351W - which intake manifold & carb?

[Blueoval_Bowtie_Guy]

I'm at the stage where I'm going to have to order my intake manifold and carb.

I'm concerned about hood clearance and driveability.

I've got a 408W stroker with AFR-185 heads. I'll be running around 9.5:1 compression (dished pistons) with a hydraulic flat-tappet cam. The cam delivers power in the 2000-5500 rpm range. I want the intake/carb to also run best in this range. I'll be on the street with this 99% of the time. My machinist is estimating 490 lb/ft of torque and 450hp.

Any suggestions, recommendations? Am I overlooking something?

Thanks!

[JAM1775]

I am not an engine builder but I imagine you could get more than 450HP from a 408 through
55-5700rpm. I made 455HP/425TQ with a FMS 351W crate motor, their crate motor flat tappet cam ,GT40X heads ported and milled to 55cc's for an increase from 9 to 10:1 compression, Weaind Stealth intake with 3.4" spacer and 650BG carb. Your 408 makes big time torque ! I would suggest the Stealth or EDL P-RPM as they make the same power than any single plane through 55-5600 rpm. If you want to reduce some TQ I guess the V-Jr is choice which will fit with no spacer. Another low profile option for your RPM range may be a EDL Torker II single plane intake which comes polished rom Summit. According to carb size formula HP x RPM X .85 divided by 3456 you need around 620CFM at 5600rpm. I am sure you will get more input. These are just my opinions.

[Todd Buttrick]

I have Edelbrock Performer RPM dual plane intake plus 1/2 spacer with speed demon carb and 14x2" air cleaner and still have an inch to spare under the hood. Energy Suspension mounts under a 351W

[04 Cobra]

Based on the cam rpm range I would say the EDL-RPM intake would work best for the street application.

For carb I would contact deman carbs made by Barry Grant. They will tell you exactly what you need for your application.

Don't go too big for the carb. A lot of guys do. I have seen 750cfm and larger on a very mild 302. JAM has given you a good start with the formula provided.

Fuel Injection from Edelbrock would be an option as well. They make a kit for the 351W.

Raymond

[Klayfish]

My 351W, fairly well worked over, has the Edelbrock RPM and Holley 750 carb. I've seen debates both ways, but it seems my carb may be a little too big for the car. It tends to bog or cough at the hit of the throttle. Nothing I couldn't deal with, but it's noticable. But the RPM seems to work well, and the motor is a horse!!

Steve
[img]graemlins/yellow.gif[/img]

[cwood]

I have worked 351w with 10-1 comp, edelbrock performer and holley 670. Its tempting to go big on the carb becuase bigger seems better but I resisted.

You might be able to fit an air gap.

[Budge]

Hi...The Weiland Stealth on top of my 351 Ford crate motor worked for me to solve the clearance problem and give much better low and mid range performance and behavior...Budge

[turkeymaster1]

Blueoval_Bowtie_Guy: I see the time on your post. You told me you were working on a problem. I assumed you meant a business problem. You're docked ... get back to work!

(No, I did not hijack this post. I'm the boss!)

"Hey Boss, what are you doing on the Forum at 2:14?"

[JAM1775]

Budge...I'm with you on the Stealth. My V-Jr just came off Weds and the Stealth reinstall will be complete tonight.

[Churchill]

hmmm, intake, I would use a single-plane if possible, the edelbrock torker II is one option, IIRC it doesn't sit any higher than the ROM intake, to me the trick with cars in this power class is to strech out the powerband, and a single-plane helps do that. with 400+ inches and a relatively mild cam, you are going to have traction issues big-time off-idle. I always prefer to run a little more gear and have an engine that really breathes well up top... even the AFR 185 with a matched intake should be good enough to make peak power above 5500... we're anticipating peak HP at or slightly above 6500 with a 13:1 408 & AFR 205s....

carb??? BG or Demon, can't really go wrong.

[Blueoval_Bowtie_Guy]

Geeze, somehow I just KNEW there'd be lots of answers! Thanks guys - really appreciate it. I was looking at the Weiland Stealth in the Summit catalog last night.

What is the purpose of the 'spacer' a couple of you have mentioned?

Sorry TurkeyMaster - mental health break! (yep - he is my boss!)... Or you can think of it as a non-smoker's smoke break!

[Churchill]

spacer is many times used to increase plenum volume (open) or enhance intake charge velocity (4-hole)...

or for throttle linkage clearance!!!

[NAH]

I recently replaced my Victor Jr with a RPM and it is like a totally different car. The Victor Jr. was very tame in the low rpm and came on like gangbusters around 3500 or so. It was very driveable around town. Now with the RPM manifold I can't floor the car in 1st, 2nd or 3rd without the tires breaking loose and that is with 3.27 gears. It is much more of a handful to drive (and more fun I guess)now. for those with a speed demon carb look for my safety post on the secondary linkage.

[Zulu]

While the technical reasons for the spacer are listed, I needed it on my RPM Performer intake to clear the Distributor with the 14" air cleaner.

Carb I stayed simple , Holley Street avenger 670.

Hood clearance still no problem.

[FattyBri]

My 2 cents. I have a a 351 with Vc. Jr heads. I went with the Vic. Jr. intake with a 700cfm double pumper. My thought, and it could be completely wrong, was to have the power higher up in the power band with such a light car and 3.55 gears. With just go-carting around, it will still throw your head back around 2k rpm- im not too worried about the loss of low rpm torque. Do you want a torque monster or a high rpm screamer? Sounds like if it will be mostly a street cruiser you will be more happy with a dual plane, lower rpm intake.

[Blueoval_Bowtie_Guy]

Sounds like I shouldn't have a clearance problem with either of the recommended intakes that I've been seriously considering (Weiland Stealth, Performer RPM).

I had a great ride in Olli's Cobra at VIR and was astounded at the rush when the power came on (think it was around 4000 rpm). That head/body slam backwards rush...

I thought I wouldn't be able to rev this up beyond 5500 or 6000 due to the square bore (too much stress on the rods). That's why I told my machinest to get the power on early. Maybe I was being a little conservative there. I Hadn't thought about rampant wheelspin. I kept thinking about how I have to downshift my '91 LX 5.0 convertible from 5th to 4th on some hills / mountains on the interstate around here to keep from lugging the engine (about 1600 rpm at 65mph).

As far as the carb (670 vs 750). I'm leaning towards a Holley. I know lots of people swear by the BG carbs, but it seems a lot swear at them too. I have a few friends that are very familiar with tuning a Holley.

What's the +/- of going with a 670 or 750? What does too much carb do?

[Wayne Presley]

I'd do this but that's just me... [img]smile.gif[/img]

[Blueoval_Bowtie_Guy]

Wayne,

I talked to your briefly about your setup when you were parked next to Olli at VIR. VERY nice! If I had the extra $$$ I'd go for it. In a heartbeat... Talk about something that'll drop someone's jaw when you open the hood!

[Todd Buttrick]

Klayfish,

You may be feeling a lean stumble with a carb that big. Measure your manifold vacuum at idle. I'd bet your pulling 10PSI max. You'll have less vacuum than a 650 so you're not pulling the needed fuel. Jet up two steps and take it for a long cruise at temp. If it gets better, jet up another tow sizes. Do this until you see no change then back down to the last size. Your vacuum will drop to near zero when you stomp on it. If you're pulling 10PSI, try running a 65 power valve or even an 75 if the larger jets don't do the trick.

[Hoosier]

Here's what I have:

393 Stroker
9.5 : 1 Compression
AFR 185's
Mid range flat tappet cam
Air Gap intake
750 CFM Edelbrock Carb

467 ft/lbs torque
410 HP

With a Holly 750HP numbers were:

490 ft/lbs torque
426 HP

Have been told to stay with the Edelbrock Carb as it will be much more "streetable". And it's cheap.

[Churchill]

where were the power peaks????

[Frank Messina]

Check my signature line. This motor has the Victor Jr manifold which I've found to be very streetable. I was concerned at first that I might have too much carb, but it is very tuneable and runs great from idle all the way up. Throttle response is very crisp and pulls like a freight train. I could not be happier with this combination.

Klayfish, if you have a stumble, the accelerator pump needs tuning. The main jets have nothing to do with that problem. Check to see that gas comes out of the accelerator pump nozzles as soon as the throttle moves. I'll bet you have several degrees of movement before you see gas. If that's the case then check which color pump cam you have and which hole it's in. (the pink cam is preferred) There are two holes on the linkage marked 1 and 2. It's most likely in hole 1. Take the screw out and move it to hole 2. That should fix it. Good luck
Frank

[Snakes Skin]

Edel has carb head man cam combos for almost all engines. and trhey are tailored to the powere curv and horsepower you want.

[Tim Burns]

Air Gap and a Holly 700 Double pumper p/n 510-O-4778C

[Todd Buttrick]

Whoops. Guess I gave bad advice there, huh? Check your tire pressure.

[Steve]

I'm going to run the Weiand Stealth dual plane part# 8023 and keep my Holley 650DP. Heads are going to be Trick Flow TW and cam is still undecided.