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Author Topic: Engine restoration and improve performance  (Read 6291 times)
emanuelK
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« on: May 20, 2007, 02:13:36 AM »

Hi
I plan to replace or restore my engine during the year. The main reason for this is that the engine (350) is a low performer, probably about 250hp (a guess).
I would like at least 350-400 hp but still nice to drive. There is a lot of engines on ebay with this criteria for approx $3000. Anybody having experience of such an engine?

The current heads are double hump type with casting # 3890 462 and they where available with big and small valve size. Is it possible to determine the size without removing them?

I would like to start with a minor restoration to see if the performance improvement can be good enough:

New cam, headders, new intake and carb. Maybe remove the heads and do some job on them. Any ideas of a good configuration?

Thanks /Emanuel
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hotrod68
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« Reply #1 on: May 29, 2007, 12:25:27 AM »

  You have an excellent set of heads. From my experience you CAN tell the valve size without removing them, although this isn't 100% reliable. I found by scrounging countless heads in junkyards in the '70s, that the 1.94-valve heads always had a slash cut off of one camel hump, and the hump wasn't fully rounded. The heads with the 2.02 valves (and factory machined combustion chambers) always had fully rounded camel humps. This holds true for the mid-'68 and later heads with the alternator bolt holes up to 1972.
  For my part, use a cam around 260-270 duration advertised and as much lift as you can get up to .480", 1-5/8" headers, an Edelbrock Performer intake and a 600 Holley. You may get 350hp. You won't get 400 hp  without a lumpier cam.
  My 2 cents, and good luck!
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HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior
emanuelK
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« Reply #2 on: May 29, 2007, 05:33:35 PM »

Thanks, I will try this.
Other reasons for this restoration is that I have bad idle and low vaccum on idle rpm. Maybe there is cam used today that's not matching the rest of the configuration (to wild??). There's also a risk the timing chain set is uncorrect assembled. I already have a high performance Edelbrock intake but I don't know the type. Can I use it? The carb is new 600 cfm Edelbrock - is it OK to keep?

http://xs.to/xs.php?h=xs215&d=07223&f=IMG_0062.JPG
http://xs.to/xs.php?h=xs215&d=07223&f=IMG_0065.JPG
http://xs.to/xs.php?h=xs215&d=07223&f=IMG_0064.JPG

Can I get 350 hp I'm fine. If the heads are expected to perform I will probably only replace the cam and add the headers.

About headers - there is a lot of different brands. Does anybody have experience of better or worse types? I have a possibility to buy brand new Summit racing headers from a guy never installed them. Are they worth add on the car? Even if I don't expect more power than 350 hp?
« Last Edit: June 01, 2007, 02:40:19 PM by emanuelK » Logged
hotrod68
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« Reply #3 on: June 05, 2007, 10:31:48 PM »

For my 2 cents, grab that Edelbrock carburetor, rear back and sling it as hard as you can against a wall!   chuckle  It's just an ancient Carter AFB reborn into a still mundane fuel mixer, with all the headaches of the original AFB. A 600 cfm #1850 Holley is ideal from my experience and a lot easier to tune. If your Edelbrock intake is dual-plane it will be fine--an engine as mild as yours doesn't need a single-plane intake. As for headers, any will be fine as long as you stay with 1-5/8" tubes. Summit headers are great and well worth it. I've found that a 350 with around 9:1 compression, stock pocket-ported #462 heads, a 268-degree cam, Edelbrock Performer intake and a 600 Holley will make around 325-350hp if tuned right. It's a fun, peppy engine that will put your car well into the 14s in the 1/4-mile--that's real life, not magazine numbers.
   Anything over 350hp is on an entirely different level with a 350. Good luck!

   
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HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior
emanuelK
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« Reply #4 on: June 06, 2007, 05:30:25 AM »

I had a lot of doubts about this carb. Especially of the reason itís completely new and I found out it has some air leakage through the butterfly shaft (??) . The supplier says theese new carbs have more play and this is normal!!

I planned since a week ago to go for a Holley instead. Any recommendation on witch one is best for my configuration??

It also seems I have a low ratio on the rear end (probably 2,7:1 or close to that) so itís still important to get good torque on low rpm:s. The converter is also a standard so the idle needs to be smooth. Maybe something to take into account when selecting a carb, I think perhaps vacuum secondaries is the best?

Thanks /Emanuel
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dab67
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« Reply #5 on: June 06, 2007, 09:57:51 AM »

I just rebuilt my 350 for my 67 Camaro. Other than replacing the cam with a Crane 2102, which is just above the stock 350 cam The guts of engine are stock. I do have headers and electronic ignition which uses the stock distributor. The horsepower is rated between 330 and 350, which for me is more than enough. I have a Quadrajet carb and cast iron manifold which they recommend I replace. I am not going to do that. Even though the car is not numbers matching, I want it to look as close to original as possible. But do what you feel comfortable with and enjoy it!!!!

Dave
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sam
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« Reply #6 on: June 06, 2007, 03:27:25 PM »

Nothing wrong with a Q-jet and cast intake. Grin
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hotrod68
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« Reply #7 on: June 06, 2007, 09:56:55 PM »

Emanuel, since you have such high rear gears--guessing 2.76 or 3.08--you need to worry more about the cam duration than the carburetor. A 268 cam might be too much with that tall a gear since the car is an automatic with a tight converter. It'll work and sound great, but be a little lazy just off-idle. An RV-grind cam sounds like what you need to me. As for the carburetor--I'd go with a list# 1850 600cfm Holley. It's vacuum secondaries and very responsive to tuning. You do NOT need a double-pumper...chuckle. I'm no expert by any means, but this has worked very well for me and I've fooled around with a lot of engines in my time. Like dab said--enjoy it! And good luck!
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HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior
dab67
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« Reply #8 on: June 07, 2007, 06:41:42 AM »

Sam:
I agree, nothing at all wrong with the quad and cast iron manifold. And that is why I'm keeping them Cool

By the way, how's your car running? Are you still heading to Missouri for the Yenko show?


Dave
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sam
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« Reply #9 on: June 07, 2007, 02:02:34 PM »

Car is running good. Can't make the Supercar Reunion this year Dave. Would be close to $400.00 just in gas to go there and back. I would rather go to most of  the DIV-1 points meets instead. The SCR is a VERY good show to attend. Many great cars and people! The Thursday nite jam session in the hotel parking lot and drag racing at Gateway on Friday is the most. Sam
« Last Edit: June 07, 2007, 02:04:49 PM by sam » Logged
dab67
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« Reply #10 on: June 08, 2007, 11:34:47 AM »

Sam:

I hear on the price!!!!!!!! We are limiting our travels with the exception of 2 large shows, to a 150 mile radius of home, The two big ones, St.Paul, Mn and Iola, WI are the exceptions for this year. Those two trips alone are about 1500 miles round trip total. But what the heck,,,,,,,, can't take it with you!!!!!!!! or can ya?HuhHuhHuh?? Undecided

Dave
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wtexz10
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« Reply #11 on: June 08, 2007, 01:57:42 PM »

Several years ago, I picked up a slightly used ZZ4 crate motor for $2200 on ebay.  After $175 of freight the delivered price was around $2375.  I added an edelbrock carb and ceramic headers which kept me in the $3000 range.  The engine is factory rated at 355hp and 405lbft or torque.  And the original engine sits quitely on a stand should I ever wish to reinstall.

Believe me a ZZ4 will transform your car.

Good luck,

Kris
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69 Camaro Z10
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79 Mazda RX7
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emanuelK
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« Reply #12 on: June 10, 2007, 02:32:27 PM »

Thanks.
This weekend I replace the cam with a Crane H-272-2. I also replace the intake with a edelbrock performance RPM (I assume it is close to my existing) and a Holley 750 vacuum. Finally I add the headders. We ran this configuration on the computer and it is expected to perform approx 350hp. If it's true I'm fine, otherwise I will probably go for a crate engine imported from US. /Emanuel
« Last Edit: June 10, 2007, 05:24:16 PM by emanuelK » Logged
emanuelK
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« Reply #13 on: June 16, 2007, 04:43:07 PM »

Old camshaft removed. It's marked with 2880. Anybody having a clue what kind of cam this is? I'm just curious.  Grin
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JohnZ
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« Reply #14 on: June 17, 2007, 06:55:30 PM »

Old camshaft removed. It's marked with 2880. Anybody having a clue what kind of cam this is? I'm just curious.  Grin

Where is the marking, and is it stamped on the end, or is it a raised casting number on the core between the lobes?
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emanuelK
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« Reply #15 on: June 17, 2007, 10:11:23 PM »

It is stamped on the end. Perhaps there shall be another marking to look for??
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JohnZ
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« Reply #16 on: June 18, 2007, 08:59:57 AM »

Most aftermarket cams are stamped on the ends; original GM cams have a raised casting number and other raised casting symbols cast into the shaft between the lobes, with no stampings on the ends.
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emanuelK
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« Reply #17 on: June 19, 2007, 05:53:50 PM »

Engine is up and running. I started to break in the new cam and noticed the response to thrust is much different (better) than before. So far so good. The vaccuum is also much higher, I can tell by using the power brake at idle. I drove the car up to 60-70 mph and the performance is absolutly better. I still waiting for my new headers to arrive and expect some more can be done.

Unfortunatly I have problems with my starter - se topic under maintainance.

Thanks all for you're support. /Emanuel
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