Will a 750DP drown my engine?

65ShelbyClone · Apr 15, 2005

I searched and found conflicting information, hence my asking now.

I have access to a Holley 750 DP for use as a loaner with the option to buy later for cheap if I want. I'm tempted, but also concerned that it will be too big for the roller 302 going into my '68. I originally was thinking a 600 ot 650.

Here is what the engine already has:
Edelbrock Performer 60379 heads
Crane 2031 cam(.513in/.529ex, forgot duration)
Flat top Speedpros, about 9.6:1 squeeze.

Here is what I have planned:
Wieand X-Celerator single plane
Either Hooker 4-1s or Tri-Ys

Will a 750 be grossly too large for this? Keep in mind I already read the cfm formulas and associated discussions.

bnickel · Apr 15, 2005

with a good tune and your 4spd it should work just fine, it would definitely be overcarbed with an automatic tranny, but not by much

12sec67 · Apr 15, 2005

it will work for now... but its not the best for your combo.

my car dyno'd great with the 750db but the times and the track didn't reflect it. it was too much air/fuel off the line for my set up.

65ShelbyClone · Apr 15, 2005

I figured it would be too big. I really just plan on using it to get the car on the road. I used to have a 600 single feed/vac secondary and would have used that, but I think it got sold at a swap meet since I cant find it .

Thanks y'all .

Edbert · Apr 15, 2005

if you only had more cubes I'd say do it. I have 357 of them and was worried my 750vac would be too much. While it might still be a little too big it wont meet your definition of grossly

65ShelbyClone · Apr 15, 2005

Thats good to hear also. I think back to the 65-66 GT350s and they had, what, an Autolite 715 on top of a 289? Then again gas was like 35 cents/gallon.

If only my 351C was in better shape, right? .

65ShelbyClone · Apr 17, 2005

NEWS:

I guess the little 600 didnt get pawned. My dad found it in a seldom-searched shed and it was in the box my 600 DP came in when I had the '65 notch. Too bad its a single feed vacuum secondary. Now for the million-dollar question:

What would be good baseline jetting? It worked fairly well on a 90% stock 289, but I figure I'll need more fuel for the 302 in my first post.

65ShelbyClone · May 17, 2005

Rather than start a new thread, I thought I'd recycle this one.

I got a 600dp about a week ago, so now I dont have to use the 4160. Its just as well too because the 4160's bowls were glued down with varnish. Now I just need an X-Celerator intake. Anyway...

Any baseline jetting suggestions?

84convertablegt · May 17, 2005

id start with a 65 primary and a 68 secondary jet and go from there.

302 coupe · May 17, 2005

normally the rear jets should be 6 sizes bigger than the fronts. I think a 65 or 67 would be good starting point for the primaries.

351LX · May 17, 2005

I usually take the list number and go to the Holley website and start at the factory Holley jetting which is usually pretty close unless there is something wrong with the carb.I have got some nice deals on used carbs that the previous owners said were fubared and once I restored everything back to the original settings they always ran great.Keep in mind that Holley jets on the rich side for safety reasons so make your first jet change a couple leaner and see if it improves.Holley has at least 5 different versions of the 600 dbl pumper, from a straight list 4776 up to a 4776-4 and there are broad variations of the original jetting.Some originally had 69-71 jets and some had 66-76.Here is a link so you can see what the original jetting was http://www.holley.com/HiOctn/ProdLine/CarbList.pdf

65ShelbyClone · May 17, 2005

Thanks everyone. I think I bounced back and forth between 64s and 66s on the primary side with my previous 600 dp on a 289. I dont remember what the secondaries were. The 600 dp I have now came off Ebay and I havent opened it up, so I dont know whats in it.

HistoricMustang · May 17, 2005

Have seen a 780 on 289 with Tick Flow heads but it was used in a performance situation. Actually saw a 950 on a 347 - again under road race conditions.

I use a 650 (tuned by Barry Grant) on mine.

HistoricMustang
www.historicmustang.com

65ShelbyClone · May 17, 2005

I may step up to a 650 in the future, but only if the 600 proves to be too small for my goals. I think I'll buy the 750 off my old man anyway because I plan to eventually have a 4V 351C or possibly a 390FE.

HistoricMustang · May 17, 2005

65ShelbyClone said:
I searched and found conflicting information, hence my asking now.

I have access to a Holley 750 DP for use as a loaner with the option to buy later for cheap if I want. I'm tempted, but also concerned that it will be too big for the roller 302 going into my '68. I originally was thinking a 600 ot 650.

Here is what the engine already has:
Edelbrock Performer 60379 heads
Crane 2031 cam(.513in/.529ex, forgot duration)
Flat top Speedpros, about 9.6:1 squeeze.

Here is what I have planned:
Wieand X-Celerator single plane
Either Hooker 4-1s or Tri-Ys

Will a 750 be grossly too large for this? Keep in mind I already read the cfm formulas and associated discussions.

Cool avatar. Here he is in jail.

HistoricMustang
www.historicmustang.com

65ShelbyClone · May 17, 2005

65

HistoricMustang said:
Cool avatar. Here he is in jail.

Hehe, thanks. I made a few others inlcuding where he jumps the car and also where both the Dodge and Mustang fly around a sweeper past the camera. The hard part is keeping the file size so small.

Is that mugshot for real? Did he truly get booked or that from a film? He doesnt look too worried....

HistoricMustang · May 18, 2005

65ShelbyClone said:
65

Hehe, thanks. I made a few others inlcuding where he jumps the car and also where both the Dodge and Mustang fly around a sweeper past the camera. The hard part is keeping the file size so small.

Is that mugshot for real? Did he truly get booked or that from a film? He doesnt look too worried....

Believe the photos are real. The hand may have been added. Steve was like James Dean, Elvis and some of the others. They sometimes lived out there on the edge.

You should see the photo I have of Johnny Cash "shooting the bird" at his fans!

HistoricMustang
www.historicmustang.com

Capt Dan · May 18, 2005

HistoricMustang said:
Believe the photos are real. The hand may have been added.

http://www.thesmokinggun.com/mugshots/mcqueenmug1.html

65ShelbyClone · May 18, 2005

HistoricMustang said:
Steve was like James Dean, Elvis and some of the others. They sometimes lived out there on the edge.

Hey, for 1972 I guess it fits the times as well.

Will a 750DP drown my engine?

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