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Yup, that's what I mean, pushes the piston farther up, who knows what I was thinking at the moment, but is was backwards wasn't it. But that doesn't mean it has more compression, it depends on the valve relief cut volume, could still have the same compression even though it has a different compression height. I've run hypers before, they tout the tighter bore clearance attributes to better ring seal which makes sense. Better than regular cast aluminum pistons. Since your running aluminum heads then you can easily run 10:1 on pump gas IMO. Compression is not much of a factor as compared to cam selection as a whole when matched to the entire engine combination.

 

You'll find that even with low compression, tight LSA's matched with small duration cams like about 210 to 215 at .050 yield great TQ in the low to midrange and make pretty good daily driving motors.

 

I tend to opt for stall converters to eliminate the lazy bottom end TQ plus it gives you a better TQ multiplier in the converter.

 

Bet your z will scoot with whatever you choose. Damn sleeper cars. :mrgreen:

Edited by dr_hunt
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http://kb-silvolite.com/calc.php?action=comp

 

Cylinder Head Volume (cc) 64 Cylinder Head Vol (cubic in.) 03.904

Piston Head Volume (cc) 5 Piston Head Vol (cubic in.) 00.305

Gasket Thickness (in.) .039 Swept Volume (cubic in.) 44.389

Gasket Bore (in.) 4.125 T.D.C. Volume (cubic in.) 04.985

Cylinder Bore Diameter (in.) 4.030 Gasket Volume (cubic in.) 00.521

Deck Clearance (in.) Note: Neg. nubmer above deck, Pos. number below deck .02 Deck Volume (cubic in.) 00.255

Stroke (in.) 3.48 STATIC COMPRESSION RATIO 09.905

Look about right? That's using this head gasket http://www.summitracing.com/parts/FEL-7733PT2/Application/?prefilter=1

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Oh, and Doc you had me second guessing myself there for a minute! Haha :)

 

I'm going to use the third set I linked to, 5cc valve reliefs and 1.565 compression height. That's what's used in the calculations above and for 10 bucks more, why not! :burnout:

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Yup, the metal shim head gasket, used by GM and still available, has a compressed thickness of .022 which will effectively give you a theoretical static compression of around 10:1. I didn't go that route, but instead used the 4 valve relief speed pro forged pistons so I'll bet it's around 9.7:1 or so. Not bad.

 

I second guess myself sometimes too, but at least I have you guys to tell me when I'm all wrong.

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bschiltz: Don't know whether you are on a limited budget or not. I have chosen to go with longer connecting rods and lighter piston with reduced compression height. As for cylinder heads the smaller the chamber the better. Suggest going with what Doc has for aluminum cylinder heads at 64cc per chamber. Went with SRP Professional pistons (4032 forged alloy) which are expensive but very good and THE LIGHTEST. Went with LIGHTER Scat I beam connecting rods. This should allow the engine to spin up faster. Coated the piston crowns and cylinder heads with Ceramic Coating and Moly coating on the skirts. The SRP professional pistons also have thinner metric rings which have less friction in the cylinder bore. Less friction = more horsepower. Coated pistons and cylinder heads = detonation resistant combustion for using less ignition timing lead and using lower octane gasoline for the same amount of power.
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I believe he got the heads I got also. For street use the wider rings are going to last longer IMO but let us know how the oil control is on those. Aren't the oil rings low tension on the metric set since they are predominantly race only? Interestingly though the I beam design is superior IMO to the H beam design but what is the HP rating of the light weight rods?

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Doc: The light weight Scat I beam rods are good for 600hp. The newer cars are going to the metric ring package. The oil ring is not the lower tension ring. Really curious about your no-name aluminum cylinder heads. Have you used them yet? If so what are the results? Very curious how those turn out. They may be good candidates for CNC porting to the latest hi performance configuration much like the AFR heads.

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  • 4 weeks later...

Any opinions on these rockers?

http://www.summitracing.com/parts/CCA-1412-16/?image=large

I remember reading about them in one of my books (Vizard maybe?) and getting a thumbs up. Only thing is it says 1.5" max spring diameter, but the springs on my heads are 1.55. Does .05 make that much of a difference or will it make the geometry all cattywampus?

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They seem to enjoy a good reputation. The spring diameter won't affect the geometry, but it might mean the spring or retainer will hit the rocker. It probably depends on which retainer you use, it's more likely to hit than the spring itself.

 

John

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  • 2 weeks later...

Ok this might be kind of a dumb question, but is there anything you should replace in the roller lifters when reusing them or can you just clean them out and put them back together. I took one apart and let it soak in chem-dip for a while and it cleaned up well, even a lot of the crud on the inside (scraped it out with a pick).

 

Haven't made much progress lately, been busy with school. Just cleaning parts mostly. I did install the cam bearings last weekend. The first two bearings were a bit nerve-racking but everything went ok. I have to drop the old rods and pistons off at the machine shop to get the new pistons pressed on, then I should be able to button the short block up.

 

Ben

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Well, I hope yours work better than mine did. Started the motor, breaking in the cam with the idle at 3500. Was setting the timing and it was up to operating temp had been running about 15 to 20 min when it suddenly died. #1 intake valve was tight in the guide and the piston broke the head of the valve off and it beat around in there and got stuffed into the head intake port. :lmao: So, checked the oil and was way over full, cracked the #1 cylinder. Took it apart and had to drive the intake stem out with a punch. Everything else was pretty good. Guys that sold me the heads said "Your not alone" offered new gasket set!! Oui, how generous! Were supposed to send call tag and have it shipped back so they could repair it. Never got tag or gaskets they said they shipped. So, I ordered another set of heads, payed via paypal. Never got second set of heads. Filed claim on both paypal transactions and got my money back on both sets of heads. block is toast, sad :( as it was decked, align honed and a one piece seal block. Oh well, dusted off a 4 bolt 400 block and took it to machine shop. Had it decked, thought it would go .030 and going 9:1 hypers used I had laying around, 5.7 eagle sir rods and stock crank .010/.010. Took my wonderfull heads and had new 2.08 and 1.6 manley race valves put in and the chamber cleaned up alittle and new seats in #1 chamber both intake and exhaust. Had guide replaced and all honed and ready to go now.

 

I did some extensive exhaust port work and since I had the heads apart really got to see the ports and stuff. Pretty nice on the intake side, which accounts for the good flow numbers. A little rough under the seat in the bowl area but just a little blending and shaping of the short side radius on the intakes and they looked really really nice. Kind of an elevated port head, I know the exhausts are quite a bit higher than stock. The exhausts had a huge boss area around the guide that needed profiling and they too were rough in the bowl area with a large step when they had been machined for the seat. About 4 hours to clean them up real nice and I bet the exhaust flow numbers top 200 easily. Really large exhaust ports and the intakes are as well.

 

So, all in all I took it in the shorts for about $1K. I could of gotten another 1 piece seal block, decked it, align honed it and bored it, bought 1 new piston, rings, and gaskets and fixed the head, but would have had a lot in that too.

 

Shop just called and my 400 block didn't clear so I'll have to send another block tomorrow. :lmao: By not clearing I mean at .030. IME 400 blocks don't get good ring seal at .040 or even .060 unless you hardblok them. I have hardblok but block is in alb and I am here. besides it takes 30 days to hard block a motor anyway to ensure it cures properly and I don't have that much time.

 

So, hi ho hi ho it's off to alb tomorrow with another 4 bolt 400 block that i have laying around collecting dust. We will try that one and if not go from there, maybe another 350 block which I have lots of laying around.

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Nope, can't check valve to guide clearance without disassembling heads, but it's worth it and to have valve size, seat checked. Might as well do bowl clean up while your there also.

 

Was the jeep motor, ahh well. Update: Budlong motorsports called this afternoon and the heads had seats cut for 2.02 valves and 2.055 valves in them, not the 2.08 valves they claimed to have. OK, so it needed 2 intake valves and 4 exhaust valves overall due to the pieces of metal that got sucked everywhere in the other cylinders and stuck between the valves and seats on several other cylinders, which bent the valves, other than the two valves in #1 which were well shall we say "toast". Ah, the joys of single plane manifolds and it is amazing how much gets sucked into other cylinders when things go south. :lmao:

 

So, machining for the 2.055 valves and it'll be good to go, but it throws the spring height all in a mess as the valves sit lower on the seats and messes up my geometry. I'll probably take my pushrods back and change for -.100 length instead of stock.

 

Anyway, it'll be 406 cubes this time around and at least the heads are ok. If you manage to get some just have them checked out. We will see how they perform in a week or so. Should be a nasty jeep. Got a hard top the other day and a new heater core for heat during the winter. LOL Then it's on to the z.

Edited by dr_hunt
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  • 2 weeks later...

Ok, it's finals week in school so I finally have some time to work on the motor. Took the oil pump apart last night and cleaned it up but I noticed some pretty good score marks on the top plate (where the pickup is). How big of an issue is this? Can I get the face milled flat again or should I just get a new pump?

Thanks

Ben

IMG_0026_thumb.jpg

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