The Stovebolt Site Forums The Shop Area Engine Shop '58 270 in a '53 1/2 ton GMC

What does it take? I see the rear mounts differently, can I use a bell housing from a 228/248 or 235, or other?

Is there a simple way to make the newer front motor mount work in the older truck?

Yes, you should be able to use the earlier clutch housing and clutch assembly, and the flywheel if the number of bolts are the same ( on the flywheel). You will want a 1955 or earlier 6v flywheel to use with your 6v starter.

Drill the appropriate holes in the front plate and you will be able to use the earlier front motor mount.

Unfortunately it is not that easy to put a later sidemount 270 in an earlier truck. The timing plate the 270 sidemount engines used is flat without the curled lip.

The "Hack" way to do it would be to drill 1 hole in the crossmember in the center between the 2 original engine mount holes, and use the 1955-1959 horseshoe mount and engine cushion. Unfortunately the rubber mount is unavailable.

The conventional way is to "simply" swap out the timing plate. This is accomplished by removing the following items from the engine...
Valve Cover
Rocker Assembly
Pushrods
Side Cover
Lifters
Distributor
Fuel Pump
Harmonic ballancer
Oil Pan
Timing Cover
and Camshaft

Now you are ready to unbolt the timing plate and swap an earlier one back in.

This job can be done in 1 day. 2 days if you clean everything up real good and paint it nice and pretty. You will need most of a complete engine overhaul gasket set.

On reassembly look in to the "old timing cover trick". The bottom 2 5/16-18thread bolts of the timing cover are installed from inside the oil pan. The oil pan needs to be removed before you could remove the timing cover. With the old trick, the timing cover and front bearing cap is drilled out to 5/16. It is then tapped for 3/8-16 bolts which go through from the front. Now you can remove the timing cover without removing the oil pan. Remeber to put a dab of rtv around those bottom bolts to insure oil doesn't leak around them.

Ouch! I like doing things the right way, but without a garage, every thing I do has to be done outside or in the kitchen Unless I can find a place to do this right, it'll have to be the "hack" way.

If you already have the engine out, it's not that difficult to change the timing plate. If you set both engines with the front up on the clutch housing and have at it it doesn't take as long as you think. Just make sure you line the lifters up in the order they came out of the 270 because they want to be on the same cam lobe they wore in on. I think the time frame mentioned earlier includes removal and installation of the engine. The 6 bolt 6 volt flywheel is a scarce item. The asking price for them is usually close to $300. However, I did see one sell eBay last week for $100. If you are planning on switching to 12 volt, your 58 flywheel will work fine.

The problem with that is the 216 in my GMC (don't ask) is a perfect engine and I've already promissed it to a previous owner. I would hate to cannibalize a good engine. I do have a couple 235s I could use parts off of but it's the same story. They are good running engines.

Guess I'll have to keep my eyes open for a junk engine.

(1) Can I use parts from a 216-235-228 and 248 on my 270 to change the timing plate?

(2) Can I use Parts from a 216-235-228 and 248 on my 270 to change the bell housing to the older style to fit my '53 frame?

I would like to keep the foot start but may have to give that up to run my 270.

(1) The timing cover and timing plates are interchangeable from the 1937 216 to the 1962 235 as well as the 1939 gmc 228 to 1959 fmc 270 and 302. Bottom line... if you have a timing plate from any other 216, 235, 261, 228, 248, pre 1955 270 and 302 gmc motors it will fit on your 58 270 and give you the correct front mount. If you don't have a spare front timing plate, put an add in the parts wanted section. I'm sure one could be had.

(2) The bellhousings will interchange to the motors from 1937 216 to 1960 something 235 and 261 as well as 1939 gmc 228 to 1959 gmc 270 and 302. Bottom line... unbolt the bellhousing that is in your truck now, and bolt it back up to the 58 gmc 270. If the 58 gmc has a 12 volt stomp starter you can use that if your truck is converted to 12 volts. If you want to stay with 6 volts, you need to find a 1954-1955 gmc 6 bolt 6 volt flywheel to use on the 6 bolt 270 crankshaft. There are 12 volt stomp starters available. the 6 and 12 volt starter will bolt up to either bellhousing. It is critical to match the flywheel ring gear to the starter. (168 tooth ring gear = 12 volt flywheel --139 teeth = 6 volt flywheel). A 6 volt starter will work fine on 12 bolts. some people say better. A 12 volt starter will not work on 6 volts.

Bigbadswingdaddy,

Thanks man. That's what I needed to know.

My truck runs 12 volts now on a 6 volt starter. I hope to run the 270 with stomp starter, T5 tranny, and 55-62 rear center section.

It's starting to sound more do-able.