freshen up 474 not good

[CDNpontiac409guy]

While talking about piston weight, I thought I'd check a few of my pistons that I have here.

348, +.060", 3.76" stroke, 6.385" rod, 10.5:1 .... 644 grams

348, +.125", 3.76" stroke, 6.135" rod, 10:1........ 662 grams

409, +.038", 3.76" stroke, 6.385" rod, 10:1........ 616 grams

409, +.060", 3.76" stroke, 6.385" rod, 12:1........ 675 grams

409, +.068", 4.00" stroke, 6.385" rod, 10.5:1..... 630 grams

 

[GOSFAST]

I may have missed this somewhere , did anybody address this question ?

Hi Rusty, I would personally try to discourage this procedure, it could take some very "deep-pockets" to pull it off. Really believe for the most part it's unnecessary in the type units we're discussing here!

I always wondered if fitting a longer rod(6.8s out there) and moving the compression distance up would lighten the piston some for us. I know the "dome" is the big deal for our wedge chambers though.

This is the correct thinking but it ends up being a "double-edged" sword.

If you make the rods longer you will definitely need "shorter" pistons, BUT, you will most likely add more to the B/W due to the fact the longer "steel" rod will end up adding more than you'll gain by shortening the (aluminum) piston.

I am aware of the new "Eagle" '09 crank, but I have not had the opportunity to work with it as of today. Don't see it happening in the near future! Also not aware if a "target" B/W has been established just yet on this piece!

One more note with respect to "longer" rods, you will only be able to make them so long due to the physical limitations involved in the program. Regardless the type/shape of the dome for this unit, the rings can only be so high in the bores. You have these "limitations" with the deck heights!! The stroke along with the "ring pack" pretty much determines what's going to fit! You can put the wrist pin through the oil rings, much like most of the BB's, but you can't put it through the comp ring.

Thanks, Gary in N.Y.

P.S. I do aplogize if I've left any unanswered questions here, it's just that at this time of year I get "flooded" with all the previous years' builds returning to either be "freshened-up" or totally changed as far as the combo! It is extremely busy at the moment during this time of the season!

 

[jim_ss409]

While talking about piston weight, I thought I'd check a few of my pistons that I have here.

348, +.060", 3.76" stroke, 6.385" rod, 10.5:1 .... 644 grams

348, +.125", 3.76" stroke, 6.135" rod, 10:1........ 662 grams

409, +.038", 3.76" stroke, 6.385" rod, 10:1........ 616 grams

409, +.060", 3.76" stroke, 6.385" rod, 12:1........ 675 grams

409, +.068", 4.00" stroke, 6.385" rod, 10.5:1..... 630 grams

Wow those pistons are nice and light and I like the way you opened up the area between the valve reliefs. I also notice that you rounded over the outboard edge like the factory TRW's, I was wondering,,, did you do that to help ring seal or simply to lighten that side of the piston?
http://www.bruneauperformance.ca/409chevy409pistonstop.html

 

[tripowerguy]

Ronnie to answer your question, I have the 302 GMC engine in KC right now it is bored to 321 cu.in. and they are porting the head to flow about 240 intake and 170 exhaust. I have 2.02 intake valves installed and 1.72 exhaust valves installed. I have an Isky cam and the guy that I work for is making me some roller rocker arms, a motorplate so I can adapt a Chev v-8 blow proof bellhousing. He is making me an aluminum flywheel. I hope to have the whole thing home in about 30 days to start assembly. They were talking about heavy pistons, you guys don't know what heavy is until you see a 4 in. GMC piston, 4 rings 5 inches long. you can't get any after market stuff for this engine. I'm going to run 8.2 in Hudson rods and custom J and E pistons. This will lighten up the piston a tremendous amount. I hope to have the dragster running by Feb and run at a nostalgia meet in Texas the 23rd. I don't remember which city but it is called the Texas Thaw. The guy I work for is a genius at fuel injection and has a cnc mill. He can make anything. He also said all distributors cost lots of horsepower. He believes in only crank triggers. He wanted to put one on the Jimmy but I said it wasn't allowed. He would have me going a 150 in this thing and if you saw it you would know why I don't want to. I believe I can be in the 10's and about 125mph. Roy

 

[CDNpontiac409guy]

Very well explained, GOSFAST

Jim, my pistons that I designed a few years ago, all utilize that configuration.
Primarilly, the rounded edge is there to help "guide" the expanding combustion around the outside of the dome, in order to help eleviate the notorious side loading... and to help get that force against the ring. It DOES do something for lightening the piston, but not enough by itself. All of my pistons have the underside of the dome milled out some on the heavy side.
There're are a couple other unique features, but it's best to PM me about itno1:

 

[Ronnie Russell]

Great news Roy!!! What a fine sounding engine. Nice parts. Hope the Texas Thaw is in this area. bang

 

[budgetrod]

I always wondered if fitting a longer rod(6.8s out there) and moving the compression distance up would lighten the piston some for us. I know the "dome" is the big deal for our wedge chambers though.

With respect for making things as light as possible, has anyone ran aluminum rods? I know people say they are no good for the street, but I remember reading that JR Thompson uses them in his blown street hemis and swears by them. I would think they could save a lot of weight.

 

[Skip FIx]

Aluminum rods are often run on the street, heard of some guys using good BMEs for 50,000 miles.

A couple of down sides. They may "grow" or stretch more so leaving an additional 0.010-0.020 deck clearance.Experts differ so what teh "correct" number is is hard to tell, especially for a street motor where you are trying to exactly calculate compression ratio.BME recommends 0.060 with their rods and they are some of the best out there.

They are lighter yes but much bulkier to attain the same strength. So block clearance on a stroker may be an issue. where a stell rod it wasn't.

They also need to be brought up to temp before zinging the motor.

None real big deals but all potential issues. The piston and ring pack is more important to be light as the big end of the rod and bearing wieght isn't calculated the same as the piston,rings and small end for bob weight.

 

[MRHP]

holy cow

I' ve been out of town and come back to all of this info. Lots to digest. Turkey to digest also ! Yes Ronnie I will corral the rpm,s a little for the good of the motor. I already have the mains studded. Will 6800 max rpm and a main girdle be enough help or should I do more. My engine I believe is an internal balance with a 30 pound flywheel. It may be a 40 but I don't think so. I have the balance card somewhere, when I find it I will post the info.Will lightweight piston pins make enough of a difference as well. I know anything will help, but it has not scattered yet. How much lighter can I make the rods, pistons and pin assemblies without adversly affecting my current balance job. I recall reading an article on "overbalancing" or in otherwards changing the normally accepted weights for oil and the like. Would this lightning after the fact fall into this catagory? Thanks GOSFAST and others for taking the time to answer my "youthful" questions. I will also be opening up bearing clearances a little and maybe a touch on the cylinder walls as well. Boy, I sure have alot planned for my freshen up! Brian

 

[CDNpontiac409guy]

the cardinal rule.....

FIX IT FASTER bang

 

[MRHP]

Fix it faster

I like that Aubrey!

 

[Ronnie Russell]

Brian, If you have a GM 454 crank and internal balance, you must have much Malory metal in it. Anything you can do to lighten piston and rod is a help, but I think your hands are tied on that. Light weight pins would be a help, but I would think if you change anything that it would require re-balance. Aubrey would know more about that than me. I hate to keep harping on the same thing, but I think if you were to dyno, you would find peak hp on the stroker at 6,200 to 6,400. I see no reason to go above that. After all, it did stay together, even with the 7,500 rpm abuse. Once you get it back together I would expect it to have a long life at the lower rpm.

 

[MRHP]

Weights

I have an aftermarket crank. I believe it is a callies, I bought through Curt Harvey. I have found the balance card. Piston and pin weight 836.1 Piston rings 58 pin locks 4.9 total rod 750 rotary 527 insert 51. Grand total 2227. Is that good? Yes there is a small amount of weight on crank. Oil holes are chamfered and cross drilled if I recall. I ordered my camshaft and lifter set last week from Comp. They recommended that I get the cam nitrated. I said to go ahead and do it. They did not ask if I wanted the lifters done. Is doing the lifters even necessary. They recommended the Johnsons lifters and again I gave them the nod. Hope I did good!

 

[Skip FIx]

I'd bet peak on a stroker even with 690 or 583 heads would be 6000 max even with a big cam. Now the higher flowing heads coming out wil be a little different story.

"One more note with respect to "longer" rods, you will only be able to make them so long due to the physical limitations involved in the program. Regardless the type/shape of the dome for this unit, the rings can only be so high in the bores. You have these "limitations" with the deck heights!! The stroke along with the "ring pack" pretty much determines what's going to fit!"

Why I was wondering if a 6.8 rod would fit. Generally trying to keep the pin hole out of the oil ring and not use a special support for it is the best. So how far away from the ring pack and a 4.0 or 4.25 stroke be with a "standard" BBC 6.135?


H beam steel rods can be a little lighter than I beams so sometimes you can still get a lighter rod than a 6.135 I beam(especially 7.16 L-88 rods) and a lighter piston too. Longer rod gives a little better R/S ratio also.

Not sure a main girdle is any better than good 4 bolt main caps and a filled block.

Lightweight pins can be a double edged sword also if you go too light. Generally they get lighter by wall thickness. Too thin and a heavy piston(not a 400 gm SBC piston) and you can distort/bend pins easier, especially if you have a little detonation, which is not always audible.

 

[Ronnie Russell]

Brian, petepedlar, tripower, and whoever may be concerned. " H " series main bearings are available if you are interested. MS458 H Clevite, can be ordered from Summit or any Clevite dealer.

 

[petepedlar]

OK Ronnie...... silly question but what's an "H bearing" ???


Dave

 

[tripower]

Ronnie, We tried to find them and was told no one made them. I will check into it tomorrow... Thanks

 

[GOSFAST]

OK Ronnie...... silly question but what's an "H bearing" ???


Dave

Hi Pete, the "H" bearings have a large "chamfer" on both sides of the upper and lower shells. They allow extra clearance at the journal radius' for many aftermarket cranks. This is on the mains only!

The "H" rod bearings have/had the chamfer's on a single edge and are marked for "upper/lower" installation positions.

The "H" original series for the most part has been given a new part number as the shells have been both narrowed! Part of "cost-cutting" no doubt!

Thanks, Gary in N.Y.

P.S. The "MS458H" main set for the "W" comes only in Stds. and .001" unders. The "MS458HX" come in Stds. only and give an extra .001" clearance. Only the "upper shells" are "grooved". These "MS458H-Std" is "stocking" number for us!

 

[hogmotors]

Rod Length

Skip, et al:
Last time I checked, Ross had a guy(no, I can't remember his name but I probably have it in my notes-if I can find them....)that seemed to know quite a bit about hogmotors(or W's if you prefer-).
They have a program that tells them exactly what length the longest rod for a specific stroke was. Seems like 6.385" was the longest available that you could use w/4.25" stroke(actually 6.405 or something shorter than 6.5"). They're looking @ deck ht., pin placment, crown thickness. He had ALL of the answers for my ?'s....it was right there in front of him on the screen & the answers as to "why not?". VERY COOL I thought!!

I guess you could have some Titaniums made w/the exact lenght that'd fit. Uh, I think in drag racin anyway, there are some more issues to look at besides bob wt./rotating wt.-like how the car reacts leaving with that rotating wt.

Hey Skippy, you sound like you DID learn sumpin @ that Farm School!!! How you bin boy??
G

 

[Ronnie Russell]

Gordon, Looking at your front wheels, I would opt for whatever bobweight you are swinging. And " farm school ",,,,,, Most likely would have to be from Texas to get that one. Bet Skip will have a chuckle with it.