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phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 24, 2016 06:22PM

I'm getting back to this project after a few years off. Got a few questions for folks who've been here before me.
I'll start at the top.
1. I have a set of '64 300 heads that I want to put bigger valves and some bowl porting. I'm looking at these valves: [www.v8tuner.co.uk] or these : [www.v8tuner.co.uk]
The question I have for you with more knowledge than I is there any more machine work involved using the larger of the 2 sets of valves? That is, is the work the same for either set? If so I'll go with the larger set, if there's more work and $ I'll go with the smaller set.
2. I was looking for a more modern piston set than the Ford 255 pistons and smaller than the Chevy 305 pistons and I found these Dodge 4.7 v8 pistons: [www.summitracing.com] which measure in @ 3.7 in dia. the down side is the wrist pin is .946" pressed in and all the small block Chevy rod wrist pin bores are for a .927" wrist pin. In your opinion do you think there is enough meat at the end of the Chevy rods to accommodate enlarging the small end .019" to fit the Dodge wrist pin? My other thought on this is if a floating pin rod was used I could remove the bushing from the small end of the rod, hone it to the right dia, and press the pin in, but right now I have no idea what the bore dia. is minus the bushing.
3. I have a 4.6 crank that I believe has a stock stroke of 3.23", rod journals are 2.185". I want to use Chevy 6" rods with the Dodge pistons, 1.24" deck height. In order to make it work the crank has to have a stoke of 3.4" for .020" below deck or 3.44" 0" deck height. Using 2" rod journal rods is it possible to offset grind the 4.6 crank to achieve the required stroke?

This will not be a race car, the engine is going into a '59 Alfa Touring Spider that weighs in about 2600lbs. The current engine in the car is a '63 Olds with a mild cam, headers and Megasquirt. It's fun to drive but it could be better. The build log is here: [www.lightningbugcars.com]


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5552 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: BlownMGB-V8
Date: September 25, 2016 10:12AM

I can help with a few points. With the 300 heads you may want to go with a zero deck, but I see the pistons are not dished so that will make a difference. Run your calculations to see what your CR comes out to. Ideally you would shoot for a .040" squish and around 10:1 CR but you may have to give some on the squish to keep the CR within reason. That will depend on your displacement but you should be close with those.

Taking 19 thou out of the top rod eye isn't going to hurt a thing. You aren't going to be running a 7 grand redline with cast pistons, so it'll be strong enough. There is no bushing in the top of the Chevy rods, it's a press fit and the float in in the piston.

I'm not sure where you are going with your offset grind unless the later Rovers used a larger rod journal. The earlier engines were all 2". Most offset grinds I've seen on SBBs were using a Honda rod IIRC. (maybe Toy)

I'll let someone else advise you on the valves, but if I was going to put that much into the heads I would at least consider a set of TA bare heads. It may not make sense for your build but it's worth looking into anyway.

HTH,
Jim


MGBV8
Carl Floyd
Kingsport, TN
(3418 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: MGBV8
Date: September 25, 2016 11:23AM

For full floating wrist pin, the rod should be bushed & have a hole for lubrication. By the time you enlarge the small end, rebush, & drill a quality custom rod might not be much more.

[www.crower.com]

I guess you are using a 4.0/4.6 block. Yes, the rod journals are bigger for offset grinding. So,are the mains. In fact the mains are the same size as the Buick 300 crankshaft that already has a 3.4 stroke & 2.0 journal size.

[www.aluminumv8.com]

Might want to spend more time crunching numbers for the engine & machining costs. I love these engine calculators.

[www.uempistons.com]


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 25, 2016 11:38AM

Hi Jim,
Thanks for the reply. I'm asking if offset grinding the 4.6 crank from 3.23" to 3.4" is possible because the difference in rod journal sizes needed. Up to the 3.9 v8 the cranks had a 2" rod journals, the 4.0 cross bolted v8 had 2.185" rod journals. If I'm using the 2" rod journal SBC rods that would give me an extra .185" of journal to offset grind. I know nothing about offset grinding and I don't know if that's enough meat to go from 3.23" to 3.4-3.44" stroke. The CR calculates out to 3.4" stroke .040" below deck = 10.3:1, 3.42" stroke .020" below deck = 10.6:1, 3.44" stroke 0 deck= 10.98:1. I considered the TA heads but even the bare heads will be more $s than I want to spend. The worked over 300 heads will run about the same as the TA bare heads and, as you said, way more than I need for this setup.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5552 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: BlownMGB-V8
Date: September 25, 2016 12:19PM

OK, the math on the offset grind is pretty basic. If you've got an extra .185 diameter that means you can move the throw up to half of that or about .090 inches from center. Since that is on the radius it increased the diameter of the throw by .180", rounding off and allowing a smidge for clean-up. If the crank grinder is good I'd think he could manage that. So your 3.23" stroke becomes 3.410, giving you another ten thou to spare. That is doable but like Carl says, why not just go with the 300 crank and skip the machine work? Taking off 3/16" from one side of the throws is not an easy or fun job and your grinder will not thank you for laying that in his lap.

Jim


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 25, 2016 05:27PM

Hi Carl,
I wasn't planning on using full floating wrist pin rods. The pistons I'm thinking of using are press fit so I would only be honing out the rod small end to press fit a larger dia. wrist pin. I have no idea how much enlarging the rod small end will run but a set of Eagle SBC rods run around $250 and I doubt the machining would run an additional $400 to $600 that a set of custom rods would cost.


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 25, 2016 05:35PM

Jim
I have a 300 crank right now but I wanted to avoid the adapters, kludged seals, flywheel adapters,and moving the bell housing/trans back to accommodate the longer crankshaft. There's extra work, machining, and $s in that as well...maybe not as much but the offset ground crank ends up being a much cleaner simpler set up. Right?



Edited 1 time(s). Last edit at 09/25/2016 08:17PM by phongshader.



mgb260
Jim Nichols
Sequim,WA
(1891 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: mgb260
Date: September 25, 2016 09:04PM

Justin, Years ago I used 2.3 Ford 1.74 IN and 1.5 EX valves with new seats on 300 heads. Chris Gill's 300 stroker (350 crank) uses GM 2.8/3.4 V6 1.72 IN and 1.42 EX with stock seats. Remember to use steel inserts or studs for the rocker arm shaft mount holes. Also on the Buick 300 heads which are approximately 55cc, when you remove the fixturing lug in the chamber would be about 58cc. Probably then around 10.5 compression with zero deck.



Edited 1 time(s). Last edit at 09/25/2016 09:13PM by mgb260.


MGBV8
Carl Floyd
Kingsport, TN
(3418 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: MGBV8
Date: September 25, 2016 09:10PM

I haven't played with your numbers, but did you look at using a 6.2" Chevy rod?

I have been looking at different piston & rods for the 3.9 for so long I have lost track. Trying to find a reasonable piston. I stumbled upon & brought up the use of a Chevy 305 piston many years ago. Kevin Jackson & I exchanged a number emails or messages via an email list. He actually built his engine with the 305 piston & a 4.2 crank.

At some point it becomes easier & more cost effective to just spring for custom pistons.


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 25, 2016 09:38PM

Originally I was going to use the 305 pistons, they're 3.736" dia., but kept hearing warnings that boring the cylinders .040" over was risky business...that's why I'm looking at the Dodge pistons. These were the pistons I was looking at [www.summitracing.com] and they would be just about perfect for comp ratio, 3.4" stroke, 0 deck height, press fit or bushed wrist pin, fit Chevy rods they're just .010" over what is considered safe to overbore. Is that not true, is it safe to overbore .040"? To go to 6.2" rods Id' have to give up a bunch of displacement...where's the fun in that? :-)


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5552 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: BlownMGB-V8
Date: September 25, 2016 10:54PM

It sounds like a pretty good combination, but talk to your crank grinder first. Years ago when I approached the guy we always used about cutting down main journals he didn't want anything to do with it. You have to consider that the average crank grinding job removes .010" from the journals. A heavy job would be .030, and they true the wheel for each crank. It's a lot of machine time and wheel wear with not much payoff. Since that time I've gone to an iron block but I understand not wanting to give up the weight. Just like I understand Carl not wanting to give up on a high redline. What you want defines the compromises you have to make. In the end Carl may be best served by ponying up the bucks for custom forged pistons where you should be fine with cast for instance. Wouldn't surprise me a bit. Personally I'd not muck around with a Rover based stroker at all, for that much time and effort I'd go straight to a 350 ci/5.7L 300 based stroker with the iron block, 340/350 crank and whatever heads I could afford. Believe it or not the iron heads are a pretty good bet as they flow considerably better than the aluminum heads. They add 50 lbs but then you end up with a 5.7L motor that weighs 100 lbs more than the 1.8L motor it replaced and the car easily tolerates that. The fly in that ointment is finding a decent aluminum intake to take advantage of the larger ports, so even then aluminum heads are tempting. I have 300 heads on my 340 but I use a blower so the smaller ports aren't much of an issue. I think Chris has 300 heads on his 350 ci 300 stroker and he's pretty happy with it.

What you're considering building has merit, but you need to get some pricing before you make a decision either way. You may still find the 300 crank to be less costly.

Jim


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 26, 2016 12:21AM

So what is the scoop on a .040" over bore on a 4.0 block? Go, no go? Anyone with experience boring to .040" over with success or failure?


MGBV8
Carl Floyd
Kingsport, TN
(3418 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: MGBV8
Date: September 26, 2016 10:02AM

I have read that 0.040 is the max. Ian Richardson at Wildcat is quoted at saying that the max overbore for a standard 94mm liner is 1mm.

The issue is not the liner so much as the thickness of the aluminum (or lack of) behind the liner. It gets worse with core shift. The block should be sonic tested.

So, yes, it is doable. A number of folks over in the UK are running 305 pistons. One with a blower. Great Rover V8 resource.

[www.v8forum.co.uk]


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 26, 2016 10:17AM

Forgive my ignorance, what is core shift?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5552 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: BlownMGB-V8
Date: September 26, 2016 11:27AM

Core shift is where the sand cores used in casting the engine block and forming the water cavities are not perfectly centered on the cylinder bores. This causes a lack of uniformity in the cylinder wall thickness. Usually the shift is either forward or back but it can also be towards or away from the thrust side of the piston. It's a judgement call as to how much core shift is allowable and in what direction, every block has some and it isn't always a bad thing, like for instance if it thickens the thrust side a little at the expense of the coast side. It can also show up in the lifter bores.

Sonic testing is the accepted means of inspection since there are no reliable visual indicators. Engine builders' recommendations are the best guidelines. In the case of the Rover, the factory marked the blocks to show essentially, Best, Usable, and Garbage. Carl would know what to look for there, something about a pink dot comes to mind. Core shift had a large influence on block cracks behind the liners. (just one reason I prefer cast iron, but those should also be tested, as Buick was using thin-wall casting techniques and core shift is very much an issue.)

Jim



roverman
Art Gertz
Winchester, CA.
(2895 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: roverman
Date: September 26, 2016 11:58AM

Justin, plan to use a 4.0 block ? The "pink" paint coded, 4.6L blocks are regarded as most reliable for wall thickness. If any of your liners are even slightly, below deck,(liner drop), then pass and get a proper block. Sonic test is the most reliable method, for plotting wall thickness. Stage I, Buick V6 valves will fit by changing to bigger/better seats. 1.77: int. and 1.5" exhaust. Rover crank driven oil pump, is a plus. Good Luck, roverman.


MGBV8
Carl Floyd
Kingsport, TN
(3418 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: MGBV8
Date: September 26, 2016 02:39PM

Pink? Well, I guess that is a shade of red. :)

Des Hammill said the colors were blue, yellow, & red with red being the thickest block. Rover assembled 4.6s were all red (except when they ran out of red they used yellow). Problem is Rover also farmed out new engine assembly to other specialists & they used all three.

I have read over the years that the 4.0 (mostly built with blue blocks) was the worst offender when it came to slipped liners & cracks in the block behind the liners. Hopefully you have a good one, Justin.


phongshader
Justin Brown
Ca
(49 posts)

Registered:
02/19/2010 04:03PM

Main British Car:
Locost Lotus 7 2.3 Duratec

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: phongshader
Date: September 26, 2016 03:45PM

I don't know what color the block is... It's covered in grime right now.
Art the main reason I want to go with the valves from V8 tuner.com is because they are drop in valves, that is no special retainers, non stock spring lengths and so on. Using the v6 valves you mentioned what additional mods are required, other than new valve seats, to make a functioning valvetrain?


MGBV8
Carl Floyd
Kingsport, TN
(3418 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: MGBV8
Date: September 26, 2016 06:08PM

It's just a dab of paint in the lifter valley.


mgb260
Jim Nichols
Sequim,WA
(1891 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Beating a dead horse? Bore x Stroke x 300 heads
Posted by: mgb260
Date: September 26, 2016 09:54PM

Justin, the V6 valves that were used in the 300 stroker used the stock seats and Chevy Z28 valve springs and retainers. Bronze guide liners and cut for Viton seals.
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