Looking to upgrade the TBI on my 90 Formula.

The Edelbrock EFI unit looks attractive, but they spec it for "pre 1986 engines", implying there is a manifold incompatibility.
Anyone got insight on how the heads/manifold mounting will be different between 90 & "pre 1986"?

kk

 

Edelbrock makes numerous systems. They make intakes for both pre 86 and post 86. Ive had 2 proflow systems on newer style sbc and vortec bolt patterns and have friends w older style ones. What are you looking for specifically? A properly running tbi should be OK(ish) but if you're looking for more power you will find lots of limitations quickly. Whats your goal?

 

Since 1990 is usually considered to NOT have occurred prior to 1986, it won't fit, directly.

However, the exact difference causing the no-fit, is that the center 2 bolts on each side, are different. On 86-back heads, all 6 bolts on each side are parallel, and perpendicular to the surface of the head. On 87-up heads, they are at an angle pointing slightly upwards. Something around a 18° difference. It's possible to slot out the bolt holes in an older style intake and either mill their pads down to the correct angle or use wedge washers to fit such a one to the newer style heads.

A better solution would be to buy the correct version for the style of heads you're using, which AFAIK is available. Of course, "upgrading" the intake while leaving those TBI heads on the motor (and the exhaust as well) is largely a waste of resources anyway, so you can choose whichever style of heads you want in order to allow the other intake to actually make some sort of substantive improvement.

 

Sofakingdom:
The story behind what I have & how I got it is long, & probably beyond interest.
That being said, the technical data is what I needed, which will enable me to make
a valid determination. I.E. w/ no manifold put in 6 bolts, & if they're all parallel,
86 & earlier. If the center two are tilted, then 87-up. Sound reasonable?

Long story short, Engine was assembled, with lots of mods & upgrades,
but never started. Life happens, & its been sitting untouched -- for that long.
Now I have the opportunity to finish the quest. Current technology &
equipment are available to replace/upgrade the original TBI injection.
If the manifold bolts are parallel...

Many thanks, good sir.

 

That is correct.

If the heads are stock ones of any sort, post the casting numbers, and they can be instantly identified. Beyond merely the 86/87 change. For that matter, if they're aftermarket, they might have numbers that can identify them, as well.

 

If you have a bunch of go fast parts then a standalone efi like a pro flow would work awesome. The newer standalone systems are extremely tunable and reliable. The air/fuel delivery ability of the tbi units is very limited, even the 454 tbi units are are limited. Then there is the difficulty in tuning.

 

What I've got now is a pretty highly modified 350, (cam, ported/polished heads, shorty headers into a 3' cat-back exhaust) w the 454 tbi on top of an Edelbrock performer. All of which has run for a total of less than 30 min's, since being assembled circa mid 90's. Life happens. Now I have the resources necessary to finish it into the sat. cruiser that was always intended. RBobs demise was truly unfortunate, & the boards lost a treasure of technical knowledge & all around great guy.. However, It left me w/ the task of dialing in the tune, that I currently would rather not try to undertake myself. The Edelbrock unit looks very attractive, if I can get the correct version. The EBL was sold a few months back, & the 454 TBI/Edelbrock Performer will be available ASAP. Removal target is this week-end, & I'll also get the casting numbers.

Good to be back w/ like-minded gearheads.

 

The pro flow xt will fit under the stock hod w some mild relief work just fyi

 

Update.

Cracker-jack Toyota tech oldest son removed the TBI manifold, & ... the heads are in fact
the post 86 versions w/ the middle 2 bolts offset. Bummer.

So that casts the upgrade to the Holley unit on a std. 4 barrel manifold.
Summit has one available w/ the middle holes overboard, & a selection of shims
to accommodate any heads.

Will try to post some pics & keep this thread as a build story.

 

​​​​​​​And the casting numbers are ... ??