Blocking Off Exhaust Crossover

[My427stang]

Any budget left in the build for an intake? 

That one is a bit of a cork for a well-built 428

[440sixpack]

I thought about it but since it's just a street driven 4x4 pickup I decided it's good enough.  if it were on a car I'd probably toss it.


There aren't any stock looking cast intakes that are any better are there ?  I'm trying to stay as original as I can, though I am leaving the headers on since the stock 360 manifolds are possibly the worst ever designed in automotive history.

[My427stang]

First, I think you'd have a blast reading Jay's intake manifold comparo and should buy the book. Even if the engine is done by then, it's good reading

However, giving him all the credit for the testing, any of the other iron FE manifolds are better on a 400 HP-ish engine

Yours as baseline
Cast iron truck could be as high +10 HP at the peak
Cast iron early car could be as high as +15 HP at the peak
Cast iron CJ could give you +40 HP at the peak

Average torque and HP follows the same pattern

Of course it all depends on the rest of the build, but knowing you are going with a bit better cam than stock, etc.  It will be hard to beat a cast iron CJ manifold for that engine you are building, but people can be proud of them and they are a killer to ship.  If you look around, try to find a 69 date coded one, they are more plentiful , and a bit less costly

Edelbrock RPM would make the exhaust crossover easier, and make more power in some areas about the same in others, but wouldn't meet your goal for looks and on some trucks (like my 71) the air cleaner gets a little tight at the rear with the set back RPM

[chris401]

I thought about it but since it's just a street driven 4x4 pickup I decided it's good enough.  if it were on a car I'd probably toss it.


There aren't any stock looking cast intakes that are any better are there ?  I'm trying to stay as original as I can, though I am leaving the headers on since the stock 360 manifolds are possibly the worst ever designed in automotive history.

I never did get the log design either but Jay's testing shows that the 360 era pickup truck logs are the better than most  and just under the 352/390/406 cast iron shorty manifolds.

I have wondered how that GT intake performed on a truck 428. The 68 GT 600 carb and 66 S GT intake was about the best pickup truck combination I ran on a .060 over 390. Does your engine pull very well to 4500 or does it cork off sooner?

EDIT: A member here said he adapted one of the larger Autolite 2 barrel carbs to his stock 428 CJ. The fuel mileage his truck got was pretty good. Maybe he will post.

[RustyCrankshaft]

I haven't dyno'd one to prove it, but seat of the pants I've never really seen/felt any gain with headers on a stock 360 and same for a stock truck 390.

I think one of the worst stock manifolds in automotive history is the EFI 460's. 100% stock EFI 460 gain about 1.5 mpg and around 20+0hp at the tires with JUST a header swap. Even using the el cheapo headman's. Dyno'd a couple of them to confirm what the butt dyno said and they were all around 20-40hp gain on the same Mustang chassis dyno. Bumping the fuel pressure 10-15psi gets you closer to 35-40hp mark. Never thought you'd see that much on a low hp smog engine, but the manifolds are really that crappy, way worse than FE truck manifolds.

Probably see more gains running a good intake and stock exhaust manifolds than the other way around on your 428.

[My427stang]

I haven't dyno'd one to prove it, but seat of the pants I've never really seen/felt any gain with headers on a stock 360 and same for a stock truck 390.

I think one of the worst stock manifolds in automotive history is the EFI 460's. 100% stock EFI 460 gain about 1.5 mpg and around 20+0hp at the tires with JUST a header swap. Even using the el cheapo headman's. Dyno'd a couple of them to confirm what the butt dyno said and they were all around 20-40hp gain on the same Mustang chassis dyno. Bumping the fuel pressure 10-15psi gets you closer to 35-40hp mark. Never thought you'd see that much on a low hp smog engine, but the manifolds are really that crappy, way worse than FE truck manifolds.

Probably see more gains running a good intake and stock exhaust manifolds than the other way around on your 428.

I forgot what year it was, but the 460 trucks with the dual inlet throttle body that looks like two radiator hoses has a necked down adapter in the middle.  They are little trumpets inside, barely bigger than your thumb, pull the hose, hack the trumpet off with a hacksaw and another easy gain in mileage and WOT power

[RustyCrankshaft]

Yeah that big S plenum deal is a HUGE bottleneck. I had a set of the fuelie heads ported along with the lower intake and got an adapter to bolt a 4150 on it. Ran it with a Holley and with a couple different TBI set ups. The EFI heads are actually REALLY good for a street rig IMO. With a little grinding and bigger valves (Ponitac RamAir IV valves area a cheap off the shelf option for big valves) they do pretty well, and with the high velocity runners and small chamber with the plug relocated they're pretty efficient for a stock iron head.

[440sixpack]

So my roller lifters are going to hit the valley pan.   just double checking to make sure with my crossover blocked I can ditch the pan right ?

I think I could modify it to work but if it's not needed I'd rather not.

[cjshaker]

With a blocked crossover you could ditch the pan with hardly any effect. You'll be fine.

[My427stang]

So my roller lifters are going to hit the valley pan.   just double checking to make sure with my crossover blocked I can ditch the pan right ?

I think I could modify it to work but if it's not needed I'd rather not.

Doug gave you the right answer, most people do ditch it.  You'd have to do a lot of cutting to make it work

[440sixpack]

Great.  thanks

[Rory428]

I haven't dyno'd one to prove it, but seat of the pants I've never really seen/felt any gain with headers on a stock 360 and same for a stock truck 390.



Probably see more gains running a good intake and stock exhaust manifolds than the other way around on your 428.

  That was not my experiance at all. Years ago, I swapped out the tired & weak stock 360 in my 74 F350 ramp truck, and replaced it with a low compression 390 4 barrel from a 75 or 76 F250. I just ball honed it, put a new set of cast rings on the original "410" pistons, and a mild "RV" cam, had a basic valve job done on the D2T heads. Stock iron 4 barrel intake manifold, and tried a few different carbs. (best was a Holley 450, worst was a 1406 Edelbrock). After having 3 exhaust manifolds crack in the period of 2 years, I installed a new set of Hedman long tube headers, and dual exhaust, and although the truck was never dynoed, or dragstrip compared, the increase in power was very noticable, as was a gas mileage improvement. To get to the dragstrip near Ashcroft BC, there is a long steep mountian climb called "the Jackass" I would have to climb on the trip. Before, if I wanted to try to crest the hill in 4th gear, I would have to have to hit the bottom at 75-80 MPH, at WOT, and watch the speedo steadily drop all the way up. Afterwards I could climb the same grade at 55 MPH, and maintain that speed all the way to the top. Picked up almost 1 1/2 MPG as well. Best money I ever spent on that truck.

[RustyCrankshaft]

I haven't dyno'd one to prove it, but seat of the pants I've never really seen/felt any gain with headers on a stock 360 and same for a stock truck 390.



Probably see more gains running a good intake and stock exhaust manifolds than the other way around on your 428.

  That was not my experiance at all. Years ago, I swapped out the tired & weak stock 360 in my 74 F350 ramp truck, and replaced it with a low compression 390 4 barrel from a 75 or 76 F250. I just ball honed it, put a new set of cast rings on the original "410" pistons, and a mild "RV" cam, had a basic valve job done on the D2T heads. Stock iron 4 barrel intake manifold, and tried a few different carbs. (best was a Holley 450, worst was a 1406 Edelbrock). After having 3 exhaust manifolds crack in the period of 2 years, I installed a new set of Hedman long tube headers, and dual exhaust, and although the truck was never dynoed, or dragstrip compared, the increase in power was very noticable, as was a gas mileage improvement. To get to the dragstrip near Ashcroft BC, there is a long steep mountian climb called "the Jackass" I would have to climb on the trip. Before, if I wanted to try to crest the hill in 4th gear, I would have to have to hit the bottom at 75-80 MPH, at WOT, and watch the speedo steadily drop all the way up. Afterwards I could climb the same grade at 55 MPH, and maintain that speed all the way to the top. Picked up almost 1 1/2 MPG as well. Best money I ever spent on that truck.

Did the truck have single exhaust or dual exhaust with the logs?

My all original 74 highboy going up the same mountain pass with the same trailer went the same speed at the same RPM stock manifolds and dual exhaust as it did with the same exhaust but headers. Same for my 73 camper special. Zero change towing up a hill. Both were stock 360's. Had a bump side high boy with a 390 of unknown origins and I might have gained 2 or 3 mph when I put the headers on. The biggest difference I ever noticed was going from the little factory single exhaust to duals. This is on stock or mildly warmed over truck engines, the build obviously make a lot of difference here.

I will say that it did seem to accelerate faster with headers and had maybe a little better throttle response, but didn't make any noticeable difference when actually working. Well, besides not cracking the logs in half every other trip it seemed like!!

Now once I started changing cams, intakes, carbs, etc the difference started to become noticeable. Just for the fun of it, on a few combos I had switch back and forth between headers and the logs. On a street driven work truck the headers really didn't seem to make noticeable gains until the engine build was getting into territory where it wasn't so good for work anymore.

The caveat here is, how I drive a "work" truck and what I think makes a good truck engine and what you have could be 2 completely different things and make you're experience differ from mine. I don't mind beating on a race car, that's what I built it for, but anything I'm actually using I tend to be pretty gentle with. I'd rather drop and gear and slow down than spin the thing 6k for another 3 mph at the top of the mountain where I probably have to slow down anyway to avoid the Prius sightseeing on a trip from California causing traffic to scatter in every lane and the shoulder.

[My427stang]

It's hard for me to say either way because it's been a long time since I had a stock 360 come through. 

However, I have always recommended, headers, exhaust, to include a balance tube, and a recurve. Those three make an incredible difference in a stocker, even back in the 360 powered 1-ton and 3/4 ton work truck days (I'll add a shift kit to the mix with a C-6)

I could certainly believe that a bone stock 360/390 with wide LSA and crappy intake doesn't benefit that much from headers but think it's likely high single digit HP, which is noticeable with a stock 360.  Regardless, I always try to package the three things above together (or at least headers and crossover/duals) as a nice gain to make the owner happy, as well as a foundation for later. 

[RustyCrankshaft]

It's hard for me to say either way because it's been a long time since I had a stock 360 come through. 

However, I have always recommended, headers, exhaust, to include a balance tube, and a recurve. Those three make an incredible difference in a stocker, even back in the 360 powered 1-ton and 3/4 ton work truck days (I'll add a shift kit to the mix with a C-6)

I could certainly believe that a bone stock 360/390 with wide LSA and crappy intake doesn't benefit that much from headers but think it's likely high single digit HP, which is noticeable with a stock 360.  Regardless, I always try to package the three things above together (or at least headers and crossover/duals) as a nice gain to make the owner happy, as well as a foundation for later.

I'd put headers on everything. I have a set on a bone stock 360 right now - just didn't get any real gain from the headers by themselves.


I'm not saying you won't pick up power, I just don't think in real world conditions your low compression 390 in your truck is going to care that much and you're still going to get to the top of the hill pulling your race car at the same speed. Like I said before, a lot of factors to be considered and this is based on my experience with the trucks I owned or drove. But I do think I did a fairly unbiased job of comparing differences between the changes. Not as good as a timeslip, but getting to the top of the hill 2mph faster with my new headers is less embarrassing than the 20 second time slip would have been!!!

But I'd put a set on anyway, because they certainly won't hurt and they WILL look GOOD even on a clapped out camper special with a stock 360 and it's 180 mildly annoyed HP. And even the 360's I've had with headers, a good timing curve and a good tuneup in the carb did respond to the changes. But I won't lay awake at night because I'm taking my 225hp truck to the gravel pit tomorrow without headers on it. Ok, ok, I won't lay awake for very long worrying about it.