Edelbrock 3870 User Manual

©2006 Edelbrock Corporation

Brochure #63-3865

Catalog #3865, 3870
Rev. 9/06 - RS/mc

PLEASE study these instructions carefully before beginning this installation. Most installations can be accomplished with common tools and
procedures. However, you should be familiar with and comfortable working on your vehicle. If you do not feel comfortable performing this installation,
it is recommended to have the installation completed by a qualified mechanic. If you have any questions, please call our Technical Hotline at:
1-800-416-8628, 7:00 am - 5:00 pm, Pacific Standard Time, Monday through Friday or e-mail us at Edelbrock@Edelbrock.com.

DESCRIPTION: Edelbrock High-Flo T.P.I. Runners are designed for use on 1985-Later Tuned Port Injection equipped 305 and 350 C.I.D. Chevrolet V8
engines. The runners feature an improved design and increased flow, and no changes to the stock computer are required. #3865 runners are designed
for 1985-1988 engines, while #3870 runners are designed for 1989 & later engines. Runners will fit OEM or Edelbrock High-Flo TPI Baseplates.
Replacement runner gaskets are available as #3866.

NOTE: High-Flo T.P.I. Runners are intended as a direct replacement for the factory parts. All

emissions related factory components are to be retained and functional. They are, therefore, legal for street use in all 50 states, and no C.A.R.B. E.O.
number is required. Check local laws for requirements.

❑  2 TPI Runners

❑  2 Left Side TPI runner Gaskets

❑  2 Right Side TPI runner Gaskets

❑ 6 M8 x 1.25 x 30mm Allen head cap screws

❑ 2 M8 x 1.25 x 40mm Allen head cap screws

❑ 4 M8 x 1.25 x 65mm Allen head cap screws

1.

Disconnect battery negative cable.

2.

Disconnect throttle body from Mass Air Flow Sensor boot and
disconnect all lines from throttle body (linkage, water, vacuum, etc.).

3.

Remove linkage attachments from plenum and move out of the way.
Disconnect plenum from runners and remove (it is not necessary to
remove throttle body from plenum). You may need to loosen lower
runner bolts in order to free plenum.

4.

Remove runners from baseplate and loosen, but do not remove the
fuel rails.

5.

Trial fit your new intake runners prior to final installation on your
vehicle. This way you can get a “feel” for what goes where and why.

Because of varying O.E.M. fuel line routing, some

material may need to be removed from the runners in order to
clear the fuel lines. Check for clearance before installing onto
engine.

6.

Thoroughly clean the flange surfaces of the plenum, runners, and
baseplate and remove any remaining gasket material. Use rags or
paper towels in the open ports to make sure your intake system is
kept free of all foreign objects (i.e., dirt, gasket material, etc.).

7.

Place runners into position on the baseplate making sure to use the
proper runner/gasket on the proper side and start bolts.

8.

Tighten down fuel rails and place plenum into position. Start bolts,
but do not tighten (make sure proper gaskets are used).

9.

Align plenum and runners and tighten all runner and plenum bolts.

10. Reconnect all connections and linkage to the throttle body and

reconnect the throttle body to Mass Air Flow Sensor boot.

If

clearance is a problem, it may be necessary to discard the original
steel hard line which runs from the O.E.M. baseplate to a rubber
hose connecting to the charcoal canister and replace with a rubber
hose. On the passenger’s side of the engine, discard the original
hard line (if so equipped) which ran from the valve cover vent to the
throttle body and replace with 3/8" rubber hose if necessary for
clearance.

11. Check and top off any lost coolant, reconnect battery, and start

engine and run briefly, monitoring the “check engine” light. Turn off
engine and check installation for any leaks or abnormalities.