First off, please keep in mind that I have done some reading and searching for info but I still lack a lot of knowledge about how everything works together and what not.

If you look to the left you will notice that I have an 87 IROC with the baby 305 TPI motor which means I also have the tiny cam. From the searches I have done on here and all over the net, it seems that the cam in my motor has the following specs... 204/209, 0.404/0.414, xx LSA

In some of the reading I have done, it seems like the cam in my motor is made for economy and low end torque. From what the books were saying, it also made it sound like using the stock cam and adding more lift would only make it more of a torque "monster". Now, is it the lack of duration that makes it great for torque or is it something else? Anyway, this got me thinking...

Since I've read that the stock iron heads can't handle more then ~0.500 lift without major machine work, would I be able to use some 1.7 or even 1.8 rockers (and appropriate valve springs) to get more lift which should increase torque? Are there any companies that make 1.7 or 1.8 rockers for the small block motors... I can only find these rockers for the big blocks. I don't think they would, but do the rockers interchange?

Main reason I was thinking if this was possible is because I don't want to pay to get the computer retuned. Would I still need it retuned after going so much higher with the lift?

The engine is one of the areas I don't know much about. So, can you please explain why this may or may not work without going way over my head since I'm first diving into this.

Thanks for anything constructive,
Mike

 

1.6 roller tip rockers are a direct bolt on and worth it. Changing the stock springs as well as the valve stem seals (so you dont get the white puff of smoke on startup) is also a good idea while you're in there. Finding 1.7 or 1.8 rockers (these are race only parts) for a stock engine is not worth the hassle, in my opinion.

No you will not need a computer tune for this mod.

 

I already have the white puff of smoke on start up so I will be pulling the top end off the motor and porting intake and completely rebuilding the heads after I port those too.

- Do you know if the BBC rockers will fit my SBC heads?
- Is it true that more lift with the stock cam will just make it more of a torque "monster"?
- Would the 1.6 rockers be a seat of the pants difference?
- Would the 1.65 rockers be worth the extra $?
- What springs are good to get, or what spring specs should I be looking for?
- Should all the components be purchased new, or can I get them used to save some $?
- Do you know if my heads are the swirl ports? I thought it was only on the TBI motors but I was told by an engine builder that my motor probably has them too.
- While the heads are off, would it be worth upping the int/exh valve sizes? If so, what should I go to and about how much would this cost?

Thanks Kevin!

 

- No I dont know if BBC rockers fit on SBC's. Probably not as I think BBC rockers are 7/16" studs and SBC's use 3/8" studs.
- Increasing the lift will give you more horsepower and torque
- Yes, its about 10 HP and 10 TQ at the wheels.
- Not on stock heads with a stock cam.
- I recommend Manley 22409-16 springs and 23651-16 retainers for stock heads and cam. Even with 1.6 rockers.
- No your heads should not be swirl-ports.
- No its not worth spending that much money on stock heads.

 

Thanks again!

So what does duration effect? I know it is how long the valves stay open, but what effect does it have on how the motor runs? One thing I remember reading is that carbed motors like a lot more duration then fuel injected motors.
Another thing I'm not totally clear on is overlap. How much of it is better for different kinds of motors? A lot of overlap is what makes a vehicle idle rough isn't it?

Mike

 

Here is my main question. If you plan to port and rebuild the heads, why are you concerned with using BBC rockers? You may as well do a cam swap while you are at it and just get 1.6 rockers. Comp Cams makes "K Kits" that include everything you need. If you get one of the tamer kits (or an LT1 cam) designed for computer controlled TPI cars, you could probably get away with the stock tune.

While I am by no mean an expert in cam design (someone toss the BS flag if I am off), a simple description of what duration and lift actually are is this:

Duration = the amount of time, or duration that a given valve is open. Lift is the actual measurment of how far the valve opens. So the amount of air that theoretically can flow (given the heads, intake and exhaust can keep up) is a function of how long the valve is open, and how far it opens. Cams with low duration, and high lift like the newer comp XFI cams open the valves much quicker than your lazy stock cam, so the engine spends more time at maximum lift. The goal is a larger area under the curve.

Also you may want to check on your cam specs again. The ones you listed are closer to the specs of the better cam offered.

Peanut cam specs = 179 / 194 .350" / .384" Int/Exh

If you have a stock LB9, your heads should not be swirl port.

 

wow... if that is my cam I am very depressed...

I'll try and look into that k-kit stuff.

Would either of you happen to know what part number my heads may be, or is that impossible to tell unless I pull the valve cover?

 

So I went on summit to take a look at what is available for those kits and the only one that was computer compatible was this one. That is a lot more then I was hoping to spend and I would still need pushrods and rockers and all new gaskets... that's gonna be over $1,000! For that I might as well jump on the band wagon and do the 350 swap to get the same power and potentially a lot more.

Can anyone confirm what my cam specs should be?

 

Yea, you have the tiny peanut cam... the one with no duration and no lift. Sorry. IMO not much point doing rockers to increase lift with it unless you're bored and they're laying around.

If you just want a better 'stock' type cam, the stock LT1 or LT4 cams are probably the best option but its a lot of work to do.

 

Now that it is confirmed that my cam doesn't even deserve to be used, my rocker idea is out the door for sure. I guess I can't avoid it now... time for a cam swap. I figured I would use the LT1 or LT4 if I can find it for a decent price. I'm just worried about the cost of a cam swap. When I do something I cant stand doing a half *** job. So, when I swap the cam, I will probably replace everything taken off the motor with new parts if it looks even remotely worn. I don't know why but it just drives me up the wall. That's why I'm always worried about the cost.

When I did my suspension, everything put on the car was new... new bolts, new bushings, new brackets, new suspension pieces themselves. For something like the PHB brace, I even took it off blasted it, repainted it and used new bolts to put it on. I recently pulled the AC from my car but didn't have time to swap the box yet (its just sitting there) and it is bugging me like you wouldn't believe. I don't have OCD or something its just that I know its there and I know it shouldn't be that way.

 

Ok, I did some more reading/searching and I found some more info.

Some cam specs with 1.5 rockers (with 1.6 rockers):
--------------------------------------------------------
Peanut cam: 179/194, .350"/.384" (.373"/.410"), xxLSA
Better Stock: 204/209, 0.404"/0.414" (.431"/.442"), xxLSA
LT1: 205/207, .447"/.459" (.477"/.490"), 117LSA
LT4: 203/210, .449"/.450" (.479"/.480"), 115LSA
LT4 Hotcam: 218/228, .492"/492" (.525"/.525"), 112LSA
ZZ4: 208/221, .474"/.510" (.506"/.544"), 112LSA

- It seems like I would want something in the range of 200-215 for duration so I can get the higher power band without having to get a chip made. The 200-215 range is supposed to be best for ~1500-3600 range, no? It seems like if I go any more then that I might have issues getting enough vacuum.
- It also seems that 1.6 rockers with either the LT1 or LT4 cam would need aftermarket springs because the stock springs are pretty much maxed out at .490 lift which would be achieved with the 1.6 rockers.
- I read that because of the overlap built into the LT4 cam is so much higher then the LT1, it doesn't need an EGR setup. If I would use the LT4 cam would I be able to take off my EGR system while still keeping emissions under control?
- Since I have an automatic tranny, would I need a higher stall converter or can the stock one be used for now? What is the stock stall?

Mike

 

Hey, the cam that I used in my car was a crane cam 114122. That cam worked really good in my car. it is
RPM Range: 1,200 to 4,800 rpm
Duration @ .050" lift: 204/214 (int/exh)
Valve lift: .423"/.446" (int/exh)
LSA: 110
my setup looks like it is identical to yours, I had frame connectors, but the car went 14.2 at 95mph with a 1.99 60'

If you are going to leave the heads alone and the intake i would not go more that, the hot cam in my opinion is to big for a stock 305, and will need a chip to be burned. the LSA made the car have a slight lope at idle but worjed really good.
I would leave all the egr stuff alone, it really doesnt hinder performance as If I am not mistaken, at WOT it is disabled.
The stock stall in the car if I am not mistaken is around 1700 or so. i got a converter out of a 93 blazer and it bumped it up to just over 2K. still has the lockup feature and works great.

 

Isn't your lobe separation too low for the stock computer to be ok with it? Main difference between our cars is that yours is a 350 and if I remember correctly, mine is a roller motor. I think it was 87 that was the first year of roller motors.

My best run (8/15/2009 82*F & very humid):
R/T: 0.085 seconds
60': 1.626 seconds
1/8 Mile: 9.950 @ 68.85 mph
1/4 Mile: 15.562 @ 93.61 mph
Weight: 3,550 pounds with me in it
That was only my 5th pass ever down the drag strip and I was having some traction issues on old street tires. I don't know how I got such a good 60' time but I ain't complaining. My goal is to get in the 13's after everything is modded and put back together. Putting the subframe connectors back on would probably help too, but that is for another thread.

- Are there special push rods or lifters I would need or are stock replacements more then good enough for my goal/purpose?
- What kind of machine work should I have done to the head and how much do you think it would cost?
- Should I upgrade to the 7/16 rocker studs or is that only for high-revving motors?

 

The motor in my profile is my new motor. I had a 305 last year with that cam, stock intake, long tube headers and stock heads. the stock push rods are good and the bigger studs are IMO not worth the amount of machine work. If you want to do that get a pair of heads that already have all the stuff you want. The computer was fine with that mod and worked great.

 

What kind of changes could you feel after the cam swap? Did you use 1.6 rr at the same time? Were you able to take a trip to the track to see what it ran?

Mike

 

I did not test the before and after. But I had a friend with a stock tpi car and i took him right from a stop start to top end. I did not use 1.6rr or rr for that matter, I used the stock ones. I took a couple of trips to the track and the best that my setup went was 14.2 at 95. I am hopefully going to the track within a week or so to test the new setup.

 

Awesome! If I use some drag radials so I don't break the tires loose, I should be able to get to the 13's no problem. I still have some more weight to take out of the car too so it looks like this is possible. Now I just have to find the money...

 

My car weighed about the same as yours and I had a sub box in the rear and 3/4 of gas. The best part after i went down the track I had the best fuel mileage and could not duplicate it again lol

 

- How long are the stock pushrods? Would I use the same length pushrods with the 1.6 rockers?
- Where can I get cheap stock replacement pushrods and lifters? On Summit it is gonna be ~$200 for all the pushrods and lifters I need.
- Is it worth the extra money to get full roller rockers instead of just the roller tip rockers?

Kevin, would the part numbers you gave still work even if I use the LT1 or LT4 cam and 1.6 roller rockers?

Once I buy everything for the cam swap, head porting, and other misc parts, it will end up costing me ~$1500. That's pretty much new everything except the bottom end. Does that sound right?

 

Here are a few K-Kits that may suit you. I don't know where you got that 4x4 kit, but it helps to get part numbers from Comp's web site rather than summit. You should be able to type these numbers into summit.

K08-500-8
K08-501-8
K08-300-8
K08-302-8
K08-464-8
K08-465-8

How many miles are on your engine? You can reuse roller lifters if they are in good shape. Same with push rods, but they are relatively cheap.

 

I just went on summit and started filling out the info to match my car and once I hit computer compatible that was the only thing left. I thought it was odd too.

My odometer reads ~40k miles but the previous owner supposedly did a lot of highway driving so maybe it rolled over. The interior is mint and I'm only the third owner so maybe it really is only ~40k. How can you tell if pushrods or lifters are bad?

 

If your car is in as good shape as you say, they are probably fine. You could lay the push rods on a flat surface, and see how they roll when you tilt the surface, look for wobbles, and inspect them to see if any are bent.

For the lifter, just check that the roller spins easily. Someone else chime in here... as for the hydraulics, I swould think if your car is running fine and is in good shape with low miles, it is safe to assume that you don't have any collapsed, stuck, or otherwise jacked up lifters.

 

Can you explain this?

The only issue is that it recently (like 2 days ago) started making a clicking/ticking noise. I've been told it could be several things. One person said I probably never noticed it before and it is just the injectors pulsing on and off, another said a rocker is the cause... basically no one ever said the same thing so I'm to the point of just rebuilding the top end completely. I don't know if this helps but it sounds like it is coming from the drivers side towards the rear of the motor.

 

You are going to need to talk to somebody more knowledgeale in order to learn exact procedures. I dont want to give bad advice. I would suggest searching and then posting specific questions on how to inspect your valve train for wear on the general tech / engine board.

 

Ok, thanks for being honest instead of rattling off random stuff.

 

I was in a similar situation a few years ago when I did my trans swap, and decided to pull the engine to clean it up and change valve seals. My car had only like 50k on it, so I just reused pretty much everything. I put in new seals, 1.6 rockers, and new push rods (they were only like $30 at summit). My car is an '85 though, so I have a cam more like the one you orginally posted and it is flat tapet instead of roller.