Even with zero deck pistons an open chambered head doesn't have any flat surfaces to create quench so you still have the problem of a high static C.R. and no quench which is going to promote detonation issues. You'll need to pay very close attention to the cam specs so you can keep the dynamic C.R. in a reasonable range. Octane rating will be a big factor as well.

Any porting done beyond pocket porting and basic clean up should really be done only if you have access to a flow bench. Trying to wring every last drop of power out of a head is tricky and can easily result in large, iron paperweights. If you can, find a good pro porter then see if he'd be willing to do 1 cylinder to max flow as tested on a flow bench and then let you do the rest of the ports using the 1st one as a model. I know the guys up at Re-Incarnation Automotive will do that. That way you save some scratch and also learn at the same time.

 

I agree from all I've read that about a 30 hp gain is not unreasonable if done well. It takes time so be patient. It is very easy to put 8 hours into a head especially on the first try. The other thing I would advise is a long shank, that is at least 6" burr on your grinder. If you use anything shorter you run a serious risk of hitting the valve seat with the collet.

 

After a bit of digging i came up with the cam specs (i'm away fromhome for christmas right now, and i don't have the rest of the specs memorized )

anyway here they are: @.050" of lift: .296int and .311ech, total of .512int @292* and .538@302*, with an SAE overlap of 72* (in case you guys are wondering the part number is 229-1884 and its a clevite cam)

Anyway, yes this motor is for mud bogging only, i would go 460, but we have more good 400parts avaible to us than 460 (plus i want to **** them bbc guys off when i tell them its just a basic 400 ). On that note, max revs for this motor will be 5500, i will get a rev limiter if need be, but i don't want to go any higher than that as i want this motor to live as long as it can. As far as CR, the closest thing to race gas in our area is propane which i do not want to do to this truck (could spend the money to convert on some better parts), and thus the cr limit is 10:1. As far as changing cams, i would but if i go to radical i will be bumped a class and forced to run with the guys pushing 500hp and 40"+ tires, and in the drags this is something i cannot compete with, as essentially this is what i am doing, building the motor enough to where i can compete and win in the drags in my class, as in the bogs i have the truck setup and i have been winning. But i'm hoping with these mods i'll be able to run in 3rd gear and low range vs. 2nd a nd low.

As far as where i'm looking for power, essentially from 2500 and up (i launch at 30-35 hundred rpm, yes i do have the drivetrain to handle it, i'm not worried breaking parts here). Since this truck sees virtually no use outside the pitts and the occasional farm chore i need the power above the 2500rpm mark. As far as switch to a 4v head i already stated why in my first post, but if from now till i tear into this project i'm going to stick with the 2v heads. Bill thats a great idea , there is a guy that built a motor for us that also builds the 514 blown monster truck motors that i think i will see if he can do this for us for perhaps a spot on the side of the truck (no sponsorships yet).

Roger , where in MT are you at, as i do a lot of bogs down there, from havre to conrad and dutton and greatfalls, been to any of those events in the last year or two?

For now thats all i got ( i know i forgot something), as its late and i'm tired, but keep the help coming, you guys are going to help me win races with this info .

 

Here's the specs I found from 2 sources. If they're wrong let me know. I'll comment on a few things later. LSA is 112 deg. If the bore is .030 or less this may be a good candidate for my infamous low buck stroker.
Ford V8, 351C-351M-400 P Hyd. Hyd. 214/224 282/292, .295/.310 .510/.536, 107/117
0 TDC 34 ABC, 49 BBC 5 BTC 229-1884

 

Thats close brian, but not quite , i know that the adv. duration is what i listed in my previous post along with the adv. duration, but i'll know for sure on the 27 when i go back home.

 

Alright i made it back home and i have the specs as listed on the cam box:

Duration @ .050" 214int 224exh
SAE Duration: 292int 302 exh
Lobe spread: 112
Valve lift: .512int .538exh
Cam Lift: .296int .311exh

Timing at .050":

BTC ABC BBC ATC
1 33 50 6

 

For whatever reason, the advertised duration is slightly different. This doesn't affect much. The duration @ .050 is more important for estimating power range.
This is a good street cam with mid-range power but I think 10:1 will be too much with pump gas.

You're peak power is going to come in at about 5000rpm. It has 5 degrees advance built in, retarding it a few degrees will help. Kinda small for a race engine but I guess you wanted something that idles like a stocker to keep a low profile.

 

Yeah thats why i picked it, the mid range power is what i need as by the time i hit the deep stuff i'm in the 4500-5000rpm range, and as you point out this is where this cam will make the power, and from what i can tell from playing with ddk2000 it'll be in the 320-350ish hp (stock 2v heads with stock 8.5cr for the motor i'm running now), and the higher cr and improved flow puts power in the 425 range with torque around 465lbft.

I was thinking of foing with a bigger cam, but then i started pricing out the other things i would want to run top keep the motor alive and was getting a bit pricey, and so i stuck with this cam, and also i didn't want to go to radical with it as then i'd get bumped a class into the guys running 40"+ tires and 500hp, and thats something i cannot compete with with the cash flow i have, and this cam was priced right and i got matching valve springs and a few other items (timing set, gaskets/seals, locks, retainers, lifters) for about 280 shipped. As far as the cr, if i have to run a bit better gas i will, but i m running a 10:1-9.5:1 cr 351w in my 82 flareside and it runs on 87 fairly decent (played with the timing tp get it to work the best), but who knows the W and C are different motors.

Yeah if you guys run across any other porting articles post em' up, as i'll take anything i can get.

 

I think you'll be stuck running higher octane fuel or excessively retarded ignition timing. The problem with less spark advance is that it cost's more power than lowering the compression. Open chambers are slow burning and prone to detonation.

This is an excerpt from page 4 of
Engine Basics: Detonation and Pre-Ignition
http://www.streetrodstuff.com/Articl...ne/Detonation/

"Now our engine was initially designed for premium fuel and was calibrated for 20 degrees of spark advance. Suppose we put regular fuel in the engine and it spark knocks at 20 degrees? We back off the timing down to 10 degrees to get the detonation to stop. It doesn't detonate any more, but with 10 degrees of spark retard, the engine is not optimized anymore. The engine now suffers about a 5-6 percent loss in torque output. That's an unacceptable situation. To optimize for regular fuel engine designers will lower the compression ratio to allow an increase in the spark advance to MBT. The result, typically, is only a 1-2 percent torque loss by lowering the compression. This is a better trade-off. Engine test data determines how much compression an engine can have and run at the optimum spark advance.

For emphasis, the design compression ratio is adjusted to maximize efficiency/power on the available fuel. Many times in the aftermarket the opposite occurs. A compression ratio is "picked" and the end user tries to find good enough fuel and/or retards the spark to live with the situation...or suffers engine damage due to detonation."

 

Good point, so a 9-9.5:1 cr would be better then i suppose, but would running more spark help matters any (i have an hei dizzy sitting on the bench waitin to go in).?

 

Detonation always comes up with OC heads. There are several factors that can cause detonation beside OC heads, lean fuel, bad fuel, bad carburation, wrong carb size, poor ignition, overheating and probably several more. Thats just the first few that come to mind. I run a similar type of cam that mustang70 is going to run, although it is a Lunati, full MSD, 2V Cleveland heads, stock 400 compression height (.056), compression was figured out to 9.5 after I got thru working on the heads and have used 89 octane gas. NO DETONATION EVER. I have ran as much as 42 degrees of total timing, plenty of jump outta the hole that night but no top end. Don't let the open chambers shy you away from them, they can perform well.

 

Running more spark will probably help an open chamber head. A stock closed chamber head may make the most power with 36 degrees advance where as an open chamber may make more power with 40+ degrees.

It's hard to compare similar cams without knowing specific details. When the intake valve closes after bottom dead center is very important to the dynamic compression. A better comparison would be dynamic compression ratios based on the same calculation method.

They say the 4V port is less volumetrically efficient than the 2V and therefore doesn't fill the cylinders as well at low rpm. It stands to reason then, a 4V open chamber head can get away with slightly more compression.

A .030 over FT piston with a 2cc valve relief, .056 in the hole with a .040 gasket and 78cc chamber works out to 9.35:1.
A .020 taller piston, 1.67 CH or .020 from decking the block would be 9.72
80cc chamber (+2cc from polishing) = 9.54

All these numbers are based on published figure. When pushing the maximum compression it's critical to take actual measurements.

 

You guys have been a huge help i really appreciate it.

I do however hae a few more questions . Its been decided that i will run with a flat top piston with valve reliefs (the first one you described Brian), along with a port and polish. Now my question relates to valve size. What kind of gains in port flow (if someone has any numbers that would great) would i see by upgrading to a larger valve such as the 4v valves, or even the large 1.76exh and 2.25int valves, like would it be worth the money to upgrade as i'm looking to get the most power i can without being overly noticeable? As far as the cost i'm going to start a new thread as i have some other cost related questions for building a 400.

 

Try this link:

http://www.jason.fletcher.net/tech/f.../cleveland.htm

 

Perfect, thanks for the link. Using them numbers in ddk2000 along with everything else remaining the same and a cr of 9.35 i see a gain of 56hp and 24tq, for a total of 462hp at 6000 and a max tq of 443 at 5000 with 422hp, which is right where i need it, so i think that this is the way i'll go providing i can afford it , well the machining bill anyway . Thanks again for all the help .