View Full Version : 4g64 carb swap.
Has anyone ever used the g63b intake on a 4g64 engine and used it as a daily driver? I know that the heads interchange but i was wondering if i would run into any issues doing this swap.
I just bought an 86 with a super clean body but the previous owner pulled the motor apart to rebuild it some time ago and never go around to it. Now years later the engine has been sitting in the truck with the head off and pistons out leaving the bores and crank rusty as hell. I have a 4g64 sitting in a storage unit that i could swap into the truck but i dont want to mess with sourcing the fi stuff for it. I already have a weber waiting to be put on something i would just need the mounting brackets.
The previous owner rebuilt this engine once before and already had it machined now on its second time around he went ahead and bought another rebuild kit but its sat open for so long i feel that by the time they take enough off of the bores to get rid of the rust it would be too much to use the rebuild kit he already bought leaving me in the boat of buying another rebuild kit.
Thanks in advance
Thomas
Also the 4g64 i have is a 6 bolt out of a mighty max.
geezer101
01-15-2020, 08:21 PM
You can use the intake off a G63B as long as it's a SOHC 8V engine. The Weber will be close to what the 2.4 will need to run (if it's jetted for a 2.0, it might be a touch lean). You will need to figure out what to do about the distributor. It might run with the ICM from the 2.4 with some dialling in (probably won't have adequate advance and will run like crap...) or you will need a distributor out of the G63B which is a straight swap. You can try pouring a little auto transmission oil down the bores through the spark plug ports and letting it sit, then crank the engine by hand a few turns to free it up. An inspection camera would be a good idea before you start panicking about tearing it down and rebuilding it.
The original engine is open with no pistons or rods in it. The weber i have i believe is the 38 outlaw with the gears instead of linkages. I will have all the parts for both engines. Just need to do the swaping. Thanks for the distributor note i never thought about it.
I figured i could jet down the 38 if needed. I bought the 38 second hand the guy had it running on a mazda b2200 and it ran fine.
geezer101
01-15-2020, 11:41 PM
The 38DGES will be synchronous. If it was jetted for a 2.2 it shouldn't be too far off the mark as far as jetting is concerned. The Weber will change the torque curve on the 2.4 so it will feel completely different to the EFI. Do everything you can to derestrict the intake manifold, even port match it to the head and clean up the ports. It will idle better and have better throttle response.
Salteen
01-16-2020, 07:58 AM
just remember that carb is 400 cfm, i have it on my 2.6 and i can get 22 in it i believe (4wd truck 4800 lbs turning 2350 down the road) it was out a 82 so its a 8V head. i would do what geezer said, but later on i would get a bigger head and a better intake to go with.
What do you mean it will feel different than the efi? Just not as snappy throttle reaponse? Would it feel different than say a g63b with a weber?
So far im seeing to port the head and intake gasket match the two swap distributors to the g63b and run an electric fuel pump. I plan on possibly getting a Schneider regrind cam and a header as well. Is there anything else i could do to get more performance out of the truck without going efi?
geezer101
01-16-2020, 02:45 PM
The throttle response will be similar but you'll have a noticeable torque band from low/mid range rpm. EFI has a linear power curve while carbs are sort of, more brutal. The 4G64 with a Weber will feel better than the G63B on acceleration and gear changes as you're already 20% up on CC's. If you can get headers for it and add 2.25/2.5" exhaust that will compliment the 38DGES nicely as a package.
What I'd do from there - use an exhaust bandage on the headers so you can be more aggressive with ignition timing. Get rid of the clutch fan and add an electric thermofan - this will improve throttle response (and is way more efficient at maintaining engine temps) Don't run an open air filter on the Weber - let it breathe a cool air charge from outside of the engine bay (this will take some messing with modified air cleaner boxes and ducting etc but this will make torque and help fuel economy which is a good thing)
DMAN9601
09-21-2023, 03:21 AM
OK so I have a 1995 mm and I've been wanting to build the engine with parts I found from rpw in Australia, they have brand new cams, header and valve springs for the head but I was thinking of doing a webber swap instead of efi because I don't want to wire a bunch of stuff, was also thinking of having it ported polished, use 63b heads or have mine decked for compression and an adjustable cam gear , the question is are there problems with this? Can I upgrade the oil pump? And what kind of things should I be looking out for in a N/A retro build? My dad used to have a datsun 720 with the z24 and similar set up but itbs and he said it dynod at 260 with a very similar engine, I'd be extremely happy with 200 mostly looking to increase powerband, rpm and a bit of torque and power
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