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Which Roller Rockers Help?

nsxxtreme said:
As far as the heads go it will either work or I will be having some not so kind words with the machine shop. This was discussed at length with him before he picked the parts. He said he builds these same motors all the time and they run fine on pump gas and stock ecu. My motor was bored .40 over. The cyclinder walls were crap, high mileage motor that was not ever taken care of.
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I'm in the same boat. Would like to know how the compression ratio works out for you... I know flat tops are available in different compression ratios, so i'm hoping my machinist knows more about this stuff than I do... Sitting on a .060 over short block -1989 with flat tops in it.(.060? yeah whatever, spare block sitting around, has all the roller cam provisions I wanted and I got to start building my motor before the old one came out...) I think all of my heads are 193 castings, all out of 1/2 ton blazer and suburbans, or 3/4 ton burb...

Machinist swore this would land me at about 9.0 to 1 on compression...
 
scouthead said:
I know flat tops are available in different compression ratios, so i'm hoping my machinist knows more about this stuff than I do...

Machinist swore this would land me at about 9.0 to 1 on compression...
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That's a good point. I'll have to call my machinist tomorrow and ask. I remember him telling me I would have 9.0 to 1 compression ratio with the flat tops as well. I'm pretty sure he knows what he is doing. I'll let you know though. Motor goes in tomorrow and hopefully running again in a day or two.
 
Forgot to mention last night. Thanks Thunder for pointing out the potential compression issue. My machinist assures me I will be fine on pump gas. I'll be doing a compression test before I fire this thing up.

He says I should expect 150-170 psi. If its in the 180s or above to give him a call. We'll see, I wont know until later today or tomorrow. I droppped the truck off to have someone figure the puzzle of brackets out :D Plus my back hurt after removing all that crap last time.
 
FWIW my TRUE compression ratio in my new engine i built is 9.42:1 and my static compression reading is 205 psi
 
The only question you have to ask your machineist is.... What CC are the heads on that engine? If he says 76 and you have 193 heads. You have problems.
It means he built the engine to go with 76 CC heads. Flat tops and 76cc heads will give you a compression ratio of around 9 to 1.
But
With the 64 CC heads, and all 193 heads are 64cc. Your compression ratio will be higher.
As I said I dont have the exact numbers of your engine. But I can get pretty close.
Figgurin
Bore of: 4.040. includes the .040 over bore.
Stroke of: 3.48. Standard 350 stroke
Combustion Chamber size: 64CC
Head gasket thickness of .041.(compressed)
Piston head volume of + 6 CC ( the area cut out for 4 valve reliefs)
Deck height of 0.02
Crunch the numbers and it Equals a static compression Ratio of aprox. 10 to 1. The numbers I used are fairly generic for a rebuild kit with flat top pistons. Your real numbers could be a little higher or lower depending on head gasket thickness, installed deck height, type of cam.

The engine should run fine on preimum pump gas. But you need a richer fuel mixture and less timing with the higher compression ratio to keep from having detonation problems. Which usually means a new chip.
I am not saying it wont run on the stock chip. It may just be able to compensate enough to make it run ok. But the stock chip is programed to run a little on the lean side at the stock compression ratio of 9.2 to one. Trying to force it to run a 10 to 1 engine will tax it to its limits and beyond.
 
Thunder said:
The engine should run fine on preimum pump gas. But you need a richer fuel mixture and less timing with the higher compression ratio to keep from having detonation problems. Which usually means a new chip.
I am not saying it wont run on the stock chip. It may just be able to compensate enough to make it run ok. But the stock chip is programed to run a little on the lean side at the stock compression ratio of 9.2 to one. Trying to force it to run a 10 to 1 engine will tax it to its limits and beyond.
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No way am I wanting to run on premium gas. Gas is to fricken expensive to be running premium. I'll be doing a compression test later. I'll know instantly once I hook the boat up and head up the hill. If he damn things pings I'll be driving it the machine shop and he can change the parts out.
 
Thunder said:
Your real numbers could be a little higher or lower depending on head gasket thickness, installed deck height, type of cam.
Click to expand...

Far be it for me to question the experts :D , but the cam has nothing to do with the compression ratio. It will effect cylinder pressures however... so the effect of a different cam can be like the effect of a different compression ratio. I'm sure that is what Thunder meant.
 
Yup that is what I ment. My posts were getting kinda long and i did not want to get into valve overlap, cyl pressure and all that stuff. I was just mainly refering to the static compression ratio. To keep things simple.
But
The cam is, and its specs, are a part of determining your Dynamic Compression Ratio. Which is your true compression ratio.

I am no expert. Shoot. I havent even slept in a Holiday Inn recently
 
Finally checked everything out...
350, .060 over, flat tops (.041 below deck height when installed), 193 heads (64cc chamber)... anywhere between 8.85:1 to 9.57:1 static compression, depending on head gasket thickness (.035 to .070), have not purchased yet, and not really sure what's available...

Stock pistons were 10cc dished, but don't know what their installed height was or how thick the stock head gasket was that came off the motor. Stock compression ratio could have been anything from 8.4:1 to 9.5:1 depending on deck hieght(.015 to .040), and gasket thickness(.035 to .070)
 
I haven't checked mine yet. I got the motor in the truck last weekend. Roller rockers showed up today. Now I have to install all the little crap. TBI,AC,alternator,air pump ect.... Can anyone snap some picture of there engine compartment to help me figure out all those brackets?

One other question Do these motors use two temperature sensors? In my parts bucket I have two sensors that look like temperature sensors. One looks a little different then a basic temperature sensor. That one has me confused.
 
One has two wires, one is a single wire.

Single wire goes in the drivers side head, other in the intake. :)
 
scouthead said:
Finally checked everything out...
350, .060 over, flat tops (.041 below deck height when installed), 193 heads (64cc chamber)... anywhere between 8.85:1 to 9.57:1 static compression, depending on head gasket thickness (.035 to .070), have not purchased yet, and not really sure what's available...

Stock pistons were 10cc dished, but don't know what their installed height was or how thick the stock head gasket was that came off the motor. Stock compression ratio could have been anything from 8.4:1 to 9.5:1 depending on deck hieght(.015 to .040), and gasket thickness(.035 to .070)
Click to expand...

If your engine has the flat top pistons with 4 valve reliefs and the piston is .041" from the deck surface and you use a .041 compressed head gasket with 64cc heads your CR = 9.311:1
 
I'm not sure how thick my head gasket was. It was just a standard Felpro gasket. I modified my stock valve covers and was able to get them to fit with the roller rocker.

I basically took a die grinder and just cut the piece of metal out of the way. They fit perfectly now.

I installed all the rear brackets on the back of the motor today. I would like to smack the engineer that designed those. It seems as though they needed to find someone something to do, so they had someone just sit and design as many brackets as they could. Fricken rediculous. Just doesn't seem like there was any intelligent thought on how things connect on the rear of the motor.
 
dyeager535 said:
What was in the way for you on the stock valve covers?
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If you look at the pictures provided in a couple pages back, it's part of the brace that holds the tube in place. This no longer fits between a pair of roller rockers. In the photo they just ground the bend on that piece out of the way. I just cut it completely off. Mine fit no problem now.

One day I'll have this this running again. Had to order a pair of exhaust manifold because mine were toast. Should arrive sometime this week.
 
Yeah those were my pics...so in your case, the rocker trunnions are wide enough that the sheet steel piece may have interfered even with the lip cut off?

Like I said earlier, just trying to figure out why others say they had more serious fitment problems, when I didn't.
 
dyeager535 said:
so in your case, the rocker trunnions are wide enough that the sheet steel piece may have interfered even with the lip cut off?
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Don't know I didn't even try to grind the lip down. I don't like to do work twice. So I didn't want to grind and find out it didn't work. So I just cut them off, easy enough. Fits perfectly now, goes on and off easily.

Thanks for the Tip!
 
scouthead said:
I'm in the same boat. Would like to know how the compression ratio works out for you... I know flat tops are available in different compression ratios, so i'm hoping my machinist knows more about this stuff than I do... Sitting on a .060 over short block -1989 with flat tops in it.(.060? yeah whatever, spare block sitting around, has all the roller cam provisions I wanted and I got to start building my motor before the old one came out...) I think all of my heads are 193 castings, all out of 1/2 ton blazer and suburbans, or 3/4 ton burb...

Machinist swore this would land me at about 9.0 to 1 on compression...
Click to expand...
Mine is running fine so far I dont hear any pinging took it up the hill no boat attached yet. Roller rockers went on easy and the motor is fairly quite with them.
 
Part#MC1730

[email protected]
INT EXH
204 214

ADV DUR
INT EXH
270 280

VALVE LIFT
INT EXH
.420 .443

LOBE SEP
INT EXH
107 117

POWER
RANGE
1500-4000

This is the cam I have with the 1.52 roller rockers.
 
Just wanted to get a few things put down here... cc of two different sets of 193 casting heads came up with 66 cc. I know for sure one set has not been rebuilt, so I doubt any valve jobs interfered with this...

Reassembled one of my TBI 350s (that I had just dismantled) just for these measurements:
DECK HEIGHT CLEARANCE ON PISTONS: .022
CENTER DISH ON PISTON: AT LEAST 10cc
OUTER DEPRESSION AROUND HIGHEST PART OF PISTON: AT LEAST 4cc(probably more like 5cc)

Using several different headgasket bore and thickness sizes, I COULD NOT calculate this motor to be more than 8.7:1 compression. EVEN USING A CHAMBER VOLUME OF 64cc I COULD NOT GET THE RATIO UP TO 9:1. The piston has too much relief in it. Going through several of my manuals I found mention of the '94-'95 year L05 getting bumped to 9:1 compression, with not much of a performance gain noted. All the listed ratios I have for the Vortec 5.7 say 9.4:1

There's a lot of talk here about too much compression with the 193 castings, and not a lot of talk about other equally important things that determine the static compression.
 
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