Anyone no what pistons these are??

[70c10stepside]

I'm trying to figure out the compression of my motor. I know they are flat tops, Supposedly stock crank and rods.. 64cc heads.




^How the motors sounds/revs

Also, while at it, how strong are stock rods/crank being they are cast?? Where should I not rev too?

Few specs of the motor..
.030 over
508 lift, 313 duration cam
Torker 2 intake
750 holley, 1 inch spacer (Clearance issue)
64cc double hump heads
A few specs....

When we rebuilt the motor, we used the same bottom end that the motor has had for a real long time...

[trac209]

Well with. 64 cc head and a 4 valve relief piston approximate compression ratio would be 9.5 to 10.0. Depending on head gasket thickness.
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[70c10stepside]

Thanks for the info. We have a stock spec, fel pro head gasket on it now I believe.

[RWB-713]

Originally Posted by 70c10stepside

I'm trying to figure out the compression of my motor. I know they are flat tops, Supposedly stock crank and rods.. 64cc heads.

Also, while at it, how strong are stock rods/crank being they are cast?? Where should I not rev too?

Few specs of the motor..
.030 over
508 lift, 313 duration cam
Torker 2 intake
750 holley, 1 inch spacer (Clearance issue)
64cc double hump heads
A few specs....

When we rebuilt the motor, we used the same bottom end that the motor has had for a real long time...

What displacement (size) is the motor?

For a true compression ratio, you need to know, Bore,Stroke, Combustion chamber volume, the size of the valve reliefs, deck clearance of the block, compressed head gasket thickness, & head gasket bore size.

I've seen stock cast rotating assemblies turn 7000 if built right, but not for very long.... stock cast stuff is generally the weakest bottom end you can go with, keep it under 5500 and you'll be fine for a good while, as long as it's not a constant 5500 lol, the more it turns, the shorter the lifespan in general

[70c10stepside]

The motor is 355. 70 model camaro block. Ive had the motor to 6400, once lol I normally just cruise around though
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[GASoline71]

My 355 has stock rods (with ARP rod bolts) and crank in it, and I spin it to 6,500 all the time.

Gary

[RWB-713]

Originally Posted by GASoline71

My 355 has stock rods (with ARP rod bolts) and crank in it, and I spin it to 6,500 all the time.

Gary

And that's perfectly possible & reasonable, I've seen stock block, stock crank & rod circle track motors turn 6500-7500 night after night, all depends on how they're put together. To be on the "safe" side tho, keeping it lower in the RPM range will generally lengthen the lifespan of any motor.

[GRX]

Originally Posted by RWB-713

And that's perfectly possible & reasonable, I've seen stock block, stock crank & rod circle track motors turn 6500-7500 night after night, all depends on how they're put together. To be on the "safe" side tho, keeping it lower in the RPM range will generally lengthen the lifespan of any motor.

Agreed. I have built several SBC for customers, from mostly stock parts, which pulled well into the 8k rpm range. A good balance job is essential of course.

[prostreetC-10]

Originally Posted by GASoline71

My 355 has stock rods (with ARP rod bolts) and crank in it, and I spin it to 6,500 all the time.

Gary

Gary.....reach around to the back of your tach and switch it from 4 cyl to 8 cyl for crying out loud!!

[RWB-713]

Originally Posted by prostreetC-10

Gary.....reach around to the back of your tach and switch it from 4 cyl to 8 cyl for crying out loud!!

[GASoline71]

Originally Posted by prostreetC-10

Gary.....reach around to the back of your tach and switch it from 4 cyl to 8 cyl for crying out loud!!

Is that what that switch is for? No foolin'?

Gary

[RWB-713]

OK, so i used a general rough estimate for the numbers you don't have. but with these specs:

4.030 bore
3.48 stroke
64cc chambers
-7cc valve relief ( a general number i grabbed from looking at several sets of 4 relief pistons real fast)
.030 deck clearance (i assumed you decked the back at least a little on the rebuild?)
.060 compressed gasket thickness w/ a 4.165 bore

C/R comes out to 10.59:1, pretty high for an iron head/iron block street motor, i'm assuming you intend to run on pump gas.

There's several other factors that would determine wether or not it's a "good idea" to run it on pump gas, Timing, overall cylinder pressure (influenced alot by Cam & the rest of the valvetrain) and Elevation...etc etc

[70c10stepside]

Thanks man, sounds good enough to me. It'll ping with regular gas under real heavy load. Ive been trying to run premium as much as possible. I mostly drive it around, at normal speeds. The motor only has a little over 200 miles lol Its quick. Probably every bit of 450 horse. The rear end steps out really fast lol
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[70c10stepside]

Really?? Wow! My crank was just balanced, end caps honed or whatever that process is. Everything is like New on the bottom end, and everything is new on the top end. Heads were rebuilt and everything so its safe for me to over 6500? I'd say it'll do it.. its rev happy. I just dont have the budget to kill parts on my high school budget lol
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[RWB-713]

Originally Posted by 70c10stepside

Really?? Wow! My crank was just balanced, end caps honed or whatever that process is. Everything is like New on the bottom end, and everything is new on the top end. Heads were rebuilt and everything so its safe for me to over 6500? I'd say it'll do it.. its rev happy. I just dont have the budget to kill parts on my high school budget lol
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If you don't have the budget, I wouldn't test your luck for fun. Valvetrain stability is also a large concern, especially with a Hyd cam & the stock rocker/stud configuration. I've seen many engine failures due to the top end.

And i'm not saying anything bad about your build by any means, but remember, the quality of any engine build, lies in the details of HOW the work was performed, not just the thought of everything being "new" or "rebuilt".

One last thing to remember.... if it pings on 86. It's on the verge of pinging on 91. Higher RPM = More heat in the combustion chamber, more heat = higher possibility of detonation.

[70c10stepside]

The rockers are arp, they are studded, guide plates, and all that good stuff lol But yea, I ***** foot around a lot. I check the oil daily lol It took like 2 years to get the money to rebuild it lol The truck is extremely babied.

[70c10stepside]

It also has arp head studs, I know the caps and main caps are after market, same with the main cap bolts.

[RWB-713]

Four words.. Rocker. Arm. Stud. Girdle. Stud mounted rockers always flex quite a bit at high RPM, which cause improper valvetrain geometry & mis-alignment. In the 6500+ RPM range, oiling becomes an issue as well, it's flying all over the place, quite frequently not where it needs to be.

I'm just trying to give some advice to protect your investment man! I'm not saying don't give er hell, that's why we build what we do. Most of us abuse the crap out of alot of our stuff, because we built it for that reason. It's fun to be throttle happy. I'm just givin ya a heads up of the possible consequences, I was in high school once I know how it is. I just don't want ya to be the guy with the oil trail followin him out of the parkin lot waitin on a tow truck!

[steves1967]

Originally Posted by RWB-713

Four words.. Rocker. Arm. Stud. Girdle. Stud mounted rockers always flex quite a bit at high RPM, which cause improper valvetrain geometry & mis-alignment. In the 6500+ RPM range, oiling becomes an issue as well, it's flying all over the place, quite frequently not where it needs to be.

I'm just trying to give some advice to protect your investment man! I'm not saying don't give er hell, that's why we build what we do. Most of us abuse the crap out of alot of our stuff, because we built it for that reason. It's fun to be throttle happy. I'm just givin ya a heads up of the possible consequences, I was in high school once I know how it is. I just don't want ya to be the guy with the oil trail followin him out of the parkin lot waitin on a tow truck!

.508 lift cam? I wouldnt worry about stud flex unless you are over .600 lift/ solid roller cam/ or 7000 rpm...

[RWB-713]

Originally Posted by 70c10stepside

They flex? Didn't realize that lol I thought they were the best that could be done. Thanks for that heads up. One day I want to get out of the 40 something year old heads and go to aluminum or at least newer flow patterns and stuff.

I know man, No offense taken what so ever. I know what you mean. The more opinions, and information the better. This forum has really helped a lot. I have another small block and a big block sitting outside that'll be the next build, so trying to take in all the information I can :P

Yeah, even the finest ARP studs will flex to some extent. Yes it does help quite a bit to use good studs, but it's still there, and it intensifies the higher the rpm. You're off to a good start for sure, do all the research you can, there is TONS of information out there for building SB & BB chevy's. But motor building is a fine art, and high horsepower/ high rpm engines are an even finer art.

Originally Posted by steves1967

.508 lift cam? I wouldnt worry about stud flex unless you are over .600 lift/ solid roller cam/ or 7000 rpm...

Yes, it does itensify with higher lift, higher valve spring pressures, and higher RPM. But it's always there. Bolt a set of splash gaurds on a set of rocker studs sometime and watch, you can see the gaurds twist even while turning the motor over with the starter. I've seen many "stock valvetrain", vacuum rule limited, circle track motors flex the studs like that. And we couldn't run anything more than a .510" (hyd flat tappet) lift cam to meet the vacuum rule in most cases.

[steves1967]

Yes, it does itensify with higher lift, higher valve spring pressures, and higher RPM. But it's always there. Bolt a set of splash gaurds on a set of rocker studs sometime and watch, you can see the gaurds twist even while turning the motor over with the starter. I've seen many "stock valvetrain", vacuum rule limited, circle track motors flex the studs like that. And we couldn't run anything more than a .510" (hyd flat tappet) lift cam to meet the vacuum rule in most cases.[/QUOTE]

Might want to check your valvetrain geometry- if you are flexing studs with a .510 lift cam something is off.... or maybe you were using the short thread ARP studs, ARP has several different thread lengths available.

[70c10stepside]

They flex? Didn't realize that lol I thought they were the best that could be done. Thanks for that heads up. One day I want to get out of the 40 something year old heads and go to aluminum or at least newer flow patterns and stuff.

I know man, No offense taken what so ever. I know what you mean. The more opinions, and information the better. This forum has really helped a lot. I have another small block and a big block sitting outside that'll be the next build, so trying to take in all the information I can :P

[GRX]

Sounds like a good build. If they installed aftermarket main caps the block was surely line bored. Sounds like your conn rods were re-sized with new bolts too. All good stuff. It all honesty you could drain your bank account dry paying for Blueprinting operations on your components. Most of which will not add much power on their own, yet all together it's what makes a good runner really perform.

[70c10stepside]

Originally Posted by GRX

Sounds like a good build. If they installed aftermarket main caps the block was surely line bored. Sounds like your conn rods were re-sized with new bolts too. All good stuff. It all honesty you could drain your bank account dry paying for Blueprinting operations on your components. Most of which will not add much power on their own, yet all together it's what makes a good runner really perform.

Yessir! We had to go .020 on those I think it was. It was due to burnt valve seals. Gas and oil doesn't mix to good lol

[GRX]

Originally Posted by 70c10stepside

Yessir! We had to go .020 on those I think it was. It was due to burnt valve seals. Gas and oil doesn't mix to good lol

Say what?