Top End Rebuild
01-18-2005, 03:53 PM
#92
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Well, the final verdict is in. Drum roll please...
You ready for this?
.250" of Play-Doh put on piston.. no valve indent.
.300" of Play-Doh put on piston.. no valve indent.
.350" of Play-Doh put on piston.. a small valve indent.
.400" of Play-Doh put on piston.. an indent.
.345-.350" of valve/piston clearance. My math estimates were damn good. I just have to wait for the price quote. If I don't hear back by Thursday, I will give them a buzz to see what'* up. As long as I can afford it.. I am going to get the heads decked after I get the porting done..
.
I am pretty damn frozen, so I am not very excited at the moment, but once I defrost, i'll be ecstatic.
-justin
You ready for this?
.250" of Play-Doh put on piston.. no valve indent.
.300" of Play-Doh put on piston.. no valve indent.
.350" of Play-Doh put on piston.. a small valve indent.
.400" of Play-Doh put on piston.. an indent.
.345-.350" of valve/piston clearance. My math estimates were damn good. I just have to wait for the price quote. If I don't hear back by Thursday, I will give them a buzz to see what'* up. As long as I can afford it.. I am going to get the heads decked after I get the porting done..
.I am pretty damn frozen, so I am not very excited at the moment, but once I defrost, i'll be ecstatic.
-justin
01-18-2005, 07:48 PM
#93
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Originally Posted by jr's3800
Originally Posted by DrJay
haha wow no kidding
I was at my friends house today( don't get to hang out there as much as I used to or would like to ) and he was showing me all of the parts a customer had brought him for him to rebuild a 305 V8... Had some nice Speed Pro flat top pistons with the 4 valve relief also teflon coated skirts( std size, Bores were in awsome shape ) they guy even had some roller tip rockers( 1.6 ) had the heads done with new valve components, valves and all... And the cam is was threw me.... I looked at the spec sheet and it showed as .466 valve lift.... So the actuall lobe lift on the cam is .291 if I did my math right..
On our 3800'* LN3, L36 I think through 96 the cam lobe lift is .250 intake and .255 exahust.... On the 97 and later( don't quote me on this on ) 3800 L36 the cam lobe lift is .250 intake and .258 exahust...
So totall valve lift 88-96 3800 intake side is .400 and the intake is .408 where as the 97 and later are .400 intake and the exahust is .413.... Odd how this is done...lol
And on top of all that, what if any diffrence does a conventional lifter/cam have over a roller lifter/cam, I know the roller lifter rides the cam lobe all the way around, but is a conventional lifter set up as good as a roller set up? Any thoughts?
I'm not sure of other differences but I know one major difference between solid/roller cams is how radical you can go. If you have a very sharp cam you'll need heavy springs, but too heavy and you'll collapse a hydrolic lifter. Solid lifters can handle much more, I've heard of 500# springs. On top of that, because of the abrasive nature of the solid lifters (and typical heavy springs), solid lifter cams are made of a heavier metal. Note the difference between a hydrolic cam profile and a solid:
This is typically why you won't usually see a "CLAP, CLAP, CLAP" type engine with hydrolic lifters. Correct me if I'm wrong somewhere.
01-18-2005, 07:57 PM
#94
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Originally Posted by jr's3800
Now there are a couple of things I'm wondering... Now the 3300 Vin N Buick V6 used in many cars from 89-93 I think, was based on a 3800... I think I have been told in the past that 3800 heads could be used on the 3300 block as they were just about the same.. Not sure, but I think the 3800 heads may have had larger valves... Now take into account that the heads were simmilar, the 3800 was an 8.5 to 1 compression engine, where the 3300 was a 9.0 to 1 compression like the LN7 3.0 V6, and here is the odd part, the 3800 had a bore of 3.80 inches and a 3.44inch stroke... On the 3.0( Buick V6 ) the bore was identical at 3.80 inches, but its stroke was 2.66 inches... On the 3300 all I could find is that it had a 3.70 in Bore...
If we were to look at a 3.0 or 3300 piston we'll see that the dish is slightly shallower than a 3800 piston( Vin C and L ).... Oh well I guess I'm just rambling pretty good..
If we were to look at a 3.0 or 3300 piston we'll see that the dish is slightly shallower than a 3800 piston( Vin C and L ).... Oh well I guess I'm just rambling pretty good..
Also, the 3800 has a 3.8" bore and 3.40" stroke. A 3.44" stroke would make it a 234cid engine. (Edit:Misread) To get 3300cc'* with a 3.7" bore you'd need somewhere around a 3.1" stroke.
01-18-2005, 08:57 PM
#95
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Stay in the .400-.420 lift range the system is optomised for it, what the "C" 3800 needs is more duration. Another 20 degrees or so would be nice.
CR without knock for a particular octane is a function of the combustion chamber geometry but basically if the plug is sorta centered (hemi is best) it is a function of the distance from the plug to the furthest point in the chamber. The larger the bore, the lower the max CR
CR without knock for a particular octane is a function of the combustion chamber geometry but basically if the plug is sorta centered (hemi is best) it is a function of the distance from the plug to the furthest point in the chamber. The larger the bore, the lower the max CR
01-18-2005, 08:59 PM
#96
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Maybe I'm not getting what you're saying, and correct me if I'm wrong, but if everything else is the same enlarging the bore will actually raise the CR because its drawing in more air but compressing it the same amount.
01-19-2005, 11:37 PM
#97
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Here'* a bunch of good calculators you guys might find handy. You have to register to use them, well worth it.
http://www.smokemup.com/auto_math/index.php
If I can toss my .02 cents in here
Dont try to go "top fuel style" with your compression. If you get into detonation it will yank out so much timing you'll have a slow pig. Just decking the heads will add a decent amount of compression all on its own because you are reducing the combustion chamber cc'*. Slapping in a cam with too much overlap and too little LSA (lobe separation angle) will kill vacuume. Fuel injected engines rely on engine vacuume for many functions. Padgett'* dead on with his cam spec
If you go adding a huge cam then you need the correct parts to work with it (good flowing heads, higher stall converter, compression,better intake, yadda yadda). Quite frankly, you cant get those things for these engines (at least on any kind of budget).
There are a few places that will give you free cam advise. Fill this out, its free
Lazer Camshaft Recommendation Form- http://www.lazercams.com/camsub1.html
http://www.smokemup.com/auto_math/index.php
If I can toss my .02 cents in here
Dont try to go "top fuel style" with your compression. If you get into detonation it will yank out so much timing you'll have a slow pig. Just decking the heads will add a decent amount of compression all on its own because you are reducing the combustion chamber cc'*. Slapping in a cam with too much overlap and too little LSA (lobe separation angle) will kill vacuume. Fuel injected engines rely on engine vacuume for many functions. Padgett'* dead on with his cam spec
Stay in the .400-.420 lift range the system is optomised for it, what the "C" 3800 needs is more duration. Another 20 degrees or so would be nice.
There are a few places that will give you free cam advise. Fill this out, its free
Lazer Camshaft Recommendation Form- http://www.lazercams.com/camsub1.html
01-20-2005, 06:42 AM
#98
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Don't worry about me putting in too big of a cam. I'm not touching anything else in this engine. I have sworn to myself this is enough. If I need any more power, it isn't going to be in this car. I think the power I will be making after this, will be plenty.
-justin
-justin
01-20-2005, 11:06 AM
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It'* composed of a metal rod, with rockers mounted on it. Little stamped steel rockers, that look like plastic. Completely different than mine. They are NOT roller. Neither are the lifters [to my understanding].
-justin
-justin