Building a Gr4 replica

You can't run in Europe vintage racing series with that engine ... It's not FIA legal

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You can't run in Europe vintage racing series with that engine ... It's not FIA legal

Maybe if I paint it blue they won't notice !!

Yes, I know it's not legal - my intention is to use it for the Danish Hillclimp series in the open class and maybe some invitational events where they have very relaxed ruling.

I'll need yet another engine if I'll do the historic races .

Do you mean a German car ?

OK, I'm trying to get back into this project and find the time and motivation to carry on. So, here's a few updates I did sometime ago:

The factory gr4 cars had aluminum skins on the headlightbuckets, so I thought I would wan't that too :-). From an old rusty set of buckets, I made this set of lightweight headlight buckets with aluminum skin and all excess metal cut off.

Here with the skin on and metal trimmed. They are out for paint now.

I also managed to fit and trim the aluminum front hood to the car, now out for paint too.

Brake masters and pedal box was mounted

Again, as the factory cars ran quicker ratio steering (2.4) I wanted to add that to the car.
Thus, we did the "goodroc" quickrack steering rack conversion using a new Ford Escort MK1/Mk2 Heavy Duty short stem 2.4 ratio rack from Burton Power in the UK.

As described in Goodroc's thread, this conversion requires a little machining of the housing. Will be interesting to experiment with the position of the rack to evaluate the effect on bumpsteer.

Hi Kristian,
always good to see your updates, it is a fantastic project!!!
Cheers, Tim.

Looking great, Kristian! Get motivated. Look how far you've come. When are you expecting to have her on a track?

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Get motivated

Ok then

Well, I suppose I was motivated enough to invest quite substantially in a set of high-end Intrax race coilovers specifically set-up for my car and it's expected use !

Expected track debut - who knows, 2025 ?

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high-end Intrax race coilovers

Those are sexy! And you will be able to show them off looking very great for quite a while before you get road-grime on them!



PS> I really enjoy this thread. You are doing great work.

Rocky

looks like you got plenty of ZF´s..Push

A little update on the brakes. Started playing around with some parts to make the Lockheed 8-pot calipers fit inside the 15" wheels.

Here are the 12-bolt AP 304 mm disc with hub, aluminum hat, screw-in studs and a small spacer.

Enough room for the caliper inside the wheels it seems

Looking through the wheel from the outside

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Enough room for the caliper inside the wheels it seems

Wow! That's impressive that you can fit 8-piston calipers inside the 15" wheel. Well done!

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Originally posted by Push1267:
Well, I suppose I was motivated enough to invest quite substantially in a set of high-end Intrax race coilovers specifically set-up for my car and it's expected use !

Great choice! The one thing I did different, was to have them set up in colors to my taste, as flashy colors do not fit a 71 car imo ;-)

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impressive that you can fit 8-piston calipers inside the 15" wheel.

The calipers were originally designed as F1 calipers in the early seventies, so they are designed to fit inside 13" wheels (I think that is what is used in F1?). Detomaso at some point in 1974-75 decided that they would homologate them for the Pantera.

Kid, you're right about the color of the coilovers, I should have thought about that !! :-). Red goes with the exterior of the car !!. What version of the intrax shocks are you using?

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Originally posted by Push1267:
Kid, you're right about the color of the coilovers, I should have thought about that !! :-). Red goes with the exterior of the car !!. What version of the intrax shocks are you using?

1K2 with titan coating. Back then I just asked whether a black/grey finish was possible, which was, and as far as I can remember, at no extra cost (my invoice doesn't mention it as an extra neither). :-)

Love it all! What an amazing job on everything. Looks fantastic!

Push,

I just came across your thread. amazing build !
I have just sent you a pm as for the 8 pistons calipers.

Thanks

I've decided to take the nascar motor apart to inspect it, just to make sure everything is ok with it and to look into detuning it a little. So here's a little engine-porn

Engine is a Nationwide/Craftsman Truck series roller motor

Heads are RoushYates CNC Ported D3s with jesel shaft mount rockers (ratio 2.1:1).

Intake is the last evolution of the Ford racing highport manifolds - also RoushYates ported

The block is a Ford racing R451 dry sump block and is highly modified by RoushYates. Note that the block appears to have been polished/machined on all inner surfaces.

The lifter bores have offset bronzebushings and a cam tunnel is installed around the cam.

Not shown is the oil scavenge system that pull oil from the lifter valley via the dry sump pump

I did a camera inspection of the cylinders showing bores to have been newly honed. There are very minor scuff marks in the bores on the piston skirt side of the bores. But, surely, it looks very fresh.

At the front of the engine is a Yates ATI superdamper

The oilpan is a stainless steel pan fabricated (by Moroso for Roush I think) with 4 scavenge ports and an oil intake port for the 8 piston squirters.

WOW!

WOW too !

Everything looks great! Love the paint on the car. Looking forward to seeing pictures of it running and event!

I talked to RoushYates (actually through SRI Performance which distributes Roush Yates parts) and they send me a 40 page file of the history of the engine. Last rebuild in 2010 before it was sold of. Hasn't been run since.

They included the dynorun after last fresh-up

Thinking about limiting the revs to 7000 ...

Not entirely convinced that this is of my engine, as the roller motors usually does not rev beyond 9000 but parts in the engine does match the buildsheets

WOW #3 Not sure you will have enough HP or RPM for Denmark's roads.

Looks like fun to me!

What is Rousch recommended refresh/rebuild interval on the engine? I bet in NASCAR they tear them down after every weekend!

A lower rev limit would be wise to get longevity, but where is the cam happy for vintage racing?

If I drop my race engine shifts by 1000 rpm to 9500 I get maybe another 250 miles between rebuilds....

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What is Rousch recommended refresh/rebuild interval on the engine? I bet in NASCAR they tear them down after every weekend!

A lower rev limit would be wise to get longevity, but where is the cam happy for vintage racing?

If I drop my race engine shifts by 1000 rpm to 9500 I get maybe another 250 miles between rebuilds....

Yes, Roush takes them apart every race and freshen them up - typically 400-500 miles. The files for this motor shows very detailed monitoring of each component with miles and last replacement. It's not clear how many miles they put on all parts, but some are replaced every race.

With the kind of racing I intend to do, I would expect a much longer service life. I may restrict it to 7500-8000 rpm, so it will not run anywhere near it's potential.

That was my initial thought about purchasing this engine, an engine with high quality parts that I can run below it's full potential with good durability. The 351C is just more fragile, and I'll only consider that if I wan't to run the FIA sanctioned races.

Regarding the cam, I ordered a cam degree kit, to help determine duration and lift. The files show a 325C cam (duration maybe), with lift around .825 in/ex.

I am considering increasing head gasket thickness (Cometic gaskets come in many thickness and are reusable), and reducing lift/duration by changing rockers arms. This engine run a 2.1:1 rocker arm ratio, and by changing that to maybe 1.9:1, lift is reduced by around 10% and duration profile is lowered too (by how much I'm not sure). Rocker arms are available used/new from Yates, at reasonable prices.

I cannot lower rpm too much as the D3 heads are ported for high rpm, - they flow around 420 cfm on the intakes.
There's an interesting article about them at D3 heads

/Kristian

Fantastic engine. Best of luck with it.

Wow, wow, wow....it's been a while since I looked at your project and not sure where to start...but suffice to say your dedication to this project is incredible. There are so many nice parts and great craftsmanship going into your build....not sure which gets more drool....the chassis work, the motor, the hubs/brake hats/disc rotors, the brake calipers, the shocks, the motor, the valve train components, the motor crank & rods. Holy smoke, just fantastic! Your build is what so many of us just dream about at night!