Edelbrock makes two TPI bases, the 3860 for "centerbolt heads" and the 3861 for aftermarket and older heads. Does anyone know if the 3861 can be made to fit the centerbolt heads and what is involved?



------------------
1990 Roadster

 

Yes it can, but why? The difference is the center 4 bolts, the angle is different on the heads so the holes wont line up until you do some massaging to the holes in the intake.
If I were to guess, you have a 90 Vette? Well then you need the 3861 manifold because the heads on the vette have the 'older heads' style of bolting the intake rather than the newer style, even though they are centerbolt valve covers.

 

Whoa, am I confused. Do you mean that the Vette heads are different then the f-body? Edelbrock lists the 3860 for the 85-92 centerbolt and the 3861 for aftermarket and older heads. Quote from the web site:

"Baseplate retains factory fuel injection parts and emission equipment. Compatible with stock or aftermarket runners. Can be ported to improve flow capacity. Requires no changes to the computer. Baseplate is stock height. #3860 has been machined to clear centerbolt valve cover heads; #3861 is for all other heads.

High-Flo Baseplate Only (1985-92 engines) #3860
High-Flo Baseplate Only (aftermarket & early model heads) #3861"

------------------
1990 Roadster

 

'90 Vette heads do not have the "newer" intake bolt pattern with the 4 off-angle bolt holes in the middle of the intake. Yours are the standard "old style" with the same bolt hole angles for all 12 bolts. Based on this, you would order the 3861 intake for your Vette.

 

Thanks for the help

------------------
1990 Roadster

 

The 3860 is machined for both bolt hole angles (45 and 72), while the 3861 only has the 45º holes. You can use either one, but the 3861 is better in your case, as was mentioned above.

------------------
West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

I'm digging this old post up from the dead. I used to have center bolt valve cover heads, so I brought the Edelbrock Hi Flo 3860. Since then I have brought Brodix heads....The 3860 has both the 45* and 72* bolt patterns so it will bolt right on. Is there any reason I cant use my 3860 and need the 3861 which Edelbrock says to use for aftermarket heads and pre 85 cars??? If my 3860 will work I dont understand why they would even make the 3861??

 

TTT

 

spoke with Edelbrock today..They told me the 3860 will work with centerbolt or after market heads no problem

 

I'm pretty sure the only difference between the 3860 and the 3861, is the 3861 uses the 86-older intake bolt angles, and doesn't have provisions for EGR. The 3860 has both bolt patterns, and EGR. That assumes that Summit's descriptions are correct. The stock photos appear to be the same.