73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jbreeves85C10 on November 23, 2013, 06:04:20 pm
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OK...so I am a newbie and obviously not too bright of a mechanic wanna be. I bought all new valves, push rods, springs, lifters, seals, rockers, etc. to overhaul my heads since I floated a valve. I was talking to my cousin and he informed me that I would have to have a valve job done on each head to get everything right and that the best thing to do was to buy fully assembled heads that have all of this done and tuned already. I check with Napa and I can return all of my purchases so I've been looking around and could use some suggestions.
Do I want to get a cam / heads combo?
The cam is probably stock hydraulic for the 5.7L 350 but I am pulling it shortly to verify.
The current head code is GM 333882.
TH700 trannie with most likely stock converter. Don't know the rear end gearing specs yet but 4 speed automatic.
Pistons have .030 on them and cousin said they had been bored.
He recommended 76cc heads.
I've looked around a bit but wondering if anyone could point me in the right direction. I am in North Dallas if anyone has local suggestions as well.
Thanks...This is my first big project so I'm learning.
JB
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Just found this code reference:
333882 – 1974-1980 350 or 400, 76cc chambers
Not sure about the history of this engine but my truck it was in is 85 C10.
JB
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76cc heads are the low compression heads (smog heads) used to meet emissions standards and run on modern (i.e. crummy) pump gas.
If you are going to go with new heads, there are more exciting choices.
The alternative is to stick with what you have, which are the 76cc heads already. You don't need to have a "valve job" on the heads; most of a valve job is replacing parts, which you are doing already. The one bit of machining work that is probably worth having done is to clean up the seats. Special grinder and grinding bits for this, but just having the seats cleaned up is a pretty cheap machining job. Then you put in all the new parts and you're good to go.
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Thank you for the reply Rich. After reading a bazillion pages and talking to folks, I am going with World Products S/R Torquer series Iron heads # 042670 and a Comp xr264hr-10 hydraulic roller cam. Comp's site says this about timing:
"Second, the factory timing set may be machined to retard cam timing."
Does anyone know if stock timing will actually retard the cam on a 65-79 chevy block #3970010? Comp says "May retard". Comp says the cam is ground 4 degrees advanced for performance already. I am calling them tomorrow but think they might scew their answer to get me to buy their timing set :-) They don't seem to like to talk to stupid people like me and got frustrated today. I got put on eternal hold because I couldn't answer a question...LOL. I now know my compression ratio though.
Thanks in advance...I'm learning as I go.
JB
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Is that a roller block?
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Here comes my non-mechanic side...I don't know but the cam is a retro fit package if that tells you anything. My cousin told me it would work :-)
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Rich can review the cam profile with you and its suitability to your purpose. Nonetheless, here are a few things to ponder when considering retrofitting a roller cam:
- Retrofitting a roller cam to a non-roller block is pricey, especially when committing to a mild grind that may only marginally benefit from a roller configuration. Beyond the advantage of decreased lobe & lifter wear, the milder the lobe profile, the less performance benefit a roller can provide over a flat tappet cam. So, with regard to mild grinds a roller configuration offers little performance benefit over a flat tappet cam, but at much greater cost.
- You'll need a double roller timing set with a Torrington thrust, plus a cam button to limit cam endplay to ~0.003" - 0.006" or you'll risk damaging the cam from the lifters scuffing sideways across the lobes as the cam walks fore and aft in its bore.
- You may need to clearance the front of the block to make space for the double roller cam gear. This is just a consequence of a double roller timing set, regardless of the style of camshaft used.
- You'll need to swap the factory timing cover for a model that's stiffer to control deflection, since the cam thrusts directly against the cover via the cam button to limit endplay.
- Although the cam you're considering is a mild grind, roller profiles accelerate valve opening and closing with steeper ramps when compared to flat tappet cams. The valve springs must be matched to the lobe profiles to prevent valve float and camshaft damage. Check with your camshaft grinder to determine whether you'll need to upgrade the valve springs as part of the retrofit. If the heads come assembled, it's just as important to make sure the supplied valve springs are not too "stiff" for the cam your installing; excessive spring pressure is also damaging to lobes and lifters.
- Find out from the cam grinder whether you can use your stock distributor gear with the specific cam you select. Steel cam cores require special distributor gears (bronze or polymer) to mitigate rapid gear wear due to hardness incompatibility.
- If you commit to the expense of a roller cam, you should consider full roller rockers, as well.
- Don't forget to inspect the cam bearings for wear and replace them if necessary.
- Liberally lube the cam lobes and lifters with Comp Cams 152 (http://www.summitracing.com/parts/cca-152/overview/).
- Check your valve train geometry to determine the correct pushrod length.
- Degree the camshaft according to the spec card supplied with the camshaft.
- Use a high quality break-in oil containing ZDDP to initially break in your new cam and valve train.
Others will add anything left out.
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BD,
Awesome post and thank you very much. I'm sure that will help out a bunch of folks in my shoes...and me as well. I have been taking notes for days and have most of what you said noted to check in to but there were a couple of great points that I did not consider due to my lack of experience..!
Points 1-6 I have in notes to check.
Point 7 - roller rockers absolutely necessary? I think I saw around 500 for a set or something crazy like that.
Point 8 - thanks for this. I didn't know to check bearings :-)
Points 9-12 on my list.
I am looking at standard hydraulic cam and I already have a set of new stock lifters so total of about $150 to purchase cam versus somewhere around $800+ to go the roller route. Is the benefit worth the cost? You mentioned in point 1, little performance benefit. Am I wasting the money since I do not have a hot rod?
Thanks..!
JB
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No high performance component is absolutely necessary. Roller rockers will benefit performance, especially if you increase the ratio to 1.6 from the factory 1.5, but in and of themselves provide greater benefit when matched with other high performance components. Every high performance component has its trade-off: initial cost, increased noise, heat, maintenance, etc. You need to decide on what you're trying to accomplish, how much you're willing to spend, then match components accordingly. Cam bearings are fairly durable, but should be inspected when the cam is removed. The more mileage on the bearings and the greater the load imparted by a high performance valve train, the more likely the bearings will show signs of wear.
In a street truck, you should focus on increasing torque in the RPM range of dominate use. Roller cams provide greater torque potential, but really come into their own as cam profiles become more robust. A mild grind may not justify the high initial cost of retrofitting a roller. Your immediate challenge is to decide on whether the cost of a roller is just too expensive - it certainly won't make your daily driver accelerate like a big block.
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Excellent points..! I got info on another head place from my cousin and a flat cam to go with. I just don't think the roller cam is going to benefit me for the cost right now since this is a daily driver. Thank you very much for the replies and making me think..!
JB
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It is ordered and I think with the help of everyone here I got a good setup for a good price.
Skip White Performance:
SBC CHEVY FULLY BUILT ALUMINUM HEADS 64CC HYD FLAT TAPPET PBM Valve Upgrade SETUP FOR HYD. FLAT TAPPET CAM.
Price: $665.00
Added guide plates, rocker studs, extended head bolts with washers, 1.52 roller rockers, correct push rods, and break in oil.
$1,000 total for heads and extras with shipping.
Sumit:
Summit K00132 cam and lifter kit.
Cam and Lifters, Hydraulic Flat Tappet, Advertised Duration 280/280, Lift .467/.467, Chevy, Small Block, Kit
$133.97 shipped
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What are you gonna run for intake manifold, exhaust manifold, and carburetion. Just curious.
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Edelbrock dual plane performer intake, hedman headers, holley 650 cfm carb
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With that cam it's gonna be slow off the line. Going to a 2000 rpm torque converter will help.
Rough idle means poor low-rpm performance.
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I was not too sure on that and you are exactly right. I may upgrade the converter after I see how it runs but the other thing I had in mind was building out a 383 roller in the future. Those heads should be golden for that rig :-)
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One thing I am confused on...ok more than one :-) I ordered the 190/68cc heads and they came back with a call stating they didn't ship those anymore so they gave me the 200's at 64cc for the same price with the PBM valve upgrades. My true flat top 030 pistons have 8.62:1 compression and they said the valve upgrade and 64cc heads would make it 10:1. Is there anything I should be concerned about with this change in compression? The cam is .467 lift and heads have max lift of .550 setup. Being the dummy here...what does compression affect that I should be concerned with...other than blowing stuff up? Is a 8.62 to 10 jump huge?
Thanks,
JB
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You will need to run 93 octane gas.
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Thanks Rich..! You guys are awesome. I'm learning :-)
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You'll also have to see where knocking starts on the timing. Some guys over in Corvette forum are running 10:1 at 36* of total timing with 93 octane, but you may need to back off to 34* or 32* to keep from knocking. Depends a lot on the dynamic compression ratio of that cam. It may be late enough on the intake valve closure that you can run the full 36*.
I should elaborate. The static compression ration (here 10:1) is the volume of the cylinder with the piston at bottom dead center divided by the volume of the cylinder with the piston at top dead center. Dynamic compression ratio is the volume of the cylinder with the piston located at the point where the intake valve finally closes completely divided by the volume of the cylinder with the piston at top dead center. Dynamic compression ratio is always less than the static compression ratio, and the dynamic compression ration will determine at what manifold vacuum and ignition timing that knocking will occur.
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I found out where my confusion was I think. They said the head is 64cc but the valve upgrade makes it 68cc which should give a tad over 9:1 compression. Does that sound right?
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That sounds right. 64 cc would be about 9.5:1. With 68 cc you might even be able to get away with regular gas, or at least no worse than 91 octane.
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I'm glad y'all are educating me :-) I was wondering about the gas and if I needed to go with the MSD Blaster kit or if that would even help.
Thanks and have a Happy Thanksgiving..!
JB
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Are these aluminum heads? Aluminum will be a little more forgiving on compression.
How does a valve upgrade change combustion chamber cc?
Are you absolutely sure you have flat top pistons? I can't remember if you said you had this thing apart yet.
If I remember right, some of the "flat top" pistons with 4 valve reliefs had some dish cc's. Maybe someone can chime in with better info on this.
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Maybe I'm a little slow, but I just realized this is the same motor you posted in your 85 piston post, with the picture of the piston with "valve clearance" issues. Did you decide to keep the current pistons in the block and only replace heads and cam, and other little goodies?
I believe you will be fine on compression. 68cc with those pistons should put you no more than 9.5:1 I think.
Also, listen to Rich on cam selection and such. He has been a great help to me.
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Yes. I lightly dremeled the dings to get burs off and hit it with a soft wire brush brush. It looks fine and the compression seems to be good on all pistons. Heads, cam, and other goodies replacement is correct :-)
Rich,
This is the cam i went with for aluminum heads 68cc 9.5:1 compression, max lift .550, PBM valve upgrade, roller rockers, push rods.
Summit Racing Part Number:SUM-K00132
Cam Style:Hydraulic flat tappet
Basic Operating RPM Range:2,000-5,500
Intake Duration at 050 inch Lift:222
Exhaust Duration at 050 inch Lift:222
Duration at 050 inch Lift:222 int./222 exh.
Advertised Intake Duration:280
Advertised Exhaust Duration:280
Advertised Duration:280 int./280 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.467 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.467 in.
Valve Lift with Factory Rocker Arm Ratio:0.467 int./0.467 exh.
Lobe Separation (degrees):110
Did I do ok? I can always change but thought that was a good choice. I will lose a little low end torque but may change converter.
Thanks,
JB
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With that 700R4 and possibly 3.08 rear gears, running down the highway in overdrive will be on the bottom end of the power for that cam. Maybe even a couple hundred rpm less. This is just me looking at numbers and not actually running the calculations. You might not get the full potential of that motor unless you are up in the RPM range.
One thing I noticed when trying to decide on cam selection was that the HP & TQ curves stayed the same shape. They just moved up the RPM range as I increased cam size. Basically just moving my usable power higher in the RPMs. It took awhile for me to admit to myself that my actual usable RPM range was gonna be from idle to 3000. Only rarely seeing foot to the floor and not over 5000. So I changed my thinking and went with the cam that fit my range.
Unfortunately I do not have my pickup assembled to let everyone know how the cam choice went. You might want to look into figuring out your rear gear ratio. I had thought about changing mine from 3.08 to 3.73 but I have a TH350 and I do want a little highway help. If I change to the 700 I might put the 3.73s in, but for the time being they will just sit on my shelf.
Just some food for thought.
Try to get some numbers figured out. Like gears, compression, head flow and use them in something like camquest or just run them by Rich. It might help make sense of any future decisions and how they affect the total package.
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I want to say I did all of that and I used camquest. 68cc, 9.5:1 compression with 700r4 and 3.73 gears. 200cc head flow...I think that is the head flow number right? Edelbrock performer dual plane intake. holley 650 carb. hedman headers to straights. stock converter...may upgrade.
Is that about right on the numbers?
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If you know 9.5 is CR for sure use it. Otherwise go to somewhere like summit and use the calculator. You will need head gasket thickness, bore, stroke, distance above piston to deck surface, and comb cc. This will give an accurate number. You can use some known numbers. Like bore 4.030, stroke 3.48.
I'm coming back from a hospital transfer and phone is dying. I'll post more in a bit.
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Just back in town from TG.
When talking cams for these engines, I recommend one of four of the Comp cams: 12-300-4, 12-231-2, 12-235-2, 12-238-2. I chose the first one. nlauffer chose the last one. They are in order of increasing lift. They are all torquey, and give great performance in the 1000-3000 rpm range where we drive most often.
Remember that, when you take your foot off the brake and punch the gas at the light, the engine is at 500 rpm. You can go to a 2000 or 2500 rpm torque converter, which will let the engine rev up before the torque converter kicks in, but this is harder on the transmission. That will help the launch when you are in a hurry, but it's an all-the-time thing, so daily driving it will not be as pleasant.
The 2000-up operating range on that Summit cam is a dead giveaway. I would want something that says at least 1500-up; 1200-up is even better for a truck application, IMO.
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You probably want to read through this thread:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=26206.0
And read this article:
http://www.crankshaftcoalition.com/wiki/How_to_choose_a_camshaft