327/210 to 327/275 - Team Camaro Tech
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post #1 of 34 (permalink) Old Sep 27th, 03, 10:18 AM Thread Starter
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Sorry for double post but I think this is more appropriate here:

I am thinking of upgrading my 327/210hp to the 327/275hp with original GM parts.

If I get the Rochester Q-Jet carb, correct GM intake manifold, plus right linkages, and air cleaner will I come close to the 275hp? It already has dial exhaust.

Would I need anything else "replaceable" to mimic the 327/275?

I don't want to get into changing cams, boring etc...And I don't want after market parts.

Thanks

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post #2 of 34 (permalink) Old Sep 27th, 03, 11:08 AM
 
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Your compression will have to come up 1.5 points, from 8.75 to 10.25 to 1.

I don't know if the 210hp/327 motor has dished pistons or just really big chambered, small valved heads but I suspect you will need medium valved, 62 to 64cc chambered, double-hump heads too..

The cams are the same old -929, I think..

Good luck with your combination change..

pdq67



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post #3 of 34 (permalink) Old Sep 27th, 03, 02:07 PM
 
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I have the double hump heads on my 210hp, its basically the pistons itself that change the engine. I'm sure the carb doesn't hurt either. I never checked valve size/not sure if GM included that in the hp change.If I can find my chiltons I'll check and post.
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post #4 of 34 (permalink) Old Sep 27th, 03, 02:08 PM
 
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I have the double hump heads on my 210hp, its basically the pistons itself that change the engine. I'm sure the carb doesn't hurt either. I never checked valve size/not sure if GM included that in the hp change.If I can find my chiltons I'll check and post.
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post #5 of 34 (permalink) Old Sep 28th, 03, 07:28 AM
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Get a copy of the Chassis Service Manual for your year. There are spec charts in the back that will give you the answers you need. The 327 in '69 was 210 and 235 hp not 275 so I can't get you any info from my book.

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post #6 of 34 (permalink) Old Sep 29th, 03, 03:46 AM
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The heads for the stock 327/210 are different from the stock 327/275 engine. The chamber size is either 72 or 76CC's on the 210 and is 64cc's on the 275 engine. The valve sizes are also different. The 275 has the 194 intake's and I don't remember how small the 210's intake is. I would suggest you verify what heads you have if you do not believe they are stock. The casting symbol on the 210 heads is two vertical rectangles and the casting symbol for the 275 heads is two half moon topped humps. You can also check the casting numbers to be sure. I do not have my books at work and can verify exact information tonight if needed. I'm sure others may be able to chime in with a better memory than mine.

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post #7 of 34 (permalink) Old Sep 29th, 03, 05:45 AM
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pdq is right the cams are the same for all the 327 engines 210 through 300 horsepower in 68. Hydraulic .2217" lobe lift which is .3325" valve lift using 1.5 rockers. That 's a pretty low performance cam. If you're wanting to get to 275 horses I'd start with a cam change, as long as the intake is off it's really pretty simple. Certainly if the heads come off too I'd do it. And upgrade the valve springs at the same time. The distributor is different also. But you can have that recurved.

That's for the engine upgrade, if you are attempting to clone the car the chassis manual for the L30 engine references front and rear springs, brake lines, distributor, coil, transmission. I believe the L30 was the starting point for dual exhaust, so you'll need the reinforcement doubler plate to weld onto the frame rail.

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post #8 of 34 (permalink) Old Sep 29th, 03, 06:05 AM Thread Starter
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Would the Cam change impact the compression? It seems the big difference is the compression goes from 8.75:1 to 10:1 for the 275hp.

Thanks

Bluesdog
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post #9 of 34 (permalink) Old Sep 29th, 03, 07:37 AM
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The compression change is from the head change as pdq67 indicated above. The pistons are the same.

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post #10 of 34 (permalink) Old Sep 29th, 03, 08:26 AM
 
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I still don't know why a 275hp motor is different from the 300hp/327??

And a 300hp/327 runs very good for no more power then it produces. Kinda like my old stock L-48, 295hp/350... Same engine, just more cubes..

Ooop's , I think a 300hp/327 motor had an AFB on it instead of the 350's Q-Jet??

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post #11 of 34 (permalink) Old Sep 29th, 03, 04:18 PM
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I have the same engine 210/327. I changed the heads to the 461 double hump castings with a performer intake, 256HE Comp cam,Q-Jet,stock ignition rebuilt to a hei, headers, flowmaster exhaust,with a turbo 350, and a 3.08 gear. If I ever get the car put back together, I think it's going to be fun. Be careful when I started I was just going to change a few simple parts. If you hang around here very much you will end up taking your entire car apart.

68 convertible, Grotto blue, 327 TH350,3.08 diff
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post #12 of 34 (permalink) Old Sep 29th, 03, 04:22 PM
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I have the same engine 210/327. I changed the heads to the 461 double hump castings with a performer intake, 256HE Comp cam,Q-Jet,stock ignition rebuilt to a hei, headers, flowmaster exhaust,with a turbo 350, and a 3.08 gear. If I ever get the car put back together, I think it's going to be fun. Be careful when I started I was just going to change a few simple parts. If you hang around here very much you will end up taking your entire car apart.

68 convertible, Grotto blue, 327 TH350,3.08 diff
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post #13 of 34 (permalink) Old Sep 29th, 03, 06:03 PM
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Ok, along the same lines....I have a question.
I apparently have a 350 truck motor from the early 70's in my car (thanks, tag team!)...160-165 net hp in stock form, so I'm told. I have cam, carb, headers, but I think the heads are stock. Can I gain more hp just by changing the heads? Or will I have to do the pistons too? And what about vacuum? Will new heads increase vacuum so that I won't have to use the MP Brakes vacuum pump? The motor is strong, just a little, well, slow. Just wondering if I should beef it up or just go with a crate. Opinions?

Steve W
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1966 GTO Convertible
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post #14 of 34 (permalink) Old Sep 29th, 03, 08:19 PM
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Got the same engine you got. 67 327/210HP. The heads are extremely weak, I know that. I ran the numbers on mine. Valves are 1.74 in. and 1.5 ex. That explains a lot of the weakness. Bolt on a pair of camel-humps with the small combustion chambers, like 62 or 64cc I think. That will boost compression and give you a major boost. Or just find another set of heads with small combustion chambers and larger valves, 1.94 on the intake would be perfect. Dart Iron eagles can be had on ebay pretty cheap so thats an idea if you don't want to pay the extra for aluminum. For my motor I'm going to bolt on a set of the camel-humps that our race motor builder had sitting around. Something to think about too is that some of the older heads don't have the hardened valve seats which they need to last with unleaded gas.

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post #15 of 34 (permalink) Old Sep 30th, 03, 02:06 AM
 
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I bet the 305HO, 1.84"/1.50" valved heads with the small chambers will do it for being cheap. Hard seats and all. pdq67



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