That has been debunked several times already by reputable builders.
any benefit to swapping heads?
- Thread starter djais1801
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Demonic
Well-Known Member
Door buzzer works with the lights on. That's cool. Beautiful car. Interior looks cool too. Need more pics of that.
512Stroker
We are all here because we are not all there.
Port the X heads and intake, swap them onto the engine and at the same time add a set of good headers .
Make dam sure your head work is done by a reputable machinist that knows Mopar heads.
You will notice a difference with a little tuning.
Nice ride
Good luck
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yellow rose
Overnight Sensation
30* seats were stupid back in the day. They are even more stupid today. I wouldn't put a 30* seat on a picture of a lawn mower.
A 2.02 valved head won't kill the bottom end so bad you can't drive it. That's rediculous.
The OP doesn't need bad info.
Seriously your not comparing a boss 302 to a 340, a 340 runs circles around a boss 302. A friend I grow up with had 2 boss 302's and I had a AAR and I would blow his doors all the time, boss 302 ports are twice the size of a X head so that's fords problem, I never had a bog coming out of the hole, on a hill or what ever it just never bogged you got some other problem if you think volocity has to do with a bog on a X head motor. get real dude, you read to many storys, just sad.
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Just to be clear my AAR had a 69 motor with X heads pocket ported and just touched up every where else and a set of mechanical carbs 4782, 4783's so when I hammered down I opened all 3 carbs with no bog what so ever and it was a 4 speed car so no convertor to help it rev.
The AAR engine was on a stand for years nice and safe in the heated air conditioned garage.
The AAR engine was on a stand for years nice and safe in the heated air conditioned garage.
I was under the impression that with 30* seats, you got better flow at intermediate lifts. If I remember right, I picked that up from watching a lecture by David Vizard.
Are there any flow tests published with identical heads with the only difference in valve seat angle? I always need more education.
Sorry for the thread derail.
djais1801
Well-Known Member
Thanks...interior had duster seat covers originally (vertical pleats). I had an upholstery shop swap the inserts. I compared price to finding a good bench seat and replacement plaid seat covers from Legendary and saved considerably just doing the inserts. Key buzzer works w key in ignition whether running or not
yellow rose
Overnight Sensation
It's not a thread derail. It's about learning. I know DV loves the 30* seat and he and I have hashed it out. He is just dead wrong and I'm not the only one telling him so. Over on speed talk there is a big thread about when to use 50* seats. It's worth the long read.
The very last thing I look at when flowing a head is low lift flow. In fact, total lift isn't even a factor in chosing a seat angle. One of the guys is using a 50* seat on his tow rig and he has less than .500 lift. He says it hauls ***.
Before I bought my flow bench, I heard everyone screaming about shape, shape, shape. And all I can say is that's a FACT and it all starts with the shape of the valve job out in both directions.
djais1801
Well-Known Member
It's low compression 8.5 and does bog. I'm looking for more low end torque...my mechanic says it's due to the cam.
advance it at least 4* it will help a lot
Wyrmrider
Well-Known Member
t's low compression 8.5 and does bog. I'm looking for more low end torque...my mechanic says it's due to the cam.
Exactly
Rose colored glasses ignore the less than half inch lift but long duration
2.02 valves will hurt without a gear and cam change, less cam change with more compression
not saying that a a pro port and valve job can make the 202's work but not stock 202's and I would not spend the money to do more than a good valve job and pocket port x heads
We're not talking a race car here and on a half inch lift build 30 degree seats flat work
now with that cam duration 45 makes sense or more cus you are trying to band aid low lift flow and overlap
what you can't do is change the intake close point much (the 4 degree advance suggestions) without problems with intake open and killing mileage with early exhaust opening
opening exhaust late is more important on low compression motor than on an high compression motor
that said
if the 202 heads already have good seats and guides and the 1.88s are tired
do a compression check and post the results, mill the heads and do a quick head swap and see the results
your mechanic is mostly correct if you are not going to up the compression
If you are not making any changes to the short block you can shorten up the duration big time while keeping about the same lift
If you are not now up for a cam change then mill the heads , advance the cam and drive it
There are others that can do some simulations for you
remember the exhaust is the Achillies heal on the SBM
if you are keeping stock exhaust because you like your stereo or wife hates headers (my situation)
do some searches on Magnum exhausts- also the cam will be different with stock exhausts
your current cam was designed for headers
Exactly
Rose colored glasses ignore the less than half inch lift but long duration
2.02 valves will hurt without a gear and cam change, less cam change with more compression
not saying that a a pro port and valve job can make the 202's work but not stock 202's and I would not spend the money to do more than a good valve job and pocket port x heads
We're not talking a race car here and on a half inch lift build 30 degree seats flat work
now with that cam duration 45 makes sense or more cus you are trying to band aid low lift flow and overlap
what you can't do is change the intake close point much (the 4 degree advance suggestions) without problems with intake open and killing mileage with early exhaust opening
opening exhaust late is more important on low compression motor than on an high compression motor
that said
if the 202 heads already have good seats and guides and the 1.88s are tired
do a compression check and post the results, mill the heads and do a quick head swap and see the results
your mechanic is mostly correct if you are not going to up the compression
If you are not making any changes to the short block you can shorten up the duration big time while keeping about the same lift
If you are not now up for a cam change then mill the heads , advance the cam and drive it
There are others that can do some simulations for you
remember the exhaust is the Achillies heal on the SBM
if you are keeping stock exhaust because you like your stereo or wife hates headers (my situation)
do some searches on Magnum exhausts- also the cam will be different with stock exhausts
your current cam was designed for headers
yellow rose
Overnight Sensation
His valve size isn't the issue. And the answer damn sure isn't a pre WWII valve job. Geeeeeezus.
I'd bet a bunch the cam was never degreed. I'd also bet rolling it forward to a 102 ICL would wake it up.
Valve diameter is not the issue.
Bog, look at ignition timing, intitial, total and curve!
Tons of carb issues are in the ignition system and timing.
I wouldn't waste the time to swap to a 2.02 head. I swapped all sorts of stuff on my 70 swinger 340... wish I would have left it alone and degreed the cam properly!
Tons of carb issues are in the ignition system and timing.
I wouldn't waste the time to swap to a 2.02 head. I swapped all sorts of stuff on my 70 swinger 340... wish I would have left it alone and degreed the cam properly!
djais1801
Well-Known Member
Agreed
djais1801
Well-Known Member
What is 102 ICL?
djais1801
Well-Known Member
So are you saying keep the 360 hands and just degree the cam? Or adjust the cam and put the X heads on?
If you are going to pull it apart do the heads, if you do the cam first you have to deal with the dial indicators and it's a lot easier with the heads off.
How to Degree A Cam - Lunati Power
How to Degree A Cam - Lunati Power
Wyrmrider
Well-Known Member
yellow
it's not the valve size it's the velocity
Think about putting your valve seat where the top cut is on your 45 degree valve job
the old 45 degree seat is most likely well sunk on old heads and impossible to put a good valve job on- well putting larger valves in is one way
sunk seats suck big time
if your cam profile is based on flow demand you do not have to kill low lift flow to prevent reversion
open the intake later
it's not the valve size it's the velocity
Think about putting your valve seat where the top cut is on your 45 degree valve job
the old 45 degree seat is most likely well sunk on old heads and impossible to put a good valve job on- well putting larger valves in is one way
sunk seats suck big time
if your cam profile is based on flow demand you do not have to kill low lift flow to prevent reversion
open the intake later
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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For a streeter, and with no other changes, I ,personally, wouldn't spend the time, or the cash, for new FellPros.
You should already have enough power to spin street tires thru two gears;but at 8.5 Scr, I bet you really have to rev it up to break the tires loose.I hated that. I hated it because it sounded so Mustang.
There are two versions of that Mopar single pattern cam, and neither one is for an 8.5 street engine; and neither one is for 3.55s.
If you have an issue at low rpm, the X-heads won't fix that. IMHO, you asked the wrong question first.
If you really have an 8.5Scr engine, and you really want to keep that cam, and those 3.55s, and can't find or afford the 3.09 lowgear Commando trans, then ............ well;
I could tell you about my 292/.508 experiences in my 11.3 Scr Aluminum headed 367. The short version is I swapped it out in a hurry, for a 270/276/110 cam with lifts of .538/.549, and lowered the compression a tad, and would still be driving it like that today,18 years later, (because it had monster torque), except it began dropping lobes in 2004.Well, that's as short as I could make it.
MopaR&D
Nerd Member
Yup heads aren't an issue I'd leave them be. The best overall performance increase for the $$ would be to swap the cam to something with less duration that's designed for low-compression engines, and have the engine properly tuned. Actual CR is always lower than advertised on old Mopar engines anyway, from roughly .3-.5 meaning your "8.5:1" 340 is more like 8.0:1, unless it was rebuilt and blueprinted to factory compression of course...
Smogger big blocks (400, 440) rated at 8.2:1 come out to 7.8-ish, I measured the 1972 440 I overhauled for my cousin's '71 Satellite project and even with .010" milled off the head and the super-thin steel shim head gaskets the true compression came out to 8.0:1 even. Might be thirsty but it'll definitely run on regular, hell probably 80 octane lol
Smogger big blocks (400, 440) rated at 8.2:1 come out to 7.8-ish, I measured the 1972 440 I overhauled for my cousin's '71 Satellite project and even with .010" milled off the head and the super-thin steel shim head gaskets the true compression came out to 8.0:1 even. Might be thirsty but it'll definitely run on regular, hell probably 80 octane lol
moper
Well-Known Member
Assuming the heads are equal condition - you won't feel anything. If you want to get more power, change the camshaft to one that will work with the factory manifolds amd exhaust. No way that swaps a 20hp gain given what you already have. Neither head is that good as cast/assembled.
furrystump
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If the x heads have never been touched they don’t have hardened valve seats. I don’t think it is worth doing a simple head swap. You know the 360 heads are good and have hardened valve seats. The x’s are not worth the effort in their stock state and can be a reliabilty concern. That said the x’s are valuable. If stock appearance of the head means nothing to you there is no real reason to put money in a 50 year old casting. There are just to many better options, but there are people that want those heads to either restore a car or are required to run that head. If thats not you sell them and put the money towards
a better head. I’m VERY VERY happy with my x heads, but to get them to flow 278 cfm cost me $3000 in work. What will $3000 get you in a one of the newer castings.
a better head. I’m VERY VERY happy with my x heads, but to get them to flow 278 cfm cost me $3000 in work. What will $3000 get you in a one of the newer castings.
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