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tips, technology, tools and techniques related to vehicle driveline components

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mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Buick 300 V8 build recipe
Posted by: mgb260
Date: January 27, 2022 04:39PM

I think the Stroker 300 to 350 has got a lot of attention lately but not too much documented on the 300. Stock connecting rods for the 300 and 225 V6 are the same with side balance pads. 5.96" long. You can use 11/32" SBC ARP bolts to replace the stock ones but you have to resize the rods. The 75-76 Oddfire 231 V6 uses the modern capscrew rods which are much stronger and the same length. Stock 9 to 1 deep dish pistons are really 8 to 1. 10.25 shallow dish pistons are really 9.25 to 1. The 340P with shallow dish is really 9.5 to 1 and 3.8 bore or .050 over. The 3.0 V6 flat top for 3.8 bore is really 10 to 1 with a cleanup decking of bock and head mill. Oiling mods are the same as the other V6 and V8 engines. 502030 Crower cam for mild build, 50232 ideal for performance and 50233 is what Chris used in his stroker and Mike Moor used in his 300. Chris used Crower camsaver lifters for a 350 Buick and Smith Bros hollow pushrods for pushrod oiling. .125 shim under rocker stands due to longer valves and to plug oil holes in heads. Rocker oil holes have to be checked. Larger valves from a 3.4 Chevy V6 1.72 IN and 1.42 EX with Chevy Z28 springs and guides cut down to .530 for Viton seals. Bronze valve guide liners. The only intake is the stock 64 aluminum 4 barrel. You may be able to mill the 2 barrel to accept a 4 barrel base but you will have to weld up the water jacket inside when you are done. Brian Mcmillan is working with Anthony Laney in Australia to make a Willpower single plane for the 300. You can use spacers and a valley plate to use the 215/Rover Edelbrock Performer and single plane Offy 360.
507FB8E8-ED6B-4C45-B718-4F5C06BEF0B8.jpeg
s-l640.jpg
340p.jpg
300 rods.jpg



Edited 5 time(s). Last edit at 02/16/2022 04:41PM by mgb260.


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: January 27, 2022 04:59PM

Picture of capscrew rods:
capscrew.jpg


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: January 27, 2022 05:04PM

They are cast Armasteel . Should be magnafluxed. Rod weight of stock 300 rods are around 600 gm Capscrew around 630 gm. They both can be lightened quite a bit by minimizing the balance pads. The capscrew rods in the picture have already been lightened. In the 350 the early rods are good to about 400HP the later capscrew to about 600Hp if prepared properly. Sanding casting flash on outside of beams and any sharp edges. Bead blasted.



Edited 1 time(s). Last edit at 01/27/2022 05:09PM by mgb260.


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: January 27, 2022 06:15PM

You can use small journal SBC aftermarket 6" connecting rods if you machine .050 off each side and both ends. Bore small end out .010. Gain about .3 in compression.



Edited 1 time(s). Last edit at 01/27/2022 06:22PM by mgb260.


Capt'n Moorgone
Mike Moor
Angola,IN
(116 posts)

Registered:
11/20/2008 07:05PM

Main British Car:
1973 MGB 300 Buick

authors avatar
Re: Buick 300 V8 build recipe
Posted by: Capt'n Moorgone
Date: January 27, 2022 07:19PM

Thanks Jim,
I can't believe this!
I have another block I was going to build into a replacement. I'm looking to go lighter with modern pistons. Do you know of any part numbers that are close enough to work with? I may go with V6 rods. I think TA Performance has a lighter steel flywheel available. I'm still deciding the cam to use. I"ve been running the Crower 502033 for 70,000 miles so far. May just order a new one and lifters.

Mike


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: January 27, 2022 07:58PM

Mike, to go with lighter pistons you need longer rods. 350 Buick 6.385" capscrew rods. 6.25" SBC have available 1.58 compression height pistons . 6.4" rods open up 1.33 to 1.44 pistons. All those rods either are large journal SBC (You could use spacer bearings but have to have 3/8" rod bolts) or NASCAR small Honda size journal. There are 6.2 Nascar rods that Jim B is useing in his stroker but you would need custom pistons. I couldn't find any off the shelf. With the open chamber 300 heads you don't have very much quench but if you used the later Rover or TA heads with small chamber you would want to zero deck to take advantage of that. Decking the block and /or milling the heads to get around 10 to one is what you want with aluminum heads.

[www.ebay.com]



Edited 4 time(s). Last edit at 02/03/2022 12:39PM by mgb260.


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: January 27, 2022 08:53PM

Mike, This 3.78", 1.478 compression height, .030 over for the 300. Piston from a 3.5 Chrysler V6 would be perfect if you have middle raised portion milled down. Edit: .020 off top including raised portion. That is with the 350 capscrew rod.
3.5 chrysler v6.gif



Edited 4 time(s). Last edit at 02/02/2022 09:50PM by mgb260.



mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: January 28, 2022 12:01PM

For those that want to use the NASCAR 6.2 rod with the rover or TA heads I've found the perfect piston. 4.2 Jeep.1.633 compression height. You would cut off the tabs extending down from the skirt.
s-l1600 (37).jpg



Edited 2 time(s). Last edit at 01/28/2022 12:06PM by mgb260.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6274 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Buick 300 V8 build recipe
Posted by: BlownMGB-V8
Date: January 28, 2022 12:07PM

Those rods with oversized big end bearings aren't going to clear the block and the cam so I'm pretty sure those are out.Here are a couple of shots of the Wiseco pistons. Cost me $1140 a set which these days is a good deal.

IMG_0002.JPG

IMG_0001.JPG

Next is a shot of the Wiseco wrist pin beside the stock SBB one. That saves about 100 grans.

IMG_0008.JPG

Last a shot of the Carillo Nascar rods that I paid ~$100 for/set. The saved money goes into the pistons. I recommend the Pankl rods if you can get them. This is for the 350 crank setup.

Jim

IMG_0003.JPG


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6274 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Buick 300 V8 build recipe
Posted by: BlownMGB-V8
Date: January 28, 2022 01:28PM

Here is the label from the Wiseco pistons. Note these are for zero deck, 10.5 CR with 350 crank and 6.2" nascar rods using the TA or 4.6 Rover heads. You might be able to use them with the stock crank and 350 rods.

Jim

20220128_124458(1).jpg



Edited 2 time(s). Last edit at 01/28/2022 01:33PM by BlownMGB-V8.


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: Buick 300 V8 build recipe
Posted by: Airwreckc
Date: February 02, 2022 11:39AM

Hello everyone. I've been stalking this forum for a long time, but now have some questions. I am beginning an MGB-GT Sebring project and have been working on accumulating components. I have a Buick 300-4 (aluminum heads and intake) that I intend to build for this project. I have learned much about Nascar rods recently and bought a set of low mileage 6.320" rods recently ($100.00). So now, I am looking at pistons. I have come across three candidates: Jeep 232ci (3.8) pistons which are 3.75" bore and CH of 1.581, AMC 304 pistons with 3.75" bore and CH of 1.581 (different pistons than the Jeep), Chevy 305 pistons--3.756 in .020 overbore and CH of 1.540. Since all of these have a greater than the stock height of 7.819 to varying degrees, I assume I could mill some off the piston tops--taking into consideration that if I use a composite head gasket, I will add about .020" (meaning a bit less to mill off). The Chevy option seems the best, but I'd be interested in getting feedback from folks here on what I'm doing. TIA.


Jeep 232 Piston.png
AMC 304 Piston.jpg
Chevy 305 piston.jpg


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6274 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Buick 300 V8 build recipe
Posted by: BlownMGB-V8
Date: February 02, 2022 11:55AM

Check your wrist pin diameters to be sure you can get a match. Without bushing the pistons if possible.

Jim


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: Buick 300 V8 build recipe
Posted by: Airwreckc
Date: February 02, 2022 11:55AM

As an aside, for those who are looking at Nascar 6.2 rods (which are much more common and generally pretty cheap), I found these 3.75" bore pistons from the 1967 Buick 225 V6 which look very promising: 6.20" rods + 1.835 CH is 0.216" greater than stock. Add in a composite head gasket and you have a combination that could be interesting.


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: February 02, 2022 12:04PM

What size pin hole in rod? Diamond piston compression calculator is your friend.

[diamondracing.net]



Edited 1 time(s). Last edit at 02/02/2022 12:06PM by mgb260.


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: February 02, 2022 12:10PM

Piston catalog to compare pin height and diameter. Look in 3.736, 3.75, 3.78 and 3.8 bore sizes.

[uempistons.com]



Edited 2 time(s). Last edit at 02/02/2022 01:47PM by mgb260.



MGBV8
Carl Floyd
Kingsport, TN
(4327 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Buick 300 V8 build recipe
Posted by: MGBV8
Date: February 02, 2022 01:02PM

I used to almost have that catalog memorized looking for a good piston & rod combo for the Rover 3.9. :)

When you pull up a piston list, click on "BORE INCH" in the header. It will relist them by bore size.



Edited 1 time(s). Last edit at 02/02/2022 01:08PM by MGBV8.


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: Buick 300 V8 build recipe
Posted by: Airwreckc
Date: February 02, 2022 03:07PM

Thanks for the feedback. That catalog is gold--I know what I'll be poring over tonight :) Just for my knowledge, is there a reason I wouldn't want to bush the pistons? Or, on the other hand, bore out the rod pin hole a small amount?


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: February 02, 2022 03:22PM

I've searched the web looking for bushed pistons. There were a few VW and Diesel that used bronze bushings but were rather complicated with a step and circlip to hold them in. I looked up expansion with heat and aluminum expands twice as much as steel and bronze falls in the middle. There was a discussion with machinists that using aluminum tubing interference fit would be the best but I'd still stake both sides for insurance. You may have enough metal in the small end to bore for the press fit pin. If the rod has a bushing you will be able to bore out that much but is it enough. Some of the Pankl NASCAR rods have small .7 something holes some are .8 something which would be better. The build Chris did used a steel bushing for press fit pin and has been running fine the last 8 years.


mgb260
Jim Nichols
Sequim,WA
(2277 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Buick 300 V8 build recipe
Posted by: mgb260
Date: February 02, 2022 03:36PM

Eric, Does your NASCAR rods have SBC 2.0 journal size with 7/16" rod bolts? The extra width over the 3/8" may cause clearance issues. Also compare the Buick rods with the NASCAR ones for thickness at the big end and small end.


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: Buick 300 V8 build recipe
Posted by: Airwreckc
Date: February 02, 2022 03:38PM

Jim, forgot to answer the question about the piston rod. The rods I got are .912 on the small end. My original thought was to bore them out slightly, if necessary (rather than bushing the pistons)--although by looking through that catalog, perhaps I might find a perfect fit.
Nascar 6.320 rods.jpg
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