corvesy
Contributor
Posts: 792
Reg: 08-07-08
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10-21-18 09:22 AM - Post#2749188
I am looking at buying a 327 300 and have found one but the pad code says HCR which my research says this is a 275 HP. My question what is the difference between the 275 and 300 hp 327?
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57tim
Valued Contributor
Posts: 3108
Loc: Cameron, Wi, USA
Reg: 11-09-01
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10-21-18 02:16 PM - Post#2749202
In response to corvesy
Its been a looooooong time since I had a 275 hp 327 in a 66 Caprice Classic but I think I could run regular leaded fuel so I think the heads might have been different, lower compression maybe.
Edited by 57tim on 10-21-18 02:32 PM. Reason for edit: No reason given.
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aghaga
"4th Year" Silver Supporting Member
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Reg: 07-05-08
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10-21-18 05:59 PM - Post#2749209
In response to 57tim
The 300 and 275 hp engines were basically the same engine. The 300 was rated @5000 rpm while the 275 was rated @4800. The 300 hp versions had 2-1/2" exhaust manifolds and the 275 hp were equipped with 2" manifolds and single exhaust. The 300 hp used Carter AFB carbs where the 275 hp were either Carter AVS, which has the same bolt pattern as a Holley, or Qudrajet carbs.
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 Rick_L
Member #409
Posts: 28053
Loc: Katy, Tx, USA
Reg: 07-06-00
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10-21-18 07:40 PM - Post#2749213
In response to aghaga
I will differ with you on the 2-1/2" manifolds on the 300 hp version - I don't think they had them. But I don't think I can offer any verification either. I think the big manifolds came on the 365 hp and 375 hp engines, not even on the 340, 350, and 360 hp engines.
The vast majority of 275 hp 327s were equipped with a Quadrajet and a Quadrajet-specific manifold.
Chevy made the 300 hp engines from 62-65, and the 275 hp engines from 66-68.
All 327s prior to the low hp 68 model 2bbl engines had 10.5:1 advertised compression with flat top pistons (250, 275, and 300 hp) and had 11.5:1 advertised compression with popup pistons (340, 350, 360, 365, and 375 hp).
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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10-22-18 06:29 AM - Post#2749230
In response to Rick_L
Big exhaust manifolds were 327 365/375 Corvette only. They weren't even offered as an RPO.
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japete92
Posts: 2106
Loc: No. Virginia
Reg: 01-18-13
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10-22-18 06:55 AM - Post#2749231
In response to IgnitionMan
Big exhaust manifolds were 327 365/375 Corvette only. They weren't even offered as an RPO.
I do not believe that is correct. According to this doc:
https://www.gmheritagecenter.com/docs/gm-heritage-...
The 63 full size Chevy with RPO L74 engine (300hp 327) came with the 2-1/2" exhaust manifolds and 2-1/2" exhaust pipes to the muffler. Tail pipes were 2".
That also matches my memory of the 63's. I never looked up, nor owned other year cars, but I think the 62 and 64 are the same. Perhaps 65 also.
Pete
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aghaga
"4th Year" Silver Supporting Member
Posts: 2369
Age: 68
Loc: Woodlawn, Va.
Reg: 07-05-08
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10-22-18 07:44 AM - Post#2749236
In response to japete92
Basically it is my belief the core difference in the 275hp vs 300 hp is that Chevrolet chose to give the ratings at two different points. 275hp @4800 and 300hp @5000
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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10-22-18 09:20 AM - Post#2749241
In response to aghaga
Nope, Corvette only. Not even in trucks. Anything can be in print, and not correct, like "President Hilary Clinton". THANK HEAVEN, and "Corvairs came with big block engines in them".
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4spd409
Contributor
Posts: 625
Loc: Sherwood ND
Reg: 10-10-02
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10-22-18 02:07 PM - Post#2749265
In response to IgnitionMan
300hp 327 62-64 Full-size Chevy used the 2 1/2 exhaust manifolds. I have parted out several and have never seen 2" on a 300hp. I have also I noted this on several original cars. In 65 when they changed the style of frame and went to a rear steer car they changed the left manifold to a swept back dump to clear the steering gear and only used the 2". I have seen the 275hp {starting in 66} with Quadrajet, Carter AVS or Holley carbs. I believe that the Quadrajet factory had a fire and they used what they could get there hands on. I think they even had Carter making Quadrajets for a while.
Edited by 4spd409 on 10-22-18 02:14 PM. Reason for edit: No reason given.
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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10-22-18 04:13 PM - Post#2749278
In response to 4spd409
I worked for GM Engineering, Chevrolet Division, and NEVER saw a 300 hp engine with anything bigger than a 2 inch set of exhaust manifolds on any non-Corvette engine.
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 dgstarr
"5th Year" Silver Supporting Member
Posts: 391
Loc: Portland, OR
Reg: 04-16-13
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10-22-18 04:34 PM - Post#2749282
In response to Rick_L
In 1963 I was 15-16 years old and talked my dad into factory ordering a 300 hp Impala SS for our family car. I have since owned a 62 and a 63 Impala SS with original numbers matching 300 hp engines. All had 2 1/2 inch rams horn manifolds. This can easily be proven by looking at a 62 or 63 sales brochure which states that the 300 hp 327 has a "large diameter dual exhaust system". The assembly manual and parts catalogs will verify that the 300 hp engine uses the same mufflers and tailpipes as a 409.
Dave
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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10-23-18 06:46 AM - Post#2749329
In response to dgstarr
Well, of the 139 cars I own NOW in my collection, 2 of them have that RPO engine, with the exhaust manifolds that came with them, and NEITHER of them have 2.50 inch manifolds. Neither vehicle has ever had the exhaust manifolds off their engines.
I figure all of you have also looked at the 300 engines and exhaust manifolds on them that you own today, right now. It appears you all currently own at least one of these vehicles with those engines and exhaust manifolds, unmolested.
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corvesy
Contributor
Posts: 792
Reg: 08-07-08
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10-23-18 07:14 AM - Post#2749332
In response to IgnitionMan
I appreciate everyone's response. So in going through all the posts it appears to me there are no big differences between the 275 and 300 hp engines except maybe different carbs and exhaust manifolds and exhaust pipes.
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rod
Member #248 Senior Member
Posts: 1779
Loc: kingman,az
Reg: 04-29-00
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10-30-18 04:50 PM - Post#2750036
In response to corvesy
I have a 1965 327 275 hp in my 1955 Nomad. it came with a Carter AVS carb. the cast iron intake was bigger than the 250 hp [62-64] Rochester 4 jet.
there must have been some different exhaust systems on cars built in different places.
when I was in HS, a senior in 63-64, I had 2 friend who bought brand new cars. Bob bought a '63 300 hp with 2 1/2" ex. manifolds, and Danny bought a '64 300 hp with 2 1/2" ex. manifolds.
after looking at the intake, I ordered a brand new one from the Chevy dealer. the AFB was much bigger [and in the end-much less problem] than the 3-2s I had on my 56. I wanted a pair of the 2 1/2" ex. manifolds. but nobody here could make me the head pipes!!!
Rod in AZ
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MikeB
Ultra Senior Member
Posts: 10073
Loc: Plano, TX
Reg: 08-28-03
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11-13-18 10:10 AM - Post#2751267
In response to aghaga
Seems like a CT member has an Impala 4-dr sedan (64 I think) that originally came with a 300/327, and it had 2.5" rams horns. He ended up installing a 383, but used the original intake, AFB carb, and exhaust manifolds to keep it looking stock. Would be nice to hear from him here.
As for 275hp vs. 300hp engines, I do know from first hand experience that a 1968 station wagon (family truckster?) had a 275hp/327 with a Q-jet. It's the first Q-jet I ever rebuilt. Don't remember a thing about its exhaust manifolds and heads though. 
***Edit -- Just wondering if it was only the Q-jet carb that made a 25hp difference vs the 250hp/327 with WCFB carb. I wonder what else, if anything, was different.  Or maybe it was just marketing.
1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.
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Edited by MikeB on 11-13-18 10:39 AM. Reason for edit: No reason given.
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Rick_L
Member #409
Posts: 28053
Loc: Katy, Tx, USA
Reg: 07-06-00
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11-13-18 02:08 PM - Post#2751292
In response to MikeB
Just wondering if it was only the Q-jet carb that made a 25hp difference vs the 250hp/327 with WCFB carb. I wonder what else, if anything, was different. Or maybe it was just marketing.
250 hp engines had "Power Pack" heads with 1.72" intake valves, as well as either the WCFB or a similar Rochester 4-jet.
275 hp engines had "camel hump" heads with 1.94" intakes, and the Q-jet or AVS carb.
300 hp engines had "camel hump" heads with 1.94" intakes, and a Carter AFB.
They all had the same cam and pistons.
Now, let's guess which one the 275 hp version is more like?
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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11-14-18 09:42 AM - Post#2751364
In response to MikeB
I remember the WCFB was not used on single 4bbl engines when the Rochester 4GC came along on the 250/327.
WCFB's were also used on 2x4 small block Corvettes.
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Rick_L
Member #409
Posts: 28053
Loc: Katy, Tx, USA
Reg: 07-06-00
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11-14-18 12:58 PM - Post#2751388
In response to IgnitionMan
I think there was a time when they were used interchangeably. Really doesn't matter, the capability of the WCFB and Rochester were very similar, both about 350 cfm, and they used the same manifold.
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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11-14-18 06:22 PM - Post#2751422
In response to Rick_L
Anyone know what WCFB and AFB stand for.
NO, It is not Will Carter Four Barrel.
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454cid
Valued Contributor
Posts: 3232
Age: 50
Loc: West Michigan
Reg: 02-18-12
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11-14-18 06:46 PM - Post#2751425
In response to IgnitionMan
NO, It is not Will Carter Four Barrel.
Googling it, it appears it depends who you talk to.
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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11-14-18 08:16 PM - Post#2751433
In response to 454cid
Actually, it depends on those that really do know, and those that really don't.
Think metal composition.
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japete92
Posts: 2106
Loc: No. Virginia
Reg: 01-18-13
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11-15-18 07:34 AM - Post#2751454
In response to IgnitionMan
Anyone know what WCFB and AFB stand for.
NO, It is not Will Carter Four Barrel.
Is not the 'A' for aluminum, and the 'wc' for wrought cast?
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Rick_L
Member #409
Posts: 28053
Loc: Katy, Tx, USA
Reg: 07-06-00
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11-15-18 03:51 PM - Post#2751506
In response to japete92
"wrought cast" would be a contradiction. "Wrought" and "cast" are two different, mutually opposite things.
"White cast" might be the answer. Think pot metal.
Why else would an AFB be "aluminum" 4 barrel, if it wasn't an improvement over pot metal?
Am I getting close, Ignition Man?
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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11-23-18 07:56 PM - Post#2752229
In response to Rick_L
Sorry, folks, I have been in
The hospital
WCFB - white Cast Four Barrel - White, or "pot" metal carb.
AFB - Aluminum Four barrell
AVS - Air Valve Secondary.
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jdk
"14th Year" Gold Supporting Member
Posts: 452
Age: 73
Loc: columbus, ohio
Reg: 02-15-10
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11-24-18 07:59 AM - Post#2752250
In response to IgnitionMan
hope you are getting better. jim
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CowboyTrukr
"12th Year" Silver Supporting Member
Posts: 4858
Loc: Salt Lake City
Reg: 06-20-09
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11-24-18 11:02 PM - Post#2752286
In response to jdk
Ditto that. Get well soon, Dave.
Greg
‘01 Silverado 2500HD 8.1/Allison 1000 Xcab/LB
'00 Explorer XLT 4.0 SOHC V6 Auto
'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500 SOLD
"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke |
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IgnitionMan
Valued Contributor
Posts: 4037
Reg: 04-15-05
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11-25-18 12:09 PM - Post#2752311
In response to CowboyTrukr
Still in the hospital. They still can't figure out legs and things between them swelling. Let alone draining them back to normal. Until then, I can't walk.
Thank you for caring.
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jdk
"14th Year" Gold Supporting Member
Posts: 452
Age: 73
Loc: columbus, ohio
Reg: 02-15-10
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11-25-18 04:43 PM - Post#2752343
In response to IgnitionMan
sorry dave. jim
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rcr3
Site Ambassador -"19th Year" Silver Supporting Member
Posts: 3828
Age: 71
Loc: MANHEIM PA. U.S.A.
Reg: 11-24-02
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11-26-18 03:56 AM - Post#2752379
In response to IgnitionMan
Get Well I-Man!!!
'67 Camaro survivor
'06 Z71 Sierra Ex Cab
'37 Chevy cp.SOLD!!6/7/14
'00 S10 Ex Cab BUILT FOR EVERYDAY,NOT JUST THE HOLIDAYS
'73 Nova pro-street project
'17 Chevy Trax LT
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CowboyTrukr
"12th Year" Silver Supporting Member
Posts: 4858
Loc: Salt Lake City
Reg: 06-20-09
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11-27-18 11:28 PM - Post#2752607
In response to rcr3
Need you back to 100%!
Greg
‘01 Silverado 2500HD 8.1/Allison 1000 Xcab/LB
'00 Explorer XLT 4.0 SOHC V6 Auto
'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500 SOLD
"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke |
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