DNV/Dennis,

   It seems like you have yourself a problem to handle.The 3970010 block is a very good block,however can be a two bolt as well as a 4 bolt main block especially if the casting date is around '77-79..Also a 400 block has a different # as well as 3 freeze plugs on both sides instead of two on all SBC V8 blocks..

    The 882 heads are a troubled set of heads along with 624 (400 heads)as they heat up in the exhaust ports of 4&6 and 3&5 exh.valves and crack easily..I once tried 11 sets of these heads looking for a set that was NOT cracked...If you can trade these for another set you will be money ahead..They can be used on SBC truck engine with a big radiator and cooling system..993 heads would be another much better head replacement if you want a76cc head,however make sure they were made here(USA) rather than "HECHO de Mexico" as they are not as good.They had a quality control problem in the Mexico plant at one time.I have had to build the stock engines for brand new cars,trucks in CA. at one time between with 40-65000 miles because a align bore problem in that plant..

   What heads do you have on your engine at this time..Also have you checked before you tear down an inspect you heads for broken springs on the two low cylinders..

    If you want performance you will need 64 cc heads like the dearly desired and wanted 186 (Vette/DZ Camaro engine)heads.

   Port and polishing has an advantage only if you are into track racing as well enhance flow,however not enough to justify the the cost (10 hrs.@ $60/hr.) or a novice at 15-20 hrs and a possible misshap and ruined heads..

   If you have reasonable heads, then rebuild them and change exhaust valve size to 1.60 exh. valves(greatly improves breathing) instead of 1.5 stock size.

   The rods and pistons will work for you,however make sure they are marked on the rod caps for the cylinder they come from, and should have been if the engine had been done by a competent mechanic/machine shop,so they are returned to the same hole they come from..Don't worry you will not have a 400 crank as it is a differnt stroke and they would have turned mains to fit 350 mains and then it would be a 383 stroker......

    If you are going to take apart the engine I  would replace the timing chain and gear to a new double row chain set.If it had run it would have already streched the 1.25 degrees it does in the intial running of the engine..

   As far as the cam, unless you know what the lift is on the cam, int./exh., you cannot set the valve springs height/pressure correctly to ensure you with not have coil bind etc.

    The use of the Vette dictates the type of cam..If you are just wanting to cruise and have low end torque and some top end then Corvette cam from the "69 350cu.in./350HP (I have the GM P/N in file) would be a great choice with 64 cc heads and not as much HP with 76 cc heads and will be a great cruiser.. 

     As  far as the intake maniifold ,you can get a drill to drill out the case harden tap bit you broke off,albeit it is going to have to be a tough bit..After you get the broke tap out you can get a Helicoil kit(which includes drill and tap and coil)and drill out the hole and then you tap for the heliciol which will be the bolt size you need which should be 3/8 bolt..

    I wish you luck in your endevor and if you have any questions that I hbe able to hellp on please do not hesitate to ask..

    Have a wonderful day,take care...

      Sal  nosal1    

[QUOTE=dnv]Joel/Ken;

I pulled the drivers side bank of plugs (one at a time) and compression checked each cyl.  I found #1 - 45lbs, #3 - 40lbs, #5 - 110lbs, #7 - 100lbs.  Leads me to believe I have either a cam going down or ring issues.

Either way, I bought a 350 motor from the wife's uncle a year or two back and put it on a stand intending to get to it one of these days.  Apparently, that day is today.

The good news, it codes out to be a 350 - 400 (GM-3970010) engine block with four bolt mains.  Casting # 333882 Heads @ 76cc for a GM 400 application. 

I'm going to have the crank and pistons miked.  The pistons are flat top with the valve groove cut in both directions.  I haven't gotten it completely apart yet. 

The story goes that the engine has less than 100 miles on it and was removed when the transmission blew up and he parted out the car.  He also says it has an Erson RV Camshaft.

A couple of questions:

1) I'm thinking it would be a good idea to replace the timing chain, rings and bearings to really zero time the engine.  I will also check or replace the oil pump, fuel pump, pan (mine on the vette has a re-brazed hole that is weeping. I'll also use the rebuilt HEI distributor out of the vette and replace the wires/plugs.  Anything else to replace/change while I'm in here?  I also intend to replace the front & rear transmission seals and the u-joints in the driveshaft.

2) If it does have a 400 crank as it is supposed to, should I change the cam or is an RV cam good enough for mainly cruising and a little autocrossing?  I intend to back it up with a 700R4 next year when I can afford it and Momma's MG is running.

Any special tips for build-up at this point?  I'm going to port & polish the heads, I was thinking of doing this myself.  Should I let the machine shop guys do this?  It'd be my first attempt. 

Also, I broke an extractor off in the aluminum intake manifold off the vette at the thermostat cover hole.  Is it a total loss or should someone be able to drill it out & retap it?

Any and all help will be greatly appreciated!!!

Thanks in advance!

Dennis


[/QUOTE]

are you saying it is a 400 or 350 with 400 crank (383) ?

Ive heard many people say 400's worked fine for them...  but anytime ive ever used a 400 in something other than a plain stock configuration I have had heat problems.  I would have SERIOUS reservations about putting an SB 400 in a car known for heat problem like a Corvette.

as for the poor compression between #1 and #3..  i would say that side by side cylinders are neither worn cam lobes or rings.

one cylinder i can believe..   but two ? still not that rare... but side by side ?

usually this is head gasket, cracked head, cracked cylinder wall.

pulling the heads is a half days work..  i would pull the heads... check them for cracks and warping, burnt valves, etc. run the two cylinder through a couple of strokes..  check them for cracks..

you might get by with fixing it for the cost of a top end gasket kit.

just be very careful putting a 400 in a vette..

Well Gentlemen and Ladies;

I just finally got thru all the crud and found that the engine in my baby has a GM Casting Code of GM 5.0L on the block by the transmission housing and on the front passenger side tab is V0719DDN and under that VDL165016.

Does this mean it is a 305 engine in the car currently?  Also the VIN code for the engine is an A or L-48 car.

This explains a lot from the PO.  The temp sensing unit and other items have not worked on this engine.  The decoder on this site doesn't say whether it is a California car or not.

Now I am confused...

Either way, it gets a new engine now.

Dennis

Dennis,

I know your questions weren't directed at me but I can't resist putting my two cents in.  First of all, if you have two adjacent cylinders with low compression that is an indication of a breached head gasket.  For what it's worth, (I'll probably open a can of worms here) when I buy parts for my toys I go for quality and Autozone and O'Reilley's fall more under your Wal-Mart grade of parts stores.  I've been turning wrenches for over thirty years and I don't buy anything from those guys unless I just don't have any other choice.  Good luck with your adventure and just a little food for thought, low compression doesn't usually cause a misfire under load unless it's caused by flat cam lobes on the exhaust side.

Rich

 

Rich;

Thanks for the response.  I have had a couple of guys tell me they thought it was a flat cam lobe, and that this was a supposed problem on the later model C3's. 

I was told by one of the local vette mechanics that if it is a cam, it would be about a $700 deal.  My thought was to go ahead and build up the 350 in my barn, which I can do for about the same $$$ and have a zero time engine.  Now that I know the engine in the car is a 305, I will be working the swap.

As for where to buy, If I need bearings, rings and a good gasket set, where would you recommend I go?  I am open to any and all help from this site.  That's why I joined.

Again, I appreciate your response.

Dennis

Summit is the place for me. I don't use Kragen, or any other of those guys unless I'm buying oil or lite bulbs. We have a AC/Delco superstore here and they have quality parts, but most of my hard parts come from Summit. My .02

Dave

Dennis, an '80 model with a 305 would have to be a California car, unless some Gomer installed the engine in it. Do the vin #s match on the engine? (CHECK here to see where the nums are.)
I'd have to agree that it sounds more like a head gasket failure on that one.

I'm with Ben on not using a 400. Too many problems with the heads/block for me. I didn't have time to check out the casting #s on what you have, but I can later...

Joel;

Thanks, I know she has a new front clip with an L-82 wiring harness (unless they all came with L82 wiring harnesses).  It is obviously not the original engine and I strongly suspect the last PO is the one who made the change.  The VIN decodes to an L-48 350 engine, so I don't believe it is a california car.

I'm kinda stuck with the motor I have in the barn for now (cash flow wise) so I was hoping to be able to make it work for 80K miles or so.  It would at least get a 350 back in the car and I wouldn't have to cover her for a year or so.

The numbers show 3970010 for the block, which is a block that lots of corvettes used.  333882 for the heads, 350 & 400 application.  I'll know more when I get the pan off as to whether it is a 4 bolt or 2 bolt main.  The above data is from the Corvette Black Book and a book on rebuilding Chevy 350's.

Thanks to all who have responded, I really appreciate it!

Dennis

Dennis,

       Depending on the casting #'s on the 305 heads, and if they are not cracked can be used on your 350 block( FYI you can use 305 heads on 350's,however cannot use 350 heads on 305's)and produce great HP,however is costly due to machine work i.e. opening 1.84 intake vales to 1.94 and if you increase exhaust to 1.6 valves,and because I only do performance engines,I have the rocker studs either drilled and pinned or remove stud drill and tap for screw in studs.Cost of these applications are pretty close,however I like screw in studs better...

     CA. 80 Vette Vin will be an H engine in the VIN,so I would suspect someone tampered with your original engine.I too have an 80 Vette that was made in St.Louis for CA. and came with 305 which is now balanced blueprinted and in my sons '57 Chevy pick up and kicks butt..

     I agree with the gentlemen who orated the FACT that a 400 would be a poor choice for a Vette compartment as it needs a lot of cooling because of the siamese cylinders and reduced water jacket..

     We use 400's in circle track racing as we have huge radiators and cooling systems..

      As I mentioned we use stock 400's in 1/2 ton trucks and Impala size cars i.e. 1972 Impala 4 dr. sedan,big radiator etc. and still a problem..

       Your 3970010 block is the best block even if it is a two bolt, as this casting along with the crank, where used in 1/2 ton trucks for hauling and are durable...Check date code up by the pinnicale of the block to see when it was cast..

        Good luck and look towards better days to come....

Dennis,

I see you've had a few responses since I was on last night. To answer your question about where to buy parts, I usually buy from my local jobber/machine shop but if you are just wanting to freshen your powerplant up with no machine work I would have to agree with Pumps and say Summit for my first choice with Jeg's as a close second.  I would still recommend having your block and heads inspected by a qualified machinist, it can save you a lot of headaches down the road and he can probably supply you with the parts you will need at a decent price.  I prefer to deal with someone I know, that way you are more likely to get good support after the sale should you have any problems or questions.  Just my two cents.  Good luck,

Rich