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Discussion Starter · #1 ·
Presently my L67 is internally stock apart from Yella Terra (Aussie brand) 1.8:1 roller rockers. Shortly the engine is coming out for some internal mods. I intended to run a cam such as the XP or similar but would like to retain the existing 1.8 RR if possible. I will be installing CompCams 130 springs and titanium retainers etc. Heads are currently stock but these will be custom ported when pulled down.

A note about the Yella Terra 1.8 rockers...they use a spacer plate to raise the rocker cover so obviously with their design, even on stock cam, it needs extra rocker cover clearance.

My main concern is if coil bind or any other clearance will be an issue with the XP and 1.8's? Or will the 1.8's simply be too radical? Or would a custom grind and the 1.8's be a better or safer option?
 

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there will be waaay too much lift with an XP and 1,8 rockers on stock heads for sure.
I don't even know if you will be able to get modded heads that will allow that much lift.
I and several others are running an INTENSE Stage 1 cam and 1.75 rockers, however the S1 cam is much smaller than the XP and 1.75 is less than 1.8..lol
I would just go with a larger cam and drop the rockers all together.

goodluck
 

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You will have way too much lift for stock heads or even heads with reduced seals and retainers. You will be at over .580 just on the intak side with the 1.8's. If you are getting them ported may as well have them mill the guides which could give you clearance over .600. You would be in Intense stage 4 cam areas with that setup though. If you want that much lift just get a stage 3 cam and sell the rockers, you will get more duration that way.
 

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Discussion Starter · #4 ·
OK thanks guys for the info, looks like I will have a set of 1.8's up for sale soon.

So what is the MAX lift that stock (unmilled) heads can handle?
 

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Rob, I'm confused about your sig. Best ET [email protected], and then you say 0-100 6.2 seconds. Is that MPH? And if so, that last 1.47 MPH takes 7.2 seconds?????
 

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Discussion Starter · #7 ·
1Hot97 said:
Rob, I'm confused about your sig. Best ET [email protected], and then you say 0-100 6.2 seconds. Is that MPH? And if so, that last 1.47 MPH takes 7.2 seconds?????
Yeah sorry guys....here in Oz virtually everything is METRIC. About the only thing that isn't is the 1/4 mile ET...and for that matter even that is often quoted as ET over 400 metres in automotive magazines etc. But generally in the drag scene it's still the traditional 1/4 mile and mph. A typically used benchmark here for road performance is 0-100 km/h.
 

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ravenvtsuper6 said:
OK thanks guys for the info, looks like I will have a set of 1.8's up for sale soon.

So what is the MAX lift that stock (unmilled) heads can handle?

Max lift is .515, you can use mod'ed retainers to get an extra .030 without any serious issues.
 

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smooth said:
there will be waaay too much lift with an XP and 1,8 rockers on stock heads for sure.
I don't even know if you will be able to get modded heads that will allow that much lift.
I and several others are running an INTENSE Stage 1 cam and 1.75 rockers, however the S1 cam is much smaller than the XP and 1.75 is less than 1.8..lol
I would just go with a larger cam and drop the rockers all together.

goodluck
Oh you can get modded heads to handle that much lift. Know someone thats gonna be doing some crazy lift with an even bigger cam and rockers soon.
 

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You can run stupid crazy lifts if you'd like but plan on using very strong valvesprings and upgrading your lifters/pushrods/timing chain appropriately to handle it, a lot of head porting to take advantage of it, and still sacrificing durability especially of the valve guides and especially if its your daily driver.

From the nature of the poster, I don't think he really wants to get so far into the project :)

With the use of milled retainers and lowcut valve seals and Comp 105 springs, you should be able to run .550" lift without issues on stock heads, which is about all I would run on the street regardless if you want something practical and reliable.
 

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Discussion Starter · #12 ·
Overkill said:
From the nature of the poster, I don't think he really wants to get so far into the project :)

With the use of milled retainers and lowcut valve seals and Comp 105 springs, you should be able to run .550" lift without issues on stock heads, which is about all I would run on the street regardless if you want something practical and reliable.
Well I want to take it close to the limit of streetablity but yeah I don't want to go too crazy. Most times I drive to the drag meetings which is 160km (100mile) and back again. I was contemplating XPZ or Intense stage 3 but yeah I think they might be just a bit too big. It's a toss up between the Intense S2 or the XP but i feel I might go for the S3 at this time as it's a fraction bigger and use Comp 130 springs with 1.6 ratio RR.
 

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You can run s3's on the street we have a guy here who does it and drives to florida in the car every other weekend!
 

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Could the 1.8 rockers be kept but a cutom cam ground up with the same specs as say the S3 intense cam but with less lobe lift lift on the cam. Would it produce the same results seeing that the rockers will still give the same amount of lift at the valves themselfs. Just don't want to have to spend another $500
 

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I did spec a Comp Cam for a local member with Intense 1.9 roller rockers that didn't want to give up his new purchase. He'll likely give it a try later this winter or next spring. Duration was 210/220 I believe, lift with 1.9s would be 541 while it'd be 513 with 1.8 SLP rockers.

When plotted on a valve lift curve, it was similar to an XP cam's lobes using stock rockers but the curve was much broader on the intake lobe above .300" valve lift, and much quicker on and off the seat on both intake and exhaust. That, plus the fact that there's less moving mass from the lifter and pushrod could both contribute to a cam/rocker combo that would have a little more performance than a standard cam upgrade.

If you were interested, PM me or email me and I'll dig up the specs for ya along with a Comp Cam custom grind #.
 

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Discussion Starter · #16 ·
I've accepted the fact that the 1.8's are just too hard so I will go for a set of Intense 1.6's.

So.....to use the IS3 cam, what exactly has to be milled on my stock heads and how much? If freight wasn't such a killer to here I would probably just go for the CNC Stage3 heads, but I will just get my heads fully ported and built up with the larger valves and springs etc.
 

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I have the S3 N/B cam and it is quite streetable.
 

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So exactly how much lift do the 1.8 RR give.

Comparatively how much lift does the XP cam have with 1.6 RR.

I will be looking into a cam upgrade in the new year. Along with major port work on the heads and match porting the inlet manifold. I was going to get a custom cam made locally, but all this talk about the XP cam is making me rethink the whole issue. Also with Intenses experience I am sure they would have a superiour grind compared to one made from scratch.

TIA

Tark
 

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Muvro said:
So exactly how much lift do the 1.8 RR give.
Depends on the cam. Take the lift of the cam with 1.6 rockers and divide that by 1.6, this will give you the "lobe lift" of the cam itself. Then multiply that by 1.8 to find the lift with 1.8 rocker arms.

Comparatively how much lift does the XP cam have with 1.6 RR.
The XP has .520/.536" valve lifts with 1.6 rocker arms.

I will be looking into a cam upgrade in the new year. Along with major port work on the heads and match porting the inlet manifold. I was going to get a custom cam made locally, but all this talk about the XP cam is making me rethink the whole issue. Also with Intenses experience I am sure they would have a superiour grind compared to one made from scratch.
The XP cam and Intense' S1x and S3 cams have all proven themselves to be excellent grinds. Unless you can look at the detailed specs of each cam grind and know exactly what you wanted to improve upon I think you'd have more success letting Intense do the R&D on what cam grinds work :)
 

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Discussion Starter · #20 ·
ravenvtsuper6 said:
So.....to use the IS3 cam, what exactly has to be milled off my stock heads and how much as in thou?
Can anyone answer this question please? ^^^^^^^^
 
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