I posted a while back about project with my son. We're converting an 88 305 TBI to TPI. The donor TPI is from an 85 305. So do we need to use a cam with specs for the TPI or can we use the existing TBI cam? It looks like they are two different cams. And, if we use the old TBI cam do we need to re-flash the ECM for the 85 TPI or what?

 

I'd take a slightly upgraded aftermarket cam over either stock grind.

 

I guess my question is this...do we flash the ECM differently depending on which cam we use? I have the computer from the donor TPI, if I use the old TBI cam, will the ECM from the donor TPI work with that cam?

 

It would work but would be a poor choice.

 

More than likely it won't work. There is quite a difference when you compare the internals of the engines. The systems are quite different, in '88 GM in the Camaros had a wicked little motor due to NASCAR homoligation rules. The cam in a '88 TPI 305 is worth about $700. They are fairly rare and you should be very sure before causing any damage. Best way is to find every number on the parts and the block and talk to a good engine builder. Mixing the parts could prove costly. Good Luck...

 

This is the funniest thing I've read all week.

 

Glad you get a giggle... Unless you go all after market, how else will it work??? Or do you only advise those who pay and give the rest smart *** remarks???

 

If there's a way to pay for advice on this site, I've never found it. Like all free advice, it's worth every penny.

There are no major differences between 85 and 88 that's significant in this context. The 88 has a roller cam from the factory but it will take an 85 cam with a flat tappet setup with absolutely no issues as well. That'd be a waste of time, though, and a waste of a perfectly good roller valvetrain.

There is no magic wicked little NASCAR homologated engine. In 88 GM introduced the 1LE package for SCCA homologation. It has exactly the same unwicked engine as any other non-1LE car.

The cam in an 88 TPI isn't rare and worth $700. It's as common as dirt and probably has a market value of about $50. At one point you could buy them from the pound from people who had removed them to upgrade. Still a waste of time.

The best solution is an aftermarket factory roller cam. A slightly upgraded grind won't cause any issues with clearance or tuning. Failing that, a takeout like an LT1 cam would work. Whatever you use, the good news is that thanks to the 88 factory roller setup, you only need to change the camshaft itself. All your lifters can be reused.

 

That is some pretty funny stuff.

Next thing you know, it'll become an Internet legend. You know... <6-yr-old> "mommy, mommy, it's gotta be true, I saw it on the INTERNET!!!" </6-yr-old>

That slice of BS right there will probably outlive us all. Nobody will believe it 50 years from now when you show em the part #s for the cams and it turns out the 88s got the same lame-a$$ stuff all the other TPI motors did, because .... they "heard" "thought" "everybody says" they're different.

 

The 88 cam should be fine, but the 85 cam is better and , no, it should not pose any problems as there looks to be a lot of other members on here with that cam swap. You will be using that tpi ecm anyway. I would put the 85 cam in while you have everything apart.

 

Just remember, the 88 tbi cam is roller if i am correct and the 85 tpi cam is a flat tappet. If you do use the 85 cam, i would throw some new lifters on there too. Also, when i used to work on Ford 5.0 motors , the same situation applied. The earlier 5.0 motors were flat tappet and the later motors were rollers allowing you to re-use the roller lifters during a cam upgrade. Thus, you have to change the distributor gear out ot swap distributors due to a roller engines having a steel gear on the distributor to match the cam and the flat tappet cars using an iron gear. You cant mismatch these. You will be likelyto tear up the gear on the cam if you use a distributer made for a roller cam on a flat tappet camshaft. So, basically you need to use the 85 tpi distributor as well just to be safe.

 

Stick with a roller cam. Find a cheap used lt1 cam at a minimum. No more than $50.

 

Right: the 88 cam, like all the 87-up ones, is a roller; and the 85, like all the 86-back ones, is flat-tappet.

The cam in the 88 TBI motor is the same one (the lamest cam profile of all time in any SBC, actually) as the lower-perf version of TPI that year. Pretty much garbage.

As far as being "better", the 85 cam has a slightly more aggressive profile, but suffers from being a used flat-tappet cam. Highly risky in this day and time to reuse, because of the characteristics of oil. Due to environmental regulations it lacks the necessary additives to assure the survival of flat-tappet setups. What once was all but bulletproof, is now failure-prone to the point of being sheer folly.

A better choice altogether is an appropriate aftermarket roller one. TPI, with its tuned effect (the "T" in "TPI") puts fairly unique requirements on the cam profile, in addition to the general requirements that EFI as a whole places on it. A cam that might work great with many other induction systems can be a complete mismatch to TPI.

A good choice for an otherwise stock TPI 305 is this one http://www.summitracing.com/parts/CCA-08-500-8/ Re-use your existing roller lifters. Make sure you replace the valve springs, as the stock ones are only just barely enough for a stock cam WHEN NEW, and are completely inadequate to support a superior cam to the weenie stock thing.

Also, GET RID OF the TBI heads; they will prevent any other improvement from making ..... any improvement. They are without question the worst head-shaped objects possible for performance.

 

Sofakingdom is right, why not upgrade the cam. Once you do that you'll want more so get rid of those swirl port heads.LOL Although that cam he posted looks a little high on the lift for tbi heads and tpi also. I think you should keep the duration below 220 and the lift no more than 470 while LSA should be no less than 112. That way the cars ecm shouldnt complain. A custom chip is always better tho. Looks like you can't go wrong with the Lt1 cam.

 

I went form a stock 305 to a 350 ZZ4 crate motor with an aggressive cam might as well replace it while the engine is getting fixed