LS1-450

iTrader: (33)

Hey guys. Can we make any changes to the 85 engine without causing non-tunable issues? Everything I've read says that an 86+ MAF operating system is required. The 85 we are looking @ has a MAF. So, why can't it be re-scaled for mods? Am not a tuning or an engine newb. Some of you may even already know me, from this site.

Basically, just want to know if we can slightly port the TB, align the intake to head runner ports, swap to 1.6:1 rockers & install a set of long tubes. Even though this isn't really that drastic, it is too much for a non-tunable operating system. What can we do to the operating system to handle the mods? Thank-you in advance.

87silverbullet

iTrader: (11)

You can do little modifications like what you are talking about but just like an LS1 if you could throw a tune in there to compliment those mods you will see even more of a gain. The problem is you have to keep on burning chips to change the tune. You tune it yourself with a few mods done to it by just playing with fuel pressure and timing, but that only goes so far.

If you plan on doing more mods down the road I would look into EFIconnection so you can put a flash style pcm and get more tunability.

http://www.eficonnection.com/eficonnection/default.aspx

LS1-450

iTrader: (33)

^^^
Thanks for the reply. I think we'll just re-build stock w/ just a set of long tubes, buy an upgraded tune & call it a day. That should be enough for what we will need. Thanks again.

NufNuffZ28

iTrader: (13)

The 1985 ECMs are different than the other years. They use a digital MAF system that is different and is harder to manipulate...

It is a relatively simple solution to change it to the 86-89 MAF systems if you desire.

IMHO, I think LT's, cam, do a gasket match on the intake at all points, rockers, and then up the timing to around 10* initial and if its lean get a FPR to up the pressure and compensate. It should work fine whether you get a new chip burned or not.

LS1-450

iTrader: (33)

Yah, it's for a family friend. We've offered our assistance & want to do only what's doable in a simple manner. Don't want it to turn into a situation where we assisted & then get blamed for an operating issue...if you know what I mean.

Thanks for the reply. If we can do it as you mentioned, w/ fuel pressure regulator & 10* base timing, that sounds good. Any recommendation for ignition? Is there a preferred distributor (similar to the improvement of a truck coil over a stock LS1 coil on an LS engine) or is the stocker good enough? Also, will any FPR do or is there a preferred FPR? I've got an older vacuum/diaphram type.

Mike Morris

iTrader: (55)

Don't forget to port that upper plenum as well. SLP used to make a CAI kit for that car that worked well as well will not screw up tune.

Love 85s-no third brake light!!!

Sublime Dak

The problem with TPI setups isn't the ECM, but the craptastic flow of the factory lower intake and runners, after 4,500 they are wheezing like a chain smoker running a marathon.

87silverbullet

iTrader: (11)

That is true but the ecm has the processing ability of about a pocket calculator.

The TPI intake was actually made for the 305. It was on the 350 when it started to act like the Hoover dam.

Sublime Dak

The factory ECM may not be as fast as modern ECMs, but it's more than capable of handling most TPI builds. The issue I have with them is the pain in the *** burning prom chips, very reason I always push for swapping to say a MS setup.

LS1-450

iTrader: (33)

We've already discussed rev limit of the 305 tpi with him. He knows that above 4500, no-one is home. So, we're good there. We'll do what we can up to 4500 & that's where we'll stop. I'm really hoping for straight & true rod & main bores, as well as, cam & somewhat true piston bores. So, that she doesn't need machining. We will see. Again, the goal is to end up w/ a descent engine w/ just a few easy enhancements along the way. Doesn't have to be perfect. Just no spun bearing related conditions.

I still can't get a straight answer on what the stock head gasket thickness is. Have heard anywhere from .015" up to .073". Will know for sure once the heads are removed. If above say .050" may reduce thickness for a little more combustion ratio. If not, we'll keep the thickness stock w/ no head milling; just clean up the deck.

87silverbullet

iTrader: (11)

I agree with that one and I have built a Tpi car with my cousin and we replaced the intake with a HSR and put in a TPIS zz409 cam and AFR/TPIS 187cc heads and his computer is handling that with a stage 5 chip from TPIS. It is a pain in the *** getting chips burned for it and I think the next step will be a setup from EFIconnection. It puts down 362 to the rear wheels now so with a little more tunability from th EFIconnection setup it might make more power.

87silverbullet

iTrader: (11)

I want to say the stock thickness head gasket is .041 or .039. There is a gasket that GM makes that is a composition gaskest that is .028 that would help bump the compression. If you are going to pull the motor apart you might as well just put a little cam in there. Check out the Crane Powermax cams, they used to be the compucam line.

http://www.jegs.com/p/Crane-Cams/Cra...69834/10002/-1

Mike Morris

iTrader: (55)

Another good one that is easy to tune is the TPIS superprofile cam which was rereleased. However I don't know if it will work well with a stock 85 computer. Used it in many stock promed later cars and it ran great

LS1-450

iTrader: (33)

Thanks, but, IDK about being able to handle that much duration w/ the tpi. We will get similar lift, but w/ much less (202* 206*) duration by using the stock cam + the 1.6:1 ratio rockers, of which I think will be easier to tune w/ fuel pressure. Am concerned that the longer duration cams in the link will feed more air than we can tune for by using the simple pressure/timing technique. Also, would be concerned about the longer duration cams regarding PTV clearance if we were to go w/ the noted .028" head gasket. Am thinking that if the stocker is .039"-.041" & we use the .028" head gasket, the 1.6:1 ratio lift w/the shorter duration stock cam has a better chance of clearing without the need for fly cutting. Of course we would measure, but that is my thinking.

Yah, I think we'll go 1.6:1 rockers, stock cam & decide on gasket based on the thickness we find when the heads are pulled. Just don't want it to turn into 100's of dollars of un-planned for tuning costs when we are done w/ the mild enhancements during the re-build. After all, it is just a little 305 regardless of mods. Thanks for all of the replies. Will update as we go.

Mike Morris

iTrader: (55)

Make sure its indeed a stock 85 305 TPI cam and not an 86 and up-those cams were TERRIBLE

zz17iroc

iTrader: (1)

I also agree that a HSR or a Mini Ram intake is a vast improvement in performance over the stock style intake. And I also agree that it is a pain to have your chip burned for tuning, but this is what I did to help me in my tuning efforts. I swapped to the 730 ECM which is speed density. Then added a 4K of memory board to the stock 730 ECM. Go to Moates.net for the NVSRAM module http://www.moates.net/nvsram-module-....html?cPath=31. That allows me to download and upload bins through the ALDL just like a LT1 and LS1 ecms. I can even make corrections to any table while the car is still running using TunerCat or TunerPro all this info can be found on thirdgen.org DIY tuning forum.

You don't need to spend $1600 on a LS1 conversion to go fast. My buddy in FL. had his 89 GTA converted to LS1 ecm by EFI Connection in two issues of GMHTP and only picked up 7 hp over his 730 swap. He didn't even finish tuning his old set up. What I'm trying to say is if I can control 461 rwhp 383 with a factory 730 ecm anything is possible.

NufNuffZ28

iTrader: (13)

Any distributor is fine and use a FPR that goes in the stock location and you can turn with your thumb. MUCH easier that way. I think it's the Holley unit.

If you're going from a 305 to a 350 throw in some 24 lb injectors as well....

87silverbullet

iTrader: (11)

So does the 730 ecm have just as much tunability parameters as the ls1 pcm? I never said you would need an ls1 pcm to go fast. My cousin's car ran 11.83 @ 116 on the old ecu which is not bad cosidering what H/C ls1 cars are doing. I already have hptuners so buying the EFI connection setup would be a breeze to put on and take on a big forced induction build we have planned for it.

Your buddys car must of made 461 on the bottle because we ran just as fast as you with less cam and less cubes on the motor plus it went 11.00 flat with just a 100shot. Full weight with A/C and 3.42 gears. Do you think that big cam was killing the 60ft or something? We are both down south so I doubt the D/A has much to do and the elevation is not a factor.

LS1-450

iTrader: (33)

Will do. Also, found that the 85 cam spins up to 5000 RPM, not the 4500 I mentioned earlier. That's an added bonus.



OK, thanks for the response.

LS1-450

iTrader: (33)

Sorry about the double post. Didn't think of this earlier.

How difficult is it to swap the flat tappet lifters for 87 roller lifters? Can we use the rollers on the flat tappet style cam? What about oiling, any port alignment issues, lifter to block? Am pretty sure that we would need to re-measure pushrod length. That's no big deal. Am thinking that the biggest issue could be whether or not the roller lifters work on the existing cam. If not, who makes a roller cam w/ very similar to the 85 flat tappet cam specs?