AMC Service Replacement Blocks

[Karvin]

OK... I have had a few Jeeps and a couple of FSJ's. Previously owned a 68 M715 and a 77 Cherokee Chief. I had to sell both of those to fix my DD and have now found another 77 Cherokee Chief. The engine was replaced sometime ago and the seller is claiming it is a stock 360 w/a 4 barrel, however something just isn't right. He claims it has a "factory" service replacement block in it, and it is no doubt an AMC V8.... however the throttle response and the lope of the cam suggests that it is FAR from stock.

What I think I know... the AMC Racing Team had service replacement blocks available to build as they saw fit, however it was a "stock" block and so fell within the guidelines for whatever racing association that required stock gear. There is a quick mention of it on the AMC V8 wiki page and that is about all I can find out.

Anyone have anymore insight into this? This "stock 360" has better throttle response than any engine I have heard short of a purpose built race engine.

(Oh, and some of you may recognize the user name from IFSJA)

[JAWs7227]

Check the usual place on the side of the block, if its a service replacement there won't be a displacement number cast into it.

[Karvin]

Yep, going to look into that once I take possession of the vehicle... it is currently about an hour and a half north of me.

All I can say is I am VERY impressed with the engine. I seriously doubt that it is a stock spec 360... not compared to others that I have test drove anyways. Displacement casting should be right next to, or slightly below the motor mount correct?

[Rockwell B1]

That's correct on displacement stamp position. Let us know what you find out for sure.

[mdill]

I can't claim to have all the info, but I am pretty sure the "service" replacment block you guys are refering to was a way to get around the "stock" car and/or trans am rules, give the 401 block with 360 bore a part factory part # so the race guy's could use it.
I don't think any AMC/Jeep dealer would buy and build the block for a warrentyor service replacement (it was just a bare block that requiered it to be machined and built up) . There were stock service long and short block 304/360/401's all avalible off the shelf with factory backed warrenties.

No sense in buying a race block and building it to "stock" spec's.
The race blocks do pop up now and again but the ones I have come across have been run out.

[carnuck]

The service block was cast with 304 bore, but could be bored out to 401 with no probs. Generally they were designated for AMC cars, so the cam was usually a little perkier, like the one in my 304 that came from the '77 AMX I parted (It homped down the road quite nicely with a 5th wheel attached. About equal to my '82 C20 with 454 and Edelbrock package)

[Grand_Wag_85]

Probably not of much help but I've heard that the service replacement blocks were painted in red instead of the AMC teal from the factory.

[mdill]

The service block was cast with 304 bore, but could be bored out to 401 with no probs. Generally they were designated for AMC cars, so the cam was usually a little perkier, like the one in my 304 that came from the '77 AMX I parted (It homped down the road quite nicely with a 5th wheel attached. About equal to my '82 C20 with 454 and Edelbrock package)

I think you are right, 5.0L was the limit for Trans Am raceing a 360 bore would not be much help. I don't think any of those blocks got a cam from the factory.
Not sure if they were painted or not, but the IH 401's were red if memory serves.

[Karvin]

Um, if memory serves me... that is a BIG if... it was actually painted black.

[Stuka]

Um, if memory serves me... that is a BIG if... it was actually painted black.

If you mean the IH 401's, they were all red.

[Karvin]

No, the block in the 77 Cherokee Chief that has the supposed service replacement block in it... it was black, and not from gunk on oil and dirt either.

[jeepguy77]

If it truly is a service replacement block it shouldnt have the displacement cast into the side it should be bare. It wont say 304, 360, or 401.

[Karvin]

Thanks, I believe that has been established. I might take another trip up there this next weekend and look again, but it is a full tank of fuel with the 4.7 Stroker in my 02 TJ Wrangler.

[AMGeneral]

Ok my grand dad worked there this how it got explained to me.
They were all cast with the high nickel and extra webbing of the 390/401's but had the bore size of the 290/304.
Than they were bored according to what was needed.

I asked about the Tall deck versus short deck his response was:
While boring to fit the CID need they got decked down if need be at that point.
You could get anything from a 290 to a 401. Your 390 n 401 were on par but the smaller engines got the extra benefits of the larger engines, If you got a service blocked 290/304 or 343/360 they were structurally stronger.

:e did make reference to the racing guys it wasn't more fudging CID as it was compression, camshafts, and so on he said a quick skim down the block and your 8.3:1 360 was now a 10:1 360 swapped the Jeep cam for an AMX/Javelin cam and you got a "stock" 360 for a 70 AMX getting put into an 80s Jeep mud racer.

Now he did mention the crank shafts were easily interchanged so a block stamp 304 could easily become a 401 tho ya lost structural strength it only had to hold up for a weekend not 200 thousand miles

So without him directly saying IT, I think he had helped some guys do a little cheating.
If NOT it did give me the impression it did happen or it could have happened with ease.

AM-G

[fulsizjeep]

Interesting read. Here is a fella with a service block and no size stamp on the 2 typical locations...
http://theamcforum.com/forum/couple-of- ... page1.html