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Old 11-17-2010, 11:27 AM   #1 (permalink)
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performance built 383 valvetrain ?

I have a 383 that has been built and run for a couple years now. Very low hours but they were all hard runs. I have opened it up to check over and reseal before I put it into my K20.

I found some valve springs that have broken or cracked inner dampener springs.

Here are the specs of the engine:
383
Flat top forged pistons with 4 valve reliefs
.015 head gasket
World Products S/R Torquer heads
76cc combustion chamber
170cc intake runner
65cc exhaust runner
2.02/1.60 valves
edelbrock RPM intake

Edelbrock RPM cam:
Duration at 0.006" Lift: Intake: 308 Exhaust: 318
Duration at 0.050" Lift: Intake: 234 Exhaust: 244
Lift at Cam: Intake: 0.325" Exhaust: 0.340"
Lift at Valve: Intake: 0.488" Exhaust: 0.510"
Timing at 0.050" lift: Open Close
Intake: 10 BTDC 44 ABDC
Exhaust: 59 BBDC 5 ATDC
Centerlines: Lobe Separation - 112 Intake Centerline - 107

edelbrock sure seat valve springs
1.5 roller rockers on exhaust
1.6 roller rockers on intake

I have the 1.6 rockers on the intake to make the cam act more as a single pattern. With the 1.6's the effective lift is .520 intake.

The broken springs are on the intake with the 1.6 rockers. I was running the engine pretty hard before and I'm not sure if the springs were weakened from that or if it was seeing to much lift.

I guess my question to the engine builders out there, should I replace the springs with the same springs I have now and replace the 1.6 rockers with 1.5's or replace the valve springs with one's with similar specs that can handle more lift and keep the 1.6 rockers?

I think I have included all the necessary specs. if not then let me know and I will try to get it.
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Old 11-17-2010, 11:39 AM   #2 (permalink)
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Hopefully Grumpy will chime in here with some good info, it sounds like to me that the wrong springs were used with that cam.
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Old 11-17-2010, 03:12 PM   #3 (permalink)
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people use 1.6 rockers all the time... since you need springs anyways just get the right ones...
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Old 11-17-2010, 04:30 PM   #4 (permalink)
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do you know the original specs on the springs, like spring bind, their height when installed? ect?
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Old 11-18-2010, 04:52 AM   #5 (permalink)
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With SR heads they should have had 550 lift springs unless someone bought them bare and added different springs. Since you have to change them anyway switch to a good set, I have Patriot cylinder heads with the springs they come with on my 383. Mine are good to 600 lift but am running about 540 lift.
I would check your specs on cam and rockers your using and retainers and seats.
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Old 11-18-2010, 05:30 AM   #6 (permalink)
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Id stay away from the edelbrock springs and go isky, k motion or at least comp cams.. If you measure(dont read the specs given on the sheets that came with the heads) the installed height of your current retainers,locks and valves, iner diameter and outer diameter it would be helpful.

Im assuming your heads came with some 1.250ish diameter springs with a flat wire damper.. If it were my heads id get a valve seat cutter and open up to at least a 1.45ish spring seat and run a dual spring, ridding myself of a damper.Keep in mind that edelbrock never recommends that you run more than a 1.52 rocker arm with it shure shit springs.They arent much more that the old gm L79 springs.

Im jumping out on a limb here but lets go with a 1.750" installed height. That would put your current springs in the 80 lbs seat pressure range, but i have seen as low as 55 in the past.Comp cams has a 981-16 spring that would up that to around 120ish binding at 1.150.That should give you plenty of room with out cutting your seats.The box i have here measures at .818" inner so they will slip over your current seals.Thats a single spring though.IIRC isky has a tool room spec spring that is about the same i just dont have the number handy in my desk. I do know ive run both on street cars for a few seasons, the isky holding pressure longer.
Running a dual spring is better so lets look at that comp offers a 941-16 that should bind at 1.130.Thats a dual spring but not knowing your inner diameter of your spring seat i cant for sure it will fit.I run these on all the motors i build with vortec heads, they are priced ok and have had good results with them.Those numbers should offer you options without cutting and buying new retainers.If you are close to bind then you could get some +.050" retainers to give you more room.

Keep in mind that coil bind usually does more than break a spring.If you suspect bind check for pulled rocker studs if they are pressed in or loose rocker studs if they are screwed in,mushroomed or scorn valvetips, bent pushrods and seat damage such as seat edges that look chewed up slightly.And of course check the springs for signs of metal to metal contact.

When its all assembled check the rocker arms contact pattern at the valve tip. Ive seen a few engines built that the roller tip ran at the edge of the valve tip, at high rpm the rockers would get off the valvetip and touch the retainer.Not a good look.
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Last edited by angryblack; 11-18-2010 at 05:32 AM.
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Old 11-18-2010, 08:59 AM   #7 (permalink)
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After doing some checking:

The installed height for the heads is 1.81".

The dia of the the valve guide boss is .765".

The spring seat diameter is 1.445" and very shallow maybe .010-.015 depth

The old springs that are on it have an install height of 1.70". With an OD of 1.265". ID .880" can't find info for coil bind. Seat pressure at IH 1.70" is 104lbs and open pressure at 1.180" is 285lbs.

I did find out that the springs are in fact to short for the heads. They were installed at 1.81" which left them loose on the pressure's. I was noticing random valve float over 4,000rpm.

I didn't see any evidence of coil bind

I have found some springs that seem to fit my needs

http://www.summitracing.com/parts/CCA-972-16/
http://www.summitracing.com/parts/CCA-26918-16/
http://www.summitracing.com/parts/CCA-26915-16/

I'm leaning toward the standard style spring because it fits my budget better.
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Old 11-18-2010, 02:45 PM   #8 (permalink)
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the 972 puts you really close to bind but you will be fine, just keep the revs to a normal flat tappet range.. 1.800 installed minus 1.195 bind leaves you .605" so they will work without you cutting your seats deeper or run retainers with +.100" installed height.Keep in mind you will need to buy a set of retainers to run the bigger springs.. I think its money well spent but you do say within your pricerange so have you looked into a K motion k-750? its a tool steel spring and wont require a new set of retainers..Not sure if summit carries k motion but jegs does as does doug herbert and barnett performance.

The spring specs you found are they from a data sheet or something you measured? I have never seen a set of edelbrock springs that strong even out of the box. But it has been a few years since ive built A 23* headed small block with them..
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Old 11-18-2010, 04:16 PM   #9 (permalink)
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I got it off Summit's info for the springs
Then I saw this pdf from edelbrock:
http://www.edelbrock.com/automotive_...700_Series.pdf

I just checked on the K motion K750 and they seem like they might be the ticket. I can shim them to get close to the pressures I want.

Thanks for the info.
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Old 11-18-2010, 04:27 PM   #10 (permalink)
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i race modified dirt track cars and those stupid 1.6 roller rockers put more stress on everything... not worth useing them at all... i have broke push rods numerous times, and valve springs to screw in rocker studs... they just put a lot more wear and tear on everything... i run the 1.5 s and dont have really any problem now like i did with the 1.6s
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