Cast manifolds upgrade

[Scotts96sploder]

Just got in one of my cast manifolds to replace the stock welded ones. I bought the parts for a 98 with the EGR port because I don’t think there is another cheap option, so I’ll have to cap that off when it comes in. The inside of these castings is very rough, would it be worth it to get in there and clean it up a little before I install them?
Also, I think I’ll need to use longer bolts, at least 1 anyway. Dose anyone happen to know the lengths?

 

[410Fortune]

did you buy the Dorman replacements?
Yes the casting is ROUGH! Not as smooth as factory parts.
Yes it would benefit you to clean up the "leftovers" the cheaper Dorman parts have in the exhaust ports.

I would also recommend not using the gaskets Dorman ships with those manifolds, instead get some good Percy's or Mr gasket sandwiched aluminum style gaskets, available at most parts stores.
The new manifolds should have come with new bolts? You should be able to re use the factory bolts?
I have installed a couple of sets of these aftermarket cast manifolds, the price is good! The quality is decent....but with better gaskets and a little dremmel work they can be awesome for the $$$ invested.

You can get the fittings to close up the EGR port at most hardware stores it is standard NPT threads

 

[Scotts96sploder]

Thanks!
I started cleaning them up last night with a dremel, I just lined up the gasket and made some lines to get it close.
They came with collector bots, but not the ones for the block. The stock are about 1/2” and it looks like I will need at least 2 that are roughly 1-1/2”.
NPT! Awesome, I’ll hit up Home Depot! and I guess I’ll pick up batter gaskets before the install this weekend. Thanks again!

 

[Scotts96sploder]

Progress!
before and after pics.
im calling these done. Now I just have to find that plug and the correct bolts and they should be on this weekend. I have already broke loose the manifold bolts so I know they come out without breaking. Going to start spraying PB blaster on the collector bolts tonight lol

 

[Scotts96sploder]

Update:
I bought 14 1-1/4” and 2 2-1/2” #8 bolts as the cast flanges are much thicker and have areas there it’s very thick compared to the steel. I’ll have a compete parts break down after I’m done.
Also, I ran out of time to find a cap or plug for the EGR port so I ended up making one. I found a bolt that fit snug and ground the head down round, cut the bolt and coupling as shown in the pic and welded it together.

 

[410Fortune]

perfect!!

Consider using map gas or oxy torch on the collector bolts....they can be a real *****
But if they are like most of these 96-97 trucks they will be rusty and frozen, you use a large ratchet you can snap them off pretty easily

not to worry......... they will be stuck in the old manifolds and your downpipes will be free and clear to re use

 

[Scotts96sploder]

Got it all done. I didn’t need to heat the collector bots, I’ve been spraying them with PB for about a week lol. They came out with a little persuasion.

 

[Scotts96sploder]

Oh yeah, I didn’t have to make a bracket for the dip stick tube, I just bent it into its new home.
All the local parts stores didn’t have the nice gaskets in stock so I just doubled the ones it came with... we will see I guess...
I ended up using 14 1-1/2” and 2 2-1/2” grade 8 3/8-16 bolts with split washers because I couldn’t find the fancy lock washers. Made the EGR plug. Replaces the plug wires. Can’t think of anything else.
If you want to do this be prepared to move the AC compressor, inner fenders, and disconnect the steering shaft. It’s pretty easy, 6/10.

 

[410Fortune]

Looks like you did a fine job!!
I am not sure about stacking gaskets..........time will tell
Re check the torque on the bolts after 100 miles and again after 500
Those old welded manifolds make a nice coat rack in the shop, at least that's what I did with them
This way when I need to show customers the available upgrade I have a set of the old crappy welded ones on the wall

 

[Scotts96sploder]

Thanks!
Add spark plugs to the list, I cracked one so the first test drive was disappointing lol, after I fixed that it runs great! I was getting a few codes for o2 sensor late response that haven’t come back yet also. I can’t prove it, but it feels like I gained some torque in the low end.
I have all the AC lines coming in next week, and since the compressor has to move to access the bolt up there, I’ll re-torque then.

 

[410Fortune]

the cast manifolds allow twice the flow the old welded ones did.
If you look at the welded manifolds there are 3 combustion chambers that share one port the size of my thumb. In the cast manifolds that is increased to about 2 thumbs

 

[Scotts96sploder]

Didn’t even think about this, but my gas mileage has improved significantly! No exact numbers but it used to take 1/4 tank to and from work, now it’s less, more than an 1/8 tank but less than it was before. That’s awesome! It’s about a 50 mile round trip. Also no CEL yet so looks like the sensors are still good and it was just the cracked manifolds.