Would 2 holley 600 cfm double pumpers be too much for a 450 CI stroked nail?

Since i'm picking up a 425 within the week, me and my engine builder are already throwing around ideas on how we can make it one of the fastest naturally aspirated Nailheads in the the Chicago land area. It would consist of a custom, water-jetted main girdle/halo, Offset ground crank, custom rods, forged J&E custom .060 over pistons, 10.2:1 compression, custom Mechanical roller cam with the T/A rockers, 11/32 Titanium/oversized valves, MSD ignition, etc. I wanted to do a Bad A*s dual quad set up with two holley 600 cfm double pumpers on a high rise Offenhauser. Maybe even two holley single pumpers. But would single pumpers be under carburating or just enough? And would double pumpers be over carburating? I plan on running on 93 octane, and running a 93/99 mix for the strip. Any feedback is appreciated. :TU:

 

Sounds good. I would lose the offenhauser:TU:

 

Check with Nailhead expert regarding the maximum bore recommended. Sonic check the block.

 

What intake would you recomend?

 

The Eelco dual quad intake is probably one of the best that's readily available. It made the most power in a dyno shootout between itself, the Edelbrock B262, and Offenhauser. The Offenhauser performed the worst...

To actually get the carbs to fit, your likely going to have to run a non-DP style carb, like a 4160, or an Edelbrock. I'm a Holley guy so I'd go that route, but I can't say I've actually seen somebody with Holley's on a dual quad Nailhead setup before.

Like Jim said, definitely have the block sonic checked. 425's seem to be a bit iffy in regards to being bored .060 over.

Can I ask why a mechanical roller as opposed to a hydraulic?

 

My engine builder taught me that you have more control over a mechanical roller opposed to hydraulic. I was thinking to just turn the carbs sideways. instead of front to back, just have them side to side.

 

If I were you I would consult with an engine builder with a lot of experience with Buicks. There are not many out there.

 

What about a single holley 4500 carb..... same amount of flow, simpler set up,,, higher volume.... :Brow:

 

Winner, winner, chicken dinner!

Dual quads definitely have the cool factor, but if you are more concerned with performance, I think doc hit the nail on the head...(get it?! Haha)

 

Control referring to what? I guess I don't think the Nailhead would benefit enough from a solid roller to justify its use. That's just my opinion though.

You could mount them sideways. You might have to get a little creative with the linkage and float setup though.

I like the idea of a Dominator on a custom sheet metal intake. :3gears:

 

First off, two 600's would be too small. Carbs are calculated in series not parallel. I.E. figure the single size required then use two. A good 750 like an HP series should do well as you will be RPM limited by the Nailhead. Absolutely no need for a block girdle on a normally aspirated NH. Normally aspirated, you can never make enough power to blow out the bottom end, it is over-engineered to begin with. Contact TA Performance, I think they have stroker rods and pistons on the shelf for a NH (can't recall if 401 or 425). Spend as much time and money on porting the cylinder heads and intake as your budget allows. Definitely, what ever you had budgeted for the block girdle, put that directly into the heads. The heads just don't flow much air to make the HP. Also realize that stroking it will increase your low end torque and lower your overall RPM so don't be surprised if you are all done between 5000 and 5500 rpm. You might pick up a little power with a solid roller, but generally their benefit is at higher RPM, which again, you won't see with the NH. Having said all of that, they are very reliable and will hold up very well.

On a total side bar, if you have the budget, forced induction will bring it to life. Think similar to the differences between a normally aspirated diesel and turbo-charged diesel. And of course that is best served with fuel injection, so things begin to add up quickly.

 

A single 4 barrel and a sheet metal intake are also an idea. I would like to make as much power as i can naturally aspirated on pump gas or a mix. I dont believe in power adders, Though they are cool, they're not my style. Would a bigger cam expand the RPM range even with a longer stroke? I'm only looking for 5800-6000 rpm max, I know a nailhead doesnt really like anything higher. I plan on having the block sonic checked and hard blocking it up to the bottom of the freeze plugs. I plan on spending :dollar: to get the heads nice along with better valve train. The reason why i wanted to girdle it is because i'm just afraid of blowing it up haha. I dont think T/A makes stroker rods for a nailhead, i've searched they're catalog looking for better than stock rods, doesnt look like they carry them. Anybody got more ideas? I'd love to hear them.:TU:

---------- Post added at 05:00 PM ---------- Previous post was at 04:58 PM ----------

If the mechanical roller will make a little bit more power, i wanna use it. All the power thats possible for that setup.

 

TA does have stroker rods on the shelf for a NH and pistons. They were a special order a while back and the project fell through. I worked there for years and help out occasionally these days. Plus they can make anything. You won't blow that bottom end out. You might spin a bearing if you over-rev it, but a girdle wouldn't help their either. Skip the hardblock also, again, you will never have a big enough boom normally aspirated to stress the block. I mentioned the effect of the cam in the other thread about what hp and tq the strokers will make. The killer is the heads, ported your intake CFM will be in the low 200's. Best heads (currently) for a 455 are around 400 CFM. Big Block Chevy goes well beyond that.

 

Well, I have some definite ideas about nailheads....I would take advantage of every advantage one of them had....:Brow::laugh: They are not rpm engines but can be made to do more than a stock one can do.... you could take the crank and rods and super polish them up and balance .... and a really good computer designed cam and valve gear.... Toms rollers..... super good polish and port job on the heads.... and exhaust manifolds, and naturally a Doc dual plane intake that was extrude honed.... both the intake and exhaust manifolds....with a really good tuned holley 4500 or webbers....
Make the inside of the engine look like a fine watch used to..... :idea2:
Forged custom pistons,,,, no gap piston rings.... blue print e v e r y t h i n g in the engine...
make the aircleaner match the system... and the exhaust too.... and research the best trans/diff gear/suspension to get all that to the ground....
and lighten the vehicle up as much as possible.....
In short, blue print the whole car....and dont get in a hurry......

 

I think the rods your talking about at ta are aluminum.

 

ANYTHING other than stock requires CUSTOM pistons. Today, with today's technology ANYTHING can be made. It's the total combo that counts. The stock "Nail" rods are a good forging. Just massaging them & adding ARP bolts will strengthen them even further, along with shot peening, magging, polishing, etc. Longer rods can also be an advantage. Many things to think about before just ramdonely ordering parts that in the end you may not be able to use.
Just some of my thoughts.


Tom T.

 

This info has been very helpful. This would be no quick build, i plan on taking my time, making sure i get every detail right, which is exactly what i'm doing with my 401 right now. I've already got 15 hours in my intake, doing the DOC mod and sanding/polishing the exterior. I would like to get on the phone with T/A when i get the 425 build rolling and talk pistons, rods, cam, and valves. I've bought well over $1500 worth the parts from T/A alone for the 401, so i'm in their system :laugh: Also gotta find someone talk to someone who can offset the stock crank. For the 425 I will have the heads sent out to someone who specializes in them. I plan on leaving the car mostly stock, except for under the hood :Brow: the st400 trans is being built by one of the best right now, I can always change converters for the bigger motor. i still have my 401 thats nearing completion. I dont want to put a bigger gear in because i still want some streetability (gas is currently $4.50 a gallon for 93 octane here). Theres about 4 Nailheads in my area including mine, and three are bone stock with edelbrock carbs. I like to be different from the rest, which is why I'm a 19 year old with a 63 Riv, and why i'm sticking with Nailheads for the car. Not many people in the Chicago burbs would think that a car like that would have an Iron animal under the hood.

 

do the doc mod and then get that intake extrude honed.....:idea2: and it will pretty well be optimal....
On a street car, extrude honed exhaust manifolds with good 2 1/4 to 2 1/2 exhaust system all the way to the back bumper will be as good as a set of headers....and a lot less hassle.....:Brow:

 

I'll definitely look into the extrude honing. I already picked up a set of good priced shorty headers. I still have the manifolds that i'll clean up and sell.

 

Pard,,, I would keep those exhaust manifolds,,, because,,, those tube headers might not work out as good as you think....:Brow: