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Run your numbers again with a NEGATIVE 0.016 and you should get an SCR of 11.19, and a DCR that is still too high.
Your first mistake was buying pistons that weren't what you expected.
The second bigger mistake was not mock assembling the engine (after a .04 bore and hone) and measuring the decks first, and then stripping it all back down ready for machining.
But you know that now.
Your existing cam spec suggests that you want a street driven truck that does not detonate, gives nice torque and power, and is as fuel efficient as one can get with a 1970's V8..
If you continue with those pistons, and manipulate the gasket height, you won't get what you want, and you will have to buy shares in an Avgas company !
You'll be a happier man if you wait for custom pistons that have been made to YOUR EXACT specs, and choose a cam with an IVC etc that gives the engine a detonation free package.
Here is the TM track boss pic from his website, misleading due to the reflection, I though the exhaust side of the piston was also raised but now realized it is a reflection.
I honest thought it was designed to mate against the head surface pointed to below. Don't get me wrong, These pistons would work with OC heads but with a 62cc trick flow i think there is a better option. The stepped area that is .065 in the hole along with a .050 gasket is giving detonation a place to happen. If there is no place to encourage detonation it is much easier to manage with today's fuel.
Run your numbers again with a NEGATIVE 0.016 and you should get an SCR of 11.19, and a DCR that is still too high.
Your first mistake was buying pistons that weren't what you expected.
The second bigger mistake was not mock assembling the engine (after a .04 bore and hone) and measuring the decks first, and then stripping it all back down ready for machining.
(Or measuring the 'old' engine before disassembly, and comparing measurements to the new pistons. Much easier. LOL)
But you know that now.
Your existing cam spec suggests that you want a street driven truck that does not detonate, gives nice torque and power, and is as fuel efficient as one can get with a 1970's V8..
If you continue with those pistons, and manipulate the gasket height, you won't get what you want, and you will have to buy shares in an Avgas company !
You'll be a happier man if you wait for custom pistons that have been made to YOUR EXACT specs, and choose a cam with an IVC etc that gives the engine a detonation free package.
I am waiting for an piston answer from racetec and maybe Cleggs. The only reason i went with TM is they were on the shelf and it seams everything is out of stock these days. When i called comp, I got the last 280s they had at the time. No cores to machine. If i have to wait 2 months for pistons, I might choose a different cam too.
I will update when i get a quote. I am hoping RT can find this piston from a previous customer in their file. it has the correct shape to match the TF head. Only issue is the compression height at 1.518. i need 1.70 (i think)
Only issue is the compression height i need 1.70 (i think)
You know your pistons exceed the deck by 0.016.
When you remove the pistons and measure ALL of the piston compression heights, and deduct the 0.016's, or whatever, from them, you'll know exactly what you need to get zero decks.
No thinking required.
I know you've reached an ''Oh FFS !'' stage, which isn't nice, but the more good news is that you now know what you need.
By the way, you could always have a cam custom ground for you if you wanted.
I didn't notice any elevation numbers in the comp calcs you posted back in in post 16.
For info, the DCR of 8.93 remains the same at 0.00 ft and 2,200 ft, but the cylinder pressure drops from +/- 189 to 177.
The cylinder pressure is what contributes to detonation.
All the numbers provided in a calculator are nothing but estimates, but incredibly useful all the same.
What's the part number of the cam you bought for this engine ?
Yes your pistons are suited to OC heads. You need D top pistons for your ''Quench heads'' (CC heads). Yeah, you know that now as well. LOL
I will confess, I dropped the pistons off at the machine shop and didn't inspect them, (crazy busy) My shop is great and I did not catch this until i picked up the short block. They thought i knew what i had and I thought the TM pistons were the ones to have. Foolish me,, anyhow, I caught it, easily corrected. I guess i got caught up in the moment trying to get this back together.
It is unreal how this flu season has derailed everything. I had a hard time getting the heads because the valves came from argentina,, "who knew".
I will pump the brakes a little and just wait it out. Looks like this will not got back together anything soon so may as well take the rest of the truck off the frame and detail it while I am waiting. Sadly, we use this truck everyday and now I am towing a trailer to make up for it.
I found this little 66 for my 8yo daughter, we were going to start tearing it down but at only 8, I think she can wait a few more months
I have the machine shop do the rotating assembly, For what they charge it is well worth it and if there is something not right, I do not have to haul it all back, they can take care of it then and there. I said this before but this time it is for good, I will never buy anything from a business that does not answer the phone. Sure, a business model can operate that way and save time and money. If we had conversed about this build i think we would have stumbled upon the OC vs CC design. Again, 100% my fault but i hope this thread saves someone else from pumping a lot of money into a motor and not getting the true potential of it.
Not to worry about not driving the 66. I got this 67 to keep me in trouble.
406, callies, diamond pistons@11.3 with a comp 294s and AFR 195s and an AED 950. It is a super T10 with 411s. A real handful with BFGs.
I have two boys, One will get the 67 and one will get this 63 Nova ss. The Nova has a hot little 327, 4 speed, 411s, cal tracs, tube front end/R&P steering,
back to the ford pistons, Spoke to Randy at Racetech again today, he is waiting for a tech to get back to him. They should have it is the CAD program and I will post the info for a proper 400 piston when using CC heads. TM should change his website for the track boss pistons, Do not care if they have "made power" using their stepped piston before, It is not correct for a CC head. I don't have my old OC iron heads any more, I wish I did so I could clay match/mpld them and see the shape/size of the total combustion area at TDC.
Do you have a build thread for your truck? I saw some other pictures of your truck, it looks great! Is that color Corral or Medium Copper?
The truck is a 78 in the original medium copper. I bought the truck from the original owners son in Cedar City Utah ~10 years ago with 68k miles. I have no build thread, this is the first thing i have down to it other than replacing the sketchy lift kit and dry rotted swampers with a 6 inch spring kit and the KM2s.
I will document the motor build. The trans will stay a C6 with a stage 2 transgo and a Hughes converter. The 205 case is getting new seals and gaskets.
This is my first ford 400 to build. I read a hot rod article and that seamed like a lot of unnecessary machine work so i went with the TM pistons after searching and not finding much solid info. If I can have custom forged pistons made for 650$ and it works, anyone wanting to build a 400 will have a source for them going forward.
As stated Tim’s current 400 pistons are really only intended for open chamber heads. I’m not sure what effect 0 deck pistons have with the stock open chamber 400 heads but lots of guys have used his pistons with stock heads and done well.
I have read articles about needing or not needing dual quench. Some say it’s helpful to reduce detonation and others say the smaller quench pad isn’t big enough and the main quench area overrides it.
Either way these are Tim’s closed chamber pistons designed for the Aussie heads shown behind the piston. These are 30cc dish with a step to 0 deck and give a 9.4:1 compression with 58cc Aussie heads. Tim no longer makes these pistons. I wonder if the current open chamber pistons could have the tops machined to increase dish?
I would think Tim’s current pistons would work good with the trickflow 72cc chamber heads.
The truck is a 78 in the original medium copper. I bought the truck from the original owners son in Cedar City Utah ~10 years ago with 68k miles. I have no build thread, this is the first thing i have down to it other than replacing the sketchy lift kit and dry rotted swampers with a 6 inch spring kit and the KM2s.
I will document the motor build. The trans will stay a C6 with a stage 2 transgo and a Hughes converter. The 205 case is getting new seals and gaskets.
This is my first ford 400 to build. I read a hot rod article and that seamed like a lot of unnecessary machine work so i went with the TM pistons after searching and not finding much solid info. If I can have custom forged pistons made for 650$ and it works, anyone wanting to build a 400 will have a source for them going forward.
My 78 Bronco is originally Medium Copper, in fact it is the bronco version of your truck. 400/c6, brown lowback bucket interior, Ranger XLT, etc. . One of the paint ideas I've had is including a similar orange pinstriping to what was original on the trucks. Its pretty cool to see yours in original color with the pinstripes. Do you have any more pictures?
Once you get the motor figured out, it could be a great recipe for others. One thought I had was doing a similar motor with fuel injection and swapping in a 6R80.
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