Karma's Riv

ugh, 350 is all they go for now? I think it came out to 700CAD shipped when I got mine way back in the day...

If I run 1.6's they will be stock.

Wow! That's a lot of money! I really should just save up and buy some, now knowing that they are 350 us dollars new, would you say that they give a worth while performance, or should i look for a used set?

For 350, i'd say they are worth it. what I paid, perhaps not.

Soooo, back on topic....

Anyone have any comments on the potential cam? too radical with 1.8's? Experience or opinions about what I need to consider about valve train geometry if running that much lift?

So no comments eh?

Ok, well I've decided to purchase the above cam, since it seems to be one of the only games in town. Since I'll be messing with the engine on the stand, and have access to a machine shop, I'm going to see about getting the heads to take the .571/.568 lift that I would get with my 1.8 rockers on it. I know its not the higest lift thats been done on the series 2, but I'm not sure how this all shakes out on the series one heads. I can machine down the valve guides a bit or run the different retainers to get the extra movement room. Worse case is I'll just run stock 1.6 on the cam, it would still be an improvement than just running 1.8's on the stock cam.

It's too bad there isn't a 1.7:1 ratio rocker, or is there?

Yella Terra sells a 1.7:1 that should fit a series 1

http://www.yellaterra.com.au/products/car-performance/product-detail/part.cfm?partIdentity=158&modelIdentity=20&productCategoryIdentity=4

RidzRiv wrote:

Yella Terra sells a 1.7:1 that should fit a series 1

http://www.yellaterra.com.au/products/car-performance/product-detail/part.cfm?partIdentity=158&modelIdentity=20&productCategoryIdentity=4

Holden series one is our pre-series one. Holden series 2 is our series one. And Holden Ecotec is our series 2.

So not quite what you linked. Though they do make a 1.7 set. But I've got other things to spend money on. We'll see if I can get the lift to fit with the 1.8's. It puts me in the area of an intense stage 3.5 cam.

They say pre-eco, and isn't the ecotec their series two? so wouldn't that make the pre-eco a series 1?

Actually this is pretty confusing because it says Holden - V6 3800 S1 - Pre-Eco from 12/90,

I found them looking up the part number of the series 1 yella terras from intense, and these were in the same holden section on Yella Terra's website.

eh, most AU sites list their stuff slightly different. pre-eco can be their series 2 (our s1) or their S1(our pre s1). To further confuse things, I've noticed a trend lately for them to start using our naming conventions instead of the Holden ones.

Looking closer, the ones you linked are 5/16 studs so that should work on our S1.

I have a few questions for ya.

1. Would 1.9:1 rocker arms have clearance issues in a series 1 with a stock cam?

2. How long do you have to wait for your cam?

3. What will you be driving during the installation?

Assuming S1 heads are like S2 heads, I think you'd be fine with that cam but you'd have to have some serious springs (like 150lb) to avoid any float at high rpm. The lift would be pretty high but duration [207/218@.050] isn't crazy. XP cam is 212/224. so you should be safe from interference and it should be nice to tune although that exhaust duration really helps for a positive displacement s/c. For S2 heads to accept the higher lift, you should just have to machine down the valve guides with at least .030" extra for your left and use the lower profile seals. I don't see why S1 heads would be different.

Thanks Turt! Thats what I was looking for.

I read somewhere that running higher ratio rockers ontop of a mild cam ment that the spring pressure didn't have to be quite as extreme for the lift. Something about less valvetrain strain, and the ratio rockers reaching and leaving the amount of lift faster than the round lobes of a cam could. So a lower seat pressure could be used since the setup was less prone to valve float. But I really can't remember where I read that...

The guys who pair 1.8 rockers with the S1X cam usually run 130lbs so thats what I was thinking...thoughts? A lower spring pressure (obviously while still avoiding float) works in my favor since I can't do a double roller timing chain like the s2 can.

RidzRiv wrote:

I have a few questions for ya.

1. Would 1.9:1 rocker arms have clearance issues in a series 1 with a stock cam?

2. How long do you have to wait for your cam?

3. What will you be driving during the installation?

1) 1.9 rockers would be fine with the stock cam if you could find them for S1. The s1 cam stock is milder than the s2 one. You would want similar supporting valve springs as is done with s2 and 1.9 rockers though.

2) Still finding out if I need to send them a stock one or not.

3) I have a spare low milage engine that I'm doing this build on.

Karma wrote:

Thanks Turt! Thats what I was looking for.

I read somewhere that running higher ratio rockers ontop of a mild cam ment that the spring pressure didn't have to be quite as extreme for the lift. Something about less valvetrain strain, and the ratio rockers reaching and leaving the amount of lift faster than the round lobes of a cam could. So a lower seat pressure could be used since the setup was less prone to valve float. But I really can't remember where I read that...

The guys who pair 1.8 rockers with the S1X cam usually run 130lbs so thats what I was thinking...thoughts? A lower spring pressure (obviously while still avoiding float) works in my favor since I can't do a double roller timing chain like the s2 can.

I would agree that it's less dangerous to have slightly underqualified springs in a high ratio rocker - milder cam setup as you don't have long durations keeping the valves out longer which in turn gives you more room (in a timing sense) if they float, they won't be kissing pistons at least. To lend an idea to how close it can be, James degreed and plotted an IS4 cam and IIRC he said it puts the valves within .030" of the piston when you don't have any float. That's a very high lift/duration cam but I'd say that is the limit and it's not because of valve guide clearance at that point.

Also part of the lower spring rate philosophy is that using a high ratio rocker on a bigger than stock cam is pretty stressful on the rockers themselves. I haven't read enough about it to see if people are actually breaking any but the T&D or compcams? shaft mount rockers are stronger for this setup if you can get your hands on/make them. Our pedestal mount rockers are not the best for brute strength as all the force is being applied across one little pivot pole mounted in the center of a rocker that wants to twist side to side.

I guess in this case, I'd opt for 130's and avoid rpm's much over 6000 (all guessing)

PM james. He's got a turbo S1 build in the works. I'm sure he could tell you what's up.

Watch your lift amounts and spring binding. I don't think you can run 1.8 rockers on an XP cam without modifying the spring seats to avoid binding the springs. I have heard of people doing 1.7s but don't know if they are modifying the spring seats to add clearance.

The more lift and sharper the lobe dropoff, the stronger spring you need to close the valve without float.

So my mid engined riv conversion is coming along:






Haha, I wish. Could you imagine?

It's..... beautiful!

there's ;ots of room out back of the Riv for such a mod.entirely doable.

Looks like a souped up leaf blower...will it be ready by October?

What in God's name is it?

I dont like how those exhaust pipes meet with a squish. Looks like they lose some girth there and then open a bit after.

Its a Ford GT, doing a compound supercharger arrangement using a centrifugal supercharger:


(That "squish" is an adaptation of an "X" pipe, which improves velocity and scavenging effect between the banks for more HP. Its pretty common, especially for Ford guys.)

Damn...that thing will blow some leaves. I'd like to rent it for a day.

charlieRobinson wrote:

I dont like how those exhaust pipes meet with a squish. Looks like they lose some girth there and then open a bit after.

Charlie, they don't squish, its all one pipe, open, like an X pipe.

What's the benefit of roots + centrifugal?

Compound boost... Some might say worst of both worlds but at those power levels it doesn't matter that much...