383 Build - Opinions Wanted

[Cam57]

Here is the build that my son and I plan to do for our 383 stroker project.

This car will be used for street only. Pump gas. Smooth idle and good street manners.

Block - Stock 71 350 decked to 9.015 and bored to 4.03.

Crankshaft - SCAT Series 9000 Cast Steet internally balanced.

Rods - SCAT 6-inch forged 4340 Steel I-beam.

Pistons - Kieth Black flat top +7cc hypereutectic aluminum.

Rod Bolts - ARP 3.8 cap screw

Rings - Plasmamoly 1/6, 1/6, 3/16.

Intake Manifold - Edelbrock dual plane Performer Air Gap.

Heads - Air Flow Research 180cc intake runner Eliminator with 65cc chamber.

CAM - Lunati Voodoo Hydraulic Roller 270/278 advertised, 219/227 @ 0.05 with 0.515 intake lift & -.53 exhaust lift at 112 lobe separation angle, or

Howards hydraulic roller 266/270 advertised, 213/217 @ 0.05 with 0.485 intake lift & 0.495 exhasut lift at 112 lobe separation angle.

Lifters - Hydraulic roller - Lunati or Howards to match cam.

Rockers - Comp Cams Ultra Pro Magnum, 1.6 ratio intake and 1.5 ratio exhasut. The 1.6 ratio rockers should add about 32 to 34 thousands to the intake lift. The AFR heads have great exhaust flow, so don't think I need any more lift there.

Headers - Hedman 1 5/8 inch.

Carburetor - Either will have the stock Q-jet rebuilt and modified for more flow or will get Holly 750 or equivalent.

 

With this build I should have about 10.7:1 compression ratio.

 

I am thinking this build will give me about 420+ max HP at 5500 to 5800 rpm and about 450+ max torque at 4000 or less rpm.

 

I also think (hope) this will be a relatively smooth running, dependable, long lasting engine that will run on pump gas (91 octane).

This is my first engine build. I'd love to hear what you more experienced guys (or gals - are there any gals out there?) think. Especially which cam to use.

Thanks.

Craig

[Cam57]

A little more info.

This car has AC and automatic trans.

I will be replacing the TH350 with a 2004R.

Also thinking of replacing the 2.73 ratio standard (non-posi) differential with 3.31 with posi.

Thanks again.

Craig

[Sam (Bones)]

I feel that you'll have to high of a compression ratio with that duration of a cam to run 91 octane

[72MC]

IMHO I would "do" or make sure "to do" the following:

1)Whoever does your block work, be sure they notch the oil pan rail to accept a 3.75" stroke crank and 6" rods.

2)upgrade those pistons to "forged" pistons just "in case" power is added later. Also, forged pistons don't mind higher comp ratio.

3)Make sure your crank is forged and is a 3.75" stroke. I went ultralite forged crank and saved 20 lbs and its stronger. Overkilled it but I have plans of a Procharger in the future.

4)Looks like your lifters and rockers are "full rollers" which I recommend. Thats another reason I say above to go with forged pistons.

5)I agree with Sam on your compression. Those 65cc heads will make comp ratio tricky. You may want to look at 68cc instead. I went 72cc on my Canfield aluminum heads. Cam is .590ish lift on exh and int and I have a comp ratio of 10.1 . I run 91-93 octane ethanol free gas. If I would have ran a 64cc head, my comp ratio would have been more like 12.1.

6)Lastly, I would call a cam company of your choice and give them all the info they want and have a custom cam ground for your engine. You will not be disappointed with a custom cam versus an off the shelf cam. Alot of guys have dealt with Mike Schaub with great success.

 

Granted, these are my opinions but it looks like you are spending some good money on this build so why not build it right in all areas, keeping in mind that there will be the possibility of power adders later. Even if you say "no power adders ever", there is still a chance you will add them later. Plus, high compression and hyper pistons really are not great together. Hope some of that helps. - Dave

[72MC]

If your going with an OD tranny, match the rear gear with the stall converter and cam. Example: I have a 4l80 full manual tranny in mine. With a stall convertor at 3200-3300 and a big cam, my 3.31's were not matched well with my tranny. 4.10's worked much better and my tranny told me so . - Dave

[wallaby]

I ran with Keith Black hyper pistons and didn't like them. They have rings situated higher than usual, and require big ring gaps. My machinist thought he knew better than to read the instructions, and gapped them as normal...they tore up my cylinder walls. Even after a re-hone and re-ring job, they were poor at oil control.

 

My new engine has Mahle pistons with low friction rings, which were recommended as an upgrade by my builder. They weren't cheap, but good for 40hp with the same compression ratio. It's hard to find 40hp with any single upgrade. A bonus is better mileage and quicker reving with the low friction rings and lighter pistons. I have no complaints.

[Cam57]

Thanks. I appreciate all the opinions and info.

 

I was concerned that the compression ratio was too high. The AFR Eliminator heads come in 65cc or 75cc chambers. If I go with the 75cc chamber and keep the rest the same, the CR will be about 9.6. Would that be more in-line with my planned use of the car?

 

Also, any preference between the Lunati or Howards cams?

 

With under 450 HP and low RPM engine and if I lower the compression ratio, I am thinking the SCAT cast crank and hyper aluminum pistons should be ok. Most "experts" say they are ok up to about 600 HP. A forged set will run me about $600 to $700 more. The KB pistons are what come with the SCAT rotating assembly. I would prefer the Mahle. But, I don't think SCAT would put them in their assemblies if they were no good.

[Mike 57]

I can understand you wanting to keep the cost down with your choice of rotating assembly. Just keep in mind NO POWER Adders! I would go with the 75 cc heads with .040 to .045 quench you should be about 9.6 compression. Don't get head gaskets until you have the rotating assembly in the block and you can measure how far down in the hole the pistons are, then adjust piston to head clearance (quench) with head gasket thickness.

 

If you do go with the K.B. pitons make sure the clearances are done exactly as called for by K.B. The pistons will work fine for your level of performance.

 

Good luck, and you and your son have fun with it.

[USMCBLB125]

The pistons will be fine with your current application. But, can you guarantee that you wont get the power bug when you're finished and want to add a little more? Personally I'd go with forged and save yourself time and money in the future if you want to give it a little more umpf later. However, if you're certain that's all you will ever want they will do just fine.

[Cam57]

I decided to go with the forged aluminum pistons. They are the Icon +5cc flat top. Sticking with the cast steel crank.

The difference in cost for the forged pistons was only about $80.