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post #1 of (permalink) Old 04-23-2000, 12:40 PM
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Holley 390 cfm on 258

just dropped an offenhauser intake and holley 390 on my 258, runs great but heats up to about 230 degrees in a short time. ran at 210 stock. not done with the linkage so haven't had running for any length of time. ideas?

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post #2 of (permalink) Old 04-23-2000, 02:10 PM
 
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Re: Holley 390 cfm on 258

1. Idle mixture too lean.
2. Vacuum leak.
3. Thermostat not operating correctly.
4. Jetting too lean.

You didn't say if the over heat came at idle or during operation.
You didn't say if you made any other modifications while you were doing the intake and carb.

DON'T LET THE VEHICLE CONTINUE TO OVER HEAT, unless you had a major rebuild planned...

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post #3 of (permalink) Old 04-23-2000, 04:55 PM
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Re: Holley 390 cfm on 258

Just out of curiosity, how many CFM are the stock Carters on the 258's?????

MattYJ
89YJ 4.2 5"lft 33"Firehawk ATX
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post #4 of (permalink) Old 04-23-2000, 05:18 PM
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Re: Holley 390 cfm on 258

Troy
Welcome
Listen and listen good to TeamRush . Troy TeamRush is probbly the best
you could of found to get that holley running right. Them people are hard
to find these days. If I had the bucks I would like to play with thatsetup myself.
Good luck
gregg

post #5 of (permalink) Old 04-25-2000, 03:34 AM
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Re: Holley 390 cfm on 258

I'm just thinking to do the same upgrade or go for a holley injection. I think the offenhauser should give a noticable gain in hp.
Could you give me any response about you like it? Is there a power increase? and at which rpm?
Do you have the Offenhouser 6257DP ?

Thanks a lot
Oliver

post #6 of (permalink) Old 04-25-2000, 07:43 AM
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Re: Holley 390 cfm on 258

did your origianl set up have the watercooled intake?????

Low Riders are for boys who can't get it UP...
post #7 of (permalink) Old 04-25-2000, 09:29 AM
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Re: Holley 390 cfm on 258

Thought Id drop in my two bits. I put the Holley 390 and Offy intake on my 75 258. I love it, great power increase. Most HP pick up is at low end rpms but definetly noticable throughout. A must for the Holley carb, is the quick change kit for the secondary springs. It saves alot of hassle when changing your secondary springs. I've installed the weakest springs to get the quickest secondary kick-in.

If anyone is interested in getting this 390 Holley carb. Jegs sells it for about 100.00 less than most places. And keep an eye on Ebay for an Offenhauser intake, I got mine brand new for 150.00 (shipping included). Ive seen many on there since.

That which does not kill me only makes me stronger (or dumber).
post #8 of (permalink) Old 04-25-2000, 10:25 AM
 
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Re: Holley 390 cfm on 258

I use the secondary quick change kit only for tuning.
the plastic cap likes to warp if you leave it on there permanently.
When you gut the spring that gives you the best performance in place, and you are sure of it, change back to the solid metal cap.
I know it involves taking the vacuum canister off again, but that is well worth the hassle to know there aren't going to be any unexpected problems. (like the cap cracking or warping)

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post #9 of (permalink) Old 04-25-2000, 11:06 AM
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Re: Holley 390 cfm on 258

Thanks for the advice. I will do that now that I got the best spring in place.
I think I ruined the little cork seal between the secondary vacumm housing and the carb. I basically lost my secondaries until I found that...I used some silicone[img]/wwwthreads_images/icons/blush.gif[/img] to seal it again. Can you get a replacement gasket for that tiny Seal??

That which does not kill me only makes me stronger (or dumber).
post #10 of (permalink) Old 04-25-2000, 11:10 PM
 
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Re: Holley 390 cfm on 258

You sure can, any Factory Authorized Holley Dealer will have them.
There should be a couple of extras in your changeable secondary kit...
If you can find one local, let me know, and I'll send you one.
I don't have all of the Holley part numbers memorized, Sorry...
It's the same one for the Holley Vacuum Diaphragm and Auto Choke, and it's SOFT Cork...


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