Thread: 383 stroker profile 6" rods??.

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I have read about 6" stroker profile rods for a 383 that don't have to be clearance for the cam.<or a small base circle cam isn't needed>.Who makes them and is there a downside for use on a street driven vehicle??.What kind of price range can I expect??.

I am going to talk to Wiseco for the pistons.

I run Scat H-Beams I my motor. I also have a small base circle cam and I didn't have to clearance anything. Plenty of room.

Keith

Originally Posted by blwn31

I run Scat H-Beams I my motor. I also have a small base circle cam and I didn't have to clearance anything. Plenty of room.

Keith

yep did a 383 with a scat Hbeam and a solid roller and room the only time i had to nip the rods bolts was a std base circle with 5.7 gm rods

I have had my heart set on a GM hydro roller cam that is not over 500 lift and is nick named the 383 cam.It has a lobe center of 109 which I really like.I'll get the spec's and post them tomorrow.

that cam is a marine cam that i used a 350 build . you could use the I beam cap screw rods if you do not want the the H beams rods you can get the rods with a shorter rod bolt so you do not have to rework so much things to fit . but you still have to check every thing and if the block has any shift in it when casted

Originally Posted by 1gary

I have read about 6" stroker profile rods for a 383 that don't have to be clearance for the cam.<or a small base circle cam isn't needed>.Who makes them and is there a downside for use on a street driven vehicle??.What kind of price range can I expect??.

I am going to talk to Wiseco for the pistons.

Hello Gary... build a lot of 383 cid strokers for the street & strip...i use RPM's 4340 I beam 6.00 rods with ARP cap screws & Eagle & Scat & RPM cranks....# 2 cyln & # 6 cyln cam lobes are trouble ...these rods with lots to spare @ .500 to .650 lift...
BUT ALWAYS CHECK FOR ROD TO CAM LOBES FOR CLEARANCE ... RPM & EAGLE & SCAT cap screw loaded rods clear very well small base circle cam not needed.


Rod bolts clear blocks @ bottom of bores pretty good.... MOST clear BUT check all rods for clearance shoot for min .050th rod to bottom of bores.

Also watch # 7 & #8 rods for contact on side of block were dip stick hole in block is just behind that pad is a trouble spot.... also same area check crank counterweight for contact on edge of block inline with oil filter pad on block.
MOST cranks are very close or hit / rub on block ( OLDER BLOCKS WITH DRIVER SIDE DIP STICK)

Gary a good 4340 I beam rod 6.00 ARP cap screws loaded your looking @ $250 to $300 set prox... RPM OR SCAT ... EAGLE CHEAPEST.... also P/C has 6.00 rods cheapest @ prox $ 150 set....NO ARP BOLTS... i'd spend a tad more & go RPM /SCAT /EAGLE......... on a budget.

Pistons.... on budget KB claimers are not bad.... @ prox $220.00 set.... Forged we use Probe or Mahale... priced competetive.

Regards Daryl


Regards Daryl
PS: Also check your oil pan for clearance... rods to pan # 7 rod & # 8 again
they tend to hit pan side/ on right side of engine just behind that oil stick hole pad on block... take ball peen hammer & dimple out pan @ side were rods touch pan.

Originally Posted by 1gary

I have read about 6" stroker profile rods for a 383 that don't have to be clearance for the cam. Who makes them and is there a downside for use on a street driven vehicle??.

I won't use 6" rods on a 383 build because the pin gets up into the oil ring, requiring rail support. Just more stuff to go wrong in my opinion. It's a slam dunk to make over 500 hp with 5.7 rods in a 383, so I don't see the need for longer rods.

I rebuff the 6" rods based on what Iskenderian says also. He knows a little bit more than I do about some of this stuff......

"Tech Tip - 2005
Rod Lengths/Ratios: Much ado about almost nothing.

Why do people change connecting rod lengths or alter their rod length to stroke ratios? I know why, they think they are changing them. They expect to gain (usually based upon the hype of some magazine article or the sales pitch of someone in the parts business) Torque or Horsepower here or there in rather significant "chunks". Well, they will experience some gains and losses here or there in torque and or H.P., but unfortunately these "chunks" everyone talks about are more like "chips".

To hear the hype about running a longer Rod and making more Torque @ low to mid RPM or mid to high RPM (yes, it is, believe it or not actually pitched both ways) you'd think that there must be a tremendous potential for gain, otherwise, why would anyone even bother? Good question. Let's begin with the basics. The manufacture's (Chevy, Ford, Chrysler etc.) employ automotive engineers and designers to do their best (especially today) in creating engine packages that are both powerful and efficient. They of course, must also consider longevity, for what good would come form designing an engine with say 5% more power at a price of one half the life factor? Obviously none. You usually don't get something for nothing - everything usually has its price. For example: I can design a cam with tremendous high RPM/H.P. potential, but it would be silly of me (not to mention the height of arrogance) to criticize the engineer who designed the stock camshaft. For this engine when I know how poorly this cam would perform at the lower operating RPM range in which this engineer was concerned with as his design objective!

Yet, I read of and hear about people who do this all the time with Rod lengths. They actually speak of the automotive engine designer responsible for running "such a short Rod" as a "stupid SOB." Well, folks I am here to tell you that those who spew such garbage should be ashamed of themselves - and not just because the original designer had different design criteria and objectives. I may shock some of you, but in your wildest dreams you are never going to achieve the level of power increase by changing your connecting rod lengths that you would, say in increasing compression ratio, cam duration or cylinder head flow capacity. To illustrate my point, take a look at the chart below. I have illustrated the crank angles and relative piston positions of today's most popular racing engine, the 3.48" stroke small block 350 V8 Chevy in standard 5.7", 6.00", 6.125" and 6.250" long rod lengths in 5 degree increments. Notice the infinitesimal (look it up in the dictionary) change in piston position for a given crank angle with the 4 different length rods. Not much here folks, but "oh, there must be a big difference in piston velocity, right?" Wrong! Again it's a marginal difference (check the source yourself - its performance calculator).

To hear all this hype about rod lengths I'm sure you were prepared for a nice 30, 40, or 50 HP increase, weren't you? Well its more like a 5-7 HP increase at best, and guess what? It comes at a price. The longer the rod, the closer your wrist pin boss will be to your ring lands. In extreme situations, 6.125" & 6.250" lengths for example, both ring and piston life are affected. The rings get a double whammy affect. First, with the pin boss crowding the rings, the normally designed space between the lands must be reduced to accommodate the higher wrist pin boss. Second, the rings wobble more and lose the seal of their fine edge as the piston rocks. A longer Rod influences the piston to dwell a bit longer at TDC than a shorter rod would and conversely, to dwell somewhat less at BDC. This is another area where people often get the information backwards.

In fact, this may surprise you, but I know of a gentleman who runs a 5.5" Rod in a 350 Small Block Chevy who makes more horsepower (we're talking top end here) than he would with a longer rod. Why? Because with a longer dwell time at BDC the short rod will actually allow you a slightly later intake closing point (about 1 or 2 degrees) in terms of crank angle, with the same piston rise in the cylinder. So in terms of the engines sensitivity to "reversion" with the shorter rod lengths you can run about 2-4 degrees more duration (1-2 degrees on both the opening & closing sides) without suffering this adverse affect! So much for the belief that longer rod's always enhance top end power!

Now to the subject of rod to stroke ratios. People are always looking for the "magic number" here - as if like Pythagoras they could possibly discover a mathematical relationship which would secure them a place in history. Rod to stroke ratios are for the most part the naturally occurring result of other engine design criteria. In other-words, much like with ignition timing (spark advance) they are what they are. In regards to the later, the actual number is not as important as finding the right point for a given engine. Why worry for example that a Chrysler "hemi" needs less spark advance that a Chevrolet "wedge" combustion chamber? The number in and of itself is not important and it is much the same with rod to stroke ratios. Unless you want to completely redesign the engine (including your block deck height etc.) leave your rod lengths alone. Let's not forget after all, most of us are not racing at the Indy 500 but rather are hot rodding stock blocks.

Only professional engine builders who have exhausted every other possible avenue of performance should ever consider a rod length change and even they should exercise care so as not to get caught up in the hype."

Thank you guys for your input

Originally Posted by pat mccarthy

that cam is a marine cam that i used a 350 build . you could use the I beam cap screw rods if you do not want the the H beams rods you can get the rods with a shorter rod bolt so you do not have to rework so much things to fit . but you still have to check every thing and if the block has any shift in it when casted

Pat,

Just to be sure we are talking about the same cam here is the GM part#14097395 and the specs:


This hydraulic roller design is used on the 383 truck. The duration at lash point in degrees (intake/exhaust) is 288/308; duration at .050" tappet lift (intake/exhaust) is 196/206; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 431/451. Valve lash is zero/zero and lobe centerline is 109 degrees.

It is a smooth idle in a 350 with a good torque in the lower RPM ranges.

Originally Posted by techinspector1

I won't use 6" rods on a 383 build because the pin gets up into the oil ring, requiring rail support. Just more stuff to go wrong in my opinion. It's a slam dunk to make over 500 hp with 5.7 rods in a 383, so I don't see the need for longer rods.

I rebuff the 6" rods based on what Iskenderian says also. He knows a little bit more than I do about some of this stuff......

"Tech Tip - 2005
Rod Lengths/Ratios: Much ado about almost nothing.

Why do people change connecting rod lengths or alter their rod length to stroke ratios? I know why, they think they are changing them. They expect to gain (usually based upon the hype of some magazine article or the sales pitch of someone in the parts business) Torque or Horsepower here or there in rather significant "chunks". Well, they will experience some gains and losses here or there in torque and or H.P., but unfortunately these "chunks" everyone talks about are more like "chips".

To hear the hype about running a longer Rod and making more Torque @ low to mid RPM or mid to high RPM (yes, it is, believe it or not actually pitched both ways) you'd think that there must be a tremendous potential for gain, otherwise, why would anyone even bother? Good question. Let's begin with the basics. The manufacture's (Chevy, Ford, Chrysler etc.) employ automotive engineers and designers to do their best (especially today) in creating engine packages that are both powerful and efficient. They of course, must also consider longevity, for what good would come form designing an engine with say 5% more power at a price of one half the life factor? Obviously none. You usually don't get something for nothing - everything usually has its price. For example: I can design a cam with tremendous high RPM/H.P. potential, but it would be silly of me (not to mention the height of arrogance) to criticize the engineer who designed the stock camshaft. For this engine when I know how poorly this cam would perform at the lower operating RPM range in which this engineer was concerned with as his design objective!

Yet, I read of and hear about people who do this all the time with Rod lengths. They actually speak of the automotive engine designer responsible for running "such a short Rod" as a "stupid SOB." Well, folks I am here to tell you that those who spew such garbage should be ashamed of themselves - and not just because the original designer had different design criteria and objectives. I may shock some of you, but in your wildest dreams you are never going to achieve the level of power increase by changing your connecting rod lengths that you would, say in increasing compression ratio, cam duration or cylinder head flow capacity. To illustrate my point, take a look at the chart below. I have illustrated the crank angles and relative piston positions of today's most popular racing engine, the 3.48" stroke small block 350 V8 Chevy in standard 5.7", 6.00", 6.125" and 6.250" long rod lengths in 5 degree increments. Notice the infinitesimal (look it up in the dictionary) change in piston position for a given crank angle with the 4 different length rods. Not much here folks, but "oh, there must be a big difference in piston velocity, right?" Wrong! Again it's a marginal difference (check the source yourself - its performance calculator).

To hear all this hype about rod lengths I'm sure you were prepared for a nice 30, 40, or 50 HP increase, weren't you? Well its more like a 5-7 HP increase at best, and guess what? It comes at a price. The longer the rod, the closer your wrist pin boss will be to your ring lands. In extreme situations, 6.125" & 6.250" lengths for example, both ring and piston life are affected. The rings get a double whammy affect. First, with the pin boss crowding the rings, the normally designed space between the lands must be reduced to accommodate the higher wrist pin boss. Second, the rings wobble more and lose the seal of their fine edge as the piston rocks. A longer Rod influences the piston to dwell a bit longer at TDC than a shorter rod would and conversely, to dwell somewhat less at BDC. This is another area where people often get the information backwards.

In fact, this may surprise you, but I know of a gentleman who runs a 5.5" Rod in a 350 Small Block Chevy who makes more horsepower (we're talking top end here) than he would with a longer rod. Why? Because with a longer dwell time at BDC the short rod will actually allow you a slightly later intake closing point (about 1 or 2 degrees) in terms of crank angle, with the same piston rise in the cylinder. So in terms of the engines sensitivity to "reversion" with the shorter rod lengths you can run about 2-4 degrees more duration (1-2 degrees on both the opening & closing sides) without suffering this adverse affect! So much for the belief that longer rod's always enhance top end power!

Now to the subject of rod to stroke ratios. People are always looking for the "magic number" here - as if like Pythagoras they could possibly discover a mathematical relationship which would secure them a place in history. Rod to stroke ratios are for the most part the naturally occurring result of other engine design criteria. In other-words, much like with ignition timing (spark advance) they are what they are. In regards to the later, the actual number is not as important as finding the right point for a given engine. Why worry for example that a Chrysler "hemi" needs less spark advance that a Chevrolet "wedge" combustion chamber? The number in and of itself is not important and it is much the same with rod to stroke ratios. Unless you want to completely redesign the engine (including your block deck height etc.) leave your rod lengths alone. Let's not forget after all, most of us are not racing at the Indy 500 but rather are hot rodding stock blocks.

Only professional engine builders who have exhausted every other possible avenue of performance should ever consider a rod length change and even they should exercise care so as not to get caught up in the hype."

Hello Yes T.I. ... the o'll rod length ? is longer better issue.... i 've spoke with the Cam Father / Ed Iskenderian on this... and the above was generaly his answer... and i've spoke to Smokey way back in the 80's on this rod length issue...

Well good o'll Smokey had complete differant answer & approach he said.. son load the longest dam rod you can with in reason / budget and proceeded to explain the reasons why eg: better rod angle ( less) with long stroke cranks , less piston thrust side loading on block cyln walls / less wear , longer piston dwell @ TDC ect ect .. / Read Smokeys Power Secrets a good book to have in your book collection

Anyway.... my 2 cents is with longer stroke cranks as with 383 / 3.750 stroke use 6;00 rods.... to boil it down i'll quote Smokey.... " It sure as hell can't hurt your HP output or the life of your engine"



Regards Daryl


Regards Daryl

Originally Posted by 1gary

Pat,

This hydraulic roller design is used on the 383 truck. The duration at lash point in degrees (intake/exhaust) is 288/308; duration at .050" tappet lift (intake/exhaust) is 196/206; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 431/451. Valve lash is zero/zero and lobe centerline is 109 degrees.

It is a smooth idle in a 350 with a good torque in the lower RPM ranges.

Since you are building a relatively mild engine, 6.0 rods provide no appreciable advantage. Go with 5.7 inch rods.

well.. first say you did not ask about the 6.000 rods in your build . some have posted on not using the 6.000 rod in your build . so now i will post on it .i build some big engines were we have a short CH under 1.125 and a stack up ring pack were we run a thinner top ring and run the pin thru the oil ring land and there less piston in the bore. i still think your better with along skirt if you can get it for evey day use and use the shorter rods. were i seen longer rods can help on side thrust one build comes to mind is a 496 bbc pull truck engine that runs up past 7500. were the pistons want to flip over in the bore s but a longer rods just may not help that much there is trade offs were the piston get short fast and the piston see s the load pushing the rod down as for side thurst there is pin off set on the piston this helps .if you build a 383 and run at w.o.t all the time you may see a longer rod helps it has alot of what your building most all builds your not going to get hurt to much by using a shorter rod .some of the 4.750 crank and 5.000+ cranks your never going to be were some say it great . the rods would be 10.000 long and the block would be better then a 13.000 deck i seen them run and talk to many as well as built many big crank engines . first 5.7 is not a short rod for the 3.750 crank gm used a shorter rods in the 400 and knew of one short rod 400.that went way past 6500 many times . for a driver i would build it as a 5.7 rod and a speed pro hyper piston with a scat cap screw bolt I beam rods and scat cast steel crank tru deck the block and deck plate hone the block balance the mass call it good