Chevy & GMC Vans

I did a search based on the engine numbers of:10243880 which come out as a 96 to 2000 vortec truck Gen I create zz4 roller cam one pc seal.(so did Blazer and I came up with the same results.Thing I am looking for is the compression ratio of this engine.

I am planning on running this on 87 gas.

Thing is I want to do the research,but I am having a hard time finding the links for it.We have links to confirm what I know and links for the older stuff,but after that we have that nothing for the details on the engine it's self that I could find.

I tried to post a link here for you BUT, it was too long for this forum I guess. In your search engine, type in Chevrolet ZZ4 and you should get the info I hope.... HP

It's http://www.crateenginedepot.com

Tried Stan and didn't come with anything.Looks like a drive to the parts store will be needed here.

You know the old stuff I'm there all the way.So excuse me with a learning curve on some of this newer stuff.

So here is what I found so far.Given the I.D. numbers I found it is a L31 that stock would be 255hp@4600 rpm and have a torque of 330 @ 2800 rpm.It has a compression ratio of 9:4:1.That is the good.Now the bad.This engine was purchased as a crate to replace one that was in a 1995 truck.The truck as I think I said was involved in a rearend crash and purchased after that for the donor van I bought.Well during the engine replacement they reused the TBI that was on the 1995 engine.Not the SFI that from what I have found so far completed the power output on the L31's.Damm.Sounds like a expensive system to get and harder to swap because of the computer system needed for the injector.I wanted to set a base line from stock and do minor mods from there.

Any comments of suggestions?????.

I would run it the way it is after you get it to idle properly and see how it performs. If you do change cams then your choice of a 383 cam would be better for towing than the ZZ4 cam.

Rockwerx wrote:I would run it the way it is after you get it to idle properly and see how it performs. If you do change cams then your choice of a 383 cam would be better for towing than the ZZ4 cam.

Rocky-Thanks.I've missed ya man.Thanks for chiming in.Yes I agree.Blazers suggestion of changing the PVC valve(not the EGR)is one thing I am going to try and spray the base of the TBI gasket etc.

The seller of the donor van emailed me back.He said he downloaded a chip image off the internet and changed the value for the cop injector size and thought he had removed the ERG controls,but apparently not.The image was from a 92 2wd 1500 with a 350 and a 700R4.He wasn't sure if it had a roller cam,but given the fact it has a 1996 engine block code,it does.He didn't think it had vortec heads.I will have to take off the valve covers to get the head numbers to see if it does.

From what I found out about about the 1996 vortec truck engines,GM did a update which resulted in a 55% increase over the 1995 one which used the SFI injector system.This I don't think is now at the power increase because of the TBI in use and the computer chip burn that was used.

Once I find out if it does in fact have vortec heads,the question becomes if I should return it back to the stock L31 1996 vortec upgrade with a computer,and controls from one of them and the SFI injector system as a base line starting point.By doing that I would pick up the 55% increase on that alone.Then add on a GM 383 cam and roller rockers and chip burn for that.

The other approach would be to use the current set-up with the TBI I guess was from a 1995 truck and redo the chip burn with a GM 383 cam and roller rockers.The chip burn I would send out with the changes to someone who does it as a pro.

It seems to me a better way to go about this is to return the engine back to it's 1996 stock form taking the 55% increase and build off that.

Thing is I think remember someone who did use a L31 engine and don't remember the details.Not sure if or how the computers from the Astro's and the 1996 trucks would work out.The Astro the engine is going in is a 1985 anyway so to get one from a 1996 truck wouldn't matter much because the 1985 is a carbed Astro.The plan was to use the computer from the donor van which was a 1989 Astro,but if using a 1996 truck computer would be a better move and use some parts of the 1989 Astro harness.

Any thoughts guys????.

Going now to do a deep search on the site for who it was using a L31 engine and that thread.

Sorry for the long thread guys.Just want to put together the best plan I can and start to gather the parts for it.

Ok I did look for a thread about L31 engines and found on from RickU when he joined the site.Any others??.

BTW: he did kind of say the SFI injector system was weak performance element.Comments??.

If by "383 Cam" you're referring to one designed for a 383 stroker, I wouldn't go there with the smaller engine. The 383 by design, already has more torque than a comparable 350, and the cam design would take this into consideration and NOT have to program as much bottom end into it. If you want to tow, the truck cam should be fine. I'd certainly try it first. If you MUST change the camshaft, use an RV or towing camshaft desinged for such a task. You'll be happier and so will the van! Call a couple of the cam manufacurers 1-800- hot lines to verify or dispute this info and to get really good advice for free!! It will save you a lot of time and money! Good luck!

wagonmaster wrote:If by "383 Cam" you're referring to one designed for a 383 stroker, I wouldn't go there with the smaller engine. The 383 by design, already has more torque than a comparable 350, and the cam design would take this into consideration and NOT have to program as much bottom end into it. If you want to tow, the truck cam should be fine. I'd certainly try it first. If you MUST change the camshaft, use an RV or towing camshaft desinged for such a task. You'll be happier and so will the van! Call a couple of the cam manufacurers 1-800- hot lines to verify or dispute this info and to get really good advice for free!! It will save you a lot of time and money! Good luck!

The one I am refering to is GM part number 14097395.It has a duration of 288/309 with a lift of 431/451 and a center line of 109.It is kind of a smooth idle RV cam.

Okay, sounds like we're talking about the same basic thing.
Good luck.

Rockwerx wrote:I would run it the way it is after you get it to idle properly and see how it performs. If you do change cams then your choice of a 383 cam would be better for towing than the ZZ4 cam.

Rocky,
I plan to rebuild the tranny on the donor van and plate it to drive it for a short time.Get a feel for what I have and see what else it needs.After that swap to Ole Yellar and do what ever mods I want to do during that.Because I have access from a friend to a shop with a lift and all the goodies we will do the swap via sub frame doing a 3" lift at the same time.Ole Yellar is a RWD.I own three Astro's and call me crazy,but I still need a 4th sub frame that I can sand blast,paint,and rebuild,ready to install so we can tie up the lift on a weekend swap Friday night to Sunday nite and not get in the way of normal business.I used to know of a place here in Roch that would powder coat ,as long as it was ready for that,
for $75.00.The thing is it you had to have all the parts ready and be done all at once because the set-up time was most of the cost.I got to go back and check to see if that company is still around because it has been sometime since I last talked to them

Thing is I gotta have all the parts in hand in advance to be able to use this shop.


Gar

Gary, we do require some pictures as you go you know. We have proof now that you can post pics....

That sounds like a good plan of attack for your project. I like to do things in stages also. This can help if a guy starts to go over budget (like normal) when you encounter problems. Takes a bit more time, but in the end you get what you want out a project.

When you get a chance try pulling a valve cover to find out the head castings you have. If you are a bit more abitious you could pull the distributer and take a peek into the cam gallery to see if you have a roller cam already. If not it is not the end of the world. Like I said to many people...a stock TBI 350 (flat tappet cam) in these vans is a huge improvement over the 4.3s. I would try it out like you plan to after the trany is repaired and give it a shake down. I am sure that it will tow a lot better than the 4.3!

Oh, one more thing, I must have been thinking of a different 383 cam than that one. The specs quoted reminded me more of an old 350/350hp cam that Chevy used to offer. I would not use a cam with that much duration if you want to tow a trailer well.

Good luck with your project!