I have a 87 tbi motor that I want to replace. I want to use the older (pre 85) block if possible. I have a good 4 bolt from 79 that I would like to rebuild and run as a TBI motor. I also want to use the older style heads.

Have any of you used an older block as a replacement motor but kept TBI instead of a carb?

Is there anything I need to know that may make me want to look at a newer block?

 

a roller cam....

the TBI can be swaped on your 79 block, you'll just need a diffrent intake since your running older style heads, witch is always a good idea anyways, its a pre block so theres no roller cam, but im sure you can come up with a cam that will suit you, and work with your set up, if your after power id go carb no point in wasteing a 4 bolt main block that wont see anything over 250+hp

 

Technically anything less than 500 hp doesn't need a 4-bolt.....I have an older block under tbi, it really doesn't matter if your burning your own chips. If you not then you'll need to get a 350 chip and try to make the motor as close to stock as you can. You'll also need a 350 knock sensor and EST module as well as the 350 injectors.

You'll also have to slot out your intake bolt holes on the center 4 bolts since the older heads aren't angled. You probably already knew that though.

If your not burning chips don't stray too far from stock, you'll end up with headaches.

 

if you where repileing to me, thats what i was intanding....

 

I have a pocket programmer but will still try to keep everything as close to stock as I can. I only want around 225 horses with the best mpg I can make it.

Can a stock roller lifter system be put in the pre block?

I know there is some sort of bracket that bolts to the block to secure the lifters.

Can the pre block be drilled and tapped to make it fit?

I want a roller system but only if I can get a good used stock roller cam. I dont want to spend all the cash for an aftermarket when I can get it at the J/Y for around $30...


Also, will the TBI manifold (that I elongated the center holes) work perfectly with older style heads?

I know there are differences like heater plumbing, maybe EGR. But I assume that ECM will not be the wiser about the heads. Is this correct?


Sorry if this is in the wrong forum, I really don't know where to put it since most my questions will be about making the entire TBI system work, not really about swapping the enginge (thats easy )

 

To answer some of the questions that you have...

The roller setup can not be put into the block as a direct bolt in. You can do some grinding and drill and tap 3 holes and get the stock setup to work.

Right on with the aftermarket stuff they are expensive.

Now about the intake and the ecm I can't tell you brother. BMmonte is pretty good with that stuff man. He would be probably be the dude for you talk too.

Good Luck

 

just my two cents but u should easily be able to make 225 hp on a 305 tbi engine w/ better gas mileage than the same built 350. an after market intake w/ exaust and headers and possibly a new cam should put u over that on a stock 305 tbi id think. if u really wanted to make better power just use some cash and get some better heads or even a lil better than the lo3 heads and go w/ the 305 tbi heads and have them ported a lil bit.

 

The intake will work fine, just elongate the center bolt heads and away you go.

The ECM might be the wiser about the heads, just because they flow differently from a set of swirl ports. If you can burn chips you are going to be ok, even if you really can't tune yet, we can get you up and running and changing basic things like injector and engine size, turning off EGR and making big fueling changes so the ECM can compensate for the differences. You never mentioned if you were swaping 350 for 350 or 305.

The roller is a no go. Not only do you need the spider that holds the alignment plates, the block has to be machined for the alignments plates. Gotta have a roller block, most later truck blocks are roller, but didn't come with a roller cam. You can tell by the 3 cast in towers in the lifter valley, and the flat machined tops on the lifter bores. I don't think a roller cam is super important, but a roller cam will give you a little more bottom end torque and response, whether or not it's worth gettting another block is up to you.

 

I currently have a 305...

A 4 bolt 350 cost the same to build and buy as a 305 and is worth ALOT more. Even though a 305 will meet my needs, the 350 4 bolt is just a better investment and has more potential for the future if I want to use it in something else.

BTW - I get 350 4 bolt long blocks for $70, as many as I want. Phoenix is great for gm parts The last one I got was a 010 with high nickel and tin content


Will LT1 heads work or do I need the LT1 block too?

I found a pair of 94 alum lt1 heads for $300 in real nice shape. I would rather rebuild those if they will work on a non reverse cooled engine...


I want a roller cam for the improved mpg via extra hp so I need to get that worked out. I may have to go aftermarket /sigh


Here are the things I plan to do to get better mpg's and HP:

Cat Back
Headers
TBI spacer
TBI fuel pressure regulator
Injector spacer
Roller rockers
Roller cam
Flow matched injectors
Electric fan
Heated O2 sensor
Improved spark system like coil/plugs/wires (still looking into this area)
Custom tuned to the best of my ability

Is there any other mods I missed that I should include?


I am going to use a 747 ecm and I am running a th400 behind it, btw



I guess I need to know what the best heads, compression, and cam I need to use the above mods BUT make sure the ECM works as designed.

I don't mind going higher than 225 hp as long as it does not cost me miles per gallons. Anything after 200hp, is a waste for me so I want GAS MILEAGE to beat the top.


Thanks for all the help, fellas

 

With gas milage in mind you may want to look to the tranny first, cutting a 1000 rpm out of your cruise speed is going to be worth more than any combo of parts you throw at your motor.

Skip the flow matched injectors, and prssure regulater (unless your just converting your stocker which is easy). Those things will just eat into your budget and get you no where. The best thing you can do is build torque where you cruise and get your cruise RPM down as low as possible. With that said you need to build torque in the 1500 to 2500 rpm area. Go with long tube headers and a good dual plane intake like a performer. Don't wast your time and money going with an aftermarket block just for a roller cam. Find a late model roller block and go from there. The money you would spend on the aftermarket block would pay for the gas difference over the life of the motor. Seriously I doubt a roller cam would be worth much more than maybe .25 to .5 mpg. The big thing about roller cams is that you can really agressive lobes that move lots of air, which you aren't interested in. Actually I need to double check, but I swear I read somewhere that a flat tappet is worth more bottom end torque down really low in the less than 2500 range.

LT1 heads are a no go without massive modifications, do a search if your still interested, but you would way better off with a set of vortecs.

 

im building a 76 model 350 engine for my 92 tbi as we speak.will need some computer mods but will be great when its done