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post #1 of 22 (permalink) Old Jan 29th, 05, 01:43 PM Thread Starter
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I have a 68 camaro with a 327 bored .030" over and it has 58cc heads on it with a 3 angle valve grind done to it. I think these heads came from a 305. Would it be better to go to a bigger cc head or is a 58cc head okay to leave on? With a smaller cc head would that bring the compression up? Please anyone let me know what you think?

Thanks,
Chris.

Chris R. 327, 10.7:1, 68 camaro, 4:56 gears, 4spd,
1.5 roller rockers, edelbbrock RPM heads, Edelbrock performer RPM manifold, HEI.
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post #2 of 22 (permalink) Old Jan 29th, 05, 01:56 PM
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Hi Chris, welcome to the site!

Yes, going with a smaller combustion chamber will raise your compression and conversely a larger chamber will lower your compression.

While increasing compression is one way to go about making power, when changing your cylinder heads you've got a few considerations to make...

First, you should try to figure out what your compression ratio currently is. That way you've got some idea of what you'll get by swapping heads. Also, do you have any idea about the cam in the engine? A longer duration camshaft will generally need more compression to run well while high compression with a shorter duration cam may cause detonation.

Second, Most cylinder heads have chambers bigger than 58cc. So, chances are that if you want to swap heads to a more performance oriented head most of them will have larger combustion chambers. This isn't necessarily bad. With a better flowing head you may likely pick up some power even while reducing compression.

For your 327, you'll want to look at cylinder heads that have intake runners in the 160-180 cc. A larger runner probably will not be beneficial (and may cause you to lose some power).

There are lots of people on this site that can help you out. Of course, the more info you can get on your current setup, the easier it is to give good recommendations.

Good luck! Again, welcome! [img]graemlins/beers.gif[/img]
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post #3 of 22 (permalink) Old Jan 29th, 05, 01:56 PM
 
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All of this depends on your pistons,if they are flat tops you are going to have a good bit of compression IMO borderline for the street.I would not want anymore than 9 1/2 compression for todays gas.Im just guessing but with a flat-top and 58cc heads I think you are going to be around 10-10 1/2 to one.That will mean super unleaded gas.Also a 305 head has small cc runners,but like I said it all depends on the rest of your combo.What are you trying to accomplish with your engine?
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post #4 of 22 (permalink) Old Jan 29th, 05, 02:04 PM
 
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boodlefoof we must have pushed enter at the same time,and said almost the same thing.
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post #5 of 22 (permalink) Old Jan 29th, 05, 03:07 PM
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With a 4.030 bore 3.25 stroke 4.180 head gasket dia..039 thick 58cc. chamber -5cc for valve reliefs .025 in the hole comp. works out to 9.82 to1.Would need atleast 89 octane maybe 91 to not spark knock.If you have the 601 casting 305 4 barrel heads these heads are suppose to work good on a mild 327.They have 1.84 in ans 1.5 ex. valves.I think Paul PDQ67 was putting a set on a 327.I think he had port volumes.There has been some discussion on these heads before and they seem to be a cheap way to pick up comp. and performance especially over the 210hp. heads.My hump head 327 has 9.48 to 1 and runs fine on 89 with 36 degrees total timming.

67 Plum Mist Met. 408 TH350 3.08 posi
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post #6 of 22 (permalink) Old Jan 29th, 05, 04:11 PM
 
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well stated 67plum. i would like to say that 1.94 intake valves can be installed for a little more intake volumn. use a cam in the 212 to 218 @ .050 duration range, and you should have a strong running 327.
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post #7 of 22 (permalink) Old Jan 29th, 05, 04:36 PM
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It looks like they would flow better with the 1.84 valves.I have seen them with 1.94 and they are real close to the chamber wall.They would need to be opened up like the factory did with the 2.02 valve hump heads.But you would have to be very careful as they are lightweight castings.

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post #8 of 22 (permalink) Old Jan 29th, 05, 07:28 PM
 
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I'm reading right along guys..

My pair of -601's measured at 160+ cc intake ports and 55 cc chambers!!

Really PLEASANTLY supprised me b/c I'm going to put them on my nephew's 283 motor.. He, He!! Onna these days I'm gonna make onna those 7,000/7,500/8,000rpm solid cam short stroke motors again!!

A standard 327 flat-top piston motor will run like a "scalded-dog" with no more then a good old CC 268HE hy-cam, a set of medium OR big valve double-hump heads, a set of 1.625" four tube long headers and an old 1850, 600cfm Holley on a 300-36 Holley high-rise!! Keep the CR. between 9.75 and 10 to 1 and hold on!!

Just make sure you have somewhere around a 3.31/3.42/3.55 rearend and a 25.5" to 26" tall tire!!! AT least mine ran like a scalded-dog!!

Sure, 3.73's and 4.10's are great with the little motor but Hwy driving becomes a drag at speed due to excessive rpm's is all...

pdq676



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post #9 of 22 (permalink) Old Jan 29th, 05, 09:01 PM
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PDQ67, Paul I've seen that you have knoweledge when it comes to the older heads. Though I've not started researching it. I thought I'd ask to pick your brain about the flow #'s of my heads. Just curious if you had a ballpark idea.

Brandon J. licence 1NASTY67

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post #10 of 22 (permalink) Old Jan 30th, 05, 05:00 AM
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Hey Nantooch, I happen to have some flow numbers for a few older castings. I think I got them out of a magazine article somewhere...

Numbers are lift/intake cfm/exhaust cfm)

462 heads (with 1.94/1.50 valves)

.050 / 18 / 27
.100 / 50 / 54
.200 / 119 / 91
.300 / 167 / 121
.400 / 198 / 134
.500 / 212 / 139
.600 / 218 / 142

441 head (with 2.02/1.60 valves)

.050 / 30 / 22
.100 / 55 / 45
.200 / 110 / 83
.300 / 160 / 118
.400 / 194 / 133
.500 / 201 / 146
.600 / 203 / 188

882 head (with 1.94/1.50 valves)

.050 / 39 / 34
.100 / 70 / 58
.200 / 125 / 109
.300 / 175 / 136
.400 / 204 / 143
.500 / 205 / 142
.600 / 206 / 142

L98 head (with 1.94/1.50 valves)

.100 / 56 / 52
.200 / 120 / 104
.300 / 160 / 133
.400 / 186 / 150
.500 / 196 / 170
.550 / 198 / 173
.600 / 199 / 175

LT1 head (unsure valve sizes on this one)

.050 / 42 / 30
.100 / 72 / 53
.200 / 129 / 101
.300 / 180 / 136
.400 / 213 / 155
.500 / 214 / 165
.600 / 215 / 171

Hope somebody finds that useful...

John

- '68 Chevy Camaro (sort of done, but always subject to improvement)
- '63 Pontiac Tempest (work in progress)
- '72 Datsun 240-Z (back-burner for now)
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post #11 of 22 (permalink) Old Jan 30th, 05, 08:43 AM
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Thanks John, now I wonder what they flow now that they were opened up to take the 2.02's and 1.6's. either way guess I wont have to rush out for some new heads next year.

Brandon J. licence 1NASTY67

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post #12 of 22 (permalink) Old Jan 30th, 05, 10:46 AM Thread Starter
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Thanks for all the replys.

I will give you some more information I know about my current setup. I have a set of flat top speed pro pistons, a edelbrock performer intake manifold, a 750cfm holley carb, a MSD billet aluminum distributor, the heads casting #'s are 14022601 but I think it has a 1.94 intake and a 1.6 ehaust, the camshaft is .488" lift with 316 degrees duration solid lift. The rear end is 8.5" with 4.56 gears in it. The guy I bought it from was going to use it for drag racing I think. I would like to make it back to more of a streetable machine but still have power when I want it. I think I will need to change the gears in the rear because of high RPM when on the highway which right now don't do much of. I'm not quite sure exactly what the compression ratio is.
One other thing about the heads is it has 1.5 roller rockers (scorpion). The distributor also doesn't have a vaccum advance on it because i'm sure he wasn't planning on doing much part throttle driving. Thanks for all the help guys.

Chris R. 327, 10.7:1, 68 camaro, 4:56 gears, 4spd,
1.5 roller rockers, edelbbrock RPM heads, Edelbrock performer RPM manifold, HEI.
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post #13 of 22 (permalink) Old Jan 30th, 05, 12:41 PM
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Wow! Sounds like she's set up for the strip! And sounds like you've got some mismatched parts.

If you've got 4.56 gears out back, you'll definitely want to change if you ever go on the highway. With 4.56 gears and a non overdrive trans you'll be turning around 3700rpm at 65mph.

Well, with that long duration cam you're probably bleeding a lot of cylinder pressure at the moment. Swapping to a shorter duration cam for the street might increase cylinder pressure enough to cause problems. You might be able to fix this problem by swapping to some cylinder heads with bigger chambers as you mentioned earlier.

When I say the parts appear mismatched it is because you have a big ol' camshaft which wants to work in a higher rpm range. At the same time, you've got an intake manifold and heads that are probably stifling the flow a bit for the cam's rpm range.

Perhaps some who are more in the know will chime in here with some more specific suggestions.
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post #14 of 22 (permalink) Old Jan 30th, 05, 01:06 PM
 
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Thanks Boodle for helping with the head flow numbers b/c I don't have that stuff saved..

Bttt, yes a mis-matched bunch of parts, Although good parts..

First stock -601's have 1.84"/1.50" valves unless somebody did add 1.94"/1.60" valves!!

Second, keep the performer and go with a CC 260HE AND no bigger then a 268HE, imho!! Personally I would use a CC 270S solid cam, but then again, I'm a solid cam guy!!

I am not into the Extreme cams b/c of shorter valvetrain life as well as noise crap but many use them fine..

Build her for grunt so you can use your cruise gearing sorta deal is all.....

pdq67



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post #15 of 22 (permalink) Old Feb 1st, 05, 06:47 PM
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Alright guys, I have been given my budget by the boss....we all know who she is. I have about 6k to play with, how would you spend it?

Currently I a 327, .030 with 461 camel humps comp cam 280H (to big...put it in 20 yrs ago in high school) holly street dominator manifold. Tranny is th350. Rear end I dont know. Probably the stock.

Would you rebuild the 327 or go crate? I want something that is a cruiser but will getup and go/ light'em up when I want it to. The heads need reconditioning. Bottom end of the motor probably has about 30K on it from a rebuild in 1983. Tranny about the same...probably needs a good going through. The tranny/rear end not part of this budget. I am a basic mechanic. I would probably have a local mechanic do the heads and bottom end if I rebuilt the 327.

How would you spend 6K? Buy the way the front end/subframe has been rebuilt for a small block. Big blocks cant be part of the dream. It is a hotchkis TVS

Rick

Rick
68 project...reassembly starting: (383, AFR 195, Air Gap, Comp Cam XR276HR, 1.6 CC Gold rollers, Holley 750, 4/09) (TKO 600 conversion from T350 4/09) (floor pan restored 6/09). (12 bolt 3.73, Wilwood disc, Hotchkis TVS 7/09), Dougs 368 with Big Dog mufflers (9/09), 383 fired up 9/30/09, Candy Apple Red 2012 with white RallyBee stripe
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