6.2 chevy swap into fj55?

[littlepiggy]

I know this has probably been discussed a bunch of times and you can give me links that may help, but what do you who have either done this swap or know of it being done think about the swap overall and do you have any details or particulars that I should consider before doing it. the cruiser is an fj55 1971 model with the stock 3 speed and f motor, and I just bought an 85 fleet truck in pretty good mechanical condition, 6.2, 2wd manual transmission with the granny low and no overdrive I think the trans is called an sm465 if I am not mistaken. it was cheap and I figured if I didn't do the swap I could get rid of the chevy easily. I now am considering buying the advance adapters adapter to mate to my present transfer case unless there are better alternatives, possibly a used adapter somebody might have lying around. I am hoping everything will fit pretty well and I won't have to change any driveline parts like driveshafts and just make new motor mounts. so, if you would be so kind, please advise as to the wisdom/foolishness of doing this particular swap, I wish I could just put in a toyota diesel but they are so expensive and difficult to find that this seems like the only cost effective way to get a diesel in my old pig. cheers

 

[handcannon]

I have never done this swap, but I am familiar with the 6.2. I think that this would be a good swap for you. My only concern would be the gearing, the SM465 is a good tranny but doesn't have overdrive. The optimum highway RPM range for the 6.2 and 6.5 is 1800 - 2000 RPM. Your FJ55 should have 4.11 gears and without an overdrive tranny and 315/75/16 tires (34.6" dia) you will be at about 2400 RPM at 60MPH. The 3.73 gears with the 315 tires gets you about 2200 RPM at 60. I used the gear ratio calculator at grimmjeeper.com to get these numbers.

I'm planning the same 6.2 swap for my FJ40 and am planning to put 3.73s and a 700R4 in for the OD gearing. I currently have some well worn 32/12.50/15 tires at about 30" dia. With these gears, tranny and tires I would get about 1750 RPM at 60 MPH. Plugging in 315 tires would put me at just over 1500 RPM at 60 MPH.

To give you an idea how gearing might affect the 6.2 for fuel mileage I have a 94 6.5TD truck. It has 4.11 gears, a 4L80E overdrive tranny and 265/75/16 tires. With this setup I get from 13 to 15 MPG. At 60 MPH the motor is at about 2100 RPM.

I'm giving you this info not to discourage you from the 6.2, but instead to show you the importance of planning. Use grimmjeeper or some other gear ratio calculator, choose the tire size you want and see what gearing and tranny combos will get you the RPM range and highway speeds you normally drive at.

Don

 

[littlepiggy]

thanks for the link, that grimmjeeper chart will be very helpful. The truck the engine/trans is still in really does scream at about 60mph, 40 to 50 mph is the comfortable speed in the highest gear, I don't have a tach in it so I can only guess how fast it is spinning and it's way too high I feel. my suburban 6.2 with the 700r4 is really happy at 65+ mph but I have numerically lower gears in it, I'll have to figure out what the ratio is to figure the rpm. I was really happy about the sm465 because of the granny gear for crawling, I can live with 55 on the freeway most of the time but it would be awesome to have an overdrive gear. I'll have to look into getting a nv4500 maybe, is it a granny low as well? thanks for the input.

 

[handcannon]

I'll have to look into getting a nv4500 maybe, is it a granny low as well? thanks for the input.

I think so but I've never driven anything with that tranny. I do know that there are two different first gear ratios available depending on age of tranny.

Don

 

[FL cruiser]

I'll have to look into getting a nv4500 maybe, is it a granny low as well? thanks for the input.

It's definitely a granny tranny. Most have a 5.61 1st gear with a few 93-94 Gm versions having a 6.34 low. It has a tall 27% overdrive. About the same as your 700R4.

 

[lovetoski]

One other option is to use the Ranger overdrive between the motor and the sm465. This gives a 27% overdrive. It's spendy though - maybe $1500? Anyway, it's an option. Another way to think about it is to use the Ranger as the overdrive + adaptor between an H41 or H42 and the 6.2. Then you won't need an adaptor between the tranny and transfer. Cost it out, compare gearing, needs, etc. As mentioned above...good up front planning is essential to make this work out well for you. Measure twice, cut once.

 

[littlepiggy]

that ranger over/under unit is expensive and I had looked into it when I was considering using it as an adapter between the chevy bellhousing and the stock cruiser transmission. I will have to look into it again but if I remember right I think it goes between the engine and transmission, I don't think it works as an adapter between the transmission and transfer case but I could be wrong so as I said before I will have to look into it. 1500 is cheaper than most of the sources for the nv4500 transmission that I have seen though and twice what I paid for the truck that will be the donor so I am kind of leaning to the sm465 to keep costs down.

 

[handcannon]

The Ranger does go between the bellhousing and the tranny. If you plan to do any towing the Ranger would be handy for splitting gears, but as you said, expensive, unless you can find a used one.

What size tires do you plan to use? Grimmjeeper defaults to 37" so I used that and plugged in 3.73 gearing with the SM465. It came up with between 1800 and 1900 RPM at 55 MPH, which is reasonable for the 6.2 on the highway.

Don