I know this seems to have been done to death, but I’m doing a 300 build and want to run some things by the experienced folks here to get some feedback and hopefully some questions answered.

I have a 76 F-250 with the a very tired 300. I want to be able to use the truck while I rebuild the engine. With this in mind, I bought a decent running used 300 engine out of a 78 van with the intent of doing a quick replacement of a few gaskets, and then do a swap so I could rebuild the my original engine. Unfortunately, once I pulled the valve cover and saw the amount of of sludge (think charcoal briquettes mixed with brownies), I knew that plan was out the window. I ended up using a shopvac to vacuum out the solids from under the valve and lifter covers (the solids were that dry). I’ve never seen anything like it; I’m amazed the engine ran as well as it did. LSS, I decided to rebuild the 78 engine and then just swap it in when it is ready.

I removed the head, disassembled the block, marked everything, and took all the vitals to the machine shop to be checked out to see if it was worth rebuilding. They reported back that the block, head, and connecting rods are serviceable. They bored the cylinders 30 over and did 10 and 10 on the crank. The cam is worn so I’m going to replace that along with the all the things that go with it.

So, I know the big question is what do I want the engine to do? How much upgrade do I want? This is a work truck. It is 2WD with an NP435 and Dana 61 rear end with 3.31 gears on 265/75 R 16 tires. With that in mind, I want reliable and a smooth idle, with a slight to moderate bump in power over stock. I’m thinking more for hauling and towing than for speed with maybe a bit extra for highway. I don’t have a certain HP or torque value in mind really, just a little more juice.

Here is what I'm thinking for the build; a lot of this stuff are the common upgrades I have read about here and on Ford Six Performance.

• EFI exhaust manifolds
  
• Offenhauser C intake (with heat plate)
  
• Motorcraft 2100 1.08 venturi carb
  
• 3/8 or 7/16 screw-in rocker arm studs
  
• Melling stock ratio rocker arms
  
• Isky 256 Supercam and Isky lifters – my thinking here is to try to everything I can to avoid a wiped cam lobe, and perhaps using the same company's lifters with their cam might help with that.
  
• I have read about the stiff springs Isky recommends and how it is more than what most feel is needed, so I think (??) the Comp 903s should work with this cam. If not, maybe I could go with the Erson/PBM Performance 3175 springs (??).
  
• I know I’ll need new retainers for the new springs and maybe 075 down keepers for the exhaust valves.
  
• For ignition, I’m thinking a re-curved DS2
  

I have two specific questions right now. First is about the proper valve springs as mentioned above. The second is about the rocker studs. I am assuming that if I change out the rocker studs I will need to adjust valve lash like my 76 engine and not just use the torque spec that the stock 78 engine requires?

Thoughts/recommendations are welcome.

 

Another thing to be aware off are poor quality flat tappet lifters. Many would recomend going to roller cam/lifters to eliminate the problems with them

 

The Isky 256 cam is a good choice.
It will work with the Comp 903 springs.
The 903 springs are meant to be used with the stock intake retainers. I believe the 78 exhaust retainers are the rotator style and need to be replaced with intake retainers.
The exhaust valve stem groove is usually lower than the intake valve stem groove so .050" up locks are needed to get the intake and exhaust retainers at the same height.
you will need to check the height difference yourself to verify if there is a difference and how much.

Yes, the screw in studs will give you full adjustment ability and are not torqued in place.
The 3/8" ARP screw in studs will not work with the stock adjusting nuts. The stock nuts will seize and damage the studs.
From ARP: NOTE: To be used ONLY with ARP’s patented Perma-Loc™ adjusters.

I you need new intake retainers.
55-6179 | QualFast High Performance Retainer| Goodson Tools & Supplies

Up locks
Locks, Keepers, Hardened 11/32" X 7 Degree, .050" Up Locks, Raises Retainer Higher, Sold in 1/2 Sets - Alex's Parts Sales (alexsparts.com)

 

Thank you to the folks chiming in. I’m glad to hear my cam selection is appropriate and thanks for the info. about the keepers. I’ll do some measuring and see where things are at. Also, I’ll be sure to get the proper ARP nuts for the rocker studs.

Regarding the lifters, a roller cam for this engine is a bridge too far for me. I have read that Isky has Johnson manufacture their lifters to Isky specs. I have gone to Isky’s website and that definitely seems to be the case for at least some of the roller lifters, but I have not found confirmation for the hydraulic flat tappet. I have read mostly good things in general about Isky cams, so I would hope that the lifters they sell would be good quality. That said, you can always find a story of someone who has had a bad experience with something if you look hard enough. Every manufactured item has a certain failure rate, and even in the “good ol’ days” cams did go south from time to time, but it seems like in the last few years it has become rather rampant (or at least more vocalized). We’ll see how it goes, keep your fingers crossed for me.

I have some questions regarding pistons. I read that these are a weak link in the 300s, and it is recommended to go to Hypereutectic pistons. I’ve been looking at Sealed Power and Silvolite on Summit and the manufacturers’ websites. My questions are:

• What is difference in piston head shapes? I get some of them like the flats with cutouts for the valves for high compression. Are the D type pistons more for EFI (and their different head), and circular for carburetor? Does this have to do with air/fuel swirl in the combustion chamber?
  
• I see Silvolite mentioned in threads a fair bit. Are these better or is it just a matter of apples and oranges?
  
• Most importantly, based on my build is there a “recommended” piston I should think about? As thirsty as these trucks are (and with the ever-increasing fuel costs), I would prefer to stay with 87 octane if possible. Is something like the Silvolite 3118H (it’s D shaped) be okay or would ~8.3 static compression be too high for 87 octane in this setup?
  

Thanks again for the help; these forums and the combined knowledge of you experienced folks is really amazing.

 

Well, after talking to my machinist, I was able to resolve my piston dilemma. I am going to be running Sealed Power H519CP pistons (.30 over). Although they are no longer made, I was able to locate a set of six on Rock Auto. They seem similar to the Silvolite 3118H I was considering. The H519s have a slightly smaller bowl than the Silvolites (~3 to 4 cc), so the SC should be closer to a 8.5:1, but I’m told that should still not be an issue using 87 octane with this build. They were also half the price of the Silvolites (always like to save a buck when I can – there is nothing cheap about engine rebuilding ). It looks like a lot of folks have used these on past builds, so I think they should work well for me.

Question on a different issue- if I install the ARP rocker studs and use the ARP Rocker Arm Adjusting Nuts with the Melling stock-style rockers, will I have issues with the valve cover clearing? It looks like the ones for non-roller lifters are pretty tall.

 

I have used those pistons on a couple of builds. I did not know they were no loger made. I'll buy every O/S set I can find.
The ring pack is "old school" but for my needs it is suitable.

 

TFF, the “no longer made” is my assumption as finding these have been difficult. The online Sealed Power part lookup does not have H519P but does still show H519CP (coated piston). Summit, Rock Auto, and NAPA all state the H519P are no longer available. Summit says they can special order the H519CP from the manufacturer. Other online sources (excluding Rock Auto and NAPA) show limited supplies of the CP (less than a full set of .30 over) or unavailable altogether. It is possible that this could be supply chain issues and not a phasing out of the piston altogether.