HaneyMotorsport.Com

I do not mean to burst your bubble, But this is not true! The oil burning issue was from back in the day when the 347 came out in the mid 90's. The main problem was the rod/piston combo. The oil ring land/rings were in the pin bore....compression height for the 5.4 rod length. This produced extra blow by and consumption. These days we run a 5.315 rod to keep the oil ring out of the pin bore. We do run a 5.4 rod with the 331. Both the 331 and 347 are great combos. I do prefer the 331 for guys that like rpm. The rod ratio on the 331 is 1.66 and the 347 is 1.56 with the 5.315 rod. Just trying to help clear things up.

Casey

w8less

Jibaro

A 5.315 347 uses the same piston as a 331.It simply comes back to the skill level and not many people are willing to admit that they know less than they think they know. And speaking of R:S why does it almost always apply to the 331 v 347 debate? A 408 has a R:S of 1.5625 and a 418 is 1.5122.
This is easy . Off set pins.
Once the stroke has been decided [and in your example it is 3.4] the next biggest item is piston design. The piston used in a 5.400 rod 347 is a better design than a 5.315 rod 347. The 5.315 rod and piston 347 is a compromise to allow those with no experience to build a 347. It also stops the discussion on the rail supports at that point. But THEN the nay-sayers jump to R:S ratio. That is absolutely retarded.

Just wait until the 3.5 stroke, 5.4 rod 357's hit. I am quite sure the crying will be heard everywhere. Already people are posting on other boards asking if the "10 cid are *really* worth it". Its more than just 10 cid. Far more but the new breed of racer wants a number. If they physically cannot attach a number to something, then it must not be worth it.

What is a drag race? It is a measure of how quick I can get from point "A" to point "B". That is acceleration. If anyone wants to argue that point, then let's go. If all you want is power, then race a 100# crank, with a 7" rod, a 4# piston, and 20# of boost. Its called a diesel. LOADS of tq and no engine acceleration.

HaneyMotorsport.Com

Some of your statments are confusing. We can all go back and worth with this discussion, thats for sure! There are tons of different combos that can be put together. Small rod ratios are not always a bad thing. Look at IHRA mountain motors. Allot of these run in the 1.3s For a street /daily driver, I personally prefer to have the longest rod / rod ratio for longevity/durability.

Casey

Jibaro

I agreed with you, we could spend hours of great discussion on this matter. I just boils down to pref.. I personally know of a few 347's with over 100k miles and going strong and the same could be stated for the 331. But I do stand by that oil burning is a thing of the past(if you know what you are doing).

greenstreak9205

the reason that those heads are so cheap is because they really are cheap (this is only what i've heard) i guess their castings are really rough, not very consistant, and the material is kinda crappy. if you plan on buying a set and then have them ported then the casting in the ports shouldn't matter much but from what i've heard (as i will admit that i have never used them myself) its just not a good quality head. just spend a few extra bucks and get a good set. jmo

MustangMadness7

The gt-40 iron heads will be fine as long as you have them ported nicely with the lower intake to match. Also i wouldnt use the TFS cam, its worth the extra money to have a custom grind.

greenstreak9205

i agree that gt-40 heads are ok. but why waste the time and money on them for a 347. most people compare ported gt-40's to a stock afr 165 set. sure the numbers show that they flow more but thats on a 302. a 347 needs more air. comparing a bolt on 302 and a built 347 is almost like comparing a cathloc school girl and a prostitute, their needs are different and one can take in more than the other.