Modern V8 Conversion

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Nov 8, 2008
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I have a 1975 fj 40 that i bought about 2 years ago and it is basically all original; except it came with a chevy V8 hooked up with the original 4 speed and original transfercase. But, the conversion is an old conversion and i was thinking of changing it with the 5.3 chevy V8 and the 4L60E transmission from a 2006 chevy silverado. Is this a good way to go and does anyone have information on this conversion?
 
Boy, are you going to like the additional mpg, better power off the line, and OVERDRIVE!!!!!
 
Thanks for the input guys.Does anyone know of a step by step procedure of this conversion?
 
Read the book avail from Downey & Advance Adapters.
 
im going to do the same conversion my self, sick of the old 350, to many problems.

I might go with a 4.8, a dime a dozen
 
Will this set up make the FJ 40 run much smoother and quieter than the set up i have right now or is the difference not too noticable?
 
Josemari and Lil'John, the Downey instruction manual is about as step-by-step as you'll find, and it's a freebie. PM address and I'll mail it to you.
Josemari, the reason a Chevota is so quiet is because:
(a) Your 6 cyl. sounds like it's ready to fling apart at 65 mph!!!
(b) When you install a V8, you keep the same tire size and gear ratio, consequently the V8 is turning exactly the same RPM as the 6 cyl. did at 65 mph, but the V8 is alittle above a purr at 65 mph. Heck, I'd do the V8 swap for that reason alone. Imagine for the first time in your life driving 65 mph and actually being able to have a conversation with your passenger, or actually hearing the radio.
 
I have a GMC sierra as a work truck with the 4.8 and its smooth and real quiet with the stock exhaust. My 40 has a 350 with a old flowmaster so its not so quiet.
 
Aside from the exhaust sound, what i really ment is the smoothness and quietness of the actual engine and transmission cuz my set up right now which is a old late 70s to early 80s 2 barrel carburated chevy V8 hooked up with the original FJ 40 4 speed trans and transfercase , although it starts right up and runs good is just noisy (specially the trans or transfercase-not sure which one) and at 55-60 mph is sceeming , so hopfully the 5.3 with the 4L60E will solve this issue.
 
Thank you Jim ( of Downey Off-Road) for offering your step by step manual for this conversion. I have seen your website and you have excellent quality products for the FJ 40, and your prices are great! Thanks again for your knowledge and expertise. You're an asset to Landcruisers enthusiasts every where.
 
Is it better to pair the 5.3 with a 4L60E (Automatic) or a NV4500 (Manual) tansmission. Thanks.
 
The early 1980's 700R4's did have an oiling problem that was solved by the late 1980's, but I understand the oiling upgrade is compatible with the older trannys, consequently none should be bad????? If you are choosing 4L60E tranny, keep in mind that you also need the engine and ECU that support that tranny. Also, if you have an engine that has a 4L60E tranny, a NV4500 tranny does not support that engine (knowing that 4L60E's send info back to the ECU, and the ECU makes decisions for the engine based upon info sent from the tranny).
 
I have a 1975 FJ40 and i am converting it to Vortec 5.3 with 460LE adn an Orion transfer case. I have someone doing all the install of the motor. He manufactures parts for Man-a-fre. his products are called 4plus.
so far I have ordered the transfer case to 460le adapters and the orion with twin sticks. the painless wiring kit for the job not cheap $800 for this motor.
Dave is going to lengthen my read axle back about 3 inches maybe 4 so I have some drive shaft. I am putting in a full floating rear end. I have not decided which one. I have an FJ60 I purchased adn rebuilt. it is 2.5 inches wider than the Fj40. it has drum barakes but the self adjusting ones with a built in parking brake. Now I am looking at an FJ80 which is 6 inches wider and has disk brakes and parking brake.
so I may be selling the FJ60 rear end.
I will be docementing all of the work done and posting it on my web site.
so far there is a lot of little things to do and cost just keeps climbing.
I am also putting in a 24 inch aluminum radiator. 4Plus makes a conversion kit that allows you to install this bigger radiator. I live in Phoenix and i need all the extra cooling I can get.
email me if you have questions. I purchased all the parts from Man-A-Fre so far and he gave me a packaged deal. I dealt with Al who owns the company.
 

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