chevy 350 interference heads?

[timswi]

If the chain is not broken I would just make reference marks, take old off, install new.

Chris

That's what I've done..If the chain is still in one piece the computer will adapt the timing, it has thus far..Why would anyone move the crank or cam with the timing set removed?

 

[brokenot]

There are quite a few posts out there on the 'net from people that have, (or want to), install higher-lift camshafts in Vortec engines and have experienced issues with valve spring bind or interference with the pushrod holes, or valve springs or retainers hitting the valve stem seals or guides at full lift. Some have also put Vortec heads on older blocks, (or vice-versa?), and have had issues with the valve clearance to the bore in the block. A lot of them have come to the conclusion as a result, that the Vortec is indeed an "interference engine". But that isn't what the term "interference engine" refers to.

Interference engine means that in stock condition, operating under the conditions it's designed to operate in, the valves will hit the pistons if the camshaft gets out of time. Several internet posters have claimed that Vortecs are indeed interference engines because their engine bent its valves when their clutch let go on the starting line and their tachometer needle ventured into territory it doesn't belong in. If that's the definition everyone agrees to go with, we'll have to expand the list of interference engines by quite a bit.

Here's a link to a Vortec "beehive" valve spring kit. A few guys that have installed these have posted that they cured the "interference engine" issue, (that they don't really have as far as I know), with their Vortecs.

Valve Spring Upgrade - Beehive Valvesprings for the Vortec V8 - Car Craft Magazine

The jury is still out as far as I'm concerned. Until I measure one myself or see it in a shop manual, I don't think the Vortecs belong on the interference engine list. Not too far off-topic, I got one of the "shop tips" emails at work from Foley Engines a while back, and it said 2.3 and 2.5 Fords are interference engines, and they aren't. They went on to say that the Deutz diesels with timing belts are too....they did get that one right.

Why would anyone move the crank or cam with the timing set removed?

It's done all the time to get things lined back up if a chain jumps or a belt breaks. A person needs to be careful and know what they're doing though....

 

[tcartwri]

You need to get your hands dirty and stop reading so much. This is a rediculous discussion.

 

[brokenot]

You need to get your hands dirty and stop reading so much. This is a rediculous discussion.

Interesting comment, it kind of sounds like you're not so convinced yourself.

And....ridiculous contains no "e". That aside, why is attempting to answer, (or find answers), for someone's question ridiculous?

Stock Vortec. Interference engine or not? Post proof.

Lastly, my hands are dirty on a daily basis.

 

[puckgrinder85]

Line the timing marks up, remove and reinstall, nothing more really needs to be said about it unless you plan on rotating something for whatever reason which it doesnt sound like you have to.

 

[dodge man]

I don't know the technical defintion of a interference engine, but I always thought of it meaning if the timing chain broke, would the valves hit a piston. Knowing how modern engines work, I'd be shocked if it wasn't, but you never know kunless you get the specs or talk to someone that knows what they are talking about.

 

[Diamondpilot]

I still think everyone is making this harder then it needs to be. Like i said earlier and others have too, just mark everything with reference marks, remove old one, and install new.

Chris

 

[mikehaugen]

well geez, this wasn't supposed to turn into a p*ssing match. The only reason I ask is because I know me sometimes and I could see myself possibly rotating the crank or something unintentionally and was just curious if it would be a problem if it did happen. As stated earlier, I will just treat it as if rotating the engine without chain will cause engine to explode immediately and lightning will strike my garage, no harm in being overly cautious. Thanks for the replies.

 

[Diamondpilot]

well geez, this wasn't supposed to turn into a p*ssing match. The only reason I ask is because I know me sometimes and I could see myself possibly rotating the crank or something unintentionally and was just curious if it would be a problem if it did happen. As stated earlier, I will just treat it as if rotating the engine without chain will cause engine to explode immediately and lightning will strike my garage, no harm in being overly cautious. Thanks for the replies.

I am sorry if I came off negative and I will apologize for anyone else also. If the chain or belt has not broken or skipped a tooth and is otherwise running perfect as you seem to suggest I would just do as we said and with reference marks made swap the parts.

Chris

 

[brokenot]

My apologies as well. I'm genuinely interested in a definitive answer. There are interference engine lists posted on the 'net by timing components manufacturers, and the Vortec isn't among them. Additionally, I saw a co-worker try and start a Vortec 4.3 for quite a while...before ending his experimenting and lining up the marks properly. No damage at all, and from the amount of time he spent fiddling with it, the crank and cam were probably lined up a few different ways. (No, I don't know why.) Then there are all of the different versions of the story you can read on other forums. One guy actually said it was an interference engine for sure, because his bent an intake valve. The kicker is, he had the truck back on the road after pulling the head and replacing the bent valve....and that's all. Nothing was done with the cam or crank positions whatsoever.....