Dougs 90

GM 12370846 - Hydraulic Roller Design

This hydraulic roller design contains eccentric for mechanical fuel pump. It is for off-road use only. The duration at .050" tappet lift (intake/exhaust) is 222/230; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 509/528. Valve lash is zero/zero and lobe centerline is 112 degrees.

Max lift would be 543/563 with 1.6 roller rockers correct?
I am looking to perk up my ZZ4 (Gen 1) 350SB. Currently running LT4 Hotcam kit w/1.6 rollers, Ported Superram, 52mm TB. Heads are currently stock 113 Dports, looking to upgrade haven't made final decision yet. Dyno2K shows this making killer torque and good hp with any head I throw at it.
1. How do I determine if it will pull enough vacuum at idle?
2. Is this too much cam?
3. How do I determine the spring load etc needed for this type of cam?
I currently have the Hotcam spring kit (LT4), is it enough or do I need more?

Thanks,
Doug

korvetkeith

Those heads are really holding you back.

gkull

I do know that 222/230 H-roller is a relatively mild cam when combined with 112 lobe centers it will have a broad TQ courve and In the 14 or so inches of vacuum at idle. Just from the specs I would guess 5600 max power depending on the heads and compression.

It's a mild cam - good compromise

Most h-rollers run 135-145 seat pressure at installed height. Then you have to know what the max the spring lift is.

Dougs 90

So it should be around 14lbs vacuum at idle, is that enough? Actually, what are the vacuum requirements for a Corvette?

So to figure spring lift I divided the 1.5 value given by 1.5 and then multiplied by 1.6 to get the value I asked about, correct?

As far as heads go, I am still trying to decide on some. I am looking real hard at AFR 195, and AFR 180. I am considering the 180 for the velocity as the flow numbers are very close. Any other suggestions?

When you say a mild cam good comprimise, do you mean it is a good comprimise for street/performance car? What I want is killer performance yet still retain streetability. Also, if I am going to got through all of the trouble to replace a cam (my first time!), I want it to be well worth my while. If all I am going to get is a small change, I don't want to do it.

Any suggestions for cams?

Thanks,
Doug

cv67

I like the 180 head size for a mild 350. You could always work over the 113's, but the $$ would be close enough to justify going aftermarket.

Dougs 90

Thats what I am thinking, and if I purchase a new set, I can sell my old (1500 miles) heads to offset the cost.

By doing a comparison, I think the AFR 180's are a better fit for a 350, it flows very close to the 195, yet the 180cc runners should develop alot more flow velocity correct?

Thanks,
Doug

gkull

Less than 10 is where you have problems.

Auto Math .509 / 1.5 = .339 .339 x 1.6 = .543

You need to find out the ratings of your existing springs. Or just go ahead and buy springs with the correct pressures for H-roller and you need at least .600 max lift rating to cover your 1.6 rockers.

Some people on this forum have had some pretty fast 1/4 mile times with the LPE 219 cam. They used it to be CA emission compliate

222/230 is bigger than 219/219. The exhaust number isn't as critical as the intake. The ported super ram also limits the intake duration that you can use. Super rams are a tuned port length. If you go with to much duration /valve overlap you ruin the port flow. I don't know the exact figure (I was told once before), but it seems to me that Ported super rams top at under 230 degrees of duration.

Anyway - I did the hopping up 350's in my Vette. In one of it's final variations it had 230 cc Dart heads with a Solid roller cam. My advice is go with the 222/230 and heads that match the ported super ram. If 180 cc are Felpro 1204 gasket size and AFR 195 are Felpro1205 gasket size and your port intake is 1205 size you have to install 195's

Dougs 90

To all of you, thanks I appreciate the help! I am not very motor literate, still trying to learn this stuff! So I think it is time to start hoarding pennies, and search for a set of heads. Anyone know what the Accel base gasket is by chance, I am still searching......

Dougs 90

Is that less than 10 at idle?

Since I am considering upgrading to this cam, would I be better off sticking with 1.5 RR?

I have considered the 219, and the offerings TPIS has, but for the price I think I can do better elsewhere. $300-$400 is alot for a cam I think. I have already consigned myself to AFR heads through asking local gearheads, here, and also evaluating the numbers and running them on Dyno2000. I think for the money, if they are as good for real as they are on paper they can't be beat.

Also saw this the other day:

Super AFR ZZ4

So I want to keep intake duration under 230 for sure. What is the advantage of a split duration vs same duration like the 219?

I have been looking everywhere for the Accel SR base intake gasket size and cannot find it. Neither Accel or Lingenfelter list it with the product.

I am assuming velocity matters at the valve port, is it better to give 2 or 3 CFM at the upper end to have a smaller runner flowing nearly the same #'s? This would create a greater velocity which is what is wanted correct? What effect does increasing the valve size have, it seems as if it would shroud the port and restrict flow along with reducing the velocity into the chamber. Also how much of an effect does milling heads down to 58cc from a 64cc or 72cc really have on flow?

Thanks,
Doug

korvetkeith

Supposedly the Accel base matches up perfectly with AFR 190s.

Red Tornado

I would say this is true, but the problem is you can't get new 190cc AFR heads anymore.

I have the AFR/TPIS L98 heads, these are 187cc's and you can buy them direct from TPIS, right off the shelf. These fit perfectly with my lightly ported Accel SR manifold, using Fel-Pro 1204 gaskets

Caboboy

My SR Accel base matches a 1205 (as do my AFR 195s), but I can't remember if we ported it out to that size. CRS disease I guess.......

I've got an untouched SR at home......... I'll check the base when I get home tonite if you'd like.

Dougs 90

That would be cool, thanks!

Caboboy

Doug, here are some links. The first is of the stock Accel base from the SR I have laying around...........it's by no means close to a 1205. Frankly, I was shocked at how crappy the casting is so I took some extra pics of the ports. I don't remember my other SR being this bad before it was ported, but I guess it was????

The second link shows the SR that is currently on my motor. I never did get any shots of the port match with a 1205 in place, but it is matched to that gasket. As you can see, everything is matched up on that particular intake and the port work smooths everything out.

Now that I see the huge difference porting makes, I can't imagine ever putting an untouched SR on a new motor

http://pg.photos.yahoo.com/ph/cabobo.../ph//my_photos

http://pg.photos.yahoo.com/ph/cabobo...oy40/my_photos

cv67

If the exhaust side of the head and the exhaust system is not retrictive, a single pattern will work fine. I think the split (in duration) on the stock cam was only like 5 degrees. Seems the trend these days is leaning towards a split pattern cam. IMO two cams with thte same specs except for a few degrees difference on the exhaust would hardly seem noticeable on the SOTP dyno. There are other factors involved too, but they get pretty confusing after poring over them.
Yes, you are right as far as the velocity factor goes on the heads. Your porter can probably get the double humps to work good for waht they are, but seriously consider the aftermarket. Lighter, better combustion chamber and runner shape all add up to power. If you go with the 219 I'd stick with the 180 head. They will outflow the ported SR with no problem and vacuum should be very liveable.
Comp has a line of Extreme Energy cams that are designed for F.I. which look very nice, also.