Engine build......

[Doc Watson]

Two photos that make my day.....

This is the block I'm using for my Mirage chassis based GT40.

Eternal gratitude to Frank Catt for getting this for me along with other goodies....

Now first question (of many) I have Tom Monroes book on rebuilding ford small blocks, and have heard that this can be used as evidence for the casting code, but there is no D1ZM listed in the book.... obviously its a 1971 but will I need to get a letter from Ford confirming the date for IVA?

Frank also supplied a crank but I havent inspected it yet so dont know what I have. As its a Mk I I'm building I want to have a 289 but with soild roller lifters and of course the 48 IDA's on top so... question 2... is it possible to have an internally balanced 289 crank as I want this engine to rev up to 7000 redline or will I need to go to 302 internal balance.

Andy

 

[Brett James-McCall]

Same casting as me Doc, welcome to the club

Brett

 

[Jac Mac]

Doc, If you have a really light set of pistons & rods getting your existing 289 crank internally balanced with the aid of some mallory metal in the counterweights shouldnt be a big deal. Having said that, if 7000 is your limit then with light pistons/rods balanced @ factory 28oz factor is quite safe too. After all every Hi Po 289 & Boss 302 + 351 SCJ/CJ ever built @ the factory was capable of more than this & were given 12/12 warranty @ the time. Only real problem is your crank & its age if its a std 289, its now over 40 years old & can probably tell a few stories.
Of course if you go aftermarket then you could get a forged item as well from the likes of Crower etc.

 

[Rick]

For the record guys these blocks were used excusively in the millions of Ford Pickups
sold all through the 1970's. They got the heavier Maincaps and were almost a clone of the original HP 289 block except for two raised bumps on the fronts of the block near the water pump inlets. I use one in my Cobra clone.

 

[Mike Pass]

I would talk to someone who regularly builds 289ci GT40 race engines.
Kenny Coleman at EDA in Castleford (Engine Data Analysis "Specialist Engine Building & Tuning" 01977516622) will know what can be achieved. He has a special milling jig for small block Fords to ensure that all is straight and square. He knows how to do a top internal balancing job. The last time I was over there he had two original GT40 motors in for rebuilds. He gets about 420hp on the dyno from them and you can watch it run the numbers. He will be able to select and balance the right crank, rod and piston combination for the power level with good high rpm reliability.
Cheers
Mike

 

[Doc Watson]

Thanks for the heads up Mike, talked to Kenny and he knows his stuff.... we briefly discussed 289 internal and a bare crank would cost £1200!!!!! so prudence dictates that I will go for a 302 engine with internal balance to save a few £££'s.

He also strongly urged me to get the block line honed and decked so that will be the first course of action along with brass freeze plugs and cam bearings installed.

Then I will get a balanced rotating assembly and install that.

 

[Doc Watson]

Just checked the cylinders for taper and all bores have a maximum 4 thou taper, the bores are 4.0047" at the top and 4.00079" at the bottom no extra wear from the end bores (which can run cooler and wear more).

So do I need it machined????

 

[Jac Mac]

Doc, some piston manufacturers make pistons to suit 4.005" bores for rectifying warranty issues etc, these would be ideal for your application, depending of course on which plan of action you take regarding stroke etc.

 

[Doc Watson]

Just to clarify I dont have any internals yet just the bare block, 5 thou over bore would sieze at the bottom of the bore wouldnt it??? I think for piece of mind it needs a pro machine job...... maybe 10 thou overbore.

 

[Jac Mac]

I must never assume anything..I must never assume anything...I must never assume any.........!

Yes Doc, the bore would need to be machined ALL the way down to accept the 4.005" pistons. There is a degree of difficulty as the 0.0047" is not likely to be concentric & therefore it would likely need a minimum of 0.010" to clean.
BUT, there are an awful lot of 289/302 motors around the world giving continued good service with a lot more than that in terms of bore wear.
Common oversize pistons for 289/302 are 0.020"/0.030"/0.040" plus the odd set at 0.005" as mentioned. 0.010" is not a common size, I have never seen a set.