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how to increase horsepower with 327

38K views 37 replies 19 participants last post by  pdq67 
#1 ·
currently i have my 327 running good was rebuilt 3 years ago wasnt driven much changed it to a 4 barrel carb and change distribitor to a hei, and hooker headers, with 40 series flowmaster exhaust, i was wondering what i can do to get it to run harder i got non posi traction 10 bolt rear end let me know what i can do to increse my horsepower
 
#3 ·
First off, what 327 engine are you talking about b/c it came in!

210, 250, 275, 300, 340, 360, 365 and 375 hp versions!

THe 210 is a small valved, low compression jobber with the 250, 275 and 300 engines darn good one's b/c they are right at 10 to 1 CR. with 62 to 64 cc medium valved heads and flat-top pistons.

The 340 was a 2x4, medium valved, high compressioned engine and the 360 just had an FI on it.

The 365 had a carb and the 375 had FI, both had big valve heads, big ramshorn exhausts and 11 to 1 CR. forged pistons.

So it matters a lot what you have here..

pdq67
 
#5 ·
Engine code from the front side of the engine on the passenger side on the "deck." The surface the cylinder head sits on the block.

There will be a 1/2 inch wide area with numbers stamped on it. Need all the info. Group of numbers on the left side of the stamping should be the same as the VIN of the body, if it is the original engine block.
 
#6 ·
PDQ67
The 327/340 hp WAS NOT a 2x4 equipped engine. That engine was only offered in a Corvette and had a alum. intake with a C series carter AFB in 1962. It WAS NOT what you called a medium valve engine as well. The 461 head was introduced in 1962 and had a 2.02 intake and a 1.500 exhaust valve. If it had a 461x head which was very rare even then the valve size was 2.02 and 1.600. The combustion chamber on the std. 461 was 64 cc's and the 461 x was 62 cc's. The next step up in HP was the Fuel Injection engine
 
#16 ·
PDQ67
The 327/340 hp ... That engine was only offered in a Corvette and had a alum. intake with a C series carter AFB in 1962. It WAS NOT what you called a medium valve engine as well. The 461 head was introduced in 1962 and had a 2.02 intake and a 1.500 exhaust valve. If it had a 461x head which was very rare even then the valve size was 2.02 and 1.600. ...
:noway: Nope ;)
I owned an original 1962 RPO-396 (note '62 was the last year for all letter engine options - '63 on used a Letters/Numbers, i.e. RPO-L79 & etc., option designation. ) 327/340 Corvette for many years and the heads (-461X) were "Medium Valves", in that they were 1.94" (most common SB sizes are 1.72/1.94/2.02") Intakes.
I took that engine apart many times :thumbsup:
All Chevy Performance heads were max. 1.94" Intake valve size until 1964 when the 2.02" valves size was introduced - most don't realize the 2.02" valve heads didn't come out 'til then.
These earlier style heads, used on both 283's and 327's, were commonly called "Power-Paks" v.s the '64 on "Fuelie" heads.
I think this older designations has gotten lost over the years and everyone I hear now just refers to any 'Double-bump' head as a 'Fuelie' - I usually don't bother to correct folks anymore ...

I also owned an original 1962 Impala SS with a 327/300 for many years, and it was a Rochester "4-Jet" - NOT a Carter carb on it - because it was an Auto ;)
The 327's got different carburators depending on the transmission type.
Only the Manuals trans cars got the WCFB's (some HP were AFB's ) on them.
I worked on many of them back-in-the-day and still have most of the service books and a full set of Carter 'Gauges' (yes, there is such a thing :D ).
I was the second owner of the Impala and the car was untouched when I got it - one of the many I would LOVE to have back, they guy who owns it in SoCal. won't sell it back - and he's younger than me :eek:

I have a data sheet somewhere that list the major spec.s for the 327 RPO codes.
There were lots of RPO's for that engine in 1962. I remember RPO-300, 397 (what was in my Impala), 396, 582, 583 and I think there were one or two more ...

Hopefully JohnZ will see this post and will have more of the original confiquration information for these early Corvette and 327 engines in his NCRS
information.
 
#7 ·
Further education
In 1962 the 327/250 hp was introduced and was a hyd. lifter cam with the power pack head. It had a 1 5/8 intake valve with a 1 1/2 ex. valve. Had a cast iron intake a Rochester 4GC carb. That engine was offered from 1962-1965

The 327/300hp had a hyd. lifter cam and a BIGGER PORT size cast iron intake with a C Series Carter AFB. It had the 461 head that had 1.093 intake valve with a 1.500 exhaust valve and a 64 cc head. Compression was up just a little over the 250 hp version as well. In 1962 -1965 the last three casting numbers on the block was 870. All had small journal steel cranks.

The 327/365 hp had a alum. intake and a Holley carb with a solid lifter cam.

The 327/375 hp had the new style Fuel Injection. i.e. had a removable top. If you lived where the weather got cold it was not unusual for the engine to backfire and blow the gasket out of place and then you would have to pull the top and sometimes have to replace the gasket.

The 327/275 hp engine was introduced in 1966 and availible in everything except a Corvair.

Had the 461 head with the 1.093 in. and the 1.500 ex. Hyd. lifter cam and a cast iron intake. Most were equipped with the spread bore Q-Jet. Also there were alot of these engines in the Nova with a big port intake and a Carter carb. In the 1966-67 Maibu wagons with air they had a Holley carb wheter it was a stickshift or automatic. This was the 585cfm holley and was a rare deal then.

The pad on the block in front of the passenger side head of the car will give you the month the day where the engine was produced what car the engine came in and if it was an auto trans or stick shift and HP. Hope this helps
 
#27 ·
Further education......The 327/300hp had a hyd. lifter cam and a BIGGER PORT size cast iron intake with a C Series Carter AFB. It had the 461 head that had 1.093 intake valve with a 1.500 exhaust valve and a 64 cc head. Compression was up just a little over the 250 hp version as well.
Does anyone know the casting number of this intake manifold or where to find one?

Thanks
Chuck
 
#8 ·
Thanks Frank,

I was thinking of the 2x4, 283 engine and got the 340hp/327 mixed up with it. And a double thanks b/c, looking back, I see that GM never made a 2x4, 327 engine AND I always thought they did, my bad ALL these years..

Guys, I sure hope I haven't confused anybody when I said that I thought the 340hp/327 engine had 2x4's on it, I appologize if I have!!! I try very hard to give out factually correct info...

Anyway, I still think both the 340 and 360hp/327's used the medium valve 461 type heads and the old Duntov, -097 cam!

I say this only b/c if they got the big valve heads, all they would have needed was to install the old 30-30 solid cam to be 365 and 375hp/327's and I don't think it is this simple b/c the big valve heads came out in '64.

Can you give me the factory spec's for the 340 and 360hp/327's???

And I have a set of virgin, big valve -461's out in my garage... Heck, I need to check their casting dates???????? But I'm almost sure they are '64's

And fwiw, the -461x medium valve heads were first ran on the 315hp/283 FI engine. And I can't say about their use on the 327 engines??

pdq67

PS., my long gone Crippled Buddy had a complete '64, 375hp/327 FI engine, 4-speed tranny and 3.08 rearend gears in his '58 'Vette ragtop

He only had an Isky Z-30 solid lifter cam in it! Talk about running on the topend!! 160 to 170+ mph...........
 
#9 ·
if you have good even compression on all cylinders, you can make some reasonably cheap hp by putting in a set of edelbrock rpm alum heads , matching cam and airgap intake its a great setup on a small cube motor, really pulls hard on the street,good luck , chris
 
#10 ·
i just found out that my cars engine is not a 327 but a 283 60 over with 327 pistons heades were rebuilt in 1991 i checked the reciptes from the lady in her folder i bought this car in 2004 it looks good i just finish putting the muncie 4 speed converstionbut runs like **** i changed the distribitor to hei chenged the intake to edelbrak and 4 barell carb no power wat could be wrong were going to check the timming but what are the spec is it suppose to be on if the block is 283 over 60 with 327 heads
 
#11 ·
You have a 292" engine!

Heck, 10 to 1 CR. a good pair of 1.94"/1.60" valve heads and a decent solid lifter cam like a CC 270S, a 600 cfm Holley 1850 carb on the old 300-36 high-rise and a cheap set of 1.625" dia., 4-tube, long headers uncorked and the old sucker can go big motor eating!!

That is if it's geared and tired right!!

These little monsters were the scourge of SS way back then!!

You can get over 400hp outta onna these little jewels EASY!!

He, He!!

pdq67

PS., use a decent single plane intake and really let her breath up top, but she will be soft down below, imho..
 
#13 ·
I'm really lost now. Are you saying now you have a 305 and not the .060" 283???
If it is a 305 you can reuse the 305 3.48" crank, 4.000" blocks are a dime a dozen and you can build a nice 350 on budget parts.
You can build big power with budget cylinder heads and I have noticed how cheap forged pistons are getting.

Competition products has some killer deals.
 
#17 ·
I know about the 1.94"/1.50" -461x double hump heads that were used on the 315hp/283 FI engine.

And that prior to '64, the double hump heads were just medium valve jobbers b/c I have a virgin chambered pair of 2.02"/1.60" valved -461's in my garage now.

I just got screwed up on the intake systems on the early 327's is all.

pdq67
 
#18 ·
im looking at this engine 350ci bored .030 over 4-bolt main #207 cast the rotating assembly bought from summit racing the crankshaft is forged steel scat, the rods are eagle forged, the pistons are alum speed pro dome top rated 10:1,
cam is a crane 485lift w/284 dur, dual roller chain,meling oil pump,
bolts are mr gasket hardend,new rings,bearings ,gaskets,chrome dress kit,edelbrock perfomer intake.
heads are camel hump w/194 valves

what doe you guys thinks about this engine heads
camel hump heads w/ 194 valves???
 
#19 ·
also owned an original 1962 Impala SS with a 327/300 for many years, and it was a Rochester "4-Jet" - NOT a Carter carb on it - because it was an Auto
The 327's got different carburators depending on the transmission type.
Only the Manuals trans cars got the WCFB's (some HP were AFB's ) on them.
I thought all 62-64 327/250s has 4GC on PG cars and WCFB on manuals w/ 1.72/1.50 Powerpack heads, and that ALL 300hp cars had AFBs and "camel hump 1.94/1.50 heads. Are you sure your '62 wasn't a 250hp car?
 
#20 ·
I've a 327 + .30" with the 4 Bolt 010 block decked .020", forged large journal 68 crank, SIR Rods, TRW Forged Dome pistons giving me a 10.75 Static Compression and the 68 1.94/1.5 64cc heads which I built to 2.02/1.6 Grumpy Jenkins Specs (Never Again - LOL). Manley Pro Flow Severe duty Valves, RKM Shaft Roller Rockers, Edlebrock RPM with a Holly 750DP. I run a Sigerson F296-1 Mechanical Flat Tappet. GM 4 Quart Vette Pan with Windage Tray. Will rev 8000rpm easily. HP (guessing) would be approx 425Hp.

This is a spare engine for my 70 z28 or if I decide to swap out the BBC.

I did one for a friend running 6" rods and 350 pistons - I've built lots of 327's in my day - LOL.
 
#23 ·
I do not mean to sound silly but there are many similarities between the 283 and the 327 depending on the horsepower level of the 327. Aside from the differences in bore and stroke dimensions between the 2 engines they can share many identical interior components. Let us assume the 327 is a small journal since there was never a large journal 283. Crankshafts will interchange to make a 301/302.

The 210 horse 327 shared the same 283 power pack heads, hydra cam, connecting rods, four valve relief cast flat top pistons (4" bore not 3 7/8"), and 2 barrel carb and intake manifold.

The 250 horse 327 was identical to the 210 horse engine except it had the Rochester 4 barrel carb not a Qjet.

The 300 horse had a different cam, 1.94" dia camel heads, the same 327 pistons, usually a Carter AFB 4 barrel on a larger runner intake manifold.

The 340, 360, 365, and 375 horse engines had forged 11.25 domed pistons all of the small journal engines used a forged steel crankshaft and 2.02" dia. valves on the higher horse engines. The cam was the 346 GM solid cam. The rods were still the old reliable cam squirters from the 283. The 350 horse used the 151 hydraulic cam. All of the higher horse engines used a Holley 600 on an aluminum intake manifold except FI was used on the 360 and 375 horse engines. The 340 used a Carter AFB carb on an aluminum intake.

I do not think I missed any of the important details. Depending on the application , car, trans etc. there were definitely carburetor variations (Carters, Rochester, and Holley that were used.

This information is being passed along based on my recollections of building many SBC throughout the years. Many of the parts do interchange between these two engines, this is why I have loved working with them since 1963.

I hope this info helps to better understand the two powerplants.
Bill
 
#24 ·
I'm not that familiar with the passenger car engines, but Corvette engines dressed out a little differently, as follows:

Cams:

'57-'61 283 and '62-'66 327 base engines used the same 3733431 hydraulic cam, replaced in '67 by the "929", which had a little less intake lift, more exhaust lift, and 10* more intake duration and 20* more exhaust duration - it remained the standard cam through 1979.

The 283's and 327's through 1963 with solid lifters all used the "097" Duntov; it was replaced in '64-'65 by the "30-30" ("346") cam, later used again in the '67-'69 Z/28. 1965 was the last year for solid-lifter cams in small-blocks except for the '70-'72 LT-1's, which used the "178" cam.

The "151" performance hydraulic cam was introduced in 327's in '65 (the L-79), and remained through 1968.

Carburetors:

Carter WCFB's were used on all Corvettes through 1961 (both 1x4 and 2x4), and from '62-'65 were used only on the base 250hp engine, then disappeared.

Carter AFB's were introduced in '62 on the 327/300 and 340, continued in '63, and were used only on the 327/300 in '64-'65, then disappeared.

The Holley 2818 (4150 - 585CFM) was introduced in '64 on the 327/365, and continued in '65 on the 327/350 and 327/365. It was replaced in '66 by the 3367 (4160 - 585CFM) on the base 300hp and L-79 350hp engines, and was replaced in '67 by the 3810 (4160-585CFM) on the base 300hp and L-79 350hp engines. 1967 was the last year for a Holley on a small-block except for the '70-'72 LT-1 350.

Q-Jets weren't used on Corvettes until 1968.


Cranks:

All 265, 283, and 327 engines used forged steel cranks; solid-lifter 327 cranks were Tufftrided for wear resistance.

Rods:

Rods were improved in late '66 by adding more meat adjacent to the underside of the bolt head, which showed as a "bump" after machining.

Heads:

All Corvette heads through 1959 (and 250hp engines through 1965) had 1.72/1.50 valves. Starting in '61, the 461 heads on optional engines had 1.94/1.50 valves; the 2.02/1.60 valves didn't show up until 1964, on 350/365/375hp engines through '65. The 462 heads used in '66-'67 and the 291 heads used in '67-'68 used 1.94/1.5 valves on 300hp engines, and used 2.02/1.60 valves on 350hp engines.

Trivia: There was never a 315hp 283 fuelie, although they were advertised as such; the aluminum heads that increased power over the 290hp fuelie never went into production, although the 315hp rating appeared in early brochures, and the "CS"-coded 290hp engines with iron heads were used in '60-'61.

That about covers Corvette usages; if I missed something, just ask.

:beers:
 
#33 ·
JohnZ,
I've looked high and low for the .050" lobe durations and events on the 3733431 cam, you seem to know them given your hint about 10* more intake and 20* more exhaust on the 929.

Would you have the 050 timing events on the 3733431 cam??
Very much thanks:)


I'm not that familiar with the passenger car engines, but Corvette engines dressed out a little differently, as follows:

Cams:

'57-'61 283 and '62-'66 327 base engines used the same 3733431 hydraulic cam, replaced in '67 by the "929", which had a little less intake lift, more exhaust lift, and 10* more intake duration and 20* more exhaust duration - it remained the standard cam through 1979.

The 283's and 327's through 1963 with solid lifters all used the "097" Duntov; it was replaced in '64-'65 by the "30-30" ("346") cam, later used again in the '67-'69 Z/28. 1965 was the last year for solid-lifter cams in small-blocks except for the '70-'72 LT-1's, which used the "178" cam.

The "151" performance hydraulic cam was introduced in 327's in '65 (the L-79), and remained through 1968.

Carburetors:

Carter WCFB's were used on all Corvettes through 1961 (both 1x4 and 2x4), and from '62-'65 were used only on the base 250hp engine, then disappeared.

Carter AFB's were introduced in '62 on the 327/300 and 340, continued in '63, and were used only on the 327/300 in '64-'65, then disappeared.

The Holley 2818 (4150 - 585CFM) was introduced in '64 on the 327/365, and continued in '65 on the 327/350 and 327/365. It was replaced in '66 by the 3367 (4160 - 585CFM) on the base 300hp and L-79 350hp engines, and was replaced in '67 by the 3810 (4160-585CFM) on the base 300hp and L-79 350hp engines. 1967 was the last year for a Holley on a small-block except for the '70-'72 LT-1 350.

Q-Jets weren't used on Corvettes until 1968.


Cranks:

All 265, 283, and 327 engines used forged steel cranks; solid-lifter 327 cranks were Tufftrided for wear resistance.

Rods:

Rods were improved in late '66 by adding more meat adjacent to the underside of the bolt head, which showed as a "bump" after machining.

Heads:

All Corvette heads through 1959 (and 250hp engines through 1965) had 1.72/1.50 valves. Starting in '61, the 461 heads on optional engines had 1.94/1.50 valves; the 2.02/1.60 valves didn't show up until 1964, on 350/365/375hp engines through '65. The 462 heads used in '66-'67 and the 291 heads used in '67-'68 used 1.94/1.5 valves on 300hp engines, and used 2.02/1.60 valves on 350hp engines.

Trivia: There was never a 315hp 283 fuelie, although they were advertised as such; the aluminum heads that increased power over the 290hp fuelie never went into production, although the 315hp rating appeared in early brochures, and the "CS"-coded 290hp engines with iron heads were used in '60-'61.

That about covers Corvette usages; if I missed something, just ask.

:beers:
 
#26 ·
If your looing for a good 383 crate motor, you might consider looking at M&R Engines out of Glendale, CA. I just purchased a short block 383 I am putting together for my 68. The short block with comp cams hydraulic roller 282hr cam with forged components and timing chain was $2500 delivered to Oklahoma!! I also found Matt very informative and easy to work with!

Tim
 
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