy a complete vortec 350 to rebuild. it'll be cheaper make more power and last longer. you can get over 400 ftlbs out of that for half the cost of your 327. if you're not worried about numbers matching its the best bang for the buck.
 
#6 ·
i agree with everyone here, vortecs or i prefer aftermarket vortec style heads, especially the RHS 170 pro torkers, they out perform the origianal vortecs and are not prone to cracking like the original vortecs. the intake would have to be vortec compatable, they are close to the same price as regular style intakes. however i wouldn't go with flat top pistons as with a 64-65cc combustion chamber would give you a low to mid 10:1 CR i would likely try to stay closer to 9.5:1 for a only street vehicle.

making 325-350hp out of a 327 will be easy due to the fact that 327's like RPM's 350tq is still very possible.

as far as head flow i would look for a head that flows 240+@ .500" lift and has a good consistante increase from .300" lift up, stock vortecs will fall slightly short of this but not by much, but the RHS 170 heads will be right on the money
 
#7 ·
:pain:
my87Z said:
i agree with everyone here, vortecs or i prefer aftermarket vortec style heads, especially the RHS 170 pro torkers, they out perform the origianal vortecs and are not prone to cracking like the original vortecs. the intake would have to be vortec compatable, they are close to the same price as regular style intakes. however i wouldn't go with flat top pistons as with a 64-65cc combustion chamber would give you a low to mid 10:1 CR i would likely try to stay closer to 9.5:1 for a only street vehicle.

making 325-350hp out of a 327 will be easy due to the fact that 327's like RPM's 350tq is still very possible.

as far as head flow i would look for a head that flows 240+@ .500" lift and has a good consistante increase from .300" lift up, stock vortecs will fall slightly short of this but not by much, but the RHS 170 heads will be right on the money
comparing apples to shoes...
 
#8 ·
my87Z is right about the flow numbers, 240@ 0.500" would make great power
at the top of the RPM range of the 327. Accomplish this with a small port
volume to assure good port velocity. These engines are fun to drive with the
light weight steel crank they love RPM. With mine I run a solid lifter flat
tappet cam and let it spin.


my87Z said:
...as far as head flow i would look for a head that flows 240+@ .500" lift
 
#9 · (Edited)
rnix999 said:
Goals:
weekend driver, no racing intentions, I'm more interested in driving winding roads but would like some off the line performance.
325-350 hp
350 minimum torque (I do understand that this is a 327 and not a 383)
$ 2500 to $ 3000 budget (hopefully including machine work)

I am pretty set on keeping this block as long as it checks outs and would like recommendations for heads and cam replacement. I plan on lowering the compression of the engine to be pump gas friendly (91 max octane in California). If my goals are unrealistic please let me know and your help is appreciated.
If the car is beyond restoring then what's the big attraction of keeping that engine in it? What you've described is the GM 350 HO crate motor. 330HP @ 5000 RPM and 380 Ft.Lbs. @ 3800, 9.1 to 1 compression, hydraulic cam, Vortec heads and aluminum intake for about $2800.00. Put the 327 under the bench for "someday", drop a 350 HO in it and go. Just my $.02.
 
#11 · (Edited)
OK, here's a combo that keeps your 327 block.

.030" over for a classic 331cid. with flat top pistons with 5cc valve reliefs, Vortec heads, Performer RPM, Comp 268HE cam, a 600cfm carb with small tube headers. On DD2000 it makes "roughly" 374FWHP @ 5500 and 391FWTQ @ 4500. Good low end TQ and compression is 9.5 to 1, DCR about 7.6 so it should run on 89 Octane, 91 no sweat. In a light car with a 4 speed and 4.11's it would be an absolute blast and have a bit of a "racy" idle but decent manners.

You'll have to get a different intake but you won't have any trouble selling the ZZ4 intake.
 
#15 ·
Hippie said:
.030" over for a classic 331cid. with flat top pistons with 5cc valve reliefs,
Vortec heads, Performer RPM, Comp 268HE cam, a 600cfm carb with small
tube headers.
I'm thinking more along the lines of porting the Vortec heads, a Comp XS274S
cam. Same flat top pistons with a smaller combustion chamber for a little
more compression. Weiand single plane with a 750 double pumper. Up grade
the connecting rods and swap the 4:11's for a 4.56 and spin it to 7200. Now
we are talking fun to drive.
 
#17 ·
C-boStyle™ said:
I agree with using a 350. A 350 will almost always have more tq than a 327 and will make lower rpm driving more enjoyable on the street. another plus to using a vortec 350 is that it has a factory roller cam.
I gave my 2 Pc. rear main 350 cores away last Fall. I won't use anything but factory roller cam blocks when building a SBC from now. GM made some great factory roller cams for budget street engines. A guy can throw together a pretty good running engine with swap meet parts and crate motor takeout cams and valvetrain parts off eBay. Just like the old days.
 
#18 ·
automotive breath said:
I'm thinking more along the lines of porting the Vortec heads, a Comp XS274S
cam. Same flat top pistons with a smaller combustion chamber for a little
more compression. Weiand single plane with a 750 double pumper. Up grade
the connecting rods and swap the 4:11's for a 4.56 and spin it to 7200. Now
we are talking fun to drive.
Not to be disrespectful, but there is some REALLY bad advice here, #1, unless you are a real WIZARD with a die grinder, porting Vortecs can be a REALLY bad idea, it doesn't take much to ruin them, and it takes a LOT of skill and experience to make even a small improvement in them, #2, that is way too high a lift without some serious machine work, stock Vortecs will only accept up to about .460"~.480" lift without machine work or some special springs and retainers. #3, they don't work all that well over 6000 rpm, but the low lift flow is so good they don't need to. #4, unless the flat tops are relatively lightweight and forged, 7200 rpm could mean instant destruction.
I'd recommend a good valve job along with cutting the tops of the valve guides for some PC seals with the proper valve springs to match a mild .480"~.510 lift cam, compression should be 9.7 to 10.5:1 depending on deck height and head gasket thickness, which will run fine on pump gas with the high swirl, fast burn combustion chambers. 375 to 400+ REAL hp is relatively easy with a combo like that, and if that's not real fun, I'm glad I don't live in your neighborhood, :D :cool:
 
#19 ·
my87Z said:
What? AP i do appriciate your knowlege and critisisim but do explain further please. what info was i wrong with? :rolleyes:
RHS uses a 4.125" bore to measure their flow. It inflates their flow numbers, most people are unaware of that.

RHS has good heads, but Vortecs aren't that far down in comparison, and the cracking problems are non-existant on engines that are tuned right and not overheated.

$1000 into a good Vortec long block can build you one hell of an engine for a daily driver.
 
#20 ·
ap72 said:
RHS uses a 4.125" bore to measure their flow. It inflates their flow numbers, most people are unaware of that.

RHS has good heads, but Vortecs aren't that far down in comparison, and the cracking problems are non-existant on engines that are tuned right and not overheated.

$1000 into a good Vortec long block can build you one hell of an engine for a daily driver.
i was aware of that AP, and the number i posted (254cfm @.500) came of of the stan wiess website not RHS. RHS has them listed at 268cfm @.500 lift. (but they also used a 4.200 bore, and i still find that hard to believe) but you're right most all head manufacturers do this to inflate there flow number in order to sell heads, i rarely look anywhere but the stan weiss site though and as a rule of thumb i still take 5% off the flow numbers for a more realistic number and even after doing that the RHS 170's are still flowing about 241@ .500 and the stock vortec is around 227 @ .500, the RHS have the same benefits that the stock vortecs do lowing in the lift as well but even better. i do understand that going the stock route is cheaper and will still produce some nice numbers but many like to put larger lift cams and have the stock vortecs cleaned up. even after they have been machined they typically still dont produce what the RHS 170's do and now you have pretty much the same amount of money in them. this is mainly where i stand, i know that some can do there own machine work and that helps them drastically but i and many others still have to pay for ours
 
#21 ·
my87Z said:
i was aware of that AP, and the number i posted (254cfm @.500) came of of the stan wiess website not RHS. RHS has them listed at 268cfm @.500 lift. (but they also used a 4.200 bore, and i still find that hard to believe) but you're right most all head manufacturers do this to inflate there flow number in order to sell heads, i rarely look anywhere but the stan weiss site though and as a rule of thumb i still take 5% off the flow numbers for a more realistic number and even after doing that the RHS 170's are still flowing about 241@ .500 and the stock vortec is around 227 @ .500, the RHS have the same benefits that the stock vortecs do lowing in the lift as well but even better. i do understand that going the stock route is cheaper and will still produce some nice numbers but many like to put larger lift cams and have the stock vortecs cleaned up. even after they have been machined they typically still dont produce what the RHS 170's do and now you have pretty much the same amount of money in them. this is mainly where i stand, i know that some can do there own machine work and that helps them drastically but i and many others still have to pay for ours
That's pretty much the most objective view of it i think a person can have.

If you can do your own porting and run rinned studs though you can save some serious coin by using the Vortec heads that come on a complete long block. I get 4-bolt main 880 Vortec long blocks for about $300-$400. With another $1000 spent on flat top pistons ($100), cam ($250), intake ($200), Springs ($100), and rings, bearings, and gaskets ($150) you have a little change left to get an ignition and rebuild a carb ($200). Hell, even if you have the heads redone you're not in for a total over $1500. If you watched your P's and Q's you could do this build for less than a grand if you surf ebay and craigslist.

A set of RHS 170 heads will eat up more than half of that budget. They're nice heads, but not that much nicer than stockers, especially on a daily driver type car.

I like RHS heads, they sell a good product, but for 400ftlb in a daily driver I think they're overkill. If we were looking at crossing the 500hp mark then they would be a great investment IMO.
 
#23 ·
ap72 said:
BTW sorry for calling you on the RHS heads, most people just follow the advertisements and take them as gospel truth, I should have assumed you knew better.

it's cool man, and you're completely right. if you can do the machine work your self than man you got it made. if you dont then you're gonna spend some more coin. like me i bought a set of DART 200cc platinum heads had then angle milled .040 to give them about 58.5cc CB's had all the casting cleaned and some port and polishing and it ran me about 690.00 on top of 1100.00 for the heads but they also flow tested them for me for free and i got inbetween 9-14cfm increase at all lift levels (4.125) with flow of 292cfm @ .550 lift, in which i'm using a cam with .560 adjusted lift from the 1.6 rockers, so for me it was well worth it but i'm using a 4.040 bore so i imagine the real number for me is closer to 280cfm. that's still better than the AFR heads and i get to keep the iron
 
#24 ·
I don’t want to be disrespectful either, we just disagree; that’s OK

Rickracer said:
#1, unless you are a real WIZARD with a die grinder, porting Vortecs can be a REALLY bad idea, it doesn't take much to ruin them, and it takes a LOT of skill and experience to make even a small improvement in them.
I disagree, these heads flow ~ 220 on the intake side stock, just a small amount of
work and a good valve job will put them in the 240 – 250 SCFM range. Even
more improvements can be found on the exhaust side. I’ll post information on
how to do this if you are interested.



Rickracer said:
#2, that is way too high a lift without some serious machine work, stock Vortecs will only accept up to about .460"~.480" lift without machine work or some special springs and retainers.
Correct, but easily resolved. We run these heads with up to 0.600” lift with
the machine work, LT1 retainers and the correct springs.



Rickracer said:
#3, they don't work all that well over 6000 rpm, but the low lift flow is so good they don't need to.
I disagree, they work very well above 6000 RPM if prepared correctly. If he
wants to make good power with a 331 he will need to spin it.


Rickracer said:
#4, unless the flat tops are relatively lightweight and forged, 7200 rpm could mean instant destruction.
I agree light weight pistons are recommended for high RPM, I disagree that a
heavy piston like a TRW will instantly destruct at 7200 RPM. I have had my
331 TRW flat tops for over 30 years with zero failures.


PS: I was very conservative with the combination I posted, personally I
would install a larger cam and put 488’s in the rear-end and let the little
331 sing, that’s what I do with mine. Or install a 350 like the others have
recomended.
 
#25 ·
rnix999 said:
Goals:
weekend driver, no racing intentions, I'm more interested in driving winding roads but would like some off the line performance.
325-350 hp
350 minimum torque (I do understand that this is a 327 and not a 383)

$ 2500 to $ 3000 budget (hopefully including machine work)

I plan on lowering the compression of the engine to be pump gas friendly (91 max octane in California).
while high revving engines are fun, pay attention to the original goals.

For 3K he could make a 500ftlb 383, but I think that is a little excessive for this application. Instead spend only half the money, exceed the power goals, and spend the rest on a set of headers, a rebuilt carb, and a set of rear tires.
 
#26 ·
automotive breath said:
.... Even
more improvements can be found on the exhaust side. I’ll post information on how to do this if you are interested....
My information coms from my machinist, who's done all my work for over 25 years, does a TON of local racer's porting work, even has some national record holders, and owns his own Superflow 600, but I'm always interested in more knowledge and/or different perspectives, :thumbup:

automotive breath said:
I disagree, they work very well above 6000 RPM if prepared correctly. If he
wants to make good power with a 331 he will need to spin it.
I used to spin my .060 over 327 over 7500 a lot, when it finally died, it was turning over 8300...

automotive breath said:
... I disagree that a
heavy piston like a TRW will instantly destruct at 7200 RPM....
The instant destruction was referring to the possibility of cast pistons. With forged pistons, I think just about any 327 would be quite safe to 6500~7000. I had some fairly heavy Speed Pro forged popups in my 336, and they lasted a LONG time, :thumbup:
BTW, it was in a Vega, had 492 angle plug heads, 4.56s then 4.88s, TH400, 3000 stall, and a .530+ lift solid cam with 1.6 roller rockers, and got street driven a LOT, so I know where you're coming from, ;) :cool:
 
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