with all of the differnet combo's people are running and what works with this and that but doesn't work with this or that. I'm confused.

I have my 390 out and on the stand right now. I have c8 heads(stock everything), c5 4brl s-code intake(stock), and headers. Everything on the engine is stock. I need an engine with 400hp and a little more torque. Do I need to port the heads/upgrade valve size(how do you home port FE heads)? Do I need an adjustable valvetrain to work with the 343941 cam(which one?)? What's the deal with quench and does it matter on a 400hp engine? Will I need a new intake or will the stocker keep up? Will the stock distributer and electronics be able to keep up? etc...?


sorry for all the questions. I have been reading for the past few weeks here to try and figure some of this out but like the title says, I can't keep up.

Max

BTW - I have been reading this board for a while now and never really contributed much, but the amount of knowledge on this board is amazing. I read a bunch of other boards and most of the info is either wrong or noone stays on-topic and nobody gets a reply that is worth anything. thanks FTE


ps. the motor I build will be going into a 1977 f150 with a 4-spd. I am not looking for a pulling truck, a drag truck, or a mudding truck( because it's 2wd). I am looking for something that is fun to drive and can keep up with the new trucks out there. It is not a daily driver and gas mileage is not really a concern.



thanks guys

 

you're on the right path!!!! if you port the exhaust side of the heads and gasket match the intake ports it'll make a world of difference!! if you're gonna completely go through the heads and have an machine work done on them, i'd recommend getting a price estimate from our machine shopand then weigh the cost of that against the cost of a set of edelbrock RPM heads. m buddy just had to have a set of FE heads gone through and between the new valve giudes, springs and retainers, as well as larger exhaust valves- he spent $900 on them and hasn't even spent any time porting yet!! at a little over $1200 for aluminum heads, he now wishes he'd have went that route... an adjustable valvetrain isn't a absolute with the 941 cam, but by the time you measure all your pushrod lengths and get the right ones, you'd be time ahead to just get the adjustable set and be done with it.. if time isn't as important as money to you, then just start measuring each length and take notes- be sure not to lose them cuz if you ever bend a pushrod you'll appreciate how much easier it is if you can reference a notepad- don't ask mehow i know.... lol quench is the area between the top of the pisons and the cylinder head at top dead center on the compression stroke. the tighter the quench-the higher the compression- but it also reduces the amount of detonation so you can actually run a higher compression ratio on pump gas... i'd upgrade to the performer RPM intake and a electronic ignition. the higher compression will test your points ignition to it's limits, and even beyond in most cases... electronic will start easier and bring you better fuel mileage as well due to a complete combustion burn...

 

to get 400 hp I think you have to port the heads. You also need to put hardened seats on the exhaust valves of the C8 heads. Kurt will know better but I think you can get to 400 hp without going to larger valves. I'm one of the ones that have had problems with the RPM intake sealing so it's hard for me to recommend it...especially because I'm not an isolated case. Many have been successful from the start though and I'm sure I caused some of the problems. I also agree to go with the adjustable valvetrain in some form or other. I got mine from dscmotorsports...I'd first check with Barry_R now.

Good Luck!

Tracy

 

you don't necessarily need the larger valves but if you're gonna turn the RPM's up a bit they'll really help your engine breathe and make more HP up top..

 

what pistons do you plan to use? and what head gasket? you are going to want to keep quench .035-.050" , any less than .035 and at higher rpms the pistons meets the heads and stuff gets ugly and any more than .05 and its pretty much useless. i would reccomend trw-L2291 pistons, kurt is running them with a .02" head gasket and a 941 cam and it has a dymanic cr of about 8.7. i am going to be useing the same pistons next summer when i tear into my engine but i am going to be useing the crane 801 cam to bleed off a little more compression and plus i like the sound of a bigger cam. but the bigger cam will require more valvetrain upgrades.

 

Here's how I have mine built, not saying this is the best or safest way:

390 .030" over, stock rods, stock crank, ARP rod bolts
Edelbrock Performer RPM
Ported / polished C7AE-A heads, standard size valves, 3 angle valve seat job
Mr. Gasket .020" steel shim head gasket
TRW L2291F30 pistons, measured .012" deck clearance
Crane 343941 cam, adjustable valvetrain
Headers, dual exhaust

Now this is only .032" quench, which is why I said may not be the safest, but I believe if I keep it under 5500rpm I'll be alright. I'll have to watch it like a hawk though. I may even invest in a rev limiter. You'd be safer with those pistons to deck the block so those pistons are flush with the deck, and run a .040" thick head gasket. I suggest the Ford Racing head gasket, Summit number FMS-M-6051-A427.

 

Oh well here we go. I'm going against another post again. You do not want to port match the intake. There are alot of posts around on this. Only clean up the casting marks in the intake. Yes do the adjustable valvetrain but even at that you still may need different pushrods depending on what resurfacing has been done on the block and heads. You will need to get a pushrod length checker, trust me it is worth it. I can't speak to the manifold from experience though many say the oem 4v ones are better then the performer. I'm not sure about the rpm. Have fun with it and take your time. Check and recheck everything. Haste makes waste...literally with an engine.

 

Forgot you asked about where to find out about porting. the following links will help. The one from standard abrasives will mention the port matching, they want to sell porting material. The other one will tell you what you should not do porting. At the yahoo link you have to go to files on the left and then look for the "port or abort" file.
http://www.sa-motorsports.com/diyport.shtm
http://autos.groups.yahoo.com/group/...1Boss351HO400/

 

The Standard abrasives web site has a diy section which is a good primer. There is also a link which won't copy here so I'll just say it is here,
autos.group.yahoo.com/group/351ClevelandsRock302c351c351Boss351HO400/.

 

I agree, dont port match the intake manifold itself. However, if the port opening of the intake manifold is bigger than the intake port of the head itself, you really do want to open up the intake port to match the intake manifold!

 

so will the stock intake be fine as long as I match the heads up with the intake?

thanks for all the info guys.

 

I was planning on using the stock pistons, is this bad?

Why so low on the CR? I thought we needed around 10:1 to make any sort of power.

I also want the sound of a bigger cam, I will have to research the 801 a little. I was just going to buy the 941 like everyone else.

Who makes the adjustable valvetrain?
thanks

 

Stock pistons.. depends on what motor they came out of. If it was a truck 390, then forget it. If it was a car 390, preferably a high compression 4 barrel 390, then they would be ok to use, assuming that the bore and the pistons are both in good condition.

Notice that we're talking about the dynamic compression ratio. This is different from the static compression ratio. The static compression ratio is simply displaced volume over combustion volume. The dynamic compression ratio figures in cam timing, more specifically, when the intake valve closes. The dynamic compression ratio is the one to look at for determining octane requirements. My engine is running around 9.8:1 static, but I can still run 89 octane.

Here's a calculator for both dynamic and static compression:
http://www.kb-silvolite.com/calc.php?action=comp

Ford originally made the adjustable valvetrain. The adjustable replacement rockers can be had from most any auto parts store, and the pushrods are available from a number of sources.

The stock intake should already be pretty well matched up with the heads. Just make sure the head intake ports are the same size or larger than the intake manifold ports. If the head ports are smaller than the intake manifold ports, then this creates an obvious obstruction to flow.

 

very cool, thanks

I think I have a 390 out of a truck. I remember seeing a post on here that if the oil filter id horizontal it's out of a truck. Is this correct? Mine is horizontal.

I don't know what my CR is, but anything less than 93 octane and it pinged pretty bad when even a little throttle was applied. My dad seems to think it's pretty high, like 9.5 :1, that's his guess anyway.

I had the engine apart a few months ago to replace the exhaust manifolds (don't ask, it's a long story )and the machine shop said that the engine looks like there is less than 10k on the motor because the cylinders have no marks on them. The machine shop said there would be ridges at the top of the cylinder where the piston does not go all the way up and they were still very clean. :dunno:

 

Maybe someone rebuilt it at some point in the past. These engines have been around for 30+ years now, you never know.

Fuel octane isn't the only thing that determines if a motor will ping or not. There is quench, which will reduce pinging by causing turbulence in the chamber, reducing hot spots, and quickening the burn. Then there is the cam timing and dynamic compression ratio, as already discussed. Then, there's timing. If the timing was set too far advanced, that can cause pinging. Chamber deposits, like you would get if the engine was consistantly running rich or cold, or burning oil, can also cause a ping. Of course, a hot engine running lean will tend to ping too.

If the engine is out, I would advise you to measure the piston to deck clearance. Also tell us if they are dished or simply have four valve reliefs. That should give us a good indication of what pistons it has in it.