Engine and Transmission Tech

Nic' and clan. Since your building an "out-there" motor anyway, AND using a custom roller cam..."maybe", you could go up on the cam bearing size allowing off-set boring on the tunnel ? U-no, up and away from rods? Kinda like what "Wildcat" does, only cheeper? Put a (3) bolt, sbc. drive on front of cam and sbc gear or belt drive. roverman.

Good idea, Art. Do you think there is enough metal for it? I think we went through this when discussing whether to make them all the same size, right?

Reviving an old thread. Reading this got me inspired again to go ahead with the stroker project that's been on the back burner for a while. So tell me if my math is correct...
Ford 4.6 3.7" flat top pistons 1.220" comp height
Eagle 6" Chevy rods
JE Rover 86.36mm (3.4") stroker crank
Merlin heads with 32cc combustion chamber
Rover 4.0 block with 8.96 deck height
So with this setup the piston is .040" shy of the deck, is that ok? I figured the compression ratio to be around 12.74:1 even with the gap, assuming that the volume of the combustion chamber is 32cc, volume of a .048" head gasket 8.5cc, and the volume of the .040" gap from the piston to the deck is 7cc and the volume of the cylinder is 599.16cc and yields a rod ratio of 1.76:1. I'd like to get the compression down closer to 11.5 -12.5:1

Most factory Buick engines used a dished piston, which gave about a 3/8" wide squish area around the outside. With the squish distance held at .040" (zero deck and .040" head gasket) the CR was determined by the volume of the dish. With double that dimension your squish will essentially be ineffective, but depending on your piston crown thickness you might be able to machine a dish into the top to get the CR you want. Going that route, you could then deck the block/heads to get the proper squish dimension. Of course, custom pistons are always an option, I understand Diamond has some of the better prices.

JB

Justin, "JE Rover crank with 3.4" stroke", sounds pricey.Stock 4.6L Rover crank can be "off-set" ground with 2.00" journal to provide same stroke,(cost about $250.00 labor ,by a top rated shop).As Jim says, .08" squish thickness will be ineffective. Decking the block, probably necessary anyway, and a thinner gasket should get it to a reasonable dimension. Have you looked at "Icon" forged 305" sbc pistons ? The Merlin head needs "chamber" work, to make it more effective, mine arrived at 37cc, for a 3.75" bore. Good Luck, roverman.

The JED crank is round about $650 before shipping but if I can offset grind a 4.6 crank I'll do that. How would one retain a 2" journal while offset grinding by what I would guess is around .08"? I know and have thought about using honda journal SBC rods that would give me about .11" to offset grind and a 1.88" journal size.
Thanks for the tip on the pistons, they look like a much better fit than the Ford pistons. Would I be able to use these in a stock bore 4.0 block? That is is there enough liner to bore to fit?
One more question, I have a set of 300 heads and have been quoted between $1.4k-2k to install oversized valves, seats, bowl porting, and a set of oversized valves as well as $2k for a set of Merlin heads delivered to my door I'm wondering what would be the smart route? A set of brand new heads or some worked 46 year old heads? I would assume that the combustion chamber design on the Merlin heads has been updated to a more modern design than the old 300 heads and would offer some advantages over just sheer flow #'s of the worked 300 heads.

I was surprised at the price you mentioned for the 86.36mm. crank, appears John has reduced his prices and of course you do not have to pay the VAT.

The 4.0 & 4.6 have 2.5" main bearings so i belive you can offst grind a finished crank to fit the earlier 2.3" main blocks or offset grind an unfished casting to maintain the 2.5" main bearing for the later blocks.

The cost for headwork to the 300 heads sounds a bit pricey even to me in the UK, if your using the normal upgrade size 1.63" in 1.4" ex. valves then the existing seats can be cut to size which only leaves the 3 angle valve job, opening out the seats and the area under the valves and then blending into the bowls, for road use I only cleaned up the port runners to maintain good fuel suspension as the ports are at least the equivalent of stage 3 Rover heads.

The standard deck height in the rover is 40 thou. so with thick 47 thou.composite gaskets you get very little squish especially with the standard rover dished pistons.

Re Merlin Heads, Real Steel sell direct and retail for £1315 inc. vat so net £1119.15 x $ @1.58 =$1768 + shipping etc.

Heres their catalogue and price list. [www.realsteel.co.uk] includes some pics of merlin heads.

Kevin.



Edited 1 time(s). Last edit at 01/09/2011 01:49PM by castlesid.

What valve and spring combo are you using for 1.63" in 1.4" ex?

Justin,

If you mean which springs, that will depend on the cam, I'm using a Crower 50232 which recommends a double spring set up, but as I set a rev limit of 5800RPM I felt comfortable using a single spring, one coil less than standard with just slightly less seat pressure and I used the buick 300 valve retainers caps which are stronger than the later Rover ones.

The springs are the DW060 in the Real Steel catalogue. they do duals DW520 I suspect that both these are US sourced anyway.

Kevin.

What brand valves as well

Justin, Stage I V6 Buick, are largest valves to fit the standard 1.660" centerlines.Seats MUST be changed. Shop I use gets $10. ea., labor and approx. $5 ea./seat. Ferrea and Manley have the valves. I suggest Comp Cams cat. for best "Behive" springs for your application. If the heads have a corrosion problem, bowl porting will help make"sprinklers".Good Luck, roverman.

May I make a suggestion? There is much to be gained and very little lost by the use of a 300 cast iron block, especially if you fit it with a 350/340 crank. At that point you have a 5.6L engine or with a .050" rebore a 5.7L and you also gain the considerable advantage of a great deal more strength in the threaded bosses which is a stupendous advantage in high output engines, aside from which the entire block is much more rigid. What does it cost you? Maybe 80 lbs. It could be less my memory isn't the best, could be 60. At any rate, for practically any application that much extra weight on the front end of the car is not going to be noticed at all but the extra displacement certainly will, and the extra rigidity means it will hold up better and longer before the next tear down becomes necessary. Plenty of head/intake combinations are available and if you are considering a $600 crank I would recommend the stock 350/340 crank instead and put that money into forged pistons which can be had for around $700. With Merlin heads and Willpower intake it would make an absolutely killer engine for the MGB, and the new TA heads would be even better if you can afford the time and money to get them.

JB

Justin,

As Art said you have good sources of valves in the US although using the valves I mentioned means you can retain the existing seats.

Don't know the brand of the valves but they are what everyone in the UK uses for stage 3 heads but not for circuit racing if you want much more than 6500 RPM.

Kevin.

Jim, I already have a 4.0 block and it appears that I can get several varieties of forged pistons for less than $700, although not with out some issues. I was considering a $600 crank but it appears I can use a stock 4.6 crank to meet my needs. If I really was going to be sane about the whole thing I could probably just pick up an LS1 off of craigslist for a little more than the price of some Merlin heads and have a bunch more, less stressed horsepower and a lot more time to drive it but I like the projects and, as foolish as it sounds, I'm committed to an aluminum block...

Justin and clan, One the of the great things about this forum,"diversity". Very little negativity for going non popular routes. One thing we all agree upon, our LBC's are worth it. Good Luck, roverman.

Art , can you forward me info on shop you use for valve and head work?
Thanks

I see that the stock intake valve head diameter of the 300 is already at 1.630", do you think that I could go to a 1.710" without replacing the valve seat?

Justin,

The 300 inlet is 1.625" you would need to measure the size of the insert to see if there is enough meat to cut them to the larger size.

The exhaust valve is 1.312"

Also unless you are going to full race spec on the heads then there is no need to go to the larger size and it will probably cost you power.

It is a fallacy that fitting the largest valves possible will give more power.

Check the lengths of the larger valves, they may be longer but this can help with the rocker geometry.

Kevin

Kevin
What do you have to support your statement that fitting the largest vaves give more power is a fallacy? Just curious. I'm getting ready to drop some major cash having 1.775/1.5" intake/exhaust valves and porting on a set of 300 heads. per Dan Jones school of thought. I realise you don't make low end power but horse power is horse power isn't it. Talk me out of it please! Heh Dan.

dave bash

I'd like to be able to add some larger valves with out having to replace the seats. The 1.4" exhaust valve sounds like a good solution but the 1.63" is basically the stock size for the 300 head. It would be great is a 1.71" valve would fit without replacing the seat, although then there's the length...so many variables... :-/
Dave what valve & spring combo are you using and, if you don't mind, how many buckets of cash do you think this is going to set you back. I'm just curious if the estimates I've gotten to do the same work are realistic, high, or low.
Thanks