next upgrade?

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

Guest
i was wondering about a few things...I just got a head gasket kit but want to wait to do it untill i figgure out the next step. I dont want performance right now, but rather a smooth running reliable inline thats better on gas than it is now. I was wondering if a cam should be the next upgrade or if i should just get a header, it would only be single outlet though so i can hook it up to me single exhaust that i have now. i read about using Vee-8 springs and retainers to change the spring rate from stock 150 closed and 54 open to 200 closed and 80 open and using the 4.0 V6 retainers...what difference will this spring rate make..could i do this upgrade and leave the cam stock and see improvement? My head has a busted bolt flange so the closest bolt on the exhaust manifold doesnt tighten, should i get a different head before getiing a header or will the header be fine on this head? I'm mostly curious about the difference that is made by the different spring rate though...thanks for any help guys.
 
Hody PW:

The heavier springs will give you absolutly no additional performance. That is unless you are currently experiencing valve float at higher rpms. Heavier springs will accelerate valve seat wear, cam lobe and lifter wear, and shorten valve chain lift.

Unless you need them to control valve action at higher rpm they are not a good return upgrade.

Now the lighter, one piece 4.0 retainers would lighten the valve train and slightly ease stress on the valve system, allowing stock springs to manage more easily.

Before a cam or headers, consider a performance valve job that would include a bump in CR, 3 angle valve job, back cutting the intake valves, some pocket porting, an adjustible rocker assembly and a set of valve springs matched to the needs of your future cam and one piece retainers. Since you have a busted bolt flange it may be easiest to find a good head build it then swap one afternoon, when you're ready. Less down time and no rush.

This will get you ready for a header to follow and maybe a bottom build, which will include the performance cam and gear.

That's my two cents, for what it's worth.

Adois, David
 
allright thanks for the help. guess i'll look fora decent head to use then and work on it for awhile then. thanks again.
 
I got my used head today...its off an 80's 200 and has the larger valves. i gotta figgure out how much it is to hot tank and then clean it up a bit...i can tell i need to do some grinding though on the head. I have one busted from the exhaust which i will drill and retap, also i have to drill and tap some holes for the thermostat housing since it had threaded rods rather than bolt holes and one of em snapped off so i will be needing to drill holes from scratch...hopefully i get them straight. I also was wondering about the 2 threaded rods which held on the exhaust manifold on the top...on my origional 78 head i could remove them, but on this head i cant...if i want to get a header than how should i go about doing this...should i remove them and drill and tap some new holes? Just curious but what exactly does back cutting the intake valves do? Thanks for all the help guys.
 
Howdy Placid Warrior:

Yes, diffinetly remove and tap any bolt holes and broken bolts now, while the engine is apart. This is also the time to get, fit and weld in an exhaust prot divider. When machining, consider flat milling the exhaust surface mating face as well as the deck mating surface.

Back cutting the intake valves is explained and illustrated on the "Hardcore Inline Tech Forum" in a stickie at the top of the page. I think it is in the one entitled " What a 3-angle Valve Job is". A picture is worth a thousand words, and my brother, Dennis is so cleaver at that stuff.

Adios, David
 
Hey PW, also back cut the exhaust valves as well to the lap in line. Remember exhaust also flow air as well as the intakes. Also round off the sharp edge at the top of the exhaust valve above the margin & this will also help exhaust flow.
David i know you only mention backcutting the intake valve but the exhaust valve flows air just like the intake. I have seen flow bench figures to prove that backcutting the exhaust valve also helps flow.
Remember this improvement is not only on the valve opening but also on the closing. So you pick up flow on both ends. Try it you will like it. William
 
Howdy Back:

William- While you are correct in recoginzing that backcutting exhaust valves increases flow, the differences that cause me to recommend only back-cutting the intake side are several. Consider-

The intake valves are washed with a cooling intake change that is being drawn in by engine vacuum. High heat is cyclical and is not much of a problem. We typically specify a .100" seat margin on the intake.

On the Exhaust side heat and the stress it adds is very much an issue. When the exhaust valve opens cylinder heat is the highest and that heat passes over the valve edges and seat. That is a high stress environment. The exhaust gases are exploding out and being pushed out with the pistons upward movement. Consequently backcutting valves has a bigger, positive effect on the intake side than on the exhaust side

We believe that the intact mass of the exhaust valve helps to deal with the added stress. We also use a margin of 120" on the exhaust side to help transfer valve heat to the head for disipation. So we are willing to forego the slight increase in exhaust flow for a little more piece of mind and durability. Narrower margins can also improve flow, but the trade off is reduced duratility.

We use 260 -264, 420" lift cams for street and are using 144 intake valves, 1.468", on the exhaust side. For an otherwise stock, low rpm, engine backcutting the exhaust may not be much of an durability issue. When offering advice I chose to remain on the conservative, reliability side.

That's my two cents, for what it's worth.

Adios, David
 
David, i appreciate your concern about durability. Any engines i have build & other friends engine built all backcut the exhaust valve to.
I built a 351 windsor with back cut exhausts & never had a problem for 150,000 miles of driving.
The valves made today are made of such good materials that durability is not a problem.
there is a lot of flow to be gained at low valve openings not to do this simple modification. William
 
thanks for the help guys. i suppose that with the cutback valves and all that i dont really need another cam then do i? i dont want to go nuts in performance...just more than what i have...say 110-125 Hp would be nice...so i will be looking at a progressive 2bbl carb for the setup as well. i think I'll stay away from backcutting the exhaust valves though, I dont want to risk anything at all...even though it works, i'll just stay shy from doing it. thanks again for the help.
 
Howdy Back all:

PW- consider- If you're only doing the head/valve job type upgrades, that is the time to do the back cut on the valves. And YES, both the back cut on the valves and the cam are worth it. The time to do the cam and gear is when you're rebuilding the block. A cam in the 256 to 265 range with .400" plus lift would be very streetable and economical.

William- As I said, we are using 40 year old valves on the exhaust side. Backcutting the exhaust valves using modern metals and technology may add durability. I plan to use SSI exhaust valves on my next head so may give it a try. Your experience with the 351 is the kind of proof I like to hear. Nothing like a "stretch-it-till-it-breaks" test to really find out.

The plan is to do extensive, step-by-step flow bench testing on this next head build to empirically document what works and how much. Even though flow bench results do not directly correlate to HP or durability, it will quantify air flow.

Adios, David
 
allright then...i have a bit more funds available to me now...i was going to get some wheels for the car but i decided to wait awhile and finish some other things first...so the cam i suppose is an option if it does make that much of a difference and doesnt ruin my economy too much. thanks again...i'll get back to u and let u know how things are going in a few weeks. thanks again for the help..
 
I was wondering...what kind of losses would i experience with a lopey cam?
 
Dave, the 264 cam @ 112 lobe center looks fine if you have a c-4 trans, if you have a 3-4-5 speed manual trans i would go with the 110 degree lobe center. This cam will have a decent idle & provide you with increased power. Yes stock valve springs are no good, you need to check with mike @ www.fordsixparts.com for the proper spring tension. You need at least 80-100 lbs. for seat pressure for these fast lift cams. Don't worry about wear, using a matched setup will provide many miles of trouble free driving. More power to you. William
 
i have the c-4 tranny, looks like thats the cam i'm going to go with then. I'll get the springs and some teflon valve seals so that they can be installed when i get the head done up. thanks again for all your advice.
 
allright...tomorrow i will see how much some '73-'75 302 springs are cause i forgot that we get like a 45% discount, so the price might be more reasonable. the springs are rated at 200 open and 80 closed so that should be good for this engine setup. I'm also just wondering about the teflon valve seals...is that a custom product from mike or are they from a 302 as well or from some other engine...i love the idea of supporting FSPP but if i can get some parts cheaper here than i am more than happy and then the money i save could go as donation or something.

talked to mike and he said that these springs are too much for the setup...so I'll be ordering from mike then
 
anyone know if the 2.5 L tempo/taurus push rods would be directly interchangeable with this setup? they're supposed to be 6.00", that would increase valve lift right?
 
Howdy Back PW:

Either you're confused or I am. The stock 200 pushrods measure 8 5/16" long. Changing the length of the pushrods will not effect the valve lift, only the geometry. 6" pushrods are way too short to even consider. Valve lift is only effected by the cam lobes and the rocker arm ratio.

The Tempo HSC 2.5 four cylinder engines use a 6" connecting rod that may be helpful in dealing with the excessive deck height of the 250 engines. Using the 2.5 Tempos connecting rods would have a slight positive effect on Rod length to stroke ratios and reduce the deck clearance by .120". It is a very interesting solution to the deck clearance problem of a 250 that I'm looking forward to exploring some day. I don't know of anyone who has been down this road yet.

Adios, David
 
OOPS :oops: my mistake. I copied down some info on parts from misc engines that could be used in the 250 and it said 6" rods...i just assumed it was push rods. that makes more sense now, I was definitely the confused one, thanks for clearing that up for me. i dont think i want to go to that extensive of a build right now, dont have that kind of time, but it would be something to consider then for the future. thanks again for clearing this up.
 
You must log in or register to reply here.

Similar threads

DON
For Sale valve springs/retainers
Replies
8
Views
733
awasson
awasson
Montytm26
All Small Six Starting new build
2 3
Replies
41
Views
3K
awasson
awasson
F
All Small Six Any difference in stroke between a '65 and '70 200 block?
Replies
5
Views
828
frozenrabbit
F
P
All Small Six O2 location and headers
Replies
2
Views
372
DON
DON
Clutch
SOLD Modified 250 Head.
Replies
3
Views
468
Glenn
G
Back
Top