383 tapping noise

[allencr267]

One of each, thrust & non-thrust.
A kid shake'em before install, banging skirt against rod?

[c1500sbc]

I’ll be sure to look everything over. At least this gives me a reason to change over the pistons to something more boost friendly like I wanted to!

[rfoll]

When the first skirt broke the piece probably got into the piston next door.

[c1500sbc]

One of each, thrust & non-thrust.
A kid shake'em before install, banging skirt against rod?

Certainly possible. Who knows. I would assume the knocking noise was caused by the piston being able to rock back and forth in the cylinder wall?


How do y'all feel about going back with some deep dish hyper pistons rather than forged? Its a forged crank and a forged rod. I'm honestly hoping to get this thing in the mid to low 8 range on compression and run 7-8psi. Get into the 600 flywheel horspower range.

[F-BIRD'88]

You will not make 600 hp with the small blower.
Try to find some piston / pin total weight combo that is real close to current.. save on re balance..

[c1500sbc]

You will not make 600 hp with the small blower.
Try to find some piston / pin total weight combo that is real close to current.. save on re balance..

You don't think the 177 will support 600hp?

Great idea. After tearing the motor down, I do see that they appear to be hyper pistons. I was told they were forged by the previous owner. I haven't done enough research but i'd assume there is usually a weight difference between the two.

[F-BIRD'88]

Yes there are many examples of 355's and 383's exceeding 600 hp on pump gas with the 177 blower (2.28:1 drive ratio) but the CR has to be low.
Lower cr = better.

more head port flow is better.
big 850++ cfm carb or dual 4 bbl carbs.

[F-BIRD'88]

Can You ID which piston they are?

[F-BIRD'88]

I believe on the deep dish (28cc) 383 hyper piston the top of rod to bottom of piston dish has to be checked.
Rod balance pad may need custom clearancing
with deep D cup pistons.

[c1500sbc]

Hard to say on which pistons they are. Maybe once I get them out I can tell. I do have the rotating assembly part number, which clearly says they are hyper pistons, but it does not give a part number for them. It's a discontinued kit but maybe Eagle could still tell me.

I did find some -31cc forged pistons for a 3.75" stroke crank. Expensive suckers, though. There's just so many mixed opinions on at what power level a forged piston is recommended. Obviously hyper is much cheaper, but if its a gamble i'd rather not take it.

[F-BIRD'88]

Its not so much the power level as its how hard you push the envelope on cylinder pressure and heat , thus risk of detonation on a supercharged engine on limited pump gas without intercooling.
Yes 383's tend to be a bit more money to build for this.

A 8-71 blower may be a better choice. Lower blower speed = Less air charge temps. 600 hp is a relative easy target

Going to a 600 hp naturally aspiriated 383 combo is an option.

[c1500sbc]

Its not so much the power level as its how hard you push the envelope on cylinder pressure and heat , thus risk of detonation on a supercharged engine on limited pump gas without intercooling.
Yes 383's tend to be a bit more money to build for this.

A 8-71 blower may be a better choice. Lower blower speed = Less air charge temps. 600 hp is a relative easy target

Going to a 600 hp naturally aspiriated 383 combo is an option.

I’d rather not get a blower that won’t fit under the hood!

I can’t ever seem to figure out how someone can build a pump gas 383 in the 600hp range. I’ve seen the dyno sheets, I just don’t get how?

[steve cowan]

Its not so much the power level as its how hard you push the envelope on cylinder pressure and heat , thus risk of detonation on a supercharged engine on limited pump gas without intercooling.
Yes 383's tend to be a bit more money to build for this.

A 8-71 blower may be a better choice. Lower blower speed = Less air charge temps. 600 hp is a relative easy target

Going to a 600 hp naturally aspiriated 383 combo is an option.

I’d rather not get a blower that won’t fit under the hood!

I can’t ever seem to figure out how someone can build a pump gas 383 in the 600hp range. I’ve seen the dyno sheets, I just don’t get how?

Some people say they can do it with "bolt on parts" but I question that.
If you want a engine to make peak power at 6500 rpm you will need peak torque at 5000rpm.
Piston demand at speed is approx 304 cfm.
Average cross section in cylinder head approx 2.30"
Pushrod pinch size and throat size and best CFM"2 as possible but hard to do on a 23 degree head.
Ported,Motown, super victor, 300-25 intakes with proper size at plenum and flange with correct taper.
Valve events for application- not sure if a shelf cam would get you there
As much valve lift as you can handle - trade off is maintaince especially if street driven.
1 3/4" headers with 3" collector should work.
To make 600 you need 1.4 ish FT/LBS per cube easier said than done for most including myself,but I know a few guys that can do it.
Be ready to swipe the credit card ALOT .

[rfoll]

Hard to say on which pistons they are. Maybe once I get them out I can tell. I do have the rotating assembly part number, which clearly says they are hyper pistons, but it does not give a part number for them. It's a discontinued kit but maybe Eagle could still tell me.

I did find some -31cc forged pistons for a 3.75" stroke crank. Expensive suckers, though. There's just so many mixed opinions on at what power level a forged piston is recommended. Obviously hyper is much cheaper, but if its a gamble i'd rather not take it.

KB pistons have the part number cast on the side.

[c1500sbc]

They are KB pistons. I know the kit number said it but I did confirm it. Piston part number KB134-04 for anyone curious. Cylinder walls looks great. Rod bearings look brand new, the picture makes them look rough but the are completely smooth with no abnormal wear signs. Crank journal is mint. I only took those two off so far, but I don’t see anything obvious as to why it happened. The pistons slide pretty easily on the wrist pin but no abnormal movement. I’ll have to check main bearings, thrust bearings and the rest of the motor out but so far so good.

I think I’ve decided on these pistons and this camshaft. The compression height is about .008 different but I don’t think that’s an issue? This will get me, with the 64cc heads I have, down to a 8.8:1 compression. If I decide later to run more boost I can buy some larger chambered cylinder heads. I think 8.8:1, 28-30 degrees timing, running 7-8 psi on 93 octane would be fairly safe?