The Sea Foam idea is a good one, and one I hadn't thought of. Think I'll do that. Thanks, guys.

As for liking the NP, yes and no. Even with 3.50's and 31's I could probably take off from a stop in 3rd. But, I guess it has as many usable gears as the C6. And, I get to pick them when I want to pick them. However, I'm really looking forward to the ZF5. Being able to drop into OD sounds great - in several ways.

Shaun - Who was it that called them a "pig" recently? I guess being a pig is better than being a boat anchor? Neither sounds like a term of endearment.

 

sounds like an aftermarket replacement valve then...
I meant to say that when people decide to "rip all this emissions **** off the engine" (i.e. EGR spacer on an otherwise stock engine) they will end up with a a carb that is sitting almost an inch too low, on their stock intake, in relation to the throttle cable bracket.

I'm glad to hear cRusty has such a healthy heart.
I think you'll like it even better in front of the ZF.

 

Yes, I believe it is aftermarket as it doesn't have the stamp that I tend to remember from Holley - although it has been almost 40 years since I worked on one. But, I don't detect any hesitation when easing into the throttle at any speed - in spite of it now being jetted 66 when the documentation in that link says it left the factory with 68's. So, either it is sorted very nicely or it is running rich since it sure doesn't feel like it is lean. And, as soft as the spring on the PV is I don't think it is opening very quickly.

Once I get Dad's transformed I'll be able to tune with the E'brock air/fuel meter as I'll put a bung in the exhaust during that work. But, for now I'll drive it and see what the mileage is as I know the performance is good.

And, as said, I am looking forward to the ZF5.

 

When I call an engine a pig, I'm referring to the fact that they swallow gas in hoards. It's no lie that a V8 swallows gas in hoards. In stock 30 year old form, the 351M/400 is definitely a great big piggy.

The only real reason people called the M-Blocks boat anchors was due to the aftermarket's poor support. M-Block owners were forced to let their engines sit on stands until they could find aftermarket parts for them. Because of this, their trucks were forced to sit dormant, just like a boat that has dropped it's anchor.

However, the aftermarket has started to better support the M-Block engines, so the boat anchor comment is null and void.

 

I somewhat agree, Shaun, but IMHO they're considered boat anchors because they're so de-tuned & restricted from their original design that they don't perform exceedingly well out of the factory.

Learn about them, un-do all the de-tuning, and the 400 is the V8 version of the 4.9L 6-banger as far as torque and a great truck engine. The 351 variant has a shorter stroke.

Tim Meyer is the best 400/M-block guru I know of....

 

But boat anchors don't perform at all, except for just sitting there.

M-Blocks still perform, albeit kind poorly.

 

The 351M/400 suffered from the same issues the 68+ FE (360/390) had. Low compression and retarded cam timing/tuning.
Bumping the CR into the low-mid 9's, a decent cam, free flowing intake/carb and exhaust will perk them right up. However, a 390 has one slight advantage over a 400, in that a person can use "stock" parts from the pre-68 era rather than having to buy "special" aftermarket stuff.
Dad built the 390 in his 74 using a factory GT/CJ camshaft and older 390 2V pistons (360 truck pistons) straight out of the Ford dealer's back counter, using his employee discount. He ended up with an engine that was built as it *should* have been, and the MPG didn't suffer but rather improved a bit when driven "normally".
Neither the FE or "M" series were known for great MPG, and thanks to the EPA restrictions, they didn't make nearly the power/torque they *could* have made. By improving the CR and cam, you can end up with an engine that makes far greater power/torque, while netting the same, or slightly better MPG.

While the "M" (335) series engine has good potential, I will always have a fondness for the FE, since it was used in cars, pickups, and with minor tweaking bigger trucks in FT form. Granted, the FE was not offered after 76, so for an 80-82, the best you could get was the "M", which filled the void left when the FE went away. I don't like saying the "M" *replaced* the FE, because it was (in stock form) a pitiful "replacement". Had the EPA not stepped in, the "M" could have been a decent replacement for the FE, which was more than 20 years old at the time the "M" was developed. FWIW, the "M" was actually developed to take the place of the FE, mainly due to the massive outer size and weight of the FE. An "M" will fit into a lot tighter space than an FE will, while saving about 100LBS of iron.


Gary, I would be very interested in seeing MPG comparisons between Rusty with the holley and edelbrock, while everything else remains the same. I've heard many times that the edelbrock carb tends to give a 1-3 MPG improvement over a like-sized holley. You have the perfect "test bed" seeing as you have both types of carbs. I would like to try this myself, on dad's truck, but the holley carb I have does not have the provision for the auto trans kickdown, and that *could* skew the results.

 

RW - I am hoping to test that. However, it might be on Rusty's engine in Dad's truck as I'm planning to make that swap awa the ZF5 installation the next major project. Of course, this is assuming that Rusty's engine checks out with a leak-down and compression test.

And, if it is getting roughly as good mileage as Dad's M is currently getting. However, if it isn't I'll be very disappointed since one runs a C6 and the other the NP435.

 

Krusty The Clown Laughing - YouTube

I just had to.

When you guys type "CRusty", it's the first thing that comes to mind.

Forgive me.

 

What are the idle mix screws operating on? Air, or fuel? The reason I ask is something in the back of my mind something tells me that Holley changed to the idle screws adjusting the air, not fuel. And that would be consistent with capping vacuum ports and opening up the screws - which I did.

 

I'd have to look up that specific LIST, but yes indeed some carbs did have air bleed screws rather than fuel mixture screws.

(I almost mentioned this yesterday, but did not want to confuse the issue.)

 

Where would I look that up? So far what I've found didn't include that info. But, that's the only way I can reconcile capping the vacuum ports and opening up the idle mix screws.

 

Gary , tell us about the diff rebuild. Is it noisey or do you hear anything that sounds funny? It was just freshly set up so that would explain the jackpot being a little warm after driving.

 

Hear noise over the Flowmaster and the 31" tires? I had to listen closely to hear the Holley open the secondaries. So, no I don't hear anything from the diff - it seems to be just fine. As for warmth, it really wasn't as compared to Dad's. Apparently you guys got the right bearings and races together and the ring and pinion are well set up, as it was only slightly warm. Again, many thanks to James, and to you, for a job well done!

Oh yes, the axle bearings are running cool - no heat at all. And, I did put the ones out of the parts truck in. And, speaking of that, I realized today that the seat in the parts truck is better than the one in Rusty, so that'll probably get changed. Not only is the bucket o' diff parts empty, but the parts truck is soon going to be empty as well!

 

The bucket O diff parts served its purpose well. You should be proud. Glad to hear the parts truck is doing the same. Whenever you are ready to be rid of it call me and I will bring the trailer out. We can load it up and take it to the scrap yard. Sounds like it will be bare bones before too long.