Long rod 306??? 400 sbc crank and chevy rods.

[Dark_5.0]

Anyone ever hear of this short block. My friend has what he calls a long rod 306. He says it has a 400sbc crank and chevy rods.

What would be the advantages to having a shorter stroke and longer rods. Torque???

Get this he has ported victor jr heads a trick flow intake and a Vortech SQ trim supercharger on it.

The motor is sitting in a 1976 280 Z.

Sweet huh,

[Dark_5.0]

[302 LX Eric]

Doesn't DSS sell a long rod 306 setup now?

E

[Dark_5.0]

Originally posted by 302 LX Eric
Doesn't DSS sell a long rod 306 setup now?

E

I dont know, but I plan on blowing up my shortblock sometime in the near future and I had never heard of a long rod 306 till he mentioned it.

I was wondering what the advantages of a long rod 306 would be.

I've heard of that combo before. Not sure if it produces more torque or top end. My guess is like any other stroked motor...top end. Does that 280Z run with the motor in the picts.? If it does I bet it's fast as hell...

[Dark_5.0]

Not yet but it will soon. Everything has to be custom made so its taking a while.

[BilLster]

one of they guy's posted on the theory .(it was huge) it is suppose to add to torque and velocity of the air , partially because of the longer lever (fulcrum?) do to the longer rod. but like everything else it has to be part of the total package and not just changeing pistons and rods for a longer rod ,

stroke stays the same just that the piston ring is normally moved up to compensate for the longer rod so overall rod and piston height stay the same.

stroke can only be changed at the crank .

[Dark_5.0]

Originally posted by BilLster
one of they guy's posted on the theory .(it was huge) it is suppose to add to torque and velocity of the air , partially because of the longer lever (fulcrum?) do to the longer rod. but like everything else it has to be part of the total package and not just changeing pistons and rods for a longer rod ,

stroke stays the same just that the piston ring is normally moved up to compensate for the longer rod so overall rod and piston height stay the same.

stroke can only be changed at the crank .

Well supposedly it has a 400 SBC crank.

[fi347]

No way in hell he has a 400 Chevy crank and rods in a 302. The 400 stroke is 3.75", no way thats going in that block without hitting cylinder wall. Not to mention is just won't even go in. And if it were in, it would displace 383 cubic inches with a 4.030" bore. I think he's mistaken.

[Vaquero]

This is just my two cents but...I dont think longer rods would add much torque improvement anywhere in the rpm range or else they would be installed from the factory. If it is so cheap, and gives you more power with no adverse side effects then ford would have installed them to begin with, and advertised about it. I think that any improvements would be very very minor. Feel free to disagree.

[Dark_5.0]

It is by no means cheap. It definitely has chevy rods and I am pretty sure he said it had a 400sb crank.

He has over 6 thousand dollars in that motor easy.

I dont know I thought it was strange myself.

[richd]

You're looking for Speed Secret #5 posted by jim_howard_pdx

http://forums.mustangworks.com/showt...threadid=31035

[andy669]

Usually when someone says they have "chevy rods" in their Ford small block, they are talking about the rod journal diameter. 2.100" diameter rod journals (standard SB chevy size) can be had pretty easily when purchasing an aftermarket crank and rods. The biggest advantage is less bearing surface. The less bearing surface there is, the less frictional loss there is. Another advantage is more bearing choices.

As for the long rod/more torque issue. I have always been told that a long rod motor will make more torque. I have never tested this theory and I dont have the knowledge to dispute it, so I have to agree with it.

As for the 400 Chevy crank in the 302 block, I am very skeptical of that.

Andy

[Dark_5.0]

jim_howard_pdx- Doesnt have a phuckin clue.

JMO,

[DblAdigger]

You believe he's got a 400 SBC crank in it? Do the math and see if you have a clue.

[red82gt]

The longer rod will allow the piston to stay down in the bore for a longer period of time and will increase piston speed without increasing stroke. I can't think of a good analogy to really explain this though. The increased piston speed is what gives the extra torque.
The reason it's not done from the factory is because the clearances are much tighter and would be difficult to keep in check on a production line. The piston also spends more time at the top of the bore so piston/valve clearance could be a problem with a healthy cam.
I also gurantee that a Chebby 400 crank would be impossible to fit in a 302 block, heck I highly doubt that the two blocks even have the same length.

[HotRoddin]

Originally posted by richd
You're looking for Speed Secret #5 posted by jim_howard_pdx

http://forums.mustangworks.com/showt...threadid=31035

Welcome back Jim. Who are you trying to kid ? You can spot your posts after one sentence.
From every thing i've read heard and seen, there are some atvantages to running a longer rod because of the extra dwell time at TDC, but there is a point of diminishing returns, and to say the longer the rod the better the motor is nuts. If a rod the length of my arm worked miracles, don't you think that building full of engineers at Ford GM BMW ect ect would have covered the highway with them by now ?
PS: I talked to the Ford expert awhile back, at one of the major piston / rod companies. One i won't name that has been around since the beginning of time. His answer when i asked him if this long rod thing was what it was built up to be was ... he chuckled and said well, it sells magazines. Then he told me, I'll put a set together for you but you'll likely be disappointed.

[Dark_5.0]

If I believed he had a 400sbc crank in his 302 I would not have posted this I wanted some opinions.

It is unfortunate that all of us cant be know it all bull shlters like howard.

Anyone that achieved a ram air effect on a dyno has more of a clue than I will ever have i guess.

LMAO!!!!

[ultraflo]

I use a 5.40" rod with a 3.00" stroke.... and no, I don't use a chevy crank.

I honestly can't see where it makes a *huge* difference. It's a good theory, though.

[jonnyk]

Actually a long rod will help you more in the topend range. The longer dwell time at TDC promotes combustion when the piston speeds are much higher, so it's ideal for high revving engines. On the lowend it will actually hurt you because you're not taking advantage of the dwell time (engine is turning slow enough for efficient combustion), and the increased piston speed doesn't allow as much time for cylinder filling when the valves are open. IMO it's just hype, the gains or losses in either area will be minimal. Spend the money on something else.