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502 performance
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bosshoss
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Joined: 08 Dec 2007
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PostPosted: Sat Dec 08, 2007 5:25 pm    Post subject: 502 performance Reply with quote

I have a 502/502 crate engine and though it`s pretty strong I feel at 46000 miles it`s ready to be freshened up a it.
What do you think.. Would I be better off going with a set of AFR`s 305 cc as cast cnc machined heads or just port match and blend the bowls on mine. Also... The engine is in a light weight auto trans vehicle and I "play" a lot between 3000-6000 rpm. I have a 2500 RPM converter. I could really use some recommendations for a hyd. roller cam to boost my mid-high HP torque.
Thanks in advance..
Tom.
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af2
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1933 Willys Coupe

PostPosted: Sat Dec 08, 2007 6:47 pm    Post subject: Re: 502 performance Reply with quote

bosshoss wrote:
I have a 502/502 crate engine and though it`s pretty strong I feel at 46000 miles it`s ready to be freshened up a it.
What do you think.. Would I be better off going with a set of AFR`s 305 cc as cast cnc machined heads or just port match and blend the bowls on mine. Also... The engine is in a light weight auto trans vehicle and I "play" a lot between 3000-6000 rpm. I have a 2500 RPM converter. I could really use some recommendations for a hyd. roller cam to boost my mid-high HP torque.
Thanks in advance..
Tom.


BigDave??? I only played with a 431 closed chambered heads. The motor had good HP from 3500 to 7800 rpm. I used a Vega converter twice then had one made once with a 3800 stall.
Launched that one too. All that was with an Isky Z33 solid cam 9.5:1 compression 25+ years ago. Still have the motor. Damned I getting old! Laughing
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Big Dave
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PostPosted: Sun Dec 09, 2007 7:55 am    Post subject: Reply with quote

First problem that I see is the hydraulic rollers and a 2,500 RPM converter. That is going to limit your cam choices to about 230° duration or comprable to what the factory chose. The specs on the factory ZZ 502 cam are 224° int., 234° exh. @0.050 lift; 0.527" int., 0.544" exh. on a 110° LSA.

You are limited to a 5,800 RPM red line because of the weight of the tappets and the springs used in the heads. You can not run stiffer springs because it will collapse the lifters, but you can gain 300 additional RPM with a Rev Kit to hit your desired RPM range. This however will still limit your maximum lift to the valves at 0.555", because the dog bone retainer will fall off the cam at a higher lift than that. (I know it sounds counter intuitive because more lift means it should stick even better onto the retainer. But to get more valve lift they have to make the base circle smaller on the cam so that the lobes will still move past the bearings on installation. This means at a higher lift, the tappet falls lower down onto the base circle and will drop out of the retainer and turn sideways.)

I would recommend a solid roller cam and a looser converter if you are racing this thing coupled with rectangular port RHS or AFR CNC’d heads. But from your moniker I see you have this engine installed in a motorcycle and I think the factory 500 horse available to you through out your chosen RPM band in a motorcycle is scary enough.

I suspect you are just looking for a more radical sounding cam. If so you will have to have a custom cam ground similar to the "Thumper or VooDoo" cams that are currently the rage. It has a tighter LSA (about 107°) and adds about 8-10 degrees more to the exhaust duration to sound like a top fuel car.

Big Dave
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bosshoss
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PostPosted: Sun Dec 09, 2007 10:59 am    Post subject: Reply with quote

So you are saying then I am basically stuck with the cam I have??? I was just reading knarly Darley`s post about a newly built 496 and here is a quote from that build...

The cam is a hydraulic roller with 230/242@.050 with .625/.610 lift on a 114 LSA.

What is the difference here??
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Knarley Darley
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PostPosted: Sun Dec 09, 2007 12:57 pm    Post subject: Reply with quote

I used a 1.8 rocker ratio to get the lift, and it is a retro fit roller set up which means it uses a tie bar instead of the factory dog bone to hold the lifters in place. With tie bars the lift is not limited. Personally I think 2500 stall is enough in a 502 even with a bigger cam, and the hyd lifters will go to 6500-7000 for short bursts. The mistake alot of people make is over adjusting hydraulic lifters so they over pump and dont let the valve close all the way at high RPMs. If im not mistaken the 502s do not have adjustable rocker arms. If that is the case, you can have the heads machined to accept a screw in stud and guide plates and use adjustable rockers, and then increase your rocker ratois to get more lift. If you are budget concious, and handy with a porting tool, just use the heads you have and port them, and get a good single plane manifold.
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squeeezer
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PostPosted: Sun Dec 09, 2007 4:30 pm    Post subject: Reply with quote

there are a bunch of boss hoss cycles in st paul area one of them has a 1003 horse bbc in it Shocked

i believe its a 6## cube engine
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Big Dave
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PostPosted: Sun Dec 09, 2007 8:44 pm    Post subject: Reply with quote

The ZZ502 head has ARP studs already installed. You have to loose the factory stamped steel rocker and install roller rockers with polylocks to get away from the non-adjustable rocker arm. When you increase the lift on a stock ZZ502 do not forget to check for valve to piston clearance (the pistons do not have notches to increase the compression). The cam is near max lift but not there exactly: Comp and Crane and Lunati all offer "bigger cams", mostly in terms of duration. More duration usually requires more stall in the converter to keep the motor from stalling out in gear.

Like I asked earlier just how much more power do you need. I doubt if they have made even a Pro Stock Motorcycle slick to hold a 502 on a bike chassis yet. So I am pretty sure you are not needing any more torque or horsepower. Have you considered the ricer solution and go to megaphone on the exhausts to amplify the noise an uncapped BBC makes?

Big Dave
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bosshoss
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PostPosted: Sun Dec 09, 2007 9:30 pm    Post subject: Reply with quote

Sound is not important to me.. We usually run these things from a 60 MPH start in first gear... 3000 RPM. I am wanting to increase my torque from that point up... I have a guy with a snotty 500 HP small block that is pretty even and I want to put him in place. We usualy go to 130 in first and then I hit the NOS after the shift and get him but... well.... you know.

The 1000 HP bike belongs to a guy in Freedly (sp) Mn. And he is running a 606 donovan... can`t really hook it up though. I am hooking up pretty good at the speed we race now but I would like to be on the edge of that so I can manage throttle below that point.
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bosshoss
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PostPosted: Sun Dec 09, 2007 9:33 pm    Post subject: Reply with quote

Has anyone tried a cam from the 572/620 in a 502? longer duration and hgher lift. If I used the springs with the cam would be be worth the $ and effort to make a dyno pull?
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Knarley Darley
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PostPosted: Sun Dec 09, 2007 10:29 pm    Post subject: Reply with quote

Funny you should ask that. I am friends with the owner of west coast cylinder heads, who happens to also have the C&C contract for all the Edelbrock heads that they sell ported. He actually did the program and the prototype for the new victor 24 heads. Anyway his brother put a 565" motor with the victor 24s together and used a stock cam out of a zz572. It made 777 uncorrected horsepower! We have not dynoed a stock zz572, but my personal opinion is that GM down graded the real power of the 572 for insurance reasons. We recently tried to insure a classic car with 700+ horsepower and they told us the limit is 650. I dont know if the 572 cam will fit in the 502, but if you are rebuilding it anyway you can cut the pistons to clear the cam.
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squeeezer
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PostPosted: Mon Dec 10, 2007 1:24 am    Post subject: Reply with quote

bosshoss wrote:
Sound is not important to me.. We usually run these things from a 60 MPH start in first gear... 3000 RPM. I am wanting to increase my torque from that point up... I have a guy with a snotty 500 HP small block that is pretty even and I want to put him in place. We usualy go to 130 in first and then I hit the NOS after the shift and get him but... well.... you know.

The 1000 HP bike belongs to a guy in Freedly (sp) Mn. And he is running a 606 donovan... can`t really hook it up though. I am hooking up pretty good at the speed we race now but I would like to be on the edge of that so I can manage throttle below that point.





are you from that area as well???
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bosshoss
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PostPosted: Mon Dec 10, 2007 8:00 am    Post subject: Reply with quote

No... I`m on the west coast. The guy in MN. owns a dealer and makes a lot of custom parts. www.choppercity.com

The boss hoss community is a pretty tight knit group nationwide. Check out www.v8bikeriders.com

I`m going to call the dealer in oregon today and see what they say about the cam. I`ll post here.
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bosshoss
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PostPosted: Mon Dec 10, 2007 5:06 pm    Post subject: Reply with quote

talked to the race shop at Gilbert chevrolet today... They build performacne engines using GMPP base engines as a start. They recommend using the cam, lifters, and springs form this engine http://sallee-chevrolet.com/frame.html?/start.html Along with some porting work on my heads. Should net close to 600 HP 600 lb ft of torque. Should be adequate for a motorcycle... Shocked

Oops.. the link just takes you to the home page. select performance engines on the left and scroll down to the bottom. it is the 502/630 ultimate street.
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Big Dave
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PostPosted: Mon Dec 10, 2007 8:04 pm    Post subject: Reply with quote

They are using the Crane P/N 168741, Hyd. Roller, Lift (.610" Int., .632" Exh.), Duration @ .050" (236° I, 244° E) with their own tie bar hydraulic retrofit roller tappets. They are not using the factory spiders.

The 572 factory hydraulic roller used in the tall deck truck block (which is not set up for hydraulic roller spiders because it does not have the studs cast internal to the valley or have the tops of the lifter bores machined for the dog bones) utilizes Crane’s tie bar system. If you get cam and lifters as well as the springs you can run that set up in the ZZ502 after you cut notches in your pistons.

The ZZ502 will take up to a 175 horse shot of nitrous and still stay together. It has all forged internal parts and has a lot of slop in the rings and piston to bore fit because the General had a pretty good idea that someone would do it while still under warranty and come crying about their broken new toy.

I figure a 150 shot of nitrous ought to either get you killed or beat your pall with the SBC.

Big Dave
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bosshoss
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PostPosted: Mon Dec 10, 2007 8:40 pm    Post subject: Reply with quote

Thanks Dave... I realize They are using the dog bone set up on the lifters as well as SRP pistons. That is what I am going to use. I have a 150 shot of NOS on it now but can`t use it until I am in second gear at 100 MPH + or it breaks the tire loose. They are also using Edelbrock victor jr. rectangle port heads but I think I am goint ot just do a nice porting and blending job on mine, Their engine dynoed at 630 HP so I think a number around 600 should be reasonable.
What are your thoughts on keeping my compression at 9.6 and using my stock forged pistons?? Just kicking around the idea of keeping my NOS. I know the SRP pistons are probably not going to put up with much of that since they are a little tighter.
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