Choosing a cam for my engine?
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Joined: Aug 2013
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From: Morton Grove Illinois
I ended up ordering a XE262H cam kit last night after reading up a lot of other threads that said a 268 is better off at higher rpms, and with being a street car too I'd want it to be good off the line. Looks like the 262 is a really popular choice though, I hope I chose the right one.. Now I just need to order the roller rockers. Am I correct to assume I should stick with 1.5 ratio rockers or go with 1.6?
Thanks again for all the help with choosing. maybe I'll pass this info down to my friends who are in the same boat as me
Thanks again for all the help with choosing. maybe I'll pass this info down to my friends who are in the same boat as me
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
Good option. Low maint, good power. Go with the 1.5. Cam already has a fast ramp. These are nice for the price and your use. http://www.summitracing.com/parts/cc...make/chevrolet
Last edited by 63mako; Dec 28, 2013 at 02:36 PM.
Drifting
Joined: Mar 2006
Posts: 1,263
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From: Wabasha Mn
I never said to use 40 year old springs, but stock TYPE springs. The isky z20 has .448 gross lift and would work fine with stock springs such as the so called z28 springs. The 097 duntov , lt 1, and 30-30 gm cams all used the same springs as a low horse power engines. I also never said my engine would not pull beyond 5000 which it will, but I choose not to. My summit/dart heads have .525 lift springs so I could use a higher lift cam if I chose to. I chose my cam based on previous use and to fit my goal of better low and mid range. Was just trying to pass on some info on what works for me without spending a lot of money.
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
I never said to use 40 year old springs, but stock TYPE springs. The isky z20 has .448 gross lift and would work fine with stock springs such as the so called z28 springs. The 097 duntov , lt 1, and 30-30 gm cams all used the same springs as a low horse power engines. I also never said my engine would not pull beyond 5000 which it will, but I choose not to. My summit/dart heads have .525 lift springs so I could use a higher lift cam if I chose to. I chose my cam based on previous use and to fit my goal of better low and mid range. Was just trying to pass on some info on what works for me without spending a lot of money.
Last edited by 63mako; Dec 28, 2013 at 11:03 PM.
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From: Edgewater Maryland
I used a Comp Hydraulic grind in a 78 L82. It pulls hard and idles smooth. I also installed Edlebrock heads and intake.
COMP Cams CL12-234-2 - Comp Cams 'Xtreme Energy' Hydraulic Flat Tappet Camshafts
COMP Cams CL12-234-2 - Comp Cams 'Xtreme Energy' Hydraulic Flat Tappet Camshafts
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
I am sure the comp cam will work out fine for him. I do agree that correct springs are important especially on the newer style cams with more radical lobe design. I am sure that over the years I have left a lot of high rpm power on the table by using old or stock springs with a new cam. I had a 327 in a 57 chevy back in 65 and had a new set of 461 heads and the 097 cam. I could rev to 6200 and probably could have gone higher if I had run a little tighter lash....was not real good at checking it. When I put the crane 274ho6 cam with only .450 lift in my carbed c4 I did not change springs and could still pull to 5200 with no problem even with 68k on them. Did not try to rev higher but figured the stock 624 heads had made all the power they were going to anyway. The Isky z20 I have in there now and the summit heads made a huge difference in power for sure even with a pretty old cam design. Glad we still have a choice to go old school or modern design on our cams with no government intervention!!! Will try to be more clear on my posts......must be my old school brain.
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Joined: Aug 2013
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From: Morton Grove Illinois
Alright so I have a question guys. I'm trying to pull my old cam out of the engine and the fuel pump pushrod seems to be getting in the way. Does the fuel pump have to come off to remove the cam or what am I doing wrong?
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Thread Starter
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Joined: Aug 2013
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From: Morton Grove Illinois
Got it out a couple hours ago, thanks! I just pulled off the fuel pump and let the rod fall down a bit. Got the new cam in, valve springs and seals done, and lifters in. Trying to pull the crank timing gear off I ended up bending my cheap gear puller, so looks like im done for the night until I pick up another puller tomorrow
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From: Morton Grove Illinois
Alright, I have everything back together and the rockers installed and pre-loaded. Would it be possible to break in the cam without valve covers installed? I am still waiting on my new tall valve covers to come in but looks like they won't be here until next week. Since the roller rockers don't fit under my current covers, how can I keep the oil from spraying everywhere when running at 2500-3k rpms? Or should I cut up a spare set of covers that I have to open up the top. I really would rather get it running this weekend just to break it in so that the lube on the cam and lifters doesn't run off.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Running it without the covers will make a mess or worse just wait. The lube shouldnt run off youll be Ok.
think why most say its gone is they put all this lube on then go OCD on prelubing washing it all off. Its overrated really.
think why most say its gone is they put all this lube on then go OCD on prelubing washing it all off. Its overrated really.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
You don't want to break it in without valve covers. It could get real ugly with oil spitting everywhere. Try doubling up two thick cover gaskets. I think mine were Mr. Gasket Ultra Seal. It worked for me with stock L-82 covers.
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From: Morton Grove Illinois
Alright seems like the break in was successful! I did it once at night for half an hour and just to be safe, when I started it up the next morning I kept it above 2000rpm for 20 minutes. Now, onto an issue I'm having tuning the thing. I have set the ignition timing and played around with the carb, but its acting like a dog down low. Doesn't have any power until it hits 3500-4k rpms and then it really takes off. How much vacuum am I supposed to be getting with this cam? I hooked up a vacuum gauge and I'm only getting about 33 inches. With it being such a mild cam I would think it'd be around 50 like a normal engine. Everything works fine but I'm trying to figure out why it's such a dog down low right now, possible vacuum leak? Intake gaskets didn't seal?
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From: Morton Grove Illinois
Excuse the messy wiring everywhere, I'll take care of all of that in the spring. Is this a normal amount of vacuum for this kind of cam? Also it does idle a little rough with fluctuating rpm.
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
Alright seems like the break in was successful! I did it once at night for half an hour and just to be safe, when I started it up the next morning I kept it above 2000rpm for 20 minutes. Now, onto an issue I'm having tuning the thing. I have set the ignition timing and played around with the carb, but its acting like a dog down low. Doesn't have any power until it hits 3500-4k rpms and then it really takes off. How much vacuum am I supposed to be getting with this cam? I hooked up a vacuum gauge and I'm only getting about 33 inches. With it being such a mild cam I would think it'd be around 50 like a normal engine. Everything works fine but I'm trying to figure out why it's such a dog down low right now, possible vacuum leak? Intake gaskets didn't seal?
I had to make a few assumptions, such as a 76cc combustion chamber, .042" head gasket, .025" deck height, and so forth, but according to my DCR calculator, you've got about a 6.5:1 (if I have mis-calculated, please correct me!) Dynamic Compression Ratio going on there, which could possibly explain why it is a slug at lower rpms. An upgrade to some smaller combustion chamber heads, and a thin head gasket like the Felpro 1094 (.015" compressed thickness) would help out a lot, I think. Just out of curiosity, could you do a compression test, and tell us what you get for compression, compared to the pre-cam swap compression?
I don't have any actual experience with this cam, so I'm really just talking out of my a$$ here, hopefully some others have used this cam in a fairly stock engine and can share their experience with you.
Scott
Burning Brakes
Joined: Nov 2012
Posts: 788
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From: Indianapolis IN
I've not used that particular Comp 262 cam , but I think that it would have more than 13" vacuum. If your gauge is fluctuating you very well may a vacuum leak.
Did you degree the cam or set it in at the "straight up" position ?
It shouldn't have any less, (or much less), torque off idle and should come on strong around 2,000 to 2,500 !
Did you degree the cam or set it in at the "straight up" position ?
It shouldn't have any less, (or much less), torque off idle and should come on strong around 2,000 to 2,500 !
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Joined: Aug 2013
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From: Morton Grove Illinois
Yeah I realized I was reading the gauge wrong, after posting that reply I thought it over and realized that sounded wrong. Thanks for the correction. They are 76cc chambers. As for the head gasket and deck height I'm unsure of because the heads were reworked by a previous owner. I will be going to 64cc heads (aluminums or vortec) during the summer. I did a compression test and all cylinders are good, 150-155psi. About the same as before the swap. As for low vacuum, I'll pull off the intake manifold again and make sure that's all sealed up (had a lot of issues with intake gaskets sealing well in the past) and Im getting a pretty good feeling that the late powerband is because of my carb. I'm running a performer RPM with a holley 650 spreadbore carb on an spread-to-square adapter and I feel like I'm losing airflow through my primaries. As soon as the secondaries open up is when I feel like it takes off. Looks like I'll be looking for a new carb now!
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Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
http://www.compcams.com/Technical/Dy...62H-10_001.asp
The above lists vacuum. Operating range is 1300-5600. Should pull hard from just off idle to redline. My guess is you have a vacuum leak as your readings are quite a bit lower than the chart shows they should be.
The above lists vacuum. Operating range is 1300-5600. Should pull hard from just off idle to redline. My guess is you have a vacuum leak as your readings are quite a bit lower than the chart shows they should be.