Factory heads
To start off I'm a newbie to engine modifications and I'm starting at the bottom of the curve.
I would like to rebuild a 400 in a 78 f250 and don't want to go crazy but would like to end up with a good running pickup. I read enough to get confused. I think I would like to leave the bottom end stock but use track boss pistons with bigger intake and 4b carb. Roller rockers and a comp cam. Is there any great advantage for aftermarket heads or is there enough benefit over rebuilding mine? If rebuilding mine is there any reason to shave them or will the tb pistons raise the compression enough?
It would be nice if there was a top end kit for the 400.
Thanks for any help you can give.
MT Cactus,
Would love to help, as I have the same questions. My advice is to seek other avenues for an answer. The products offered here are great, and I’ve bought pistons, rockers, valves, etc. from Tim for my 4oom. Top quality, fast shipping, and good customer service all the way.
However, if you ask a question about porting/factory heads/cam, you’ll get ghosted . I’ve sent e-mails, called, left messages, even referenced order numbers re/questions, and as you can see, a several months old, unanswered post on this forum.....absolute dead silence. The reason, or alternatives have never been explained to me. Folks like us that are newbies to this series of motors have to just figure it out on our own.
Find someone local who knows the 351m/400m (a needle in a haystack, I know) and see what you can find out. These are great engines...for goodness sakes, a stroker Cleveland- what a gift! I’d say your local circle track or truck/mud enthusiast gang would be a good start.
We are currently a 1 man shop. I am trying to create avenues where tech help can be shared most efficiently. The idea of this forum is to create a "Brain Pool" where others can contribute. Items like the ZF5 adapter, we have never installed and want customer to share their experience & tips. We do not know everything and there are plenty of very smart people out there. We will always give tech support to the products we sell, if and when I have time, I will jump in on other topics.
So having said that...MTcactus, OE heads have made useable power in the low 300HP range up to 400 without getting to peaky. TQ is low to mid 400s. This is typically where most people really want to be. Invest in aluminum heads and your HP can take a nice 50-75 HP jump. TQ will be in mid to upper 400s. Aluminum heads, with the closed chamber, also helps to minimize/delete detonation.
Speaking of detonation. I'm building a 400 for a tow rig with a comp cams HR260 cam (206 at .050) I machined a lot off the deck. Using original pistons and will be surfacing the heads to get about 8.5:1 static compression ratio. Pulling a car trailer. Prefer to use 87 octane. Think this will be a good setup with the factory open chamber heads with no detonation?
Thanks, Adam
I myself prefer not to use an open chamber head for a tow rig. I want a quench to help deter detonation.
What was the reasoning for the open chambers? Emissions?
I can't say for sure, but emissions were definitely a factor in many engine designs.
I bought your SI stainless valves. Can they be installed in the original iron valve guides? Or do they require bronze guides?
I would use the bronze my self and if you have not done the seat yet you need too for the new fuels so you'll need harder seat and have them peened in after you've place them in the freeze to shrink them down. I would go up on the compression though to 9:5 or 10:1. I 've had the 8.5:1 I was just not happy with it. Not near enough power for towing for me. The open Chamber were for emissions I try to put the closed chamber on my stuff I found the open chamber seem to ping. Aftermarket 2V's are great though since they were redesigned. Factory 2V's suck though, don't like those at all.