Clifford intake/ holly 390 on 250

[TheSeeker]

Hello All, I am FINALLY getting around to installing these parts I bought from months back.. I have a 250 and it already has headers, My grandfather installed them in 78, he thinks they are Hooker brand. Anyway I have the clifford intake and a holley 390 carb I rebuilt last weekend. It is in pretty good shape but we will see how tuning it goes. My questions to you who have done this are: 1.) Anything I should expect to run into as far as major snags go? Linkage, fitment, etc?

2.) Do I need to use studs in place of the original hardware to install the new intake

3.) General parts, I dont want to start and then realize I forgot washers or bolts or RTV etc..

Thanks!

['68OrangeSunshine]

Originally Posted by TheSeeker

Hello All, I am FINALLY getting around to installing these parts I bought from months back.. I have a 250 and it already has headers, My grandfather installed them in 78, he thinks they are Hooker brand. Anyway I have the clifford intake and a holley 390 carb I rebuilt last weekend. It is in pretty good shape but we will see how tuning it goes. My questions to you who have done this are: 1.) Anything I should expect to run into as far as major snags go? Linkage, fitment, etc?

2.) Do I need to use studs in place of the original hardware to install the new intake

3.) General parts, I dont want to start and then realize I forgot washers or bolts or RTV etc..

Thanks!

1] Don't know what your throttle linkage set up is now, but the bellcrank for the stock Monojet won't work. For years I had some RubeGoldberg set up to the Holley 390 and it never got WOT, was prone to jamming and even failure when a tiny hairpin would fall out. I've since gone to a throttle cable and it works great. You don't have to experiment with adapting '72 GM truck throttle cables and Lokars, there's a vendor on this board who sells the whole kit: LFD, I think.

2] Definitely you need to extract the stock manifold guide mounting pins on the ends of the head and mount studs 3/8 -16UNC / 3/8-24, with a nut on the fine thread side. Soak 'em in PB Blaster, WD40, Liquid Wrench or whatever and then they will screw out CCW with a good bite on a ViceGrips.
I used old rocker arm pivot balls to even out pressure on the header end tabs.

3] Some of the stock mounting tabs are useful, [the smaller ones] others don't work. I've found sometimes I need to double gasket the headers and intake. Or spray it down good on both sides Permatex Copper spray-a-gasket, and use red RTV around the big holes.

I have a '68 C/10 Stepside with L6 292 [original engine]. It's bored .030 over, with Badger pistons, 1.84 intake valves, Crane 260H cam, Offenhauser intake, Clifford long tube headers, Edelbrock 500 CFM 4 Bbl carb. My last engine, a '67 292 block: .030 over -- all stock or HD build-- I ran a Holley 4160 R8007 390 CFM 4Bbl. I got 250,000 miles out of it but when we rebuilt the next [current] engine, the Holley lasted 500 miles more and then wouldn't hold idle. Rather than replace the bottom plate [throttle body] it was more cost-effective to get the Carter AFB type Edelbrock Performer.
I did have fun when I put a 50cc accelerator pump kit on the Holley. By that time [on the '67 block] I had lost valve action in cylinders 3 and 4, so I was running a big FOUR. Holleys are good carbs, but take a lot of tuning, and the old ones will blow a Power Valve with every backfire. 390 CFM is ideal for a 292. Carter AFBs in 400 CFM haven't been available since the '70s, So I went with the Edel-1404 500 CFM.
I have had good luck with the Clifford headers, after a 25 year run I had them hot tanked and beadblasted and then sprayed them with VHS Cast Iron Gray and they still work great. Clifford has good customer service.
Likewise, the Offy intake came up looking new after a good soda blasting and was mounted on the new build in 2005.
Coincidence that I upgraded my L6 with high performance parts in 1978.
Good luck.

[TheSeeker]

Lots of good info there. Thank you! I'm a little bummed out I won't be able to install these parts. I have to figure out the linkage I figured I could make something work with the stock set up.. Oh well. Won't be driving the old gal this weekend again

[geezer#99]

Which way are you mounting the carb?
Front to back or sideways?

[TheSeeker]

I'm not sure. I have adaptors that look like I can mount it in v8 position or sideways like the monojet.

[geezer#99]

Here's a huge thread on what you're trying to do.
You might find an idea or two in there.
http://67-72chevytrucks.com/vboard/s...d.php?t=276823

[BCOWANWHEELS]

a note about the clifford int. there higher rpm manifolds and will slobber at low rpms. you,d be far better off with a offy and exhaust heat under it.