Another TBI build seeking advice, Head, cam options

[chris989]

Hello all,

Hard to believe it has been 6 years since my first TBI buiild for the 89 burb. Other than the GM crate motor eating the thrust bearing and having to replace the crank the motor has been flawless. The combination really runs well. We downsizes our camper to a hybrid so i have even less weight to deal with.

That said, I am considering another build.

I read many threads about aftermarket heads and cams and they all get hijacked or never conclude. If you followed my other build you see that i see it through to the end.

Anyway,, Who has sawpped their TBI heads for a set of aftermarket AFR, Trick flow, etc. Or even a vortec head. What combination did you use? what do you like or wahat would you do differently?

On big grades i have to run 3rd gear at 55-60 mph, (probably should be anyway). Big headwinds give me the most grief. I get ~13-15 mpg around town and average 11-12 on our last trip. Honestly i can't ask for better.

So all said, I am thinking of a roller cam this time and a set of heads. Considered a new 406 dart block, Had one built for my camaro and love it.

we all understand the limitation os the TBI and a 350 but there is something nice about the reliability and having parts anywhere we go.


If you have a build, advice or can point me to a forum I would appreciate it.

Cheers,

[Ziegelsteinfaust]

I watched a friend a few years ago struggle with a tbi builld. And it was all due to tuning, and parameters. Other then that the engine was a basic 95+ Vortec with a nicer cam. 330hp maybe?

There is little the tbi is technically able to do, but the tuner would be where I start first. Do you have a local expert to help you? Then hopefully dyno tune it.

If not seriously consider a LS swap for plug, and play. I am doing a 24x swap on a 5.7 LT1 I am gathering parts for there is little I will not be able solve with it as the computer is very nice.

Other then that have you done all the bolt on's? The toilet bowl is supposed to be a nice upgrade with air flow.

[chris989]

Ziegel,

There is a link in 1st post of the original build. I have a small lunati cam, intake, mandrel exhaust etc. I can data log and tune. It runs well now,, just thinking out loud and wondering who has a comparable build i am thinking of doing.

This is for towing/camping so it rarely goes over 3500rpm

[cdub2010]

With the mpg and reliability you state, why waste any time money or effort on this. Replace the crank and enjoy the campfire and beers. Seems like you have a solid setup for a camping and towing rig.

[chris989]

Originally Posted by cdub2010

With the mpg and reliability you state, why waste any time money or effort on this. Replace the crank and enjoy the campfire and beers. Seems like you have a solid setup for a camping and towing rig.

It ate the crank a few years back,,, right at 35k miles, just past warranty. I dropped in a .010/.010 from oreilllys and its been solid since.

The GM crank had .0005 clearance on the rear bearing and .001 or less on the rest. You could see the heat it was generating. When i checked the replacement crank i had just over .002.

chris

[Ziegelsteinfaust]

Originally Posted by chris989

Ziegel,

There is a link in 1st post of the original build. I have a small lunati cam, intake, mandrel exhaust etc. I can data log and tune. It runs well now,, just thinking out loud and wondering who has a comparable build i am thinking of doing.

This is for towing/camping so it rarely goes over 3500rpm

The roller cam is a great idea with today's oil.

What are you hp/tq goals.

[chris989]

Originally Posted by Ziegelsteinfaust

The roller cam is a great idea with today's oil.

What are you hp/tq goals.

I don't really know,,, Just tossing this out there thinking maybe someone had already gone down this road.

I just finished two other motors but both are over 11-1 compression with Comp magnum cams, etc and this TBI is not that type of build. Without a longer stroke it is harder to make torque under 3,000 so I was spitballing here thinking maybe someone had thrown a set of AFRs on a TBI and would share their results.

My thought is that most of it would be wasted time and money. If I have the motor apart again i would put in a roller cam but even then the Lunati Voodoo cams get a decent ramp from a hyd flat tappet.

I thought about a 454 swap but I think the MPG will suffer running around town.

[LT7A]

I went back and read your previous thread. Nice work on that. Since you are inquiring about TBI modifications, you might want to post something similar in the 88-98/OBS area. You are probably aware, but the salad bowl on top of the TBI and the ultimate TBI mods seem to be pretty effective. Metal matrix catalytic converter and the flowmaster Cat-Back system made a significant difference for me. As did going to an open element and filter top air cleaner. But those are all pretty minor compared to what you are talking about. I will be interested to see if someone has swapped to aftermarket or vortec heads and jumps in here to tell us about it.

[Mattchu60]

I rebuilt a TBI 350 6 or so years ago for my K20. I did 9.5 compression, dart iron eagle heads and one of the TBI compatible comp cams (I stuck with the stock style cam, not a roller). I put the 670 holley TBI on. used a aftermarket intake manifold with a TBI adapter plate.

For tuning, I tuned myself with Dynamic EFI system and a laptop. Lots of driving around letting it learn. I got a wideband O2 sensor and that really improved the VE table learns.

After all that it was a nicer setup than stock, but still not a powerhouse. I pulled trailers with it (live on a farm) and heavy loads gave it a massive workout.

After all that, I wish I had either swapped in a 6.0 vortec (LS Swap) or gone with a 383 for better torque.

[THI]

I have helped out on a couple of TBI builds, both SBC & BBC. For the SBC build, Dart makes their Iron Eagle SS with the correct bolt angles for the TBI intake and their flow numbers are similar to the old Camel Hump heads - by today's standards that would be a nice stock head, nothing radical but a big improvement over the TBI heads! They also have "fast burn" chambers allowing the use of lower octane fuel.

TBI computers like cams with a wider LSA like 114* to keep the MAP sensor happy though 112* will work with programing. Stroking to a 383 is the best way to increase the low-end torque and will allow a larger cam at the same time. Because of the small size of the TBI unit, do not try to build too big head or cam wise, but there is plenty of room for improvement over a stock TBI engine and still run a TBI

[chris989]

Thanks for the replies,

This may all be a moot point because as i look for parts most everything is out of stock with ridiculous estimated dates.

If i put something together i will link it in this post.

Chris