Alright, I have LT1 heads and intake that I'll be putting on either my 305 or a 350. I was leaning towards the 350, but I think I'm going to stick with the 305 for a while yet since I found where it was leaking oil, I don't mind keeping it anymore, and I want to see how fast I can go with it. Before anyone says I'm wasting money on my 305...both the heads and intake can be swapped over to a 350 in the future, so I'm not wasting anything. Funds are tight and it'll cost me quite a bit more money to drop the 10:1 350 in that's in my uncle's garage.

Anyways, I had an LT1 cam and decided that was too small for me, so I went with another one. Its a Speed Pro something or other. The specs are..

222*/232* int/exh @.050"
.479"/.501" int/exh (.511"/.534")
109*/119* int/exh centerlines
LSA 114

I was wondering if this cam is going to be too big for my 305. I have the chip tuning/burning stuff, and I know its going to take a lot of tuning, but will it work?

The motor should have 9.8-10:1 CR, the heads should flow 260ish/180ish and have 1.6 NSA RR's with guide plates, and 1 5/8" headers with full exhaust. Springs will be upgraded, and there are already 3/8" screw-in studs in the heads.

I know this cam has a bit more duration than the LT4 Hot Cam which was one of the ones I was looking at. This cam has less intake duration but more exhaust duration. The LSA on this cam was also attractive.

The reason I opted for a bigger cam was that I want some more top-end power and that I want to put the same cam into the 350 whenever I put taht in. I didn't want to have to buy two separate cams.

EDIT: Forgot to mention the car will also get a 3200 stall 9.5" torque converter and some gears in the back between 3.23 and 3.73.

 

You said that you had the LT1 heads and intake. I know it is possible to swap the LT1 heads on a L98 block, but how did you choose to do it? I won't say anymore on that right now.

That cam is big for a 305 but it sounds like you are willing to work around it. 3.73's and a lot of tuning could do it. You will have virtually no power under 2,000 RPM though. And it might suck driving in stoplights, and on the highway. But it could be done. I would worry about ballancing and drivetrain strength issues, as you will have to spin tht pretty high for the power you might be looking for.

 

Where also is Bloomingdale in Illinois?

 

LT1 heads and intake, same thing as tpi_roc did basically. I haven't gotten it all done yet, but I will be in the next few months. I just want it done by next track season.

The 3200 stalled TC should help make up for the loss in torque from a dead stop, and the 3.73s (if I go that big) will help a lot too.

And yes, I'll be spinning to roughly 6k, but the stock bottom end should be good to about that. If I blow it, then I'm forced to drop the 350 in That's not the plan though.

I'm hoping for very low 13s with this setup.

Bloomingdale is roughly a 1/2 hour west and slightly north of Chicago. Between Naperville and Schaumburg near where 290 and 355 meet...about 200 miles north of you

 

With those head flow rates (260ish/180ish), would I be better off using a single-pattern cam? That's one of the things that's been getting on my mind lately. Will I lose any performance going with a split-pattern cam over a single-pattern cam?

 

I would stay with a dual pattern cam. 180 is good, but if you have that big of a difference from intake to exhaust flow, stay with a dual pattern. My 355 with the hot cam makes peak power around 6,000 RPM. So I would say that yours will deffinatly be higher. That is why I am wondering about spin balancing it. Centrifical force can really have a major hand at 6,000 and up.

 

I'm not going to do any work to the shortblock on the 305...6000RPM will be its redline. When I finish the 350 though, that will probably be balanced out to 7k or so..

 

Yeah that seems too big for the 305, but heads and intake mods make up for it. Computer controlled car? Carbed?

 

Sorry just saw it was a TPI, its too big for the computer to read. From what I have been told and read.

 

It's big, and will require effort to tune but it isn't impossible. It would be the equivalent of tuning a 230/236 cam on a 350.

 

Hmm I suppose I'll try it. How will it affect my vacuum at idle?

 

youll probably pull around 12 inches, or less at idle. thank *** you dont have a speed density, or youll most likely be adding DFI. a MAF should be decent at handling the calibration, but a prom burn is a definate. ...tom

 

I fail to see why DFI would simplify tuning over SD when you have the right tools. Also, most DFI systems are MAP based.

In all honesty, I find tuning SD easier than MAF on a heavily modified engine. 9 times out of 10, the real issue with SD is idle. You simply have to find what the MAP value the engine is idling at, and tune accordingly. Most of the time people used a version of the stock VE table and didn't modify the upper MAF values for 600-1000 rpm. Its the lower vacuum causes it to be in the higher MAP range where it is overly rich on the factory settings. All you do is lean it out. Very easy on SD.

FYI, you also need to do a simliar adjustment to the MAF Scalar tables at the lower values due to reversion. While I don't find a Romulator to a necessity to tune SD's idle with a big cam, I do find tuning the MAF Scalar tables very time consuming without a Romulator. Not impossible but quite time consuming on some heavily modified engines.

Where SD get's time consuming is rescaling the VE tables for the rest of the engine's operating range. There, I find MAF tends to be easier as the upper VE tables tend to not require much tweaking.

To properly tune WOT, a Romulator and a WB is almost a necessity to tune either system. But not manditory. A Romulator and WB makes tuning WOT for both systems much easier and with greater accuracy. And with both a Romulator and WB, tuning either SD or MAF is a snap. And a heck of a lot cheaper than going DFI (which has it's own problems too).

 

The plan is actually to convert to SD when I switch manifolds because the LT1 has a MAP sensor mounted right on top of the manifold in the front.

It sounds like SD is fairly easy to tune as well. MAF is decent, but I don't think it gives as many choices.

The idle vacuum is what I'm worried about for my brakes. Maybe I'll have to raise my idle to like 900 or so..hopefully not more than that. 12" isn't much at all.

And yes I completely agree that a WBO2 is necessary to get exact tuning done. I want to eventually get one to dial in the AFRs everywhere.

Part of the reason for running SD is also to remove my MAF sensor from my intake. I have a K&N CAI that my buddy gave me off his old '97 Z28 and it uses 3.5" tubing and hoses. I have it bolted up around the second lip on the MAF right now because it was too big to just slip on like the stock fitting. I want to make it a full 3.5" intake, preferably out of stainless steel or aluminized something or other to make it look nice eventually.

 

FYI, a buddy of mine is swapping his cam for a solid roller 248/256 on his 383. He is currently running MAF and while he also wants to swap to SD, I won't do it UNTIL we have tuned the MAF system as good as we can.

Then we plan to take it a dyno and the track to see what it can do. Once we are all finished, I will convert him to SD and then do the same just to see if there is any difference at all.

I personally am not expecting much of a performance difference. And since we have a Romulator and WB, it really doesn't matter much to me which system he has.

So don't think you HAVE TO swap to SD. After years of tuning and working with both, about the best reason I can see for swapping from MAF to SD is because your MAF went and you can pick up the SD ECM dirt cheap at a wrecking yard.

Also, I am finding it more difficult to find MAF ECMs in wrecking yards these days, and due to the shortage, the price is going up. If my only alternative to purchase a MAF ECM was a new one from GM at their "bend you over" prices, I would look at swapping to SD for the cheaper ECM.

But from a tuning persepective, both can be tuned with similar end results. One does one thing easier and the other does another thing easier...basically a draw in my opinion. Maybe when I tune for my buddy's solid roller I might change my opinion, but for now, I am neutral.

 

glenn91l98gta, i understand what you are saying, its just that i know a few people running 434s, with stock MAF and a romulator and wide band o2, sensor, that are running 10.50s in their cars . i was just saying that the stock MAF is more forgiving with this kind of camshaft, expesially in a 305. alot of people are running too much injector, and too much camshaft, for the TPI engines. i for one would not even think of running a camshaft like the one in question in a 305 even with the LT1 heads and intake? you are involving yourself in more work than it is worth. if it were a a super ram or mini ram, it still would be too big. i have a 436 EFI engine w/ a solid roller that is reaking havoc on my speed density, and i know there is much more power in my combination, but what am i supposed to do ? im not trying to be a **** ,but until my engine delivers the amount of vacuum i need , which it wont, my next step is a DFI, and a dyno tune.

 

Would I see better times with something like a Comp Cams XE268? Assume a redline of 6000RPM with either cam (both should make power up to 6000RPM). The 268 would deliver more low-end torque for a minor loss in top-end.

These cams are a bit expensive new though and kind of hard to find used. What makes the XE series stand out from the rest? How would a cam from a different company compare with the same/similar durations and lifts?

Maybe an LT4 Hot Cam, as it has a bit less duration and a bit more lift?

 

You are right, something is not right there. I don't know what heads, intake and other aspects of your combo. But I would believe that you are running a decent set of heads and intake. Have you chatted with the guys on the DIY Prom Board?

I haven't been around for the last while due to health issues, so please pardon my questions if you've already been there and still haven't gotten any results.

Even if traction/hook-up was a problem, your MPH is way too low.

Shoot me an e-mail, I am now listing an e-mail address again...just remember to remove the "REMOVETHISPART" stuck in the middle of my e-mail address (to stop spam/phish bots).