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Old 04-14-2011, 08:35 AM
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Originally Posted by Dyna

Thanks for your answer. A Jag IRS from a V12 XJS 1981 and later all come with 2:88 rear end with LSD. Since I actually have a 89 XJS V12 as my daily driver I know this one revs about 3000 rpm at 70mph with 215/60-15 tires, if memory serves me right (not with the car at present). The tires I will use for the Burb will be 235/70-15 so you�re right I might not need an overdrive. I have a 700-R4 but also a 3speed with OD. Afraid that the 3-OD box might explode although. Preferably I would like to still have a manual box on the tree so to say, suggestions welcomed.

I don�t really aim for a specific TQ/HQ numbers but rather the result. The more the better but I don�t want a high reving unstreetable machine. At 5500 rpm this brick should be able to do 150mph in 1:1 gear with be 235/70-15 wheels. I�m pretty sure I need a ton of power for that. I think 475+ HP is the bare minimum when you consider weight and most importantly front area of the Burb.

So what is that nice roller cam , in your view? How much more would it produce compared to the Impersonator II - beside I would not lower the comp since I will drive on 91 (US) octane, and even possibly 95 (US octane). The AFR head especially the CNC once are a tad expensive too, and 421 might need bigger runners.. Hmm food for thoughts..

Why would you shy away from their rollers/rockers have you heard about a lot of failures? The issue with their heads form what I hear is casting quality which is very hard to see, while machined stuff is easier to check for faults and coming failures (the rockers looks like they are machined out of billets).

A Edelbrock performer RPM (7101 and 7104) actually has provision for the oil tube you only need to machine it in there since it�s not there strait out of the box. Hence don�t think there is a need to go for the 70-72 LT1 intake unless I got something wrong..

Sincerely Dyna
You're going to need a strong Trans for that amount of power. A manual 3-speed isn't going to cut it. I'd use a 3-speed TH400 with the 2.88 gear or a well built TH700R4 with a 3.73-4.10 rear gear.
Use this Calculator & you'll see which gears you'll need for the 70mph & 150mph and at what rpm they'll be reached>>
For 70mph @2000rpm you need about a 2.40 final gear ratio but, at 150mph you would only be turning 4300rpm. I figured this with a TH700R4, 3.42 gear and 235/70/15 tire.

Comp has a free Dyno download to play around with different Cams>>
All SBC Cam operating ranges are stated using 350ci engines so the Cam's operating/rpm range will be lower with a 406ci engine.
It's very difficult to Spec a Cam, I'd go to several Cam sites and fill out their spec sheet for best results. Lunati, Comp, Isky etc..
There're over 100 Dynoed engine combos here>>

I would not go cheap on the Valve train. Pro Comp, Proform etc.. Rockers & Lifters look cheaply made. I haven't searched to see if PC has had problems but, have read many problems with ProForm Rockers. I'd use Scorpion Rockers and Lunati, Morel or Isky Lifters.

You're correct, I hadn't noticed the machinable Boss on the Eddy RPM Intake.
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