360 installed

[Mcktiger74cj5]

well yesterday button up the 360 install on my 74 cj5. tried to start her and turned over tried a coulpe of times woudnt fire. long story short 6 broken pushrods and 10 bent ones. i had the block /head cut ,shave for 0 . .o45 gasket got the motor back from the machine shop put the heads on cam in took back to the shop for the jerk to measure for new pushrods sdaid stock would work for me. never gave me how much he took off the block /heads i will post pics. later im so mad right now. :(: :ahole: :kamahlitude2:

[82Waggy]

How much lift cam are you running?

Sounds like the cam was installed wrong or you had insufficient valve to piston clearance, or both, or all your valves were stuck (unlikely but possible).

[Mcktiger74cj5]

it a melling mta 1 mild cam. how do you put a cam in wrong?.
the shop degeed the cam .im think to long of pushrods.

[82Waggy]

The shop working for one guy on here installed the cam using the oiling path of the timing gear for the keyway on the cam, but if your shop did in fact degree your cam properly then it would seem unlikely that this is your problem.

I assume then that you have non-adjustable rockers? You need to use a length checking pushrod and find zero lash with the valve closed and the rockers torqued.

You also need to bring a cylinder up to TDC, remove the valve springs on that cylinder, and check valve to piston clearance. If a valve is going to hit a piston it is usually the intake valve as it starts to open before TDC on the exhaust stroke.

Be sure to check for damaged lifters and bent valve stems as well.

[fifesjeep]

So what's the deal/issue.... :-|

[CJim7]

So what's the deal/issue.... :-|
x2...im running out of popcorn here :-|

[Mcktiger74cj5]

im taking the engine up to the shop at 9:00 am fri.
pulled it last night.

[1980_Cj7]

The shop working for one guy on here installed the cam using the oiling path of the timing gear for the keyway on the cam, but if your shop did in fact degree your cam properly then it would seem unlikely that this is your problem.



OUCH! Sorry to hear about your problems.

Yep, I would be that guy that 82Waggy is referring to above. I wonder if your shop really did degree your cam. I just finished degreeing ours last night. I'm no expert, and it was my first time, but degreeing takes a fair amount of time to do it right. I can see the machine shops just "lining up the timing marks" and not bothering to degree the cams.

I'm glad I took the time and trouble as I found I had to retard our cam 2 degrees just to get it to the straight up specs.

[82Waggy]

Any news?

[1980_Cj7]

[quote="82Waggy"]If a valve is going to hit a piston it is usually the intake valve as it starts to open before TDC on the exhaust stroke.

[quote]

Huh???

[82Waggy]

[quote="82Waggy"]If a valve is going to hit a piston it is usually the intake valve as it starts to open before TDC on the exhaust stroke.

[quote]

Huh???

This is the beginning of the overlap period, when exhaust is exiting the cylinder and the exhaust valve is just about closed (the piston is chasing it shut) and the intake valve is opening before the exhaust valve has closed. The exiting exhaust helps pull in the intake charge.

The piston is at the top of the cylinder during this period of the exhaust stroke and both valves are open.

[Mcktiger74cj5]

hello,
i was told the valves hit the pistons. no sh?t. also every exhaust valve was bent.so the builder clayed the pistons and cut bigger reliefs in. was going to get friday but now on monday.wont give me an straight answer on what happened.there agian all i had done was cut the block to 0 deck height clean the heads up and use .045 rol head gaskets milded cam.more news next week when she goes back in.

[82Waggy]

Did you have new valve guides installed? If so, possibly they were too tight causing the valves to stick open and get smacked by the pistons. Buddy of mine had this problem on a 351C - bent pushrods too. Re-honed the guides and all was well thereafter.

Seems unlikely to have piston to valve clearance problems with such a mild cam, unless the cam was installed way off.

[Mcktiger74cj5]

he said the cam was right on 105 cl. but its monday and no motor yet. maybe tue.,wed,thurs,fri. :letitallout:

[1980_Cj7]

Ah, the ol' waitin-on-the-machine-shop-blues! I know that tune by heart, ha, ha. It has an extremely slow beat and is hard to dance to.

Did the shop put it together for you? Did you get any kind of guarantee?

[Mcktiger74cj5]

hre put the short block together and i put the heads and cam in.then i took it back to him to check the cam degree and measure the pushrods. im holding my tongue till its in my truck then figure out the rest of the story.

[1980_Cj7]

We just went thru a similar experience where a "machine shop", and I use the term loosely, put our 401 together with the camshaft key in the oil groove of the timing gear instead of the keyway. The engine only lasted 300 miles and then needed an entire new rebuild. The pistons scuffed badly from detonation from the timing being all screwed up. Not to mention there was zero oil getting to the timing belt, distributor gear, fuel pump cam, etc.

They offered to redo the engine at no cost to us, but we didn't want them working on it any more. They refused to pay for another shop to work on it. We settled with them paying for all the new parts, and us eating the machine work at a real machine shop.

Good luck to you on yours.

[Mudrat]

Mcktiger
Man that sucks. Do to time constriants I had the shop do it all (I was out of the country most of the time). I gave them my build specs, guessed on the timing ("that looks like 12*) and it fired up on the first go! Teh shop I used (in Norfolk) builds race motors, not so many AMCs, but when you routinely have a Keith Black 500 or a 750CI with Nitrus and a blower, I tend to think my guys did it right.
Sorry to hear of your woes, did you get a warranty for their work??

[Mcktiger74cj5]

yes no charge. was up there today and seen the problem upclose he put in savolite piston and the reliefs were a 1/4 " off. and now the new pistons are 40 grams heaver sohe needs to rebalance it all. but now i know it was neither mine or his fault. so he told me that i can pick it wed. and i will have the next 5 days off following the 4th. i hope im good to go.