[cdrookie]

not happy with the performance of my machine, runs ok, just doesn't run as hard as i thought it would(or should). I know the cam is too big(so don't tell me that), but think it needs more compression(120 using my gauge).

current set up:
it's a 400, .035 over, 2 valve relief JE pistons -.005 in the hole, 87cc edelbrock round ports(ported 310), solid roller(248 duration, .406 lobe lift, 108 ICL, 114 lobe sep.), performer rpm, 825 mighty demon. 75 lemans, 5 speed, 4.10 gears.


choices:
1. different cam and mill the heads to lower cc's. but how much can be safely milled, and how many cc's would that be? maybe not worth the effort?

2. get 72cc heads, and maybe new cam?

3. stroker kit

4. procharger(or something along those lines). I know nothing about this route though and can see it getting pretty expensive real fast.

what would you guys do?

[Will]

A stroker kit will net you the biggest power increase and allow you to run the heads & cam you have.

Changing heads and cam will fix your compression issues and also net you a nice power increase, but not nearly as much as more cubes. The advantage to this over the stroker kit is it's a bolt-on solution, you wouldn't even have to pull the engine.

There's no replacement for displacement but your budget and how much work you want to put into this will determine which way you go.

If I had the money and didn't mind rebuilding the engine again, I'd go stroker.

[ponyakr]

Here's a crate stroker short block. You can use your heads, cam, etc.

http://lenwilliamsautomachine.com/455_Short_Block.html

[joes455]

What years 400 blocks

[cdrookie]

don't 100% remember but think it's a 74. it's not a 557 though.

[Judas]

On thing I noticed; 825cfm seems like a lot of CFM for a 400.

Using an online carb calculator, assuming you have a full-on race engine (a Volumetric Efficiency of 1.0, which is probably way higher than reality), and a 6000rpm max, it comes up with a max size of 694 CFM- call it 700 to be even. More realistic VE's are lower.

You may be losing intake charge velocity. If you are running vac. secondaries, it can sometimes compensate for too much carb, but you aren't getting the carb's full potential either. If you are running mech. secondaries, the problem is more serious.

It might sound counter-intuitive, but you could see better performance with a smaller carb due to better air/fuel mixture flow.

Good luck!

[ho428]

Too big an intake runner, not enough compression, too much carb, too much cam, not enough cubes.
Milling would raise compression but unless you plan to spin this thing in the 5000-6000's all the time the ports just have to much volume.
Simplist using the heads and cam you have is a 4.25 stroker, I don't even think 4.0 is enough with those heads on the street.
Just looks like a mismatch of parts overall. No easy way out of it.

[69fireburger]

If you go 4.25 stroker with a .040 over-bore you'll be at 462 cubic inches and around 10.2:1 compression. That will work much better with the top end part that you have. If you don't want to go through all of that, I think I would change the cam and get the smaller chamber heads. The cost of that change could be offset by selling the heads you currently have.

-Bob

[Blued and Painted]

Sound like the cam and heads would be a good fit on a 462.. And possible the cheapest alternative.. +

[rad400]

Stroke it.

[i82much]

Option 4, the Procharger, will make the most power and have great driveability if dialed in properly.

[cdrookie]

knew someone would throw the pro charger option out there gotta research that more. looks like the general consensus is stroke it, but as one member told me... 455 stroker + 4.10 rear = a lot of tire smoke

[TransAm 474]

You can't beat the Procharger's for making power.... at 15 # of boost, (which is about one atmosphere)...it will make your 400 think that's it's an 800 cubic inch motor.... and will approximately double the horsepower of what it makes Naturally Aspirated. Procharger's can also be really street friendly with the right tuneup.... if it were mine...i would probably keep the shorter stroke and go with the Procharger....shorter stroke is easier on parts and will Rev a little higher without the stress...or if you wanted to stay Naturally Aspirated, go with the stroker. Or...even better yet, if you have a suite case full of extra cash just lying around...go with the Procharger and Stroker!! LOL

[cdrookie]

anyone have a ballpark figure for everything needed for a pro charger set up?

[Blued and Painted]

https://sites.google.com/site/ksmsin...ac-kit-pricing

[cdrookie]

that makes the decision a whole lot harder...

[fastekibeast]

More compression, tighter LSA , 1.75" primares headers and you´ll be just fine!!

Read the article it gives you some perspective.
http://www.popularhotrodding.com/eng...ht_cam_choice/

Just my

[Skip Fix]

As one who raced a 400 -cam is OK not too big(ran a SFT-255@0.050, bigger and a HFT that big with AC and power brakes) but the compression is killing it. Mine was 10.2:1 iron heads. Carb -maybe a click big but figure even smogger 400s got a 800 CFM Q jet.
With a 400 you need to keep the header size smaller 1 7/8 at the biggest.

Boost what you have now, 72cc E heads or stroker kit are the options I see.

[3fastgtos]

I just listed some nearly new 68cc heads.

[paul s.]

I agree with most on here, more compression if you want to keep it N/A. 72cc heads are a bolt on deal.

Port sizing largely determines rpm range but cam timing also plays a large role so if you wanted to go with the higher flowing 300+ cfm ports, get a cam to take advantage of the larger ports... and I don't just mean longer duration. There is a lot more to cam timing than just duration.

Lobe separation angle, specifically the intake closing point can be crucial when running large port heads because the airspeed is so slow there is no momentum built up in the intake tract... the 114 LSA wasn't helping anything in this case. A 114 LSA is common because it allows for easier tuning, especially when there is a lot of duration for a given combination. Generally speaking, a wider LSA allows a combination to hold on longer after peak power... but one of the components of a wider LSA is a.... wait for it.... later closing intake valve.

Good luck on your project!