350 305 throttle bodys

[rsgt]

I am installing a gm tbi on my 305. I have a throttle body from a 350 that is good and injectors from a 305 tbi Is it ok to install the 305 injectors on the 350 throttle body? Thanks

[EagleMark]

Yup! They are same size and bolt right in. Throttle blades are also some size. Good to go.

Always have your injectors serviced. Least this way you know they flow correctly and are a matched set.

[jhnyct]

That goes the same for the 4.3 as well if I'm not mistaken.

Is the injector half interchangeable with the 88-91 and the 92 and up? I am planning on using the throttle body from an 89 4.3 and injectors from a 92 5.7.

[EagleMark]

I'm pretty sure the injector pods are all interchangable. I have not found any yeat that are not, excluding one barrels and 366 Industrail engine has differant injectors.

[1project2many]

Some TB's use a thick spacer between the injector pod and the TB. The cast alignment pin which keeps the injector pod aligned is taller on these units. You need to use the spacer in order to use the pod without modifications, or you will need to drill out the TB or grind the pin shorter. FWIW the spacer raises the injector out of the TB slightly which has been reported to help airflow into the TB. One source for these pods and their corresponding spacer is 4.3 powered Astrovans.

Big block powered medium duty trucks use the same smaller injectors as the 366 industrial engine. The injectors are similar to the ones used in the model 700 TBI.

[EagleMark]

Good information! Wonder why GM saw fit to raise the injector pod on a 4.3 Astro Van? Also wonder if that is the same 4.3 that has differant injectors right and left?

[jhnyct]

How would that spacer be different than the ones that are sold on ebay?

http://cgi.ebay.com/ebaymotors/CHEVY-GM-INJECTOR-SPACER-86-95-TBI-UNITS-_W0QQcmdZViewItemQQhashZitem230e95c947QQitemZ15056 8552775QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

Recommended or not?

[1project2many]

Who said the spacer was any different?

Minimal gains, like many of the modification to TBI systems. Without the longer alignment pin the injector pod isn't held like it's supposed to be. Most people make it work anyway.

[EagleMark]

Who said the spacer was any different?

Minimal gains, like many of the modification to TBI systems. Without the longer alignment pin the injector pod isn't held like it's supposed to be. Most people make it work anyway.
Oh it was just a longer alingment pin...

[EagleMark]

Some TB's use a thick spacer between the injector pod and the TB. The cast alignment pin which keeps the injector pod aligned is taller on these units. .
Wait, you said the spacer was differant? and the alignment pin taller?

[Six_Shooter]

Yeah, don't worry about the pin length. The thicker gasket just raises the injector pod in relation to the main body.

[1project2many]

Here's the pin in question:
http://www.snflupigus.com/pics/pod/3.jpg
Judge the pin length issue based on your situation. The injector pod is where the fuel lines terminate and because of this the lines can place a fair amount of force on the pod if they are moved or if they're not secured properly. With only three screws at about .210" diameter there isn't a bunch of torque resistance if the pin isn't engaged in the TB and the pod is forced to twist. Then again, Holley sells a replacement injector pod which has no alignment pin at all and I've never read that anyone has had a pod fall off.

The pod can usually be raised slightly but the spray cone can't be allowed to spray outside the throttle bore. You can see some gains by reducing the height of the shoulder which extends the main bore(s) toward the pod.

I saw a fair gain in a stock TB intake by cutting the dividing wall between the main bores and welding up the resulting hole which also blocked hot coolant flow through the manifold. http://home.metrocast.net/~shannen/efistuff/L03_Intake_changes/L03_Intake_1a.jpg

Using a single plane 4bbl intake with an adapter plate is good but you'll need extra AE to compensate for the larger plenum.

[1project2many]

The edit button seems to be inoperative.

I meant to say "Using a single plane 4bbl intake with an adapter plate is also good but you'll need extra AE to compensate for plenum volume.

[dave w]

I've had excellent results with radius blending the factory throttle bores.

dave w

[mudbuggy]

What was the purpose of removing the perimeter of the tbi base? To allow more air in? More fuel air mixing? Was this for a heavily modified motor?