The Stovebolt Site Forums The Shop Area Engine Shop GMC 270 Rebuild problems

Motor is a 270 GMC Strait 6. I am trying to connect an altenator to the block instead of using the old Generator. How could a pully be connected to the front of the Crank and then allow a belt to run the Alternator from the crank. Any Idea on where to find a pully or another way of assembling an alternatior to this 6 Cyl?

Thanks for any input!

what year truck is the engine in. If it is a 55-59, it prolly has that horseshoe front engine mount that straddels the front on both sides. I took the original generater mount and redrilled it so an alternater would line up with the waterpump pulley. If ths is in a 55 1st serries or earlier, the alternater bracket that Patrick sells should work great.

If you need an extra pulley, maybe a harmonic ballancer from a 302 millitary block would do.

I'm not clear on exactly what the problem is, but I fitted an alternator to my 270 recently using the original belt (to keep everything simple) by machining up a C-section pulley and fitting it to the alternator.

I had to weld one new lug onto the original mount bracket to align the alternator,and find a suitable tensioner bracket, but there were no real problems.

I found after I had made the new pulley,that they were available off the shelf in C-section anyway.The only adantage in making it myself was that it could be made a smaller diameter than otherwise available and so keep the rpm of the alternator up, with a relatively low revving engine.

Hope this helps.

The motor is out of a 1947 GMC. It has an engine front mount. The pully on the motor is 1 in width, a much heaver belt, it's twice the size that the standard pully on the 216 that I took out of my 1948 chevy. The plan is to put the GMC motor into the 48 Chevy 1 1/2 ton. The GMC motor is a better motor for the 48 1 1/2 ton.
I need a pully for the water pump, Crank and the Alternator to all be the same size.
The alternator I have can be adapted to go where the the Generator is. The bracket is the same on the Chevy and the GMC, the problem is when the alternator is attched to the block the belt is much to big for the pully.
I have never heard of a business that sells any type of upgrade equipment for this type of engine, is there a number or web site?

While were at it, Ya know how to get the cover bolts off the Dampner / Crank. I am pulling the crank out to get it machined. The 5 bolts in the front of the pully ?

Thanks again!

Some GMCs have a damper that is an interference fit on the crankshaft. That means no bolts hold it on to the crankshaft. Others, like the later 270 and 302 have a big bolt that sandwiches the damper on the crankshaft. Either way a puller should be used to avoid damage. There are about 10 bolts that hold the timing cover on from the outside, and 2 bolts which hold the timing cover on from the inside. Perhaps you can get a harmonic balancer and waterpump for a 55-59 GMC 270. The later 270 used a smaller belt.

The 270 engine you have is a legendary hot rodding engine. Back in the early 50s it was the engine of choice for hot rodding. Its large displacement, overhead valves, and relatively light weight made the 270 a fierce engine. There were several performance parts made for that engine. There are also several venders who still sell those performance parts. Heres a quick list:

Patrick's antique cars
Langdon's stovebolt engine company
Larrowe and sons
Clifford 6=8 performance

All the venders above can be found on the links page of this site.

You will have to relocate the radiator forward, the gmc engine is longer than that 216.

Take your old wide belt, and go to the local mom and pop generator/alternator rebuild place and have them change the pulley on your alt to match the belt. The kit is about 12.00

Do you think this motor will hod it's value after the rebuild is complete?
I used a puller to get the balancer off like you said. I got it off and notice wear on the part that fits through the timming cover. I took it down to the Machine shop and they said it will leak if I don't repair it. I have the Crank down there getting turned 30 over, the mains showed a little wear and they advised to get this taken care of. When i was turning the motor over on the engine stand the lifters fell out. Woops! What now? Will it mess up the Cam if I don't get the lifters back in the same spot?

I will be calling up these business for info on the engine I have. The Plan now is to get the moter going and then later put it in to a 1/2 or 3/4 ton truck. But for now it will go into a 1 1/2 ton Dump truck.
I will check into getting a Dampner/Pully for the motor

Hold it's value? If that engine is done right and maintained right it should last you a lifetime. How's that for value?

I had a 270 with 270,000 miles on it before it went in for a rebuild. They are good strong engines.

The lifters should go back in the holes they came from. You could have the lifters resurfaced. The lifters do rotate So I would imagine it wouldn't be the end of the world if you got em mixed up. If you are woried about it, you could have your cam reground, and get a new set of lifters relatively inexpensively.

Im Looking for a replacment head for a block with Flat Top Heavy duty pistons. Not really sure which type of head to get. I found this, 2194819 head, it has small ports but is that the head to get?