Hey everyone! I'm new here!

I am wondering what the oem specs are for 87-92 305 tbi roller cams. I would also like to know what their "powerband" is. I'm trying to see if it's close to the tbi cams that came in 87-96 tbi trucks, I know the trucks weren't roller but I have one that is and I need a roller cam that matches close to oem spec.

 

https://www.thirdgen.org/mods3

near the bottom of the page; ends in 155

 

Just a thought,but,if your motor is already a roller,stick an OEM vortec cam in there.It would be a good improvement & shouldn't be a big hassle.Some tuning may be needed to gain full benefits from the swap. Specs are .414/.428 lift. 191/196 @ .050. LSA = 111*.There are lots of cams out there to choose from that would work better than the stocker w/o a lot of effort or costs,since your changing it anyway.

 

Joker, that is what I initially did. Big mistake. The powerband for the vortec cam is 1500-4800 rpms. The powerband for tbi cam is 0-3000. Now I am stuck with a roller setup (that I dont want to change) but need a cam that is roller that would match oem tbi flat tappet cam specs, somewhat. So unless I want to put some deep gears in the rear, swap heads, intake, and get a tune, I need to swap the vortec out. However, I am not going back to flat tappet. Roller is better!

Anyone know the powerband for the 305 tbi cam? I found a sealed power cs-793 cam that looks like a stock replacement but cant find the rpm powerband. I called and they said its stock powerband of whatever it goes in... So at a loss.

 

Weird...I had a LT4 cam in a TBI engine with the stock torque converter and 3.08s in my old G20.....Would boil the tires off.

The Vortec cam in a 305 TBI runs very well. The 305 Vortec came with the same cam as the 350. Even the little 4.3 V8 in the Caprice came with the same cam. I have used the vortec cams in past builds and never had an issue getting it to run well. The torque curve actually comes on SOONER with the Vortec roller cam.

 

Are you sure you have a Vortec cam?I've used them in a couple of L05's & L03's with good sucess.

 

Yes it's vortec out of a 97 Chevy. We took it out my buds dads truck when we were building it. Did y'all have swirl port heads?

I also have 700r4, stock converter, 3.42s and 32" tires. It's 4x4

 

Yep.Swirl ports on the L05 & L03.The L05's ran ok,but,benefited a lot from tuning.The 2 L03's needed tuning & tweaking on a bit more to run well.Actually saw more improvement in torque & HP than expected.

 

My problem is when my truck shifts at 45 mph into od them tc locks up it's dropping down to 1250 rpms, then it shudders some and feels powerless until I get rpms back up over 1500 rpms. After 60 mph it feels fine though but I live nowhere near interstate so it never really sees above 65.

The powerband of vortec roller cam is 1500-4800. Stock tbi flat tappet was 0-3000.

Anyone know powerband of stock 305tbi cam? I'm trying to see what powerband of sealed power cs-793 is before I purchase. I don't want to mess up and choose wrong cam again.

Stock 350 tbi cams specs are: TBI cam : 165in/175exh .382 int lift/.402 exh lift Lobe Sep: ? (FROM TBICHIPS SITE)
Vortec Cam: 191int/196exh .414int lift/.428 exh lift Lobe Sep: 111

 

What are you trying to accomplish?What problems are you having ?If all you changed is to swap from the L05 flat tappet to the Vortec roller on an L05,I would think you woulda saw improvement,but,no major problems.

 

I listed issue above. I also added long tube headers, transgo shift kit with corvette servos, heated o2, and electric fans. Changed from 3.08s to 3.42s

I'm trying to get it to run and perform correctly.

 

I would not touch the cam until you do some diagnostic work and figure out what is wrong with your truck. Bucking and shuddering is very likely nothing to do with the cam. Check the timing (should be 4-6*BTDC with the Tan/Black wire disconnected and the Vortec cam) and also check the plug wires to be sure 5 and 7 are not swapped. You might have also retarded the cam 1 tooth on the chain inadevertently which would make it run horrible. The stock 305 builds peak torque at 2,800 IIRC and peak HP at 4,400 rpm....Not the idle-3,000 powerband you speak of.

Those 350 TBI cam specs are way, way off, not even the 305 peanut cam is that small.

The 305 peanut cam was 178/194 @ .050, .350/.385, 109* LSA, 106* ICL.

The 305/350 vortec cam has faster ramps and not much more seat to seat duration, but has more area under the curve at 191/196 @ .050, .414/.428", 111* LSA, 106* ICL.

EDIT...What year is the truck and does it have a 700r4 or 4L60E? 1,250 seems AWFUL LOW (burn your transsion up low) to be in OD with the converter locked. On a 700r4 I would check to make sure that the TV cable is properly adjusted. Also keep in mind that going from 3.08s to 3.42s is going to need some recalibration to the governor or in the case of the 4L60E the shift tables. Either way if it has an electronic speedo in it, I would start with recalibrating the DRAC for the tire/gear change.

 

I don't think the cam is your problem.TC studder is pretty bad w/ the 700R4's & even mine feels sluggish @ 45 in OD.I basically have the same truck setup as you 4L60E w/ 3:42 & 33" tires.I don't think your cams powerband is the problem tho.

 

If you look here http://www.jegs.com/i/Chevrolet-Perf...oductId=753961. It shows stock replacement for 350tbi with cam specs. They even had to boost compression to meet the 210 hp factory rating.

I have done diagnostics. This isn't a new thing it's a problem I've been chasing for a year. I just put new plugs and wires on the truck. I have used winaldl to datalog and all. I get no check engine lights or anything. Timing is set at TDC 0* like it should be.

Brian at tbi chips is the one who finally diagnosed my issue as the cam.

 

I agree.If it's really that bad,I think you have some other problem.Just the swap to a roller shoulda netted you approx 10 HP.The added duration & lift,while not alot,should have added some as well.Befor I swapped cams again,I would go thru everything tuning wise before I swapped cams.Those cams work very well in a setup like yours.

 

The truck is a 1987 GMC V1500. It does have the 700r4, it also has a new tv cable, and I've tried messing with it several times.

Truck also has an instrument cluster from a 91 k5 blazer so I do have drac and electric speedo and I did the drac mod and have adjusted it to correct speed.

 

if you look here: http://67-72chevytrucks.com/vboard/s...=599897&page=6
I posted videos of what it is doing.

 

That IS STOCK COMPRESSION RATIO for a light duty 350 TBI and it came with a 195-210 HP depending on application. There were about 4 different exhaust setups and several intake/air cleaner, and 50+ different stock chips for a 350 TBI.

Timing needs to be higher than 0*BTDC....4-6* works out well with some engines liking up to 8*. Watch your WINALDL datalog for knock counts. Also if you can screen shot the BLM table and post so I can see what is happening. You may be running lean and need some additional fuel pressure. Many stock TBI regulators came running as little as 9-10 psi of fuel pressure. Most stock engines need 12 PSI MINIMUM to keep from going lean above 3,500. With airflow mods they often need 13-15 psi.

Brian is a horrible fraud of a tuner, watch out for him. He will try to sell you stuff you don't need to cover for his poor tuning abilities.

 

Really? He hasn't tried to sell me anything. Weve been chatting for over two weeks w/ 60 emails and he's been nothing but helpful.


What youre telling me about timing is totally different from truck forum.

here is my thread over there. http://67-72chevytrucks.com/vboard/s...d.php?t=624050

 

Is your engine healthy?Have you ckd compression,etc?Even if that is your problem,I would stay out of OD @ the lower speeds before I would swap back to a lower spec cam,but,I honestly don't think the cam is your problem.

 

Yes compression was good, I had a fuel issue where the dual tank setup was clogged but that has been fixed and now holding good fuel pressure and compression. No issues on that point.

It is so weird when I first crank up truck and drive it, before its fully warmed up, it shifts decent and the power doesn't feel robbed but once it warms up it does this. It used to shudder bad but now it doesnt even shake truck. I just feel its trying too hard.


Also, this truck will barely even bark the tires. On originally setup it would smoke the tires the hell off! and that was with a nasty oil burning high mileage stock engine!

 

If thats the stock compression shouldnt I have always needed to run premium? I never have.

 

Also just noticed in this thread you are talking about it being a 305...Yet on the other site you said its a 350. Which engine is it, what injectors, what knock sensor and what chip BCC are you running???

 

Not at all....Even my old 305 was 9.5:1 with the Q-Jet. Fed it 87 for years.

 

I apologize if I never clarified. It is a 350, 5.7. I was asking about 305 tbi Bc it came with a roller cam that is close to specs of stock tbi cam.

Stock injectors, stock knock sensor and stock chip.

 

I had a LT4 corvette cam (203/210 @ .050, .476/.480", 115 LSA, 116* ICL) in my 8.75:1 350 in my G20 van. Stock 1992 G20 Chip with Tri-Ys it would BOIL the tires off. Stock torque converter and 3.08 gears.

 

Actually it is NOT.

The stock 350 had a cam with specs as follows 194/203 @ .050, .383/.410, 112* LSA, 108 ICL

 

Yeah the original 350 tbi in the truck would do the same. Now after I out a new rebuilt engine in it wouldn't spin jack with 3.08s, now with 3.42s it will barely bark tires.

 

Sounds like your timing way off.You shouldn't need premium gas.The L05/TBI is tuned to run on regular @ 9.4:1.If you have made tuning changes that require premium,IDK.If the ECM senses detonation,it will pull timing,killing power.It could even be false knocks being picked up from a noisy valvetrain,timing set,etc.What timing set & rockers did you use?Are you sure the cam is timed correctly.Not advanced or retarded?Somethin ain't rite & it ain't the cam.

 

How are you 100% sure of that? Even when jegs replacement engine says otherwise.

 

x2....With all the information it certainly, 100% without a doubt is NOT the cam.

 

I don't run premium I run regular.

 

100% sure of this and every autoparts house across the nation lists the stock replacement cam as this. It also lists a 204/214 grind as a replacement for more torque. The 204/214 cam, known as the MTC1 or the CS1014R runs GREAT in a stock TBI 350 with the stock chip.

 

Idk what to do now I have like 3 opposing opinions.

 

I am certain of one thing however. Under load your transmission should never allow your RPM to drop that low. My G20 would shift around 2,400 rpm at light part-throttle and drop back to about 1,600-1,800 rpm. It was NEVER under 1,600 rpm unless coasting. 700r4s do not build much line pressure at that RPM and it is EASY to smoke the clutches out of it at that RPM under load. It sounds like you have a governor or governor calibration problem or perhaps a TV spring that is too weak.

 

Did you watch my vids in the link?

 

Did you rebuild the engine or buy it.If "rebuilders pistons"were used w/o decking the block your pistons are sitting .020" farther down the hole than stock,killing compression & power.If you compounded that by using a thick headgasket,it'll be even worse.You would have virtually no detonation resistance due to lack of quench/squish.

 

Read part 1, 2, and 3 of the TV 101 article by bowtie overdrives. Might just save you a transmission.

http://www.tvmadeez.com/article/index.php

 

I didn't pay anyone to rebuild it. Machine work was done then we assembled it at my friends shop. Stock style headgaskets were used

 

I've read over that before.

 

Yea I did and it is shifting WAY too early even for light part-throttle at that speed.

One other thing for diagnostic purposes remove and plug the EGR line to the EGR valve. When you added headers you may have altered how the EGR functions, allowing it to open more than it should, bogging the engine. I had to change from a positive to a negative backpressure EGR valve with headers or else I got code 32.

 

1.54 or 1.56 compression height pistons?

Felpro rebuilder .038" compressed or the hard to find factory style .028" gray colored graphite ones

 

I did have to change egrs!! Gm one kept throwing code, I swapped to one that was opposite of it and no more code.

Your saying take off the vacuum line from the solenoid and plug on the egr side on the intake? I could try that. It does only shift and end up that low rpm until after it's warm. But that still doesn't explain low power feel where I can't spin a tire.

 

Felpro gasket kit, never let me down before. I can't remember what compression height pistons. That was almost 2 years ago. Even though truck doesn't even have 8k miles on it since rebuild.

 

Not enough fuel pressure or timing could definitely explain it however. The dynamic compression ratio on your engine is slightly lower than stock. Usually this means it will want more timing.

Not to mention most stock TBI engines enjoy 4-6* of advance over stock.

 

Did you put in new pistons?If so,do you know part#,brand,or specs?Stock style headgaskets is not a good answer.LOL.There are several "stock" gaskets out there with different thickness.If you bought 1 of the budget rebuild kits,it most likely came with .041 gaskets & short pistons,which could have your pistons as much as .080" in the hole.You would virtually no detonation resistance which could have your ECM pulling timing.Your CR would prolly be almost 1 point lower & power would be way down.Then on the other end of that,if you threw some flat tops in there,had the heads milled etc,your CR would be too high,again timing would be pulled robbing you of power.

 

They were speed pro I think, with the lightning bolt. It wasn't a kit. .030 pistons were purchased seperately. I bought a complete gasket set with rings from autozone at the time I think. Felpro blue headgaskets.

 

Where the pistons flat top with 4 eyebrows, dished with 4 eyebrows or dished with 2 long valleys on each side?

Unfortunately Speedpro offers both a 1.56 and 1.54 compression height piston.

We have already established you have a .038-.041" compressed head gasket.

While both will reduce compression ratio and quench, I still do not feel this is your issue.

I am thinking its running lean and does not have enough timing.

What do your knock counts look like on WinALDL?

 

Flat with 4 eyebrows.
Knock counts were crazy when my return line was blocked but I fixed that. Would have to check again and datalog some.

 

That makes little sense to be honest. The fuel pressure should be higher with a blocked return line. A rich mixture burns cooler and should have made for less knock. I have seen some of these fuel pumps get so weak they cannot even wet the return line, yet the truck will start, idle, drive, just runs with no power. I have also seen the regulator springs break, causing low fuel pressure.