Pulling the trigger on my 351C rebuild

[PeteG41]

You may want to just keep the manifolds and get a nice dual exhaust system. That allows you to avoid all the hassles of cheap headers and give yourself time to save up for a quality set of headers later. When you add the headers later your muffler shop can adapt your duals to fit the headers by making a new h-pipe. You may find the manifolds aren't a bad way to go, too!

Yep that also crossed my mind! I guess if I can find some for $400 or so I can live with that. It would just take me a little bit longer to realize the performance gains from the rebuild with the factory manifolds

 

[Hemikiller]

That was the exact part number I googled about 20 minutes before seeing your post. I saw it on the Holley site and it showed discontinued product, but that obviously just has to be from them. Sweet! The other one I found said not compatible with PS without some sort of bracket.

All of the listings regarding power steering are screwed up, as the 70-earlier Mustang and 71-earlier Fairlane/Torino used an external ram assist power steering setup. The 71-73 Mustangs have an integral box, so they clear just fine without any other parts required.

 

[Sheriff41]

Yep that also crossed my mind! I guess if I can find some for $400 or so I can live with that. It would just take me a little bit longer to realize the performance gains from the rebuild with the factory manifolds

If your engine builder knows his business, you will realize the performance gains with either exhaust set up... especially over your current engine's performance level!

FWIW, I have been running Hooker headers with Jet Hot coating for a couple decades with no problems. Just use good header gaskets and you'll experience the same. I'll defer to the others on here as to what are currently good header gaskets. I've had some soft aluminum or copper gaskets on mine since new, but I don't recall the brand.

 

[PeteG41]

All of the listings regarding power steering are screwed up, as the 70-earlier Mustang and 71-earlier Fairlane/Torino used an external ram assist power steering setup. The 71-73 Mustangs have an integral box, so they clear just fine without any other parts required.

Much appreciated! It was easy finding headers with my 72 C-20, pretty much any store carries them for a 350 SB.

 

[PeteG41]

If your engine builder knows his business, you will realize the performance gains with either exhaust set up... especially over your current engine's performance level!

FWIW, I have been running Hooker headers with Jet Hot coating for a couple decades with no problems. Just use good header gaskets and you'll experience the same. I'll defer to the others on here as to what are currently good header gaskets. I've had some soft aluminum or copper gaskets on mine since new, but I don't recall the brand.

Touche!! I assumed as much! Correct me if I am wrong but a lot of the disclaimers on the headers are saying not to use them when breaking in a fresh motor rebuild. Is that accurate?

 

[Sheriff41]

Touche!! I assumed as much! Correct me if I am wrong but a lot of the disclaimers on the headers are saying not to use them when breaking in a fresh motor rebuild. Is that accurate?

That's a new one to me.

 

[PeteG41]

That's a new one to me.

I had never seen or heard that either. But reading a description on some of the headers, some of them said that using them on a break in would get them too hot causing them to crack. I dug it up so you can see I'm not losing it. About 1/2 way down under the "Tech Resources".

https://www.holley.com/products/exhaust/headers_and_exhaust_manifolds/all_headers/parts/6921HKR

 

[Sheriff41]

Looks like a ceramic curing issue so painted headers may not be an issue.

 

[PeteG41]

Looks like a ceramic curing issue so painted headers may not be an issue.

Sweet. If I would have taken another 10 seconds it would have registered these were just painted for shipping. Hence the cheaper price. Being in AZ im not concerned about rust with the steel ones, am I good to go on just letting that paint burn off and calling it a day with them?

 

[Sheriff41]

I don't think I'd want to leave them bare, even in the Sonoran Desert (I grew up in Tucson). They will get rusty and end up looking like crap. There are some good header paints that hold up well. It may be worth a little research for techniques/brand of paint and time to paint them before you install them.

 

[PeteG41]

I don't think I'd want to leave them bare, even in the Sonoran Desert (I grew up in Tucson). They will get rusty and end up looking like crap. There are some good header paints that hold up well. It may be worth a little research for techniques/brand of paint and time to paint them before you install them.

Noted! I knew they would end up getting discolored/crappy looking. Nothing a couple hours with brake fluid, shop towels, and the correct rattle can can't fix. Fun weekend project while I wait to take the car in.

 

[c9zx]

If you want them to last, get them coated. You need to get all that shipping paint off before coating or painting. Suggest having them blasted. If you use paint, say VHT, use their primer as well and follow the directions exactly. Use the manifolds for break-in. Chuck
https://www.vhtpaint.com/high-heat/vht-flameproof-coating#Curing

 

[PeteG41]

If you want them to last, get them coated. You need to get all that shipping paint off before coating or painting. Suggest having them blasted. If you use paint, say VHT, use their primer as well and follow the directions exactly. Use the manifolds for break-in. Chuck
https://www.vhtpaint.com/high-heat/vht-flameproof-coating#Curing

Yep going to completely strip them, prep, and looked into that paint. Definitely took note that ceramic coating can't be used for the break in. If I just go enamel high temp rather than ceramic, does that process still apply?

 

[mrgmhale]

You may want to just keep the manifolds and get a nice dual exhaust system. That allows you to avoid all the hassles of cheap headers and give yourself time to save up for a quality set of headers later. When you add the headers later your muffler shop can adapt your duals to fit the headers by making a new h-pipe. You may find the manifolds aren't a bad way to go, too!

If you plan to simply drive on the public roads I would concur with Sherif41's suggestion that you use the factory exhaust manifold to prevent problems with the headers interfering with steering linkage points. And, yeah, I get that headers are really cool and "can" provide additional power. But, frankly, having a nice set of low back-pressure, high performance mufflers on a dual exhaust system with an H or X pipe will get you a decent exhaust system even using the factory exhaust manifolds. That having been said, under the heading of "Do as I suggest, not as I do," the prior owner of our 1973 Mach 1 with 302 engine originally, dropped in a 351W that was built to put out 360HPP. The Mach 1 has factory power steering. 302 headers fit the 351W perfectly, which is what he did. He selected Hooker long tube ceramic coated headers, and they fit perfectly with no interference with any steering linkage. Had he not already installed headers I doubt I would have installed them, as I am not after blazing, maximum performance from the Mach 1. We just wanted to end up with a great cruising vehicle, and after installing an AOD tranny with it OverDrive gearing we accomplished just that. A great cruising car that looks great and performs very well. We have a pair of 1969 and 2020 Shelby GT500s we can brea out if we feel the3 need for some neck snapping performance.

 

[PeteG41]

If you plan to simply drive on the public roads I would concur with Sherif41's suggestion that you use the factory exhaust manifold to prevent problems with the headers interfering with steering linkage points. And, yeah, I get that headers are really cool and "can" provide additional power. But, frankly, having a nice set of low back-pressure, high performance mufflers on a dual exhaust system with an H or X pipe will get you a decent exhaust system even using the factory exhaust manifolds. That having been said, under the heading of "Do as I suggest, not as I do," the prior owner of our 1973 Mach 1 with 302 engine originally, dropped in a 351W that was built to put out 360HPP. The Mach 1 has factory power steering. 302 headers fit the 351W perfectly, which is what he did. He selected Hooker long tube ceramic coated headers, and they fit perfectly with no interference with any steering linkage. Had he not already installed headers I doubt I would have installed them, as I am not after blazing, maximum performance from the Mach 1. We just wanted to end up with a great cruising vehicle, and after installing an AOD tranny with it OverDrive gearing we accomplished just that. A great cruising car that looks great and performs very well. We have a pair of 1969 and 2020 Shelby GT500s we can brea out if we feel the3 need for some neck snapping performance.

Always coming in with the knowledge!! So I was looking at the Hooker 6921. They won't break the bank, are still quality, and I can do the prep work on them myself. Although not sure how I can cure the paint in my oven because I doubt they will fit. Assuming its something that will be done after the break in with the manifolds. The car currently has factory single exhaust right now, which is shot and definitely needs to be replaced. So my thought process was to just do it now in one swoop? Rather than getting the exhaust replaced a couple times, seeing as I will be doing dual for sure. I could be way off in my thought process, but that's why you guys are here for me!

 

[PeteG41]

If your valves are original there is no question that they should be replaced. Period. The majority of guys on the forum will most certainly concur that the original valves are a ticking time bomb. The guys doing your engine work should be aware of that. I am not a fan of Comp cam products. The story behind why is long. There are many other cam options other than comp to look into before you decide. I would use a Cloyes double roller timing set for starters. I am not trying to bum you out, I am just offering information from my experience.

Ron

Alright got an update on my questions regarding replacing the valves. He said the exhaust valves may be a problem, but has never seen an intake valve go bad. Exhaust valves will run me $80 for the set, but new intake valves aren't available. If there are already hardened seats in the head they are going to resurface them, and surface the valves and the seats. He informed me that work was already tied into the quote I had gotten.

 

[Ron Tanzi]

Alright got an update on my questions regarding replacing the valves. He said the exhaust valves may be a problem, but has never seen an intake valve go bad. Exhaust valves will run me $80 for the set, but new intake valves aren't available. If there are already hardened seats in the head they are going to resurface them, and surface the valves and the seats. He informed me that work was already tied into the quote I had gotten.

You may already have hardened exhaust valve seats and possibly replacement valves as well if there was previous head work performed. Refresh me as to if your engine has been apart before. Anyone on the forum know and if so confirm or deny if both the intake and exhaust valve heads are induction welded to the stems. I have my original intake and exhaust valves and they both appear to use that method. $80 is pretty cheap for the set. I am surprised there are no intake valves available.

Ron

 

[PeteG41]

You may already have hardened exhaust valve seats and possibly replacement valves as well if there was previous head work performed. Refresh me as to if your engine has been apart before. Anyone on the forum know and if so confirm or deny if both the intake and exhaust valve heads are induction welded to the stems. I have my original intake and exhaust valves and they both appear to use that method. $80 is pretty cheap for the set. I am surprised there are no intake valves available.

Ron

Yep it has been rebuilt before, or so I was told. I’m thinking that’s why my shop didn’t quote replacing the valves yet, because it’s possible they may not be needed, just machined. And he would obviously figure that part out once he got it apart. I am inclined to believe it had been rebuilt “maybe poorly or something went wrong”, because there’s really no grease or grime around the heads or on the motor, so decent evidence it was out at some point.

 

[Ron Tanzi]

Yep it has been rebuilt before, or so I was told. I’m thinking that’s why my shop didn’t quote replacing the valves yet, because it’s possible they may not be needed, just machined. And he would obviously figure that part out once he got it apart. I am inclined to believe it had been rebuilt “maybe poorly or something went wrong”, because there’s really no grease or grime around the heads or on the motor, so decent evidence it was out at some point.

That may save you a few bucks. That is a good thing. Especially needed these days. As I said before avoid Comp if you can. Comp is more enthusiastic about GM products than Ford products.

Ron

 

[PeteG41]

That may save you a few bucks. That is a good thing. Especially needed these days. As I said before avoid Comp if you can. Comp is more enthusiastic about GM products than Ford products.

Ron

Definitely a good thing. And I’ll for sure take the Comp parts into consideration! This is a whole new area for me so I appreciate everyone who has chimed in. Unbelievably helpful