the 351w i just bought has the heads decked, what will that change as far as performance. the guy did a complete rebuild. has "mild" cam, reman crank, mild cam, somethin about connecting rods
351w with decked heads ?
- Thread starter strangeice69
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Turbo II
Founding Member
strangeice69 said:
Depends on how much material was removed, the more that was taken the higher compression..a good thing in moderation (with today's pump gas)
IIRC every thou removed "roughly" translates to one less cc in chamber volume? Or was it every 10 thou
parthos
Founding Member
maybe the heads were "decked" so that the gasket surface was completly flat. Sometimes when you remove material from the head to gain compression, you end up with funky angles and intake manifolds don't match up anymore, then they have to be "decked" to get them to mate properly. Another consideration is pushrod length. Even though this should be checked with every engine build, it becomes more critical with machining such as this. What you want is the rocker arm centered over the valve at mid lift. Just some stuff to check.
the guy tore the motor down to build it up and put it in his 89 but plans fell through ...now its MINEEEEEE
zwhitr said:
Then it's better to machhine the intake as they are way cheaper and easier to replace than heads. {Edit} In case the machinest takes too much off or otherwise screws the pooch or if the heads are going to be used on another engine.
BTW, heads are ''shaved' or 'milled', blocks are 'decked'.
parthos
Founding Member
maybe the block was decked. They do this for two reasons, to make sure the piston is flush with the top of the bore, and it provides a flat surface for the gasket to seal to.
Dano78
Founding Member
Normally every engine, block and heads gets decked/milled on a rebuild. BUT- this is only about a .003-.005 decking and/or milling on a normal basis to 'true' up a head or deck surface on the block. If you gotta cut .005 off, you had a pretty seriously tweaked head or deck.
You're close Francis, .008-.010 will give you about 1/4 point in compression on the average. To get a full point you'll need to either cut the block deck .020 or mill the heads. For Mopars i think it's like .012-.014 to get 1/2 a point, which is what i'm toying with at the moment.
Personally if you wanna raise the compression, get the piston with the largest compression height or a dome. If you need to do milling (cost effective) take it from the block. Whan you do that they can mill down the lifter valley rails (at either end where the intake mates) which will enable you to use any intake or head without it needing to be milled. And another thing, for no reason should you mill more than .020 unless you have no other choice or you're going for ubsurd compression. If that's the case, then your intake may have to be milled to correctly line up.
I buy partially built engines all the time. Saves on $$$. You just need to take a little more time and check all the clearances. Hell, the last one I bought, the rods were in backwards (chamfer wrong way and piston notches 1/2 were backwards) Invest in plastigauge and a good ford smallblock rebuilding guide and you won't have a bit of trouble.
As for your mild cam... that's a matter of opinion. Mild to one can be knarly to another. Get the actual specs if you need to. be sure to get the .050 duration numbers. Advertised Duration is a crock and is hardly accurate, especially when comparing other manufacturers' cams.
Reman Crack- Most likely just a stock crank sent out and cut .010/.010 or .020/.020 to refinish the bearing surfaces. No frills. They can cut up to .040/.040 when thay turn a crank, but I wouldn't advise that at all.
He probably 'Reconditioned' or 'resized' the connecting rods. This means the rod and cap mating surfaces were cut down and then bolted together and the hole where the crank would go is then re-machined to a 'true' circle again. And if applicable, you get new bushings on the smaller end if you have floatin pin pistons. Most all SB Fords are press fit pins unless you have some high-end race stuff.
You're close Francis, .008-.010 will give you about 1/4 point in compression on the average. To get a full point you'll need to either cut the block deck .020 or mill the heads. For Mopars i think it's like .012-.014 to get 1/2 a point, which is what i'm toying with at the moment.
Personally if you wanna raise the compression, get the piston with the largest compression height or a dome. If you need to do milling (cost effective) take it from the block. Whan you do that they can mill down the lifter valley rails (at either end where the intake mates) which will enable you to use any intake or head without it needing to be milled. And another thing, for no reason should you mill more than .020 unless you have no other choice or you're going for ubsurd compression. If that's the case, then your intake may have to be milled to correctly line up.
I buy partially built engines all the time. Saves on $$$. You just need to take a little more time and check all the clearances. Hell, the last one I bought, the rods were in backwards (chamfer wrong way and piston notches 1/2 were backwards) Invest in plastigauge and a good ford smallblock rebuilding guide and you won't have a bit of trouble.
As for your mild cam... that's a matter of opinion. Mild to one can be knarly to another. Get the actual specs if you need to. be sure to get the .050 duration numbers. Advertised Duration is a crock and is hardly accurate, especially when comparing other manufacturers' cams.
Reman Crack- Most likely just a stock crank sent out and cut .010/.010 or .020/.020 to refinish the bearing surfaces. No frills. They can cut up to .040/.040 when thay turn a crank, but I wouldn't advise that at all.
He probably 'Reconditioned' or 'resized' the connecting rods. This means the rod and cap mating surfaces were cut down and then bolted together and the hole where the crank would go is then re-machined to a 'true' circle again. And if applicable, you get new bushings on the smaller end if you have floatin pin pistons. Most all SB Fords are press fit pins unless you have some high-end race stuff.
Dano78
Founding Member
Wart said:You also never know if what they say has been done has actually been done, and if it was done how well it was done.
Ask Glenn.
I agree, so you must, check, and check again. Have the proper books and if you not sure, ask questions. Some things, like the boreing or hone job, you'll never know till you fire it up. But the rest of it is all pretty easily measureable. As long as a reputable machine shop did the work, I doubt there will be any problems. It's the fly-by-night garage based machineshops i worry about..
Dano78 said:Hell, the last one I bought, the rods were in backwards (chamfer wrong way and piston notches 1/2 were backwards) QUOTE]
Old racing trick.Adds like 30+ Ponies, as long as the piston had an offset wristpin. Only problem is it scrapes the crap outta the cylinder and piston skirt.
JonDawg said:Dano78 said:Hell, the last one I bought, the rods were in backwards (chamfer wrong way and piston notches 1/2 were backwards) QUOTE]
Old racing trick.
????
How does it add 30+ Lil mustangs
zwhitr said:
it changes the rod angle against the crank. That way, the rod pushes harder (sorta) against the crank. more push = more power.
This only works with an offset wristpin though. I know Im gonna get flamed on about this theory1, but I swear to ya that its true. I was in a Mopar 383 before and after, and I makes a REAL difference.
Turbo II
Founding Member
Turbo II said:Thanks! You guys are making feel better (I'm 38 going on 19
)
sorry Turbs, but Im 24, so 38 is old for me
of course, I remember thinkin 24 was ancient too. 
jeffnoel
Founding Member
Great avatarGlenn_MII said:Furthermore, it's good to see that you still conduct yourself in a polite and friendly fashion.
