Clearance for cam
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From: Near Lockport NY Black 1986 Coupe
Swapping for new intake.
Okay, I'm in plans for switching my current EFI intake for a carb and dual-plane manifold. I need to know the maximum amount of lift and duration I can have on a zz4 block with L98 heads and flat-topped pistons. Suggestions for a cam? Looking for a roller tappet with atleast .490-.510 lift and around 200-220 duration, but still with adequate low-end power.
Last edited by Master__Shake_; May 6, 2008 at 11:58 PM.
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From: altered state
St. Jude Donor '05
that should fit with 0 issues. Always a good idea to check piston to valve clearance but honestly I wouldnt even bother checking with that cam and a crate shortblock. Make sure your springs are set up correctly.
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From: Conroe TEXAS!
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From: Near Lockport NY Black 1986 Coupe
http://store.summitracing.com/partde...4&autoview=sku
Going to call up summit and see if this will work with the stock heads and also a good carb to run it with.
Drifting
Joined: Nov 2006
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From: Ontario
eh??? I thought you wanted a roller tappet? the one you listed is mechanical flat tapper.
Also you know that cam is mechanical right? You know how to adjust valves? you would need to do it once or twice a season with mechanical lifters.
110 LSA will be harder to tune with the '86 computer (mine hated it), the overlap causes the O2 sensor to permanently read lean as intake air passes into the exhaust. The tune can be done though, just a word of warning.
Finally 248/248 at 0.05 duration is a lot, especially with L98 heads. On my 383 build with new ported Brodix 200cc heads I'm only running 230/238 and that'll pull me to 6000rpm. Yours will peak near 7000rpm, is your bottom end built for that?
just trying to help someone with the knowledge I gained from my mistakes.
Also you know that cam is mechanical right? You know how to adjust valves? you would need to do it once or twice a season with mechanical lifters.
110 LSA will be harder to tune with the '86 computer (mine hated it), the overlap causes the O2 sensor to permanently read lean as intake air passes into the exhaust. The tune can be done though, just a word of warning.
Finally 248/248 at 0.05 duration is a lot, especially with L98 heads. On my 383 build with new ported Brodix 200cc heads I'm only running 230/238 and that'll pull me to 6000rpm. Yours will peak near 7000rpm, is your bottom end built for that?
just trying to help someone with the knowledge I gained from my mistakes.
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Pro
Joined: Jan 2008
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From: Near Lockport NY Black 1986 Coupe
eh??? I thought you wanted a roller tappet? the one you listed is mechanical flat tapper.
Also you know that cam is mechanical right? You know how to adjust valves? you would need to do it once or twice a season with mechanical lifters.
110 LSA will be harder to tune with the '86 computer (mine hated it), the overlap causes the O2 sensor to permanently read lean as intake air passes into the exhaust. The tune can be done though, just a word of warning.
Finally 248/248 at 0.05 duration is a lot, especially with L98 heads. On my 383 build with new ported Brodix 200cc heads I'm only running 230/238 and that'll pull me to 6000rpm. Yours will peak near 7000rpm, is your bottom end built for that?
just trying to help someone with the knowledge I gained from my mistakes.
Also you know that cam is mechanical right? You know how to adjust valves? you would need to do it once or twice a season with mechanical lifters.
110 LSA will be harder to tune with the '86 computer (mine hated it), the overlap causes the O2 sensor to permanently read lean as intake air passes into the exhaust. The tune can be done though, just a word of warning.
Finally 248/248 at 0.05 duration is a lot, especially with L98 heads. On my 383 build with new ported Brodix 200cc heads I'm only running 230/238 and that'll pull me to 6000rpm. Yours will peak near 7000rpm, is your bottom end built for that?
just trying to help someone with the knowledge I gained from my mistakes.
http://store.summitracing.com/partde...4&autoview=sku
Just worried about the duration is all.
Drifting
Joined: Nov 2006
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From: Ontario
sounds like you have everything under control. Is it a forged balanced because I personally wouldn't run a cast balanced past 6200.
That's still some massive duration is right though, for a 350 with not the best heads I'd personally tone the duration down.
Also still don't ZZ4s take roller cams? I thought the did, that'll get you better drivability with higher lift. (the one you listed is still only flat tappet though hydraulic)
Just trying to get a feel where you're going.
That's still some massive duration is right though, for a 350 with not the best heads I'd personally tone the duration down.
Also still don't ZZ4s take roller cams? I thought the did, that'll get you better drivability with higher lift. (the one you listed is still only flat tappet though hydraulic)
Just trying to get a feel where you're going.
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From: altered state
St. Jude Donor '05
That cam is way too big for what youre using it for; youll hate it.
Even with 10.5:1- 11:1 and a good breathing head I wouldnt go bigger than 24X on the intake as far as a soild flat tappet goes.
Try Ron over at Isky cams, they have something that will work; some of them are older grinds but they sure do work well . Get those heads ported, too youll need it..
Even with 10.5:1- 11:1 and a good breathing head I wouldnt go bigger than 24X on the intake as far as a soild flat tappet goes.
Try Ron over at Isky cams, they have something that will work; some of them are older grinds but they sure do work well . Get those heads ported, too youll need it..
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From: Near Lockport NY Black 1986 Coupe
Okay, I'll ask questions then. What do you guys suggest as a cam? The motor has around 500 miles on it so far and I can't afford new heads so trying to find a cam that will work with the current heads and a carb. I'm looking for a powerband somewhere between 2k-7k. 6k is still a nice max but I'm sure the motor will wind up higher at WOT. Oh, and a mean, lopey idle is a must. 
The closest I've come across is a Lunati with 246/246 and .515/.515 @ 108 ls. I know I need lower duration, but I want atleast .510-520 lift.
The closest I've come across is a Lunati with 246/246 and .515/.515 @ 108 ls. I know I need lower duration, but I want atleast .510-520 lift.
Drifting
Joined: Feb 2003
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From: San Antonio Texas
Neither of those Cams you listed were Roller Cams. Try Comp Cams site, or call Jegs or Summit for a good choise. I'd say 230 IN/ 236 EX @ .050 would be max Duration, and get all the lift you can. 110* Lobe Seperation (LSA) will give you a "lopey" idle. Later if you get some heads, all you'll have to do is add 1.6 rockers and you're good.
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From: altered state
St. Jude Donor '05
With stock 113 heads they just arent going to flow enough. To crutch it youll have to run a tight lobe center like a 108 and less duration. Youre keeping the dual plane?
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From: Conroe TEXAS!
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The factory got 355Hp @5250 (405 ft/lb ) with the ZZ4 carb engine (113 heads )
BUT had to change to the Fastburn heads to step up to 385HP using the SAME zz4 cam.
Does that not tell you something about the flow capability of your heads.
Go figure.
You may get it to rev to 7000 but bet there is no usible power over 5500; the HP curve would go flat or even drop.
Even the GM ZZ383 (425Hp ) crate engine only has .509/.528 lift 222/230 dur with much better Fastburn heads
Last edited by rodj; May 8, 2008 at 01:40 AM.
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From: Texas
Your valve springs will have to be able to handle your cam and then possibly piston to valve clearance will be a issue at a certain point. When you start going over 230 at .050 on duration with a 110 lobe sep angle vacuum for brakes starts to become a issue also,also will need a converter if its a auto, just a couple things to consider.