Hello all!
I have just ordered an upgrade kit from jegs.

Offenhauser 6019-DPK Offenhauser Dual Port 6-Cylinder Manifold

Offenhauser Intake 750-6019-DP
Hedman Headers 500-89300
Holley 390CFM Carb 510-0-8007
Holley Secondary Spring Kit 510-20-13
Spectra Fuel Filter 865-2369
Jegs Carb Studs 555-15840
Mr. Gasket Intake Gasket 720-260
JEGS Carb Gasket 555-16100

Has anybody done this and needed to go searching for misc. parts to complete?
Throttle linkage, brackets ECT...?

And most of important, did make the right choice?!?!?!

Thanks in advance!!!
-John

 

I think that is a very nice kit. There are many members who have done similar upgrades. If you do a search regarding any aspect of upgrading the 300, you'll find ample information you may need.

I would install studs for the header, with crimp nuts. You'll also need the oem large washers. You need to grind down one side so it will sit flat; header flange and intake flange are different thicknesses.

Consider your starter. Buy a new one b/f the install b/c of the header heat may affect it.

I think I'd get the 4v spacer that separates each carburetor bore, rather than the open type, otherwise you're defeating the purpose of the dual plane manifold.

You'll need a heating plate to mount on the bottom of the intake and run coolant through it.

You will most likely need the throttle cable bracket sold by Lokar on Summit Racing dot com.

Note: Nothing will help that kit like a good port and polish of the head, and a mild cam. However, I'm sure you'll see a nice improvement over stock just as it will be with the kit alone.

Good luck. K.

 

Thanks K,
When you say i need a heating plate on the bottom of the intake and run coolant through it.. is that required?
i will take your advise on the 4v spacer... looking for one right now.

 

K,
Is this what you are referring too?
Lokar Throttle Cable Brackets SRK-4000 - SummitRacing.com
Thanks!

 

If you don't provide heat to the intake manifold via a water heat plate you will be back here posting about issues with drive-ability and wondering how to correct them. Best do it right from the start and significantly reduce/eliminate the problems associated with a non-heated intake manifold.

 

Here is a photo of the heating plate. You also need a gasket for it. You can buy the oem gasket for the oem intake to exhaust manifold, and trace it.



Regarding your throttle bracket: I don't know what you are going to use from the pedal. I use a Lokar cable b/c with the DP manifold the carb sits 90* to the engine. The cable seemed the easiest option. And yes, that is the bracket I use.

BTW, using studs as opposed to bolts to mount the intake/header will save you a lot of hassle during the install, and a lot of maintenance--retightening--in the future. Remember to keep and grind the oem think washers, as mentioned in my last post. Use grade 8 for the studs.

With that header you need a well flowing exhaust.

 

I take it there is holes in the intake for the water to flow? blanked off from factory?
And i will get the studs.

Thanks!

I seen this peice on another thread i read a few days ago!

EDIT** i am looking for the studs on jegs and i do not see a spec on the grade....

 

I think I'd get the 4v spacer that separates each carburetor bore, rather than the open type, otherwise you're defeating the purpose of the dual plane manifold.

Good luck. K.
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This is a standard 4 hold spacer that's available at any auto parts store right?

 

Yup...but why a spacer? JMO based on experience, a spacer on a DP 1. doesn't provide any performance benefit 2. Insulates the carb base which can lead to carb icing. If there are carb/manifold clearance issues a spacer might be needed.

 

[QUOTE=Harte3;12651590]Yup...but why a spacer? JMO based on experience, a spacer on a DP 1. doesn't provide any performance benefit 2. Insulates the carb base which can lead to carb icing. If there are carb/manifold clearance issues a spacer might be needed.[/]

So no spacer?
!!!!
I have it all torn down, got new water pump. Removed, cleaned and painted everything. Lol
Parts come Wednesday!
Thanks!
-john

 

The spacer is a personal preference. From a practical stand point it just doesn't do much if anything on a DP manifold. Now on a C manifold, that's different because throttle response can be improved with a 4 hole spacer on the open plenum manifold.

 

I had to use a spacer b/c the throttle linkage hit on the manifold w/o it. I also use a 1/4" thick base gasket and a heat shield. Even with those, the carb gets so hot from the header that I can not work the throttle w/o a rag on the throttle.

You can find the studs and crimp nuts at Hillco dot com. Google it. Torque to half specs first, from center out in in c-clockwise spiral. Then again to spec. The second bolt/nut from front of engine can only be reached w a boxed end from below. Run the engine to temp. Let it cool completely, then retorque as above. Run. Cool. Repeat the last time and forget about it. Apply copper anti-sieze compound to head side threads of studs. Apply high temp RTV sealer around both sides of int/exh gasket, around the exhaust ports.

Good luck. k

 

I really appreciate the help, I am looking on hillcofasteners dot com and I think I need help selecting the correct studs. I only see stainless and I don't know what size.... Any help is appreciated!

Thanks
John

 

I would suggest converting to a mini-starter. The original starter is too big to remove once you have the headers on. I did this same upgrade except I used an Edelbrock carburetor. I had to get creative with the throttle linkage because of the 90-degree orientation of the carburetor.

 

I will get the part # for you. You want grade 8 steel studs, 3/8" 16 (coarse) to 3/8" 24 (fine). The coarse end goes into head. Over all length is 2.25". You also need crimp nuts, and two type of washers, unless you still have the oem thick washers?

The mini starter is a good idea. I used a A.Zone rebuilt one, and it has been more than two years, but I dread the day it goes out. I guess that is when I'll install a new cam. k