anLS1x2

I'm wondering if I should keep the stock rods that are in the motor right now? I'm not sure if they are forged or cast. I have new .030 over forged aluminum pistons. The heads are stock cast heads that have been milled. The block was bored .030 over before I got a hold of it. I believe that the crank is a stock forged crank. This motor is a 010 1978 motor. There is a piston in the motor right now that is different from the rest of them. The guy I got the motor from said they put that in there to bring the compression ration down. Why would you do that?

3rdgentug

iTrader: (23)

that guys is an idiot or figured he could put one over on you, ive never....and i mean never heard of any sbc high nickel block that came w/ forged steel pistons, rods or forged pistons. most people would not mill the heads and then put in lower compression pistons, if they were mileld .05 or .10 then they compression incresse wouldnt be that great and could even be compinsated w/ a thicker head gasket, much cheaper then replacing pistons.
as far as the rods ect.... depends on what you plan on doing w/ the motor, if your makin it a driver keep the stock rods, if ya plan on sprayin those forged pistons and/or running 6000+ rpms change the rods

anLS1x2

I'm sorry I should have been more clear. The pistons are brand spankin new still in box. They are .030 over. The heads were not from the same block. But they were sent off and milled. The block still has a crank in it and rods and pistons that I don't beleive are forged and it was bored .030 over. I'm not going to spray the motor, so do you think the stock rods will be okay to use? Also, I still don't get why the "decompression" piston is in there, it's just one piston?

3rdgentug

iTrader: (23)

you wouldnt change 1 piston to bring down comporession, it would only lower compression to that 1 cylinder only, sounds like they broke one and replaced it w/ what they had laying around.
the stock rods will be ok if your not spraying it or going to be running alot of over 6000 rpms pulls.

distortion_69

iTrader: (20)

Which cylinder is the slightly lower compression piston in? I was thinking of what it might be in, and there are cylinders in SBC's that receive the most stress (7? I think). It could be possible he put that in because he's had past failures or something. Don't know, honestly. Chances are he busted a piston on spray or something, and just threw a replacement in there to sell it. I wouldn't trust the guy.. I don't think any of it is forged from the factory. As far as I know most forged cranks came in short stroke motors, and still were relatively weak in comparison to today's forged pieces.

Good Luck,
Josh

anLS1x2

It's in the number 4 cylinder. Turns out this motor has been raced or built up before. When I was going to turn the crank yesterday I noticed that the end of the cam shaft said "Comp Cams". So now I guess I need to have everything thoroughly inspected before I reuse any parts. Would you reuse the cam? I get some people saying that's okay, and some saying don't waste your time. Right now I'm not sure what I'm going to do because I can't get the crank to turn.

redbandit98

iTrader: (13)

i personally would get rid of the .30 overs..if the motor is .30 over now,(which it may not be, you need to make sure it is,,bc if its say .60 over you wont be able to bore it anymore). i would get me a new set of .40 over pistons,rings,etc..have the block machined and magnafluxed for cracks..have it bored (line too),new bearings,cam lifters. have the rods fluxed also and tanked. good luck

Z-Convert

If the crank has a wide parting line it's forged. If the parting line is narrow then it's cast. If this is just a daily driver then a cast crank will be fine. Block castings with the last 3 numbers of 010 are pretty common.

uberLS-1

Honestly I think in this day and age re-conditioning rods is a thing of the past. You can now buy a brand new set of 5140 rods with ARP bolts for $150 in a few places. If you get a factory rod re-done to hold any power that means typically smoothing the beams, Magnuflux them, re-sizing the big end after adding (and paying for) ARP bolts. and for all of this you will be paying $$$. Also considering you can use them later on if you step up on power or spray it....Just my .02

anLS1x2

Thanks for the replies. My wife and I tore the motor completely down last night. When we started removing the rods you could really smell a "bad" burnt smell. And when we removed the mains it was even worse. I'm not sure if that means anything but I know that smell isn't good. We also inspected all of the bearings to get and idea of how the rotating assembly was doing. We found that one of the rods was bent because of the opposite wear on the lower and upper bearing. So we will be getting new rods. We also found that the cam is a 270H Comp Cam. It looked to be in decent shape, just a little wear on a few lobes but it's rusted in some spots so I guess I can't use it . Something I noticed also was that one of the cam bearings was being very stubborn when I was pulling the cam out. I had to really force the cam to get it to come out. We inspected each piston and each cylinder wall and found those to be okay. Next we'll need to send the block off to get inspected and dipped.

anLS1x2

Where can I find rods at those prices?

redbandit98

iTrader: (13)

yes i have to remind myself of that sometimes..i always say have this and that done..forgetting that you guys pay top dollar for machine work..my dad has worked in a machine shop for 20+years..i can basically get anything done for next to nothing..or free sometimes..

uberLS-1

bastard, LOL

anLS1x2

I'm going to go the route of a 383 stroker motor. Can you guys help me with the specs? The heads I have are stock flowing 64cc. The New pistons I have are forged aluminum with floating pins and they are .030 over. The block itself has been bored .030 over. I know I need a 400 crank. Should I do anything with the heads? What kind of rods should I get? What size cam?
What size valves, pushrods, springs, rockers etc. I know I'm asking a lot but I want to do it right. This is a street/strip car and I'm on a budget. I appreciate any replies. If you know of any sites that cover building a 383, please let me know.

uberLS-1

Might want to change this first, a 383 wont make phenominal power breathing through a set of stockers....I have some Pro Toplines for sale, LOL

You don't want a 400 crank, you want a 383 crank, you have to deal with machining B.S. if you get a 400 crank, go to www.kskustoms.com I got one from him awhile back, I like the Scat 9000 cranks, better material then stock and not pricey....if anyone doubts the strength then I will ask how a circle track 400ci has lasted 3 years at over 7000rpm making 650 N.A. hp on methanol is working still, sometimes at 50 1/2 mile laps at a time.

Yeah, buy new ones.

Also Scat, they make a decent in-expensive rod, same website as above. If you plan on spraying it go into a H-beam, if this is going to be under 500hp and 6500-7000rpm, then the 5140 will work decently.

Depends on alot more then what we have so far.....

Depends on heads/head work

Will have to be checked when you mock up the motor.

Depends on cam

I like the Comp Pro Magnums, but if you keep the cam mild a set of Crane Gold race will work well.

No problem and your welcome Hope I have helped

Check AFR's website they have alot of builds in the article section, also try going directly to a magazine site (Chevy high performance and Car craft are a couple of my favorites), they will have detailed information into what goes into it. Honestly, anything on building a small block Chevy will work, you are just using different parts, process is the same.


Good luck!

anLS1x2

Thank you very much uberLS-1! What a class act! I really appreciate your responses.

Is there anything I can do to the stock heads I have to make them flow better? I know that I can port the exhaust and intake ports but what about the chambers? It makes me nervous to go anywhere near that area. Thanks again.

anLS1x2

What size Rods do I need? I was told that I had to use the stock 5.565" 400ci rod by a few folks. Also was told that if I bought the SCAT 9000 I could use 5.7" or 6.0" rods. What did you use?

CTSV05

Don't waste your time with stock heads, honestly you can find some decent deals on all kinds of heads.

Chamber size will be determined by your piston. But, if you have a 350 piston it won't work with a 3.75 stroke. Go with a 5.7 rod minimum.

Just to make everyone nevous, my 421 lost the oil p/u so it hurt the rod bearings, anyway I just threw together a cheapo short block, a cast steel stock replacement crank, stock X rods, a set of Speedpro Hyperuetectics, and its holding up just fine to 7k plus shifts, and I'm only running about a tenth and a half slower than my big motor with my smaller cam, of course the new one is still sealing up, so it may be just as quick when all is said and done, total invested?=$900.00!!!

Oh, and the new small motor, sheared off all the wheel studs on the driver side fri., and bent 3 on the pass. side, they were the ones Moser supplied with the axles. So, I put ARP studs in, but I think its making some nice torque!

uberLS-1

ahhhh rod length....Smokey Yunick said it best "Take the longest rod you can find and make everything else work with it!"

If you can get a piston that will yield the desired compression in your CC with a 6" rod, then I would do that, if not, move down to a 5.7"....under NO circumstances would I go shorter then that in a street motor. Just buy a ready to roll rotating assembly and call it a day.

uberLS-1

LOL, I built a "Spare parts" motor more then once that reached levels most people strive for.......but they only last for so long, then BAM! new parts for the "Spare" parts bin....usually alot of fun though, LOL.

On the subjecy of cylinder heads, I agree, but can understand the need to save money at the moment, as long as it is understood that you are leaving A TON under the table it is ok. When this is back together you know what you need to save for, get them to a given CC to keep your compression (Or go smaller for a bump) and pick up a bunch of power everywhere, it will be worth the wait.....