347 question
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Posting Guru
Joined: Sep 2006
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From: Bristol TN.
347 question
T&L engine builders in NC, build 347 engines either in roller cam or flat tap cam versions. They say that they use 5.400 rods and stock like pistons (5.09 size rod). Is does this make the rod angle better? I told them That I wanted an engine that would last and they recommended there roller cam version wich makes sense but then I told them I was also worried about the rod angle and piston ring wear for daily driving and they said that they use a that type of rod and piston and It would be sufficient for a daily driver. I thought that 347 strokers had to have special type pistons (some with the wrist pin intersecting with the piston ring, or thoughs that don't intersect using the 5.315" rod). Is T&L just taking 302 pistons and modifying them to work?
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
You cannot use stock pin height pistons in any 347 with 5.4 rods. The math doesn't add up. a 347's stroke is 3.4", 3.4 divided by 2 = 1.7, 1.7 + 5.4 + 1.610(stock 302 pin height) = 8.710. The deck of a 302 is only 8.206" Someone's clearly not communcating in your case. If what he told you is true, find another 347 builder.
Cargo Master
Joined: Dec 2004
Posts: 2,232
Likes: 3
From: NE Texas
Uh, it would be kind of important to know what chassis you plan on putting this engine into, wouldn't you think? Is it safe to assume that it would be a truck?
If you are putting this engine in a truck, you would be FAR better served to build a 351W due to the lack of hood height constraints. It would outlast even the best built 347 by a LARGE margin.
The only reason to settle for a 347 is when you have limited hood height. The short rod, short piston 347 is NOT a longevity queen, not to mention they are oil drinkers due to the pins proximity to the oil ring groove.
The SBF is famous for being hard on piston skirts even in 289 form. When you stretch the stroke you end up with a terrible rod ratio.
Build a 351W and you will have more stroke, same induction possibilties without that piston/cylinder killing rod ratio.
My $0.02,
If you are putting this engine in a truck, you would be FAR better served to build a 351W due to the lack of hood height constraints. It would outlast even the best built 347 by a LARGE margin.
The only reason to settle for a 347 is when you have limited hood height. The short rod, short piston 347 is NOT a longevity queen, not to mention they are oil drinkers due to the pins proximity to the oil ring groove.
The SBF is famous for being hard on piston skirts even in 289 form. When you stretch the stroke you end up with a terrible rod ratio.
Build a 351W and you will have more stroke, same induction possibilties without that piston/cylinder killing rod ratio.
My $0.02,
Cargo Master
Joined: Jan 2004
Posts: 2,512
Likes: 8
From: Cook Forest and Irwin PA
I think you will find that regardless of combo, the pin will intersect the oil control ring.
(as such I used SRP pistons with the rail supports)
it will daily drive, but oil control will always be an issue - but hey, it was a ford 302 which has had oil control issues since its invention! lol
You can get a 331 kit that has a relocated pin and reduced compression height to not intersect the ring - hindsight being 20-20, I woulda went this way, but so far I got over $5G into the motor and the heads aint screwed on yet....
while it is true a worse r/s ratio wants to push the piston thru the thrust side of the block, at higher rpms this is alleviated, AND the ratio in this case is better than the chevy 400, with the chevy 350 sitting smack in the middle. - we are talking hundreths here.
Increase the rear end ratio (which you are likely doing anyways to experience the 347 cubes) and this wont be the big worry
(as such I used SRP pistons with the rail supports)
it will daily drive, but oil control will always be an issue - but hey, it was a ford 302 which has had oil control issues since its invention! lol
You can get a 331 kit that has a relocated pin and reduced compression height to not intersect the ring - hindsight being 20-20, I woulda went this way, but so far I got over $5G into the motor and the heads aint screwed on yet....
while it is true a worse r/s ratio wants to push the piston thru the thrust side of the block, at higher rpms this is alleviated, AND the ratio in this case is better than the chevy 400, with the chevy 350 sitting smack in the middle. - we are talking hundreths here.
Increase the rear end ratio (which you are likely doing anyways to experience the 347 cubes) and this wont be the big worry
