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Messages - AC Ventura

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Very easy to repair a radiator pin hole with RADWELD.

Success! A fine spring day in England and perfect conditions to properly test the new improved half tonneau. I like a half tonneau when driving solo. They reduce in car buffeting and make it much quicker to cover up the car when parked. Trouble is, the one supplied with the Mk IV flaps like a dimented bat, even at 25mph.
 So I had a trimmer, first split the tonneau into two halves, then sew in a full length sleeve underneath, next to the zip and into this inserted a 1/4” dia rod, which protrudes at each end of the passenger half tonneau. Between the mirror base and the front scuttle is a barely visible aluminium plate with a hole in that locates the front end of the rod. At the the other end, the rod drops into a recess and simply held down with a cord. No tethers required and it barely moves, even at 70 mph.
 A simple, inexpensive and worthwhile upgrade, with no storage issues.

 I concur that the ClubCobra US forum is an excellent knowledge source. I certainly have a lot of friends on there and they helped me extensively, engineering-wise, when I was converting my car. By the way Tom, most of my comments were tongue in cheek, so don’t take them too seriously! Most of us own and/or admire other great cars. Anyhow, I think you’ll find a SPF, ERA or Kirkham an excellent choice, if you are not in the market for a Mk IV. Regarding other choices, you can find/run a Corvette with little effort or commitment. But nothing makes other people’s day, like a Cobra.
 Incidentally, by the time the Mk IV arrived Autokraft was the manufacturing arm of AC Cars. The cars were registered as AC’s once they had acquired the brand from the Hurlock family. However, the model name Mk IV was it seems never officially registered, despite its appearance on the company’s literature. But is how the model has generically become known and distinguished.

Sorry guys must dash, I’m off to the Superformance Forum to ask what everybody thinks about the Autokraft Mk IV and then decide that actually I’d prefer a 390 GT Mustang, but definitely not one with leaf springs 😜 

That’s great, why don’t we turn this in a Corvette forum now? In case anybody is confused this is supposed to be the AC Owners Club forum.

Now it’s the aluminium big block car that Shelby and Ken Miles said they always wanted to build. I would have liked to have been able to show them how sweetly it handles with the ultra lightweight engine. I think they would have been as pleased as everything worked out particularly well in the end. I hope I’m not coming across as immodest, but I think it’s simply sensational in every department. It’s far from the disappointment everyone told me to expect. Some old men are not so wise.....😜

The engine bay after it was remoulded 76mm wider and the foot boxes shortened 150mm to expose the wing vents. Also the crossmember here is new after the Mk IV one was cut out. Luckily I discovered some genuine Shelby 427 chassis drawings. The Mk IV is comprised mostly the 427 chassis already, but a few mods were required. The big block in a RHD car is much more difficult than LHD, so meticulous planning and engineering are required. The scoop for the exhaust You can see here, I later decided to redo so O could enlarge the footwell. The exhaust now runs in front of the footwell not next to it, where it would get uncomfortably hot.
The original Autokraft engine bay finish was restored, regardless of the effort and complexity. Here I have made the replacement mirror finish bulkhead from scratch as the original one was no longer wide enough.

I designed and CNC’d my own super secure engine mounts. Todays repro original type engine mounts are poor quality. Some people have had the entire engine rip out and the bonnet with it...

Custom headers have huge 1 7/8” dia primaries to help run cool. Everything was optimised I hope. Tuned length not possible, but doesn’t matter...

The new dash..with full size 16” Mota Lita wheel. Brake reservoirs in new glovebox. Everything to allow air free passage through the engine bay. Finish is non original black crackle, but people think it’s original. I like it and a lot easier than trimming.
The entire dash can be removed, once you have disconnected all the multi connectors.

Here is the engine bay. It was a huge undertaking to remould the footwells and make everything look like it was done by, or better than the factory. In fact the gap between the footwells is 76mm wider, yet the footwells are spacious enough.
I produced a 45 page illustrated journal, on every step of how I modified this car, in case other owners want to consider the same route. I also produced a one off Workshop Manual, in case I forget myself! You can take the gearbox and clutch out without removing the engine, or you can remove the entire engine in one hour or so.
The gearbox is the T-5’s bigger brother the much stronger TKO 600. It’s much bigger, so the entire transmission tunnel was modified 40mm higher, but you’d never know. 5 speeds give a little more flexibility  compared to the original 4speed Toploader. The first four ratios are almost the same. The fifth you can have progressive (.0.82) or overdrive (0.62). Go for 0.82. You didn’t buy this car to save money on fuel....
Cooling system (original Mk IV radiator) holds a staggering 19 litres and fan is so powerful, it can suck your overalls off the bench!

1000 miles already! Yes Barry’s book was quite useful and sometimes easier to get the information from than the man himself ! However, it’s a little out of date now.

This is the car developed now with no changes envisaged. Exhaust is a bit loud and clutch heavy, but easily manageable. I fortunately got it all right first time, barring the motor fine tuning, which has taken nearly 12 months to understand. I’m pleased I went the more difficult route of staying with the 427 and not the more common 482.

Endured 300 miles of wind battering on the M1 motorway today, to visit John Sleath Race Cars in Doncaster, UK. He’s an old school knowledgeable engine guy. Has a good rolling road, but it doesn’t offer so called ‘corrected power’ readings, that is rear wheel data converted to flywheel or Dyno equivalents. He says it’s pointless because losses vary between min 20% and 35% and can’t be reliably ascertained. So all his graphs are at the rear wheels. Anyhow, after an afternoon of timing, distributor weight and jet adjustments we improved the low down running and unplugged the power. The new straight through (loud) glasspack exhaust has also made a big contribution. Final figures show car now produces, at the rear wheels, 412ft lbs and 380bhp, which clearly makes Michigan based engine builder and FE guru Barry Rabotnic’s originally dynoed 503 tq /532 hp beyond doubt and pretty good for an OE bore/non stroker, all aluminium 427. Car drove great and has taken me unawares by the seemingly bottomless acceleration into the 6000rpm area. With the old 302 it was all over by 4000. Anyhow, glad I made sure of a long accelerator travel. 😬 😁 😀 Also 17.3 mpg overall on the journey seems pretty amazing for a 7 litre and car ran faultlessly without any dramas. Taken me 3 years to complete the Autokraft Mk IV small to big block metamorphosis, so looking forward to exploring this fabulous combination 😀

PS The new 1/2” higher Blue Thunder air cleaner element gained us 20hp.

Here we are at a theoretical 156mph

Recent ACs / Re: Two new models
« on: July 27, 2020, 23:38:08 »
What exactly is the attraction of a electric Cobra? Who would choose it over a modern electric roadster? What’s the point?

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