Chevy & GMC Vans

hum,? I might need to drop the crank.

-Vance

Jinmajay wrote:Here is a photo of mine (just out of the donor). You can see how much room there will be to turn the rod while keeping the other in place. Seems like a tight fit. Where you going to bore scope each cylinder first?

Good luck.

Is that an optical illusion, #7 rod looks at an odd angle?

That is actual. The motor is tipped in the stand so that the side facing us is at a 90* angle to the floor.

I see what you mean.

I would just pull the engine and get it onto a stand to work on. Then you will know that the engine is assembled correctly (rings in the correct position ect ect). I do not believe that you will be able to just rotate the pistons. Also you may run into problems half way through your proceedure and have to remove the engine anyway.

I tried about 22 years ago to remove the crank out of a 350 without pulling the top end...the engine was upside down in the back of a pickup and I had a heck of a time getting it out without damaging the journals. In the end I got the crank out but at the time I was thinking that it would have been very difficult to reinstall a new crank. I found out that you can remove a few pistons out the bottom end but not all of them. For one piston I had to break the rings off and push it out the top after I removed the heads. So if you do try pulling the crank make sure that the pistons don't fall out onto the floor of your garage.

I would chaulk this one up as an expensive (but not as expensive as it could have been) learning experience. You are not the first person to do this and I am sure that you won't be the last person to make this simple mistake. Good luck with your repair!

Ok, looking at the bottom of the vortec heads(which are on it), It lookes like the reliefs need to be at the bottom like they are. With thim 180'd, it looks like they would be completly wrong.

My question is are the old chevy 350 heads different than the vortec heads in terms of were the valves are located/angled and are they recessed into the heads more? Judging by this picture, it looks like the piston would hit the head way before it would hit the valve. I would have to have one crazy cam to keep a valve open long enough for it to get hit by the piston.

http://images.customclassictrucks.com/t ... ad06_z.jpg

The above link is a good picture compairing the two heads. The one on the right is a vortec head. On the left is an old 350 head. The combustion chamber is for sure differant, but is the valves in the same spot?

Anyways, I am going to borrow a snap on bora scope from a buddy from work and check how close the clearances are. I know the wrist pin is not offset'd so premature wear shouldn't be an issue and I know it is not off ballance. This is the smothist aftermarket V8 I have ever felt. If the clearances are not too close for comfort, I am NOT going to dig into it. I am only worried about the piston to valve clearances being too tight.

The specs on my cam are:

Part number is 14097395
The duration at lash point in degrees (intake/exhaust) is 288/308; duration at .050" tappet lift (intake/exhaust) is 196/206 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 431/451. Valve lash is zero/zero and lobe centerline is 109 degrees.

I am running 1.5 rocker arms. The pistons are .030" over 9.7:1 compression ratio(increase over stock from 9.1:1 and this is due to the extra stroke and bore). 5.7" full floating rods. The heads were flattend approx. .004" at the machine shop. The valves and seats were also machined (3 angle) so the heads being shaved shouldn't play a part.

here is a link to an ebay auction that is identical to my stroker kit that I bought.
http://cgi.ebay.com/ebaymotors/SB-CHEVY ... 0102381555

This is all of the factors that I can think of that would impact this situation. I will let you know what happens with the borascope. Thanks for all the help people.

-Vance

When looking pictures of valve reliefs and the valves them selfs in relation to the head bolt holes, it looks like the reliefs need to be in the middle of the pistons. Its beginning to look like it wouldn't provide clearance in eather position. Urg!! I don't know.

The bottom line is this:

Does it really matter? Is it attualy gonna hurt one way or the other? I personaly dont think so. Its pretty easy to say "drop the sub frame, remove the motor, tear it down, spend 200 bucks to get a gasket set and other things to put it back togeather and put it back in" when you are on the other side of this computer screen. I dont mean any affense to this comment, but you can see the delema im in. Yes in a perfect world they SHOULD be rotated, but do they need to be rotated?

Is there anyone that backs me on this one?

-Vance

ok, I guess I could just use my head. The curve of the valve relief is backwards of the curve of the valve itself. It is backwards.

Anyways. I doesn't hit now. I didn't put in a huge cam. The pistons do not have offset wrist pins. It doesn't vibrate so it is not unballanced. Unless I can find a dam good reason, it is not getting "fixed". If I can get some facts telling me something "WILL" fail or "WILL" hit, I will remove to motor and flip the pistons. If not, I am gonna leave be. Once again, Thanks for everyones concern and help. I can't express how much I appriciate all of this. This includes you Danny and your old man.

I would like to hear from all of you. I would post pics and videos but for some reason I cant upload to photobucket. Not sure what the problem is but when I figure it out, I will get posting. Thanks one more time people.

-Vance

I understand your frustration. It is a lot of extra work to repair this problem. If it were mine I would repair the problem before it grenades. It could be only 1/1000th of an inch away from blowing up...as your engine wears and carbon builds up on the piston tops those clearances will become even more critical.

Maybe you can paint that subframe properly so it matches the rest of your show machine when it is out...

my dads a gm master tech here in 2 weeks if all goes well he will be on of around 1300 people to be world class technician and he was telling vance you have thousandths of inches of clearance normally so yes its tight but all motors are, vance has had to hit the rev limiter 3 times to learn the vcm and as long as there no cops here he has seen close to 120mph a few dounts and my burnout. the only way we can see them honestly hitting(we all talked awhile last night) is if you lose the rod bearings and if that happens you have to tear it apart anyways. i guess basically if it was gonna hit, i think it would have. i agree it should be rebuilt but without the space now its getting cold it would be difficult for him. he has a 2 car garage that smaller than mine.
Danny

I think you are getting away with this because of the stroker crank. With the conrod ratio being shorter than before the piston spends less time around TDC and may be not getting there in time to hit the inlet and getting out of the way in time to miss the exhaust valves.

nitropyro wrote:my dads a gm master tech here in 2 weeks if all goes well he will be on of around 1300 people to be world class technician and he was telling vance you have thousandths of inches of clearance normally so yes its tight but all motors are, vance has had to hit the rev limiter 3 times to learn the vcm and as long as there no cops here he has seen close to 120mph a few dounts and my burnout. the only way we can see them honestly hitting(we all talked awhile last night) is if you lose the rod bearings and if that happens you have to tear it apart anyways. i guess basically if it was gonna hit, i think it would have. i agree it should be rebuilt but without the space now its getting cold it would be difficult for him. he has a 2 car garage that smaller than mine.
Danny

All of this speculation is just that...speculation...or guessing what is actually going on inside this engine. I can not believe that a GM master tech would endorse running this engine this way.

Good grief, here is a guy driving around in a stroker power plant that will turn 5500rpm in neutral without hurting anything. What are the odds he will do anything worse to it on the road? Idealy he would be able to fix it but this is a time of year in Ohio that driving something that seems to be working trumps working on it for no other reason than to satisfy someone on a forum.

If you are going to run as is, it would be prudent to limit the high rpm blasts to fuel cut on the engine. Those valve springs look like the stock ones that come with the vortec heads and your cam is slightly hotter than stock, add to that the fact that a hydraulic roller valve train is heavy. With all new components everything works properly but valve springs get weaker as the mileage on the engine builds. The engine may run fine for a long time but I don't think it will tolerate any valve float.

HPbyStan wrote:Good grief, here is a guy driving around in a stroker power plant that will turn 5500rpm in neutral without hurting anything. What are the odds he will do anything worse to it on the road? Idealy he would be able to fix it but this is a time of year in Ohio that driving something that seems to be working trumps working on it for no other reason than to satisfy someone on a forum.

Do you actually believe that telling him that it is okay to run it with out repairing it is sound advice? I do not care one way or another what people do with their machines, but I would not tell him that it is okay to run it that way.

Have you considered what will happen when the timing chain stretches over time? The problem with this scenario is that we do not know how close the parts actually are. I am only trying to give this young man good advice and telling him that it is okay to continue running it is bad advice im my opinion.

What is the use in building a performance engine if you can not rag on it without wondering when or if it will fail. Not worth it in my opinion.

By the way Stan I am not playing the devils advocate by stating my opinion. I appreciate your input as we can all learn from your experiences.

I also mentioned to Vance in a PM that he should probably consider stronger valve springs if he has not changed them from stock.

Anyway, the final decision has to be made by the owner of the machine. He now knows the risks and he can make his own choice. If it fails maybe he will be lucky and only bend a few valves or push rods.

i think everyone including vance knows the right way is to rebuild it but sometimes we take chances. it is his sole decision not ares. we all keep thinking if bearings go bad and timing chains go bad things will break well it doesnt matter if that stuff goes it need rebuilt anyways.

dad and i were talking today and were gonna suggest checking vaccum if there is un steady vaccum he my have slightly bent a valve alreay but not enough to cause major failure. if that shows good run it. we have already ran this thing hard its gonna be drving that way we are young dumb and you know the rest. he knows it not gonna last 200k this was built to drive and drive hard it will be rebuilt again im sure and i bet he will put the slugs in right next time lol.
So i say vance do as what will make you happy im there either way. and either way i dont think wrong of you or will think you hacked something as i know you have learned from this error
Danny
ps. i like all the help that has been givin out but i have a serious question we know that they are normal pistons so there cant be any extra wear if he leaves it this way but if the vavles DO NOT hit what does this hurt? i cant find any legit answer.