To Matt Martin of Centerville Auto Repair- Centerville California

of coarse it is in the article, clean the heads, .005 off the block .049 head gasket. no after market cast pistons move the pin height enough, plus smaller dome than a stock piston. we had a nailhead thread about the pin heights of after market pistons besides showing domes and pin heights. plus they said they tried to lower the compression for pump gas, did they know it was't really 10.25 to start with or tying to make us think it was 10.25 to start with i don't know that part.

 

Ok...

Head cc?
Dome cc?
Head gasket thickness and hole diameter?
Deck height?

You're guessing on most of these numbers.

 

IF they knew ANYTHING about a "Nail" they would know that just by using the normal Felpro head gasket because of the extra thickness on a 401 there is a loss of .77-1 compression. ADD to that the normal pin height of an off the shelf cast piston can be ANYWHERE in the hole of about .065"-.080" in the "Hole".
This does not take into account of the .049" compressed thickness of the head gasket installed on this particular build.
MY experience tells me it's a bunch of B.S.

 

Again, the pin height change is not exclusive to nailheads... and any engine builder knows that fel pro head gaskets are thick! The blues have the reputation for a reason.

Lots of smack talk going on here without the facts to back it up. The facts are you don't know the chamber volume, deck height or dome volume! Therefore you dont know the compression ratio! They ordered a custom cam! There is no way in the world an engine builder does that and doesn't measure/set the compression ratio!

 

ok again what we know. chamber volume stock is about 128 cc it said they just clean the head, as for deck height the piston will be more in the hole then stock because all after market pistons pin height were made that way.. they stated the dome was smaller than the stock piston so that is less compression. they stated they wanted less compression than stock and we all know that stock is less then 9.75. .049 gasket they used vs .015 stock head gasket will really cut the compression down. i had a least 8 nailhead a part and check head cc and piston in the hole. who knows how many Tom T. has had a part. head cc 126-129. in the hole .050 to .059

 

Didn't the instigator join, ambush, and screw???

 

All that is cool. However you're still making a ton of assumptions. Any engine builder will tell you the factory specs are a guide. They say they cut the deck .005. Cool. You have no idea of the deck height. The heads were "cleaned up". Cool. You have no idea how much or if they were previously milled. You say the pistons have a smaller dome.. Cool. Compared to what?

So, tell me what you can say, with certain, that you "know" that the compression ratio is? Oh, you read in a forum once...

Tom could have 1000 nailheads apart and thats cool, too. But any decent engine builder never assumes anything. They measure every damn thing possible.

 

i will post soon what i would guess there compression ratio was, a guess for entertainment purposes only lol

 

Greg 66gsconv had a nice build from AMP in 2013. his thread is on the nailhead forums. close to my build numbers. had 353.5 HP@ 4700 and 454 TQ @3500. 9.85 compression with Egge pistons with out cutting dome down, but using steel head gaskets, milling heads quit a bit and cutting block way more than .010 than the hemming's article. i will never believe they got 500 TQ either with a 401, maybe with a 425 would be a little more believable. thinking they really were about 9.10 compression ratio if that. everybody can think or believe what they want, this is just my opinion. if you build a 401 and go by hemming's or nailhead Matt your going to be disappointed by not getting the stated HP and TQ numbers.

 

A reply to ALL.
Of ALL the "Nails" I've done, & it's NOT 1000's, the best stock compression ratio I have come up with is 9.75-1 with the piston in the "Hole" .040". Normally the majority of them are closer to .055" in the hole. Less than 9.75-1.
As I stated previously off the shelf pistons are in the hole between .065" to .080". Even lower compression. ALL the deck heights I've checked, and I do it on every one, has been between 10.0085 to 10.0205 which is a diff. of .012", BUT usually within .001" side-side, the reason why ALL off the shelf pistons sit deeper in the hole as they have to fit ALL the various deck heights including squareing/decking the block to make them flat/square, normally between .005"-.008", they HAVE TO fit.
Nothing Custom Made here. AND, they stated that they removed material from the dome of the off the shelf pistons to help lower the compression so they could run today's fuel. Even more compression loss. That's why I designed "MY" Custom Made Forged Pistons for the "Nail" which covers ALL the normal problems that come up associated with off the shelf pistons. As I've mentioned previously going from a stock steel gasket of .015" compressed to a Felpro that is normally in the .040" range compressed is a drop of .077-1 loss of compression. .049" thicker head gasket is even MORE compression loss. Normally the majority of heads, unless they've been overheated pretty badly sometime in their life, usually take a clean-up of .004"-.006" to make flat again. It's approx. 1cc lost for about every .005" removed from the head. So there's normally NO compression increase there if done just to flatten/make straight again. AND, remember IF you take too much off the head the intake will normally not line up properly & the "Nail" can't be straightened out by milling the manifold/head as can done on a "NORMAL" V-8. Then you ALSO have to think about the water manifold alignment that connects between the heads. Too much off the heads & now you have to play "Tricks" to try & even resemeble ANY kind of alignment mis-matches. So it may not be as easy as some/you may think.
Most original, untouched heads, cc in around 124-128 cc's.
Now go back & think about what was said in the article & you will see WHY Joe & I have come up with the conclusions that we've had.
Enough for tonight.

Tom T.

 

Not all the problems Tom. your Pistons have the same dome to combustion chamber interference issue in the exact same place all the off the shelf Pistons have.

 

Sorry to disagree with you Rob, BUT that was part of the building process. Now I have decided to do BOTH the top & bottom rounded off corners on ALL of them for the last 3 or so years.
How long ago was it that you had problems OR have you even bought pistons from me OR is it that you have heard???

Tom T.

 

I got a set of your pistons and your roller rockers and quite honestly I'm not impressed with either. There's a lot of talk in back channels about how you're special made Pistons use the same dome as every other piston and hit in exactly the same spot. Funny how there's plenty of clearance everywhere except for in that one spot. Now I've got a set of custom JE pistons and TA roller rockers and all is well.

 

Sorry to hear that Rob. I really wish I'd have heard about the problems. I don't know what I could have done about it at the time, BUT every day is a learning experience.
Nobody died & left me God. I always try to do my best & sometimes some things are out of my control.
I know that talking doesn't fix the problems you had.
Again, sorry.

Tom T.

 

never could make sense of it. others have had problems with JE and rac-tec or auto tec what ever you want to call them. i never had a problem with either. what were some of your specs, head gaskets thickness ? and pistons in the hole ? heads milled ? dome height ?. one thing that i was wondering if you cut the valves notches to deep taking off a lot of cc's lowering compression you would have to make it up with a higher dome causing interference, or if the piston is going end up in the hole a lot you make it up with taller dome to get the right final compression.

 

Joe,

I've gone through ALL my Corespondence & Notes concerning pistons & rocker arms & have NOTHING on a Rob Franklin that he EVER bought ANYTHING from myself. With that in mind MAYBE I was dealing with a ghost???

Tom T.

 

yes very weird.

 

I said I have a set of your pistons and rockers. Didn't say I bought them from you Tom. Doesn't change anything about the design does it?

 

i think it does, did you buy them direct from auto-tec or from someone who get them from Tom who had them custom made to there custom build. it would be helpful to know your specs to see why they were hitting.

 

The original thread was about the 400/430/455 that's ALL I can find from a few years back.

I DON'T BELIEVE that ANYONE who bought pistons from myself would have sold them to someone else being they were CUSTOM MADE for someone elses engine & specs as there have been NO exact matches for not one engine in ALL the sets I've sold.

I call this BOGUS Rob Franklin.

Tom T.

P.S. Joe if I get time in the next couple days I'll give you a call.