'98, Possible to swap engine to 400 Small Block (650HP) easily?
 

Hey guys,

I must have spent a couple hours on the web searching for more information on this topic...

Long story short, I threw a rod on my 400,000KM Original engine and my Jimmy is no good to drive right now. a friend of mine has a rebuilt 400 Small Block that he is willing to send my way, which he had done up for a rockclimber that he has now decided he wants a Diesel engine for, The 400SB engine has 200 hours on it and they clocked it at 650HP, runs premium gas only, has all the bells and whistles and quality components... He is asking me for 1000$.

I have read that I will need to change the suspension to quarter ton, Which is no problem. My biggest question mark is this: I have heard there are adapters to keep the 4x4 and Transmission that is stock, The tranny I have has been recently rebuilt with latest OEM Specifications and components so thats all good... So do these adapters exist? Will my existing components work?

How does the computer hook up to this engine? Is it possible to use my existing parts, if so, does anyone have any suggestions as far as Kits or Adapters goes and what they approx. would cost?

Is this even worth it?

I really need some help as I am on vacation for the next few days and need to decide on this or I could spend 850 on a Vortec V6 with 120,000 original KM's on it as well.. But I have heard that its not too bad of a job to mount the 400 on. I just need to know what I need in advance, and what won't work.

You're trans (4L60E) will bolt right up to a small block, no adapters needed.

Are you planning on running a carb or fuel injection?
Fuel injected motor would be a little harder, I would contact Wait 4 Me tunning or PCM for less about this question.

Carb would be a little easier swap, but you lose some reliablity / gas milage.

It's not an easy swap, you would need motor mounts, headers, cooling system upgrades and other small things to make it work, but it would be a badass swap if you pulled it off.

On the other hand, pulling the V6 and just swaping it with the same is much easier / back on the road faster deal.

Swapping a V8 into these things aint easy, so don't plan on doing it in a weekend, some have been working on swaps for months / years..

Dear Dysfunctional,

I appreciate your thorough/quoted response, a rarity these days. Sincerely appreciated.

I am pretty sure the 650HP engine would be fuel injected, I am waiting for a response, But if it is carb, as you said its much easier.... In the event its not, I will ask Wait 4 Me tunning or PCM for less, As you suggested.

In regards to the cooling system, when my Rad failed years ago I upgraded to an all-aluminum, slightly larger radiator aftermarket, Not the cheap plastic crap that comes with OEM, would this be good enough?

Motor mounts, headers, any recommendation for a cheap part source for Canada? Is there a header/mount kit available for this V6-V8 small block swap SUV, or any other reccomendations?

I was considering purchasing a guide I found somewhere online that included a ton of information written on the process of dropping a 400 small block into a Jimmy, it mentioned the jimmy would need stiffer suspension, you said "It needs other small things", could you or would you care to please elaborate on what those might be to save me from surprises?

Beyond all that, There is an 80,900KM engine OEM available for the same price... But my step dad just bought me a 1988 Jaguar xj6 and I now have the time before winter arrives to either pull off this badass swap or have a friend do it for me over the next 4 months for a good price.... so in that event, I'd like to collect enough information so that we have everything we need at the starting point :)

Cheers, and I hope this response helps other obscure searchers like me...

Here's a how to I wrote when I carb swapped my fullsize, same applies to Blazers.

I've seen alot of these threads pop up asking about how to swap a carb and still keep the 4L60E functional.

Here goes.

Here is a how to on how to keep the 4L60E working.
Well, I finished swapping a Carb 350 into my truck, i am using the stock TBI PCM to control the 4L60E. and here is how!
DO NOT ATTEMPT THIS IF YOU HAVE EMISSIONS!
Transmission Control Via TBI PCM:
First off, Here is what the PCM needs to operate the 4L60E
-VSS
-CTS
-TPS
-A RPM Signal

I am running a Stock GM HEI distributor, and it is what i would recommend for a similar swap, I WOULD NOT keep the TBI Distributor, you have no clue as to what the PCM is gonna do without seeing fuel.
Now with a TBI engine, there is no crank sensor telling the PCM if its running.
It took me about a week to figure out what to do, but when i did its easy as 123.
1.Find the plug that used to plug into the Distributor and lead to the PCM.
2.Find the Purple/White wire
3. Take Wire and run it into the TACH position on your HEI Distributor.
4. Done!

Here's the TPS kit I used.
http://www.summitracing.com/parts/HLY-534-202/


So now that your 4L60E is working, lets carry onto Fuel.
Fuel:
Here is what i used.
-Stock TBI In-tank Pump
-Holley 12-803BP ByPass Regulator (http://www.summitracing.com/parts/HLY-12-803BP/)
-Marshall 0-15PSI Gauge, (Not shown)
It is VERY Important that if you are keeping the stock pump, you HAVE to have a return, i dont care what anyone else says, just capping off the return is gonna kill the pump, THE RETURN IS THERE TO COOL THE PUMP!.
Picture of my setup.

I used the stock TBI Fuel Lines, i just bent them a bit and cut off the fittings and installed some new ones.
I then ran a hose barb out the left side to the carb
at first it ran great, but i still wanted to check my PSI, so i added a gauge. using some fittings we had laying around, i dont have any pictures of it, sorry.
I found that my demon likes 6.5-7PSI. and the Holley Regulator is factory set at 5PSI.
After this, the engine ran very well, i would recommend this swap to anyone wanting a bit more out of their engine.

Now Fuel Injected.
A Vortec intake wold make things a lot simpler, but there are hurdles that have to be overcome.
First, somewhere around 1988 GM changed the intake bolt pattern, all have 16 bolts but up until 88 all where slanted like / \.
after 88 the four middle bolts are straight so a Vortec intake will not just bolt up.
You could use Vortec heads and the intake would be great but, the 400 SBC use steam holes and the Vortec heads would have to be machined for them.
Then you would have to re pin you're PCM for a V8 or send it of and have it done and tuned for you're setup.

Yes sir, you're good there.

Jags That Run is a great site.
Stealth Conversions S10 V8 & V6 Parts

Also, try Summit or Jegs


I think you're biggest hurdle is the oil pan, most have to be cut / fabricated to fit the cross member. I've seen somewhere, maybe Summit that has a S10 V8 swap oil pan though, but I think it's pricey, and some just use an H3 pan.

Then you'll most likely have to shorten the drive shaft
A V8 isn't that much heavier than you're 4.3, I wouldn't worry about stiffer springs. It might drop the front end 1".

You've got another ride while the swap is down, so I say go for the V8.:icon_wink:

Sorry for the novel, just trying to include as much detail as posible.