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Discussion Starter #1 (Edited)
I just pulled the intake off to investigate the oil consumption issue and found my intake gasket is most likely the cause. Very oily and most likely leaking into intake ports. Can anyone identify the pistons and rockers I have. Am going to maybe change the heads ( casting 333882 ) did some research and found they don't seem to be very good. Pistons are domed a bit just below valve reliefs, about 1/4" above deck when at TDC. Also the rockers have numbers on the top side opposite the valve. Not sure what they are. I know what the 1.5 is but on the other side there is also a number. Most are 5 but there are some 2's & 6's also?







 

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I have no idea which pistons they are but the rocker arms look like Crane 1.5 ratio roller rockers. I dont know what the other numbers on the rockers stand for. Maybe it is a serial or casting number for the manufacturing date.....?

-Dan
 

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I'd be a little concerned about the flakey paint from the lifter valley getting into the oil pump (and beyond).
 

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If they are a Crane rocker they will say it right on there. Since your pistons have a .250 dome with 882's will work ok. Most .250 dome pistons that I have seen are 11.0:1 to 12.0:1 compressionor even higher. So with the 882's you would be around 10 or so. The 882's flow ok for stock heads just noone wants them because of the 76 cc that drops your compression.
 

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The rocker arms are Crane Energizer rocker arms. The main body is made from vacuum die-cast aluminum. NOT FORGED BILLET.

They are the ECONO rocker arms from Crane and should not be associated with the High Quality Crane Gold rockers.

NOTE: IMO, I would not recommend those with a roller cam.


http://www.summitracing.com/parts/CRN-11745-16/?image=large


Pistons look for part number on top.
Post ##

Al



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Discussion Starter #6 (Edited)
Thanks for the help. Al those are the exact rockers I have. The link you posted shows the numbers I was referring to. Does anyone know if that number means anything? I cleaned the top of one of the pistons and there are no markings at all on the top of the piston. I will post a better picture when I get home.

Thanks again for the help !!



 

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Interesting bunch of parts.....looks like somebody swapped out the good heads before you bought it....head studs and a roller cam wouldn't be something I would use in an engine with those castings. And I'd have to agree with Al about using those rockers with an aggressive cam; I've seen a few of those broken into pieces.
 

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They look like crane rockers, i had camdynamics back in the day that looked the same they were made by crane also. As for the pistons, i had set of std. .100 LT1 cast with my 76cc heads and compression was 9.7 to 1. With a .250 dome i guessing your closer to the 11 to 1 relm.
 

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Interesting bunch of parts.....looks like somebody swapped out the good heads before you bought it....head studs and a roller cam.
Yes, very interesting!!!

Those are not cheep pistons, been fly cut also.

Al
 

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Discussion Starter #10 (Edited)
Al, how can you tell those were fly cut? I just assumed they came that way? yes I know what happens when we assume.

How would I go about selecting heads if the exact piston information isn't known? Don't want to spend a fortune on this motor because when I completely redo the car and front clip I am going to go big block I think. Been back and forth on that several times. I just enjoy driving it too much to leave it sit for too long. Would like to fix this motor on a budget and drive for a year or so till the real fun begins. Don't have a problem changing heads if thats what I need to do.

Thanks
 

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Al, how can you tell those were fly cut?
See the big round cut on the intake side? That piston was probably the same on both sides when new.

How would I go about selecting heads if the exact piston information isn't known?
Unless you got some used heads that have been milled a bunch, it shouldn't be an issue. Just about any aftermarket head, and a lot of factory heads are better than those you have...even a stock Vortec head will be better, unless those have a whole lot of work we can't see.
 

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Discussion Starter #12
What about Chamber size 64 cc or 72 cc ? I want a good running engine if possible and still be able to run pump gas. Will the compression with those pistons and 64 cc chambers be to high for pump gas or is that an unanswerable question?

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If you got the heads off, Just cc the thing and be sure. I agree, it looks like a fairly worthwhile short block that someone swapped out the heads.
Probably had a ton of porting done on them and didn't want to let them go.
I'll bet with some 300 cfm AFR heads you might have a good engine.
 

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Discussion Starter #14
The heads that came off are 76 cc. How do I check the cc's to see what head I should use to keep compression reasonable for pump gas without knowing the piston spec's?


Thanks
 

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The heads that came off are 76 cc. How do I check the cc's to see what head I should use to keep compression reasonable for pump gas without knowing the piston spec's?


Thanks
Hmmm, if you get me some pictures from directly above and some direclty to the side of the pistons, I might be able to make a 3d model and give you a size. Some basic measurements in millimeters will help too. The diameter of the piston, height of the dome, the depth of the relief and the depth were the piston is cut deeper for the vlave relief.

I cant say it will be 100% accurate but I can give you a number much closer then guessing. Again, the more info and accuracy you give me with the measurements the closer I can get.

Another way would be to measure using a graduated cylinder and water. Fill the vlave relief area level with a piece of clay and put that in the grauduated cylinder to give you its volume. Then use clay to make a mold of the dome. Use that as a negative and fill it with clay and measure its volume in the graduated cylinder. Then subtract the volume of the dome by the volume of the valve reliefs.

Thats the only two ways I can think of coming up with an accurate measurement. Maybe someone else has some more ideas.

-Dan
 

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To cc the piston, you drop it down, (enough to allow dome clearance to the cc plate), a set amount, say .100". Use white grease around the rings and to seal the cc plate. Rotate the engine so the deck is level (if your hole is in the center) or so the hole is at a high enough point to allow air to escape. Drip in the cc fluid until all the air is out.

See how much volume is used.
Now calculate the "extra" volume caused by dropping the piston with the formula:
V = height * pi * radius^2
Radius is one half the bore so r= 4.030/2 or 2.015
squaring that =4.0602

.100 * 3.14 * 4.0602 = 1.2749 cubic inches
now you convert to cc's

1 cubic inch = 16.387064 cc

1.2749 * 16.387064 = 20.89 cc's

subtract this from the total volume measured with the burette and that will give you the actual volume at TDC.

You can use that with gasket and chamber cc to calculate the CR -or-
If you want to know just the piston dome volume
You measure your piston to deck clearance (height) and calculate the volume above the dome with the same formula and subtract that.
 

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Just looking at that dome says it's got to be at least 11-1 static compression even with 76cc heads. I wouldn't look at any heads with a combustion chamber smaller than 72cc's on pump gas and the cam will need to match. One of the photos shows number 2 piston from the front and it appears it is rocking quite a bit in the photo. Top of the piston looks maybe .005 below deck and bottom appears .005 above deck-maybe there's more going on here to cause the oil consumption? I'd do a teardown and see what cam is in it, see what the parts look like and measure-gaskets are cheap.
 

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Discussion Starter #18
Bob,

That picture of the piston Is one of those illusions. It just looks that way. I was plan on tearing things apart and measuring and checking bearings before putting things back togather anyways. Just need to figure out what other parts I might need. If the pistons work out may be able to end up with a good motor. If not guess I'll will start over.

Thanks for the help !!
 

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Discussion Starter #19
More pictures of pistons and crank

Well I got back from vacation yesterday and decided to go ahead and pull motor today. Pistons look like they are KB 180. I did find that one cylinder wall has some pretty good scratches and the piston has a few marks also. I took pictures of the crank also because it looks like someone has ground on the end for some reason not sure what for. What do you guys think is this worth putting back together or should I just start over? Maybe go back to the original 383 stroker I was first thinking about.

Thanks for all the help !!

















 
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