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Old 08-20-2004, 09:08 PM
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rebuilding the 383...need ideas!

After way too long looking for all kind of troubles I decided to pull out my 383 stroker and have it going over everything. This engine (bought second hand) is supposely a fresh built engine but I have good reasons to doubt about it not beeing a good quality rebuilt.

It is a 1978 4 bolt main .030 over I would think the crank is an older 400 one standard sized, flat top hyper. pistons, G.M. pink rods, ARP everywhere,the cam is a hydraulic flat tappet extreme energy 268 with about .480 lift,the heads are good fresh brodix 8, 67cc chambers, the carb is a 600 edelbrock,the ignition is all MSD,the headers are custom 1 and 3 quarter inch. I was told this combo had an approxim. 350H.P.

Now the engine isn't balanced and I didn't like the way it would reved-up...kind of shaky, unstable nothing smooth like my old small ford 289 to compare with!I wasn't afraid reving up the 289 but this 383 at anything over 4500 sends me messages it doesn't like it there! I am thinking having it balanced now but could it be a 383 not beeing a smoth running engine balanced or not? I don't mind spending money to end up having something good but in the case of a 383 is it well spent money?
Is a fluid damper worthed the extra bucks? I have an OEM style one actually.

The actual flywheel is an older Hayes cast...should I go with an alumnium or just make sure the cast is well balanced with the engine rotatings?

The actual crank show at many places some rough grinding on its counterweights for clearance purposes I would say..now what ever happened to the engine balancing after such treatment?? I am thinking about a new cast Eagle.

I would like a roller cam but I don't know wich one would be a good match...the actual double springs couldn't take more than .500 lift and if of any importance the compression ratio is 10.25...any cam suggestion?

The engine is in a 2600 pounds TVR english two seaters and what I want first is a highly reliable and lasting engine for pure street enjoyment so big H.P. is not my first goal. Low end torque but also something one can push over 5000 once in a while without worries the piston will come out!

Sorry for beeing so long but I know there is fellows here with good experience that could help me out with this.

thanks, Ronald.

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Old 08-21-2004, 01:12 AM
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Sounds like somebody just made a cheapy 383 and never had it balanced. A lot of people don't know how much imbalance they have created with such a setup.

Have the entire rotating assembly balanced. Balancer, crank, flywheel, rods, bearings, pistons, rings.The fluid damper is not worth the money on a street car. They are also difficult to balance, and the fluid material is only good for a few years. A good 400 Chevy balancer or aftermkt replacement is fine.

The flywheel issue is a personal taste matter. A light flywheel works in a light street car with street tires. A heavier wheel is good for big tires and drag strip type starts. Remember it must have a 400 balance weight on it, or a suitable crank weight.

The valve springs that are compatible with a flat tappet cam are not usable with a roller cam setup. Rollers need a much higher spring pressure rating.

With the proper balance and assembly you will be very impressed with the torque and smooth revs this engine will make..
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Old 08-21-2004, 02:57 AM
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Well to begin with I wouldnt go with an alumium flywheel in anything other than an extreme racing application where the engine is constantly in the upper rpm ranges and long term durability isnt an issue. The steel flywheel is a much better for street and performance applications simply because the inertia from the wieght help move the car from a dead stop and is more prctical for your strret application.

As for the balancing problem, anytime an engine like this is built especially a stroker balancing is a must. It sounds like he skipped this process in building this engine. Just remember that the 350 is internally balnced and the 400 is externally balanced, meaning the fly wheel and balancer have to be included in the balancing process. If you wish to upgrade your balancer. I would buy one of the SFI approved sealed balancers like the one I have from Powerbond http://www.precisionparts.com.au/Pag.../powerbond.htm much cheaper than a fluidamper which in my opinion is overkill for a street motor. Then take your exsisting fly wheel, new balancer, and rotating assembly to a reputable shop and have them balanced. That should do it.

If you wish to run a mild roller cam I would check with the cam manufacturer and see what the spring rate spec.'s are on the cam you choose. Then have the seat pressures of the springs you have now meassured to see if they will work. They are rated at seated pressure which is the amount of pressure they are applying to the valve when its closed and open pressure which is the amount of pressure in FT. LBS. it takes to hold them open at maxium rated lift. If they dont measure up then you'll need to have the recommended ones installed.
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Old 08-21-2004, 08:47 AM
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Here are just a couple of my thoughts on your set-up. It is very similar to my 383.

A well built 383 with Brodix heads, and xe 268, should be closer to 425 hp/450tq at the flywheel.

The carb seems a little small for your setup. What intake are you using? Your CR is most likely closer to 9.5:1. (I actually CC’d mine with -3cc flat top forged, block decked to .020, 64cc Iron Eagles and it came out 10.25:1. The piston manufacture clamed 11.3:1)
The rough grinding on the crank may be fine and part of the original casting. I have the cast eagle and it also has marks that look like rough grinding in spots on the counter weights.

I paid $195 for the rotating assembly balance. It runs very smooth way past 5000 with the 268. There is no reason to go roller cam for your intended purposes.

The stock Brodix heads/springs should be good for more lift than .500 and you can probably go to 1.6 rollers on top and still turn over 6000. Check with Brodix. The XE-268 is a good cam for what you are looking for; good horse power without sacrificing much low end torque.

This engine running right in a 2600 lb car should make Goodyear very, very happy.




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Old 08-21-2004, 10:53 AM
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Thanks all for the suggestions.

Wings,

I did calculate the CCs a while ago and I remember some details...it may be as following: 7 CCs keith black flat tops hyper. piston only .008 in-the-hole and 67 CCs brodix and the formula was giving me 10.25 matching the ex-owner sayings. Compression testing all eight cylinders was giving out all around 205-210 PSI wich makes me believe the 10.25 making sense.

I really don't know wich crank I have...been told Eagle cast but from it's appearance (rather rough..) I am thinking an older 400 but it is standard sized not been milled down so I don't really know what I have! In any case should I prefer an aftermarket cast over an original 400??

The heads have been redone by Brodix themselves this winter and came back to me with max. lift ticket attached to them of .500
and spring pressure (uncompressed) of 120 pounds. I guess they have been recently installed to match the 268.

You are right about it beeing undercarb. but that engine was surely not feeling like 400 horses...wonder if carb. alone can make such a difference?I never could tune the edelbrock very good always too lean according to the O2 sensor-maybe I should go for a Holley?That engine was(and maybe still!) consuming oil very much like a quart at 200 miles that is why I had the heads redone and finally it came out only the exhaust sealswere done. This problem kept me looking for way long and ever yet I can say I definitly found the responsability hence another reason to tear it down and have it measured (blueprinting process).

The idea of a roller is from my desire of smoothnes feeling of the engine..as I said in my initial posting the engine is rough..I mean it will speed up without hesitations but I would just qualify it as rough but maybe its unbalanced internals are just what does it like this and I shouldn't care of a roller...but gee that little 289 I had with a lunati roller...was like a swewing machine with muscles!

Can't wait to hear that 383 finally running good!

Ronald.
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