[PonchoV8]

Will the small block HEI fit into the big block 366 engine? Someone said there's a shaft difference but by swapping a few parts it can be done.
Anyone know for certain how/if it can be done?
Isn't the 366 the smaller version of the 427?

[68gtoMN]

http://www.hotrodders.com/forum/366-...ei-171155.html

[PonchoV8]

Thanks, that was fast. But I'm going to have to read that 3 more times to see if they came to a concensus. It looks like they're saying it won't work, but also saying it will work?

ETA: It looks like it's a go by swapping the gear on the distributor--providing that the oil pump shaft is hte correct length.

[A.W.Dille]

The 366 is a tall block truck engine and has a longer shaft in the distributor than the small block Chevy. The only other distributor that will work is out of a tall block 427 truck engine. These engines are normally found in the larger trucks or school buses.

[PonchoV8]

Can the shaft be swapped?

[cuz68]

Originally Posted by A.W.Dille

The 366 is a tall block truck engine and has a longer shaft in the distributor than the small block Chevy. The only other distributor that will work is out of a tall block 427 truck engine. These engines are normally found in the larger trucks or school buses.

You are right a friend has one out of a school buses that came with a holly carb in it.

[A.W.Dille]

I ran into one several years ago at a garage I worked at, old Chevy school bus a church had bought, had to do some work on the distributor on it. Luckily we had a tall block 427 for parts if I needed to swap it out.

[bigunde]

Here ya go:

http://cgi.ebay.com/ebaymotors/CHEVY...Q5fAccessories

[PonchoV8]

I see that the shaft isn't something that's removable. It'll have to be points, Pertronics or the HEI dist swap--or a used unit.

[PonchoV8]

How common is it for the mechanical fuel pump push rod to get stuck in the bore? This one is jammed in the bore and can't be lowered anymore, nor will it push back up under moderate pressure. It wasn't feeding fuel, so the previous owner installed the wrong electric fuel pump to bypass the problem and it's overloading the engine, pushing gas into the oil and obviously causing problems.

I had him bump the engine to see that the rod was moving, and I think it did and got stuck. I levered at it with wooden bush but it didn't want to move back up.

[PonchoV8]

I removed the dist and laid it out beside a 1969 Chevelle 350 dist I have and the length is almost identical. There is about a 1/16" diff in any one measurement. According to some apparently good information, the VERY early 366 had a diff dist and gear. The later units were the same. This being a 1974, it would be the very last of the breed.

Fuel pump rod IS binding in the block. The eccentric pushes it down but there is too little clearance and resistance for the pump lever to push it back up. I have to mod some needle nose Vise-Grips to see if I can coax it out and take a little off the middle so it moves.

[SRR]

There are two holes on the front of the block. I believe the upper one goes through to the fuel pump push rod. If a too long bolt is in there it will lock the rod in place. Squirt some PB blaster into the hole to try to loosen the rod.

[PonchoV8]

Oh yeah, I forgot about that. I'll check it.

I've had the bottom bolt where you access the fuel pump rod out and cleaned it. I had it off again tonight and there is oil in it again. Oil is getting through. I hope it's just a long bolt that I can replace.

Thanks for the reminder.

[455Grandville]

Originally Posted by PonchoV8

Will the small block HEI fit into the big block 366 engine? Someone said there's a shaft difference but by swapping a few parts it can be done.
Anyone know for certain how/if it can be done?
Isn't the 366 the smaller version of the 427?

Tall deck BBC; .400 higer and have 4 piston rings instead of 3. The 366 has a 3 16/16ths bore (3.9375") I believe vs the 427's 4.251"
Good engines, but fuel pigs from hell in medium truck use.

[hurryinhoosier62]

Chevy used the 366 up until the late 90's. We overhauled scads of them for Schwan's.
Their Chevy C4000 delivery trucks had them. Additionally, they were all propane-fueled.

[455Grandville]

Originally Posted by hurryinhoosier62

Chevy used the 366 up until the late 90's. We overhauled scads of them for Schwan's.
Their Chevy C4000 delivery trucks had them. Additionally, they were all propane-fueled.

Im surprised they had athat much demand for them even in the 90s; diesel was cheaper then and fuel economy was greater. Then again, I never heard much good about the CAT 3116s.

[bignate]

The later '70s to the '80s and '90s 366 and 427 used the same distributor as the short deck big blocks and standard small blocks. The mounting point on the manifold was cast lower to compensate for the taller deck. Only difference most medium duty trucks I've seen didn't use a vacuum advance. But just to be sure measure your distributors to make sure.

[Cammer-6]

Originally Posted by PonchoV8

Oh yeah, I forgot about that. I'll check it.

I've had the bottom bolt where you access the fuel pump rod out and cleaned it. I had it off again tonight and there is oil in it again. Oil is getting through. I hope it's just a long bolt that I can replace.

Thanks for the reminder.

yes that was an old trick I use to hold the pushrod in place while installing pump.
Im guessing it also has varnish on the rod.
Polish with 600

[Cammer-6]

Originally Posted by hurryinhoosier62

Chevy used the 366 up until the late 90's. We overhauled scads of them for Schwan's.
Their Chevy C4000 delivery trucks had them. Additionally, they were all propane-fueled.

Ran across about a dozen of these in local equipment auction minus the boxes.
all had 150K or less and went for about $2k or less.
The propane thing killed it for me,wish they were diesels.

[hurryinhoosier62]

Schwan's used propane because they could refuel at ANY farm if they had to. I don't
know of ANY farm around here that doesn't used propane to dry grain crops. I do know
this: those were some of the cleanest engines we had to overhaul. No carbon or sludge
deposits. I used to use the bolt to hold the pushrod. After you polish the rod with 600,
go back over it with crocus cloth,assuming you can find crocus cloth.