Holley 300-66 manifold, Anyone using it - Third Generation F-Body Message Boards

tanager11 · 09-22-2002, 10:05 AM

Guys, any of you out there using the Holley 300-66 manifold out there. I am interested in hearing your feedback on it in terms of performance and any issues in terms of problems with installation of it.

What do you guys think about me putting it on my L03 which is fairly stock (really just headers and other small stuff) and has a cam to come? Good choice, or not?

Thanks

Chuck! · 09-22-2002, 02:29 PM

I always take **** for saying this lol but Ill say it again.

With stock heads/cam you really dont need a better intake manifold and larger tbi. I'd save your money and get gears if you dont already have them.

But the manifold is solid. My friend greg runs it and he likes it , also has the 670 tbi. Didnt really help him out when he had stock heads/cam, but now he has ported 187s and the lt1 cam, it gets movin pretty good.

tanager11 · 09-22-2002, 06:54 PM

Thanks for the input even if you take **** for it!

The cam is over the winter, so hopefully once the summer comes things will be ready to go (new intake/cam)

Anyways thanks again for the input

therealalkybird · 09-29-2002, 01:48 AM

I have the intake and the 670cfm on my bucket and they work pretty well on the built 350 in there just one problem, there is little to no chance of putting the EGR back in place without a throttle body spacer. But besides that it is a nice setup.

Snowdog 91 Formula · 09-29-2002, 10:51 AM

Yes you definitely need a spacer... about 5/8" at least if you are to use your EGR valve.

MericanMuscle · 10-08-2002, 08:30 PM

Using the spacer will you have enough hood clearance on a stock hood.. and would you have to use the spacer if you use the egr from a late 70s truck or something like that?

Snowdog 91 Formula · 10-09-2002, 12:44 AM

You will need the spacer if you are going to use the EGR valve.
No getting around that.
I'm sure you can get away with a drop base element or a lower height air cleaner... say 2.5 inch.
Worth it.

MericanMuscle · 10-09-2002, 11:38 AM

For the spacer should get one that was meant for the 7.4 since i will be running the 300-66 with the holley 670 tbi or the one the one that is for the 4.3 5.0 5.7 with the adaptor plate for the 670 tbi. this is from the jegs catalog. Also will the fuel lines give me any trouble??

Snowdog 91 Formula · 10-09-2002, 11:44 AM

I had mine made custom for me, I have no clue about the ones from the magazines. Just be sure it's for the 2" bore and not the 1 13/16" bore.
Edit: I meant 1 11/16"

tanager11 · 10-28-2002, 10:45 PM

With the HLY 300-49 it says it is for Aluminum Heads.....will this work with my 89 stock L03 heads (cast)

Snowdog 91 Formula · 10-29-2002, 09:57 AM

Difference between the 300-49 and the 300-66 is the angle of the two center bolts on the intake manifold.
The 300-49 would not be a direct bolt-on and the 300-66 will.

tanager11 · 10-29-2002, 06:14 PM

Thanks...I am assuming it will fit under the stock hood, provided I am not running a 3" air cleaner