Ambulance engine

[67_C-30]

Originally Posted by prg machine

Yea! is what the guy concluded the final qualification to make this truck what GM produced as an "Odd Duck!" now that is a whole nuther subject..................the odd duck!!!

According to my literature they were 242 produced, so by my estimation, that officially makes in an "Even Duck"!!!

[larry may]

[QUOTE=El Jay;2635192]I hate to sound stupid, but aren't all 350's 4 bolt?[/QUOTE

R U serious. Betting U R. lol

[Big D]

I know of one, This one only has the the ultra rare police interceptor/cobra jet/super hemi commando 350 CI motor however....
The original 427/435 HP motor was removed because it was so fast the ambulance would arrive before the accident took place !


This is the only 4x4 suburban ambulance I have ever seen. It was built by my buddy Bob out of a ultra low mileage (19K miles) 69 Suburban ambulance and a 71 4x4 chassis

[67_C-30]

Originally Posted by Big D

The original 427/435 HP motor was removed because it was so fast the ambulance would arrive before the accident took place !

[El Jay]

Originally Posted by 67_C-30

Nope! They could be had either way. Generally highe performance car and a lot truck engijnes were 4 bolts.

thanx.

I've never messed with a car 350.
Trucks only.

Never opened one up that wasn't a 4 bolt.

You now know why I LUV this site.

Lotsa info, & no "Man, are you dumb!"

[streetstar]

Originally Posted by prg machine

So, tell me guys, does a 4-bolt go faster than a 2 bolt?
or is this a whole nuther argument???

:

A 4 bolt block in theory can handle more power than a 2 bolt block if the proper camshaft, oiling system, pistons and all the other variables are in place. But if you built up 2 engines identically with the only difference being the main caps, they would make the same power.
The 4 bolt "advantage" really doesn't come into play until you are pushing 450 hp or so, so it is more for racers than anything (and good bench racing ammo)

Reality is, if your building a racing or hi-po street motor, a 20 or 30 year old block thats been run through the mill is not going to be the best choice anyway, regardless of the main caps, but "splayed" main caps can be installed on a 2 bolt block at a machine shop to make it stronger than a 4 bolt block if needed.

[jgrh64]

Originally Posted by streetstar

A 4 bolt block in theory can handle more power than a 2 bolt block if the proper camshaft, oiling system, pistons and all the other variables are in place. But if you built up 2 engines identically with the only difference being the main caps, they would make the same power.
The 4 bolt "advantage" really doesn't come into play until you are pushing 450 hp or so, so it is more for racers than anything (and good bench racing ammo)

Reality is, if your building a racing or hi-po street motor, a 20 or 30 year old block thats been run through the mill is not going to be the best choice anyway, regardless of the main caps, but "splayed" main caps can be installed on a 2 bolt block at a machine shop to make it stronger than a 4 bolt block if needed.

chevies are so well made they rarely need a 4 bolt main, but the other GM makes could have really used it .

[prg machine]

so the weekend warrior with a stock 350 with the 4 bolt is realy no "better" off than the guy with the 2 bolt engine when we are talking 250 horsepower or so.

Boy!!! Could this fact ever burst some bubbles!!! All I ever here is how much better the 4 bolts are than the 2 bolts. My 383mild street engine is a studded 2 bolt. 400 horse estimated! The engine builder said the 4 bolt is unnessecary for this application.

[WorkinLonghorn]

This is just a guess but I think the engineers at GM choose the 4-bolt mains for trucks,not because of any tremendous high-reving Horse Power,but because they believed that full throttle operation at just past idle on up,say pulling a 10,000 Lb trailer out of a hole or starting out on an incline tended to put extra stress on the crank. That's just how I see it though. It could have just been a promotional thing,but really,how many buyers check the main cap specs when choosing a purchase?

[67_C-30]

Originally Posted by prg machine

The engine builder said the 4 bolt is unnessecary for this application.

He's right. The only engines I've seen that have had failure due to a problem with the mains were dirt track engines. The sustained high RPM can cause the cap to "Walk" and spin main bearings that can even break the crank (and the caps). I've seen that happen of on some budget dirt motors, but I've never seen a street/strip even bracket car have the engine fail because of a problem with mains. I ran a few hundred 1/4 passes over about 3 years on a 2 bolt, Vortec headed 350 in the 12.40 range on motor and a handful of 11.90 passes with 150 HP Nitrous Works plate system. The engine was still sound when I took it out to upgrade to the 383. I did have ARP main studs and Miloden windage tray on it.

[67_C-30]

Originally Posted by WorkinLonghorn

This is just a guess but I think the engineers at GM choose the 4-bolt mains for trucks,not because of any tremendous high-reving Horse Power,but because they believed that full throttle operation at just past idle on up,say pulling a 10,000 Lb trailer out of a hole or starting out on an incline tended to put extra stress on the crank. That's just how I see it though. It could have just been a promotional thing,but really,how many buyers check the main cap specs when choosing a purchase?

Your exactly right about that. That is reason that themajority of medium trucks with SBC's not only got 4 bolt mains, but forged steel cranks as well. The torsional stress on an engine is a lot different pulling a bunch of weight than a high RPM sprint in a relatively light vehicle is. Heavy loads have a pulling, twisting effect on the bottom end, and most bigger truck engines failures are due to the thrust bearing being worn completely out and allowing the crank to have excessive end play. The end plays eventually causes the rotation assembly to bind and lock up, throw rods and spin bearings. I've pulled a lot of engines out of medium duty dump trucks, box trucks, and pulpwood trucks (to get the 4 bolt engines and steel cranks) and seen as much as .030 - .060" end play. For those who don't know, factory end play of med duty truck engine is .005 - .011". One was so bad that big end of the rods had worn shiny spots that looked like chrome on the crank shaft couterweights.

I can say that I really don't think 4 bolts are necessary for a 1/2 ton truck. You run out suspension and brakes WAY before you'd ever pull the weights consistant with the need for a 4 bolt main block. It was a good selling point though. Some people worship the 4 bolts like a mini-Buddha or something!

[El Jay]

[quote=larry may;2635213]

Originally Posted by El Jay

I hate to sound stupid, but aren't all 350's 4 bolt?[/QUOTE

R U serious. Betting U R. lol

I was as serious as a brain tumor.

I've built a some 350 truck engines & helped on more than a few circle track engines, none of them, ever, was a 2 bolt.

So we'll just say that with my 35+ years of messing with vehicles, I'm not real bright; and let it go at that.

[stllookn]

El Jay....you probably have more experience with engine work than about 90% of the guys currently "building" hot rods. Don't feel badly that you might have missed something. The real crime is not asking the question!

[LONGHAIR]

I always "heard" that 4 bolt mains were used in trucks and cars with 4 barrel carburetors....this seems to be one of the ones that is not 100% accurate though.

[El Jay]

Originally Posted by stllookn

El Jay....you probably have more experience with engine work than about 90% of the guys currently "building" hot rods. Don't feel badly that you might have missed something. The real crime is not asking the question!

I don't feel badly at all.

I just wanted to make the point that all the 350's I'd worked on personally (mine, family, friends); & those I helped while "pitting" the race cars; I never saw a 2 bolt, 350, upside down on the engine stand.
So I mistakenly assumed that 350's were all 4 bolt.

That's what I like about this board.
The members' knowledge is encyclopedic & they're willing to share it all.

BTW, thanks for the input.

[Bob 68327]

I was trying to give you a honest answer so I hope you don't think I was being a smart a@@ . I didn't know if you had ever seen the inside of an engine ? Just don't want to give the wrong idea! Just trying to help. Bob

[El Jay]

Originally Posted by Bob 68327

I was trying to give you a honest answer so I hope you don't think I was being a smart a@@ . I didn't know if you had ever seen the inside of an engine ? Just don't want to give the wrong idea! Just trying to help. Bob

It wasn't you. It was somebody else.

Either it way, it don't matter.
I'm never too damn old to learn.
No harm, no foul.

I've kinda wandered through life with the idea, "The only stupid question is the one that doesn't get asked."
And, constructive criticism is a good thing.

Have a good evening.

El Jay

[Bob 68327]

I've kinda wandered through life with the idea, "The only stupid question is the one that doesn't get asked."
And, constructive criticism is a good thing.


I couldn't agree with you more !!!! Bob

[El Jay]

Dayum!!

We're getting pretty philosophical for a couple of dumb assed gear heads!

[Bob 68327]

Originally Posted by El Jay

Dayum!!

We're getting pretty philosophical for a couple of dumb assed gear heads!

Yup !!! Better slow down with the big words At least now I know how to spell philosophical !! Who am I kiddin I just copied off you !! Bob

[El Jay]

Originally Posted by Bob 68327

Yup !!! Better slow down with the big words At least now I know how to spell philosophical !! Who am I kiddin I just copied off you !! Bob

Dayum!!!

Somebody knows how to make light of stuff!!

[67_C-30]

How many philosophers does it take to change a light bulb?

Depends on how you define "change".

[BigSky71]

All I have to say is this is a funny thread right here! And I have no idea how many bolts are in my main caps, but I just tell people 4, always .

[El Jay]

Originally Posted by 67_C-30

How many philosophers does it take to change a light bulb?

Depends on how you define "change".

I thought that nowadays it was "hope & change."

[prg machine]

So if it "was" a "real" "factory" ambulance engine .....................then it must have been a 400, with 202 heads, 4 bolt, high compression Corvette bottom end, a divorced custom transfercase with a built turbo 400, and the guy had no idea what he had and the guy who got it scored a gold mine!!!!

Oh, I guess it supposedly had the rare factory tach as well!!!