Bushing down the little end of rods

[CTX-SLPR]

Howdy,

Well as many of you know, I am very fond of digging through catelogs and combining parts across manufacturers to make oddball combos of parts. This time it's working on my 3.0L Destroker V6 for S//NP (see the LSR section for details).

Buick made a factory 3.0L V6 but it was a lower deck height unit that means despite the same 3.8in bore, a stock 3.0L rotating assembly puts the pistons 0.064in in the hole and the decks are thin enough as it is that I'm not cutting them down more than I have to to get it flat and maybe a 0.010ish cut for a 0 deck. There are 2 options I see, cut the rod journals down to 2.200in and run a 6.375in BBC rod that's been narrowed and/or rod journal widened then bush the 0.990in wrist pin down to the Buick 0.940in. Or use a 455 BBB rod with the same treatment (narrowing and/or journal widening) and a "short rod" 0.020in over 2.3L Ford I4 piston; but still need to bush the 1.0in wrist pin down to now a 0.912 wrist pin.

If I start with a set of press pin rods, I would think I could get custom/generic bronze bushings and have them reamed out to put the piston at minimum head clearance to maximize quench but this idea hasn't really made it out of my head so is that even possible? What if I start with a set of already bushed floating rods? Knock the existing bushing out and put a new one in with the right sizes?

Any experience or comentary would be appreciated. Thanks,

[Beagle]

the bushing part is no big deal, they do it all the time and have forever. Press and hone to fit. The only question I would have on it is oiling a Press Fit rod modified for floaters.

I've asked on here before, there are several folks who said that even running a floating pin in a steel rod with no bushing would work although not the best plan in the world. This kind of mods used to be a LOT more common when you couldn't off the shelf anything you wanted...

look at this guys channel. He ain't skeered. I don't have video, but see if he says anything about the pin hole at the top of the rod for oiling the bushing. I think you might have to add one if the rod was not originally a floater setup.

[MR P-BODY]

I've done it before... the biggest thing is finding a bushing
that is close... I didnt want to machine the whole thing...
I put Chevy pistons on a Mopar rod... I had the rods and
didnt feel like buying the Chevy rods... that engine is still
running as my back up engine in my race car.... the pistons
were full floaters so it was easy... the rod started out as a press
fit but I keep that stock diameter and machined the bushing to
press fit then drilled in a oil hole and beveled it on the top then honed
the ID to fit the chevy pin
EDIT
I got my bushings from CV Products... they tend to be more roundy round
stuff but carry lots of stuff... I get my valve grinding stuff there also

[OldMachinist]

It's not desirable to try to widen the rod journals on the crank or even very possible as you will soon be into the counterweights.
At least if I am understanding you right on what you want to do. Narrowing rods on a mill is feasable and the way to go just keep the offsets correct and pay attention to the tang reliefs for fitting the bearings. If possible it is always desirable to bore pin bushings on a pin boring machine to keep the C to C distances equal and the bores parallel with the big end. I know not many machine shops have the machine to do this so check around and I have a guy here in western Colo. who can do it if you are interested.

[CTX-SLPR]

There are 2 bearing widths for the Buick V6, "narrow/production" at 0.854in and "wide" at 0.890in. I'd only take it out to 0.890 on the 455 rods then take the rest out of the rod to offset them like the stock V6 rods. On the BBC rods I'd have to dig around for what width bearings I can get but the local Indy Lites builder has the crank shop (same one I'm talking to) take it out to 0.905 but I'd not take them that far most likely.

Definately interested in your machine shop. Still finding out the local machine shop capabilities but I know I have good resources in Loophole Racing and Mile High Crankshaft. Shipping would be easy to the otherside of the Rockies and I think Bamfster in Denver goes over the mountains enough I might be able to relay them back and forth if needed. I have a mill so I'd likely just rough the rods down to +0.010 the final width and have the professionals take them all the way down to get them square and smooth. Definately not doing the pin bosses myself.

[OldMachinist]

I would think someone on that side of the hill has pin boring capabilities. Should just take some research.

[OHC 6 Sprint]

There are 2 bearing widths for the Buick V6, "narrow/production" at 0.854in and "wide" at 0.890in.

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I have a mill so I'd likely just rough the rods down to +0.010 the final width and have the professionals take them all the way down to get them square and smooth.

My experience with narrowing rods is to take them to a Blanchard grinding shop. They are already square, and the Blanchard will keep them that way. They can do a set of 6 rods for about $75. You might do yourself more disservice by rouging them on your own. A Blanchard can remove a lot of material in a single pass, yet still hold .0001" tolerances in the final pass.

Just my $0.02 worth.

[CTX-SLPR]

My experience with narrowing rods is to take them to a Blanchard grinding shop. They are already square, and the Blanchard will keep them that way. They can do a set of 6 rods for about $75. You might do yourself more disservice by rouging them on your own. A Blanchard can remove a lot of material in a single pass, yet still hold .0001" tolerances in the final pass.

Just my $0.02 worth.

I'd definately consult with a shop before doing any of the work myself with in reason. Some shops just want to make as much money as they can by doing as much work as possible but a lot of the smaller and in my experience very good shops are happy to have you do work for them to cut down on the amount of things they have to do since they are typically overloaded.

Looking more and more like I'm going to be running 6.385in BBC rods narrowed on a turned down OEM 2.66in stroke crank with regular cast 3.0L pistons. Should survive 300ish HP for the short term till I can find a forged 2.66in crank and/or afford custom slugs. Given the choice I'd do the pistons first. I doubt even 450hp would tax the OEM crank excessively with good machine work that should make it stronger than factory.

[CTX-SLPR]

So "Ask and ye shall receive". I put a call for 3.800-3.820in bore flat top forgings on Turbobuick.com and netted a set of forged TRW's in 3.800 with an old BMS (Buick MotorSports) part number. So there is the good pistons on top. They are heavy but that doesn't bother me much as the extra weight will help the motor from lugging down as I shift with the tall rear gears.

The current dilema is rods. Found a local shop to do the work for me and they suggested that I get unbushed press pin rods to bush down. Now I'm sure they are thinking I'm likely buying a new set of rods and they don't want to have me waste the money on a set of rods that already have a bushing. However I am not an expert so can anyone think of other reasons they'd want me not to get a bushed rod even if I could get a used but higher quality rod for the same money?
Think it's the need to knock a bushing out?

Thanks,

[anotheridiot]

this sounds like fun. remember stories of guys knurling wrist pins to increase their size in the old days of hot rodding. plus your bushed rod is so much better than a press fit rod anyway.

I use mcmaster carr alot, they have pretty standard bushings, sometimes you can buy metric to get closer.

[CTX-SLPR]

Getting a ton of sass back from the machine shop now that I fully discribe what I want to do with the rods. The local guys have told me that they won't do the little end work!

This leaves me in a bit of a stuck position. I have the pistons though I'm not that much into them. It's possible the block will have enough deck height to get away with just bushing the rods in the center but I'd still have to narrow them and the bearings to get them to work.

The alternative is to get custom pistons, new or used Buick V6 rods, and the crank slightly reworked to put a better radius on the rod fillets and potentially widened from the 0.854 production BE width to a 0.890 Stage II BE width.

Custom pistons are ~$700 plus rings (already have Buick 0.940 pins and rods set up for 0.927 SBC pins can be enlarged to work), rods new are ~$525 but used 6.5 and other long Buick rods are cheaper, crank and work is around $350.

[Caveman Tony]

lol... 'sass'...

Sass = they'll do what they want to your parts, whether thats what you want or not.



Find somebody else, even if it means mailing stuff. Just use plenty of bubble wrap.

[CTX-SLPR]

Well I rejiggered my plans last night (see the Project Cars thread). Looks like I get to shave the pistons crowns if needed. I had a dramatically wrong compression height in my calculations.

[blown away]

From: [email protected]
Subject: bushings
Date: Wed, 13 Oct 2010 08:27:53 -0700

Rob,

We can produce custom bushings for you but we would need to know the exact diameters. We recommend .002-.003" interference on the OD, but the bushing ID depends on your method of finish work. Custom 954 bronze bushings are $10.00 each and must be prepaid. They would take about 5-7 days to make.

Thanks,

Don

Customer_Message
hi wanted to know if u build pin bushings, using a hemi pistons with 1.09 pin holes, but have rods with .990 pin size, want to bush my pistons, to except a .990 pin, dont want to bush the rod small end due to failure, with a boosted hemi that I am using the steel billet rods for. please get back to me thx robQUOTE=CTX-SLPR;736358]Getting a ton of sass back from the machine shop now that I fully discribe what I want to do with the rods. The local guys have told me that they won't do the little end work!

This leaves me in a bit of a stuck position. I have the pistons though I'm not that much into them. It's possible the block will have enough deck height to get away with just bushing the rods in the center but I'd still have to narrow them and the bearings to get them to work.

The alternative is to get custom pistons, new or used Buick V6 rods, and the crank slightly reworked to put a better radius on the rod fillets and potentially widened from the 0.854 production BE width to a 0.890 Stage II BE width.

Custom pistons are ~$700 plus rings (already have Buick 0.940 pins and rods set up for 0.927 SBC pins can be enlarged to work), rods new are ~$525 but used 6.5 and other long Buick rods are cheaper, crank and work is around $350.[/QUOTE]

[blown away]

hi just posted a guy who does jobs like that. I asked for it to be down the other way around put chevy rods on mopar pistons.

Well I rejiggered my plans last night (see the Project Cars thread). Looks like I get to shave the pistons crowns if needed. I had a dramatically wrong compression height in my calculations.