[ratlover]

Hi Guys,
anybody got any experience/advice whether or not an 800 cfm spreadbore holley 9023 double pumper/ mech secondaries,has any redeeming qualities for a 9.2:1 454 BBC/268H comp xe? I picked one up at a local swap meet for $100. appears to be in great shape. Threw a kit in it, although I kinda had to piece it together as they are kinda an obscure carb. Could possibly be a marine carb. Got it running reasonably well, playing with the jets. started with a 61 that was stock in the primaries. has 86 stock in the secondaries. bumped it up to 72's on the primary side, but I think I might back it off to 65's tomorrow. has a power valve front and back. the kit came with 6.5's, but it was originally 8.5 front and 6.5 rear. What I am thinking is with those tiny primaries it may be fairly economical on the street until you open it up to those great big secondaries? think this will work, or should I just scrap it and get a sqaure bore carb of some kind? please let me know what you think!

[tresi]

I haven't messed with an 800 speadbore but I have a 650 speadbore that I had good luck with for street strip use. If I were you I would not richen the jets until you run it with the stock jets. Often they are a little too rich to begin with. Holley doesn't want to have someone burn up a motor because they took one of their carbs out of the box, bolted it on and went racing. It's been so long since I had run that carb that I can't remember what jets I ended up with but I do know that the primary jets ended up being around a 57 when I hit the best mix of power and gas milage.

[bracketeer]

454s come from the factory with a 750 spreadbore. The 800 may be a little large but can be jetted down. Still may not idle great.

[ratlover]

yeah,
it did take a little coaxing for the idle, but I think I got it now. I had to balance the secondaries to the primaries very cautiously.It's pulling 15" vac at idle, so it seems happy. I had a bit of a stumble at first, so I had the jets kicking around for testing. The 72's definitley got rid of that. I advanced the primary pump cam from position 2 to 1. It has a white cam right now.It has 30cc front pump and 50 cc back pump. I am wondering if the small diameter bores up front might have some negative characteristics. I am thinking jetting it down to 65, and getting a 10.5 power valve instead of the 6.5 currently in there. whaddaya think, compromise with an 8.5 and go back to the stock 61 jets?

[speedfreak2]

I run an 800 spread bore on my 350 small block and it is the best carb I've used and I have tried many different carbs over the years. The second best carb I've used is a model number 4010 list number 84013 which is a 750 double pumper. The spread bore is great for street/strip because the small primaries will give you great throttle responce and when you mash the gas those huge secondaries kick butt. You will be happy with your purchase.

[lluciano77]

Get th 4011. It is the new version of the 800 CFM spreadbore. It is far superior to the old style.

[ratlover]

well, I just got back from a cruise thru the beach strip and it behaved really well. even in stop and go. It did have a slight surge at very light throttle holding 2nd or 3rd at a very slow 10-15 mph. More of an occasional hiccup. It is cruising at about 16-18" vacuum at 40-50 mph (cruise not mashed of course). stuck a vac gauge on it driving and it drops down to about 5" at a full primary 1/2 mash on the throttle. seems very crisp and a little lighter on torque, which right now is not a bad thing as I have problems connecting on the launch. The top end compared to the 650 dbl pmp I had on there is night and day! wow! now I just need the suspension to handle it all. maybe just a skid pan for those country bumps! welcome any more input for the jetting and power valve selection given these variables. seems to have a spot in the transition from idle to main circuit with the 72 jets up front and 6.5 " power valve (not real big but subtle stumble-momentary).. could be indicating over rich? I have not seen the plugs yet. a little early to tell, and I feel like drinking!(not wrenching) Thanks.

[ratlover]

for those who care,
to follow up I went with 65 jets and a 10.5 power valve in the primaries.set initial timing to 12 degrees, running 20 degrees mechanical and 20 degrees of vacuum,fulltime manifold. recurved the distributer with silver/blue spring combo and installed an adjustable vacuum advance, which I am still dialing in. I still have a little detonation when I mash on the throttle at 10 mph, but it's getting better. So far, I like it, but it's still too early to tell. anybody got any tips for adjusting the vacuum can for a BBC? how many turns do you figure?

[GoneNova/406]

i looked it up and came up with 64/90 for stock jet sizes.i have always liked the quadrajet and have always wanted an 800 spread bore but haven't come across a deal on one yet you lucky dog you.

[ROCKETWAGON]

@Speedfreak i have a 350 small block and was wanting to go with 800 spreadbore instead of q-jet. do you have any suggestions for me on jet size and power valves. also what secondary position do you recommend. it came off strip only 383

[68NovaSS]

You not only hijacked this thread, (which is seven years old), but you have another thread with the same question, please don't double post.

[vinniekq2]

Its a great carb,enjoy learning it then enjoy the power

[lg1969]

This post is 7 years old.

[ROCKETWAGON]

yeah i know. i didnt notice that when i asked the question because i came to it off of a google search. sorry for the 7 year old post coming up. im new at this forum.