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Discussion Starter · #1 ·
I bought a 78 truck that had a 350. i Was told it was all original. The former owner didn’t know Much about that. He really believed it had a 350. The a/c compressor and power and 2 power steering pumps with different brackets were in the bed of the truck.

‘’someone along the line had put an 85 305 in there. The harmonic balancer is wider and the timing mark at the 12 o clock position. I ran the numbers on the block. It’s 85 for sure. Passenger side dip stick.

I bought another 78 truck that was stock and had all the original parts. I now had a pretty good reference as to how it was supposed to come.

So ….…..one of the power steering pumps in the bed of the truck was 100% correct For 1978. All the correct brackets were there.
the correct a/c compressor and brackets for 1978 were also there.

the pulleys, alternator, water pump……I have No idea which engine they came from.

here is the problem.
when I bolt the power steering pump and a/c compressor. They do not line up With the 85 engine.
the a/c compressor falls short about 1/4”. since it’s mounted to the exhaust manifold bracket on the backside. There is no way to move it forward

the power steering pump also falls short about 1/4”
I was able to use washers to space it pretty close.

why are these not lining up?
is it because the harmonic balancer is thicker On the later 305 by 1/4 inch?


can I put an earlier, thinner harmonic balancer on there to make them line up with the ac bracket. As in put all 350 front end on there or will it mess with harmonics.

ive not dealt with later blocks. Just the 70s stuff.
 

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Thick balancre or thin, the front pulley mount face is the same distance from the front of the block.

The added thickness in the wider balancer is all put on the backside, towards the timing cover.

Changing balancer won't help you.

Sounds like you don't have the correct crank pulley. Should have 3 belt grooves on it.
 

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I’m going to try to attach a picture of the brackets on my ‘75 350 in my GMC. The PS pump mounting bracket has several pieces when used with the A6 compressor. If you have an R4 it may be different . I'm not sure mine is completely correct, but it works.
 

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Discussion Starter · #7 ·
I’m going to try to attach a picture of the brackets on my ‘75 350 in my GMC. The PS pump mounting bracket has several pieces when used with the A6 compressor. If you have an R4 it may be different . I'm not sure mine is completely correct, but it works.
They changed that style in 77 I think. I’ve got a 75 and it’s set up just like that. the 78 is different
 

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Discussion Starter · #8 ·
The thing is……
I have a couple of 78 trucks. One of them is original and has all the stuff intact. All the parts work and are bolted in the right place. I have a good reference.

the other one is a 78 truck as well…….that someone put an 85 305 in. The power steering pump and ac compressor don’t line up.

however……the power steering pump, ac compressor brackets, are all correct 78. They just aren’t working with this 305 engine.
I can’t figure out yet which part is making it not work.

78 should have the a6 compressor.
 

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I have a 77 truck, and the brackets look exactly like yours. I had to grind some of the lower lip off the big compressor bracket that bolts to the head, in order for the pump tank to clear. All the pulleys line up good.
 

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Discussion Starter · #10 ·
I have a 77 truck, and the brackets look exactly like yours. I had to grind some of the lower lip off the big compressor bracket that bolts to the head, in order for the pump tank to clear. All the pulleys line up good.
that’s exactly where I’m at. I would have to grind that same area. I’ll try that and see what happens.

I’m wondering why that happens. That bracket is the same on the 75 and the 78 and they both work fine on the other 2 Engines. The only difference is those are older blocks and the problem child is the 85 305. It’s almost as if the block dimensions are different Or somethings are shorter and longer. What year is your block?
 

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My engine is the original 77. I'm sure it is the same as yours and earlier blocks as far as the dimensions are concerned. My truck did not come with air, so I got a complete bracket and pulley set off another truck. I have no explanation why the pump tank hits the lower part of the compressor bracket, but I shaved about a quarter inch off the bottom lip and it worked fine. Could you post a picture of your misalignment problem?
 

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Discussion Starter · #12 ·
I will get one tomorrow and let you take a look.
I also have a complete 78 with no issues we can take a close look at.
my compressor is a big mystery as well. It sits 1/4“ back and lines up with nothing. It has to be right. What I mean is…….it bolts to the exhaust manifold bracket in the back of it. Then to that front mount you ground down. Which also has the piece for the power steering pump alignment. There’s no way the a/c compressor can be in the wrong place with that style of mounting.
‘’so it’s everything else that’s off.

I’ll take a closer look at that.
 

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I have an 80 camaro with AC. The crank pulley is a bell shaped 3 grove, top skinny face goes to balancer, opening of bell points out. The power steering is a 2 grove, flat on the back and a nipple/flange on the front of pulley . Nipple must be away from pump, pulley most be pressed on until it stops, it will hit a stop. Water pump pulley is a bell shaped 2 grove pulley, pulley goes over pump.

AC is first one installed, it goes around back grove of crank pulley, then power steering back groove ( it does not touch water pump pulley) the top of belt passes behind the water pump pulley and just under water pump neck, it then goes around the AC pulley.
The 2nd belt is goes on middle grove on crank, runs up to back grove on water pump pulley, runs over to front grove on power steering and back to crank. The 3rd belt goes around the front grove of crank pulley, over to alternator and around the alternator pulley, back over to front water pump pulley, then down to the crank.
Tighten the 2nd belt installed 1st, then AC belt, then alternator
The 80 camaro have AC over drive side valve cover and mounts off of exhaust manifold.

I will post photo later, the odds are the trucks and cars got same bracelets and pulleys when running AC, power steering and alternator.
 

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Discussion Starter · #14 ·
Took a little closer look at this. Haven’t taken measurements or pictures yet.

with a true 78 original engine. We have the a/c bracket in he front that bolts to the front of the engine. This is the one you ground down to make the power steering pump fit. The same one in the picture that my power steering pump is hitting when bolted on correctly

The original 78 a/c set up has the same one. However…….it has the power steering pump 1/8” from the bracket, and there is no grinding.

so here’s a problem…..

look at the picture above with the large spacer. That spacer is press fit in. It’s also the same exact spacer that the true 78 has. It also fits perfectly inline with the front a/c bracket.
the conclusion is that the front a/c bracket and that piece with the spacer that bolts to the exhaust manifold are correct For both 78 and 85 engines.

what does that leave that could be wrong. The crank pulley, water pump pulley, water pump itself, alternator pulley and bracket. but mainly……

the bracket that holds the power steering pump in place. Looks the same for both engines. However……I’m going to measure it. While it might look the same. The true 78 power steering pump bracket, might allow the power steering pump to space further from the a/c bracket instead of hitting it. Even though they look identical…..one might be shorter Than the other in back spacing .

I’ll keep,working in this until it makes sense.

on your 77 engine…….what color is it and where is the timing mark. My 78 engine is at the 12 o’clock position in the timing cover…..directly behind the water pump. My engine color is turquoise. I don’t know what year they changed from orange to turquoise but it might be 76 or 77, the orange engines like my 75 have the bracket in post #5. I‘m trying to figure out which year they transitioned. 77 was a mix match year. A lot of 76 stuff and a lot of 78 stuff. The trucks are a mix of both years.
 

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I have an original 75 engine, it's orange and the timing marks are about 2 o'clock. My 77 is blue, and the marks almost straight up. I believe 76 was the last year for orange engines. The blue was supposedly to represent the transition to a more "corporate" engine used in cars besides Chevrolets. But, other than the timing marks, I can find no difference in the 77 and earlier engines.
 
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