81 Engine swap or rebuild

[smooth-rider]

Hi all, first post but boy I need some advise. I bought an 81 vette that had a cowl fire, engine harness fried, as well as I have to fiberglass a new cowl into place. Easy enough, the big ? original motor has some pitting in one cyl., should be able to be bored. Have done a great deal of reading, one rebuild site showed were the 383 stoker could use standerd junk gas even at 10 compression ratio, becuase of the longer time piston is at top of cylinder, less detenation, not sure if thats feassable, I do wanna run pump 87 gas, it will be a DD for me and my wife.
Stock 190 hp for a vette is a disgrace, would like to get to say 300hp, stock drive line should be able to handle it from what i've read. Now the skinny, might need a new carb might as well add a new intake, all new hoses and wiring, belts, sending units sensors and so on. Maybe more cost effective just to buy a 80+ or 90+ TPI engine tranny with wiring and accs. off ebay to retro fit. Will one of those fit the car and would I have to reweld engine mounts tranny mount and possibly shorten or lenghen or mod the drive shaft.
Car only has 56k on it so I wanna do it good, body off atm and frame has been POR15 Fantastic stuff!!! Energy suspension suspension kit and body mount kit. Have true duel exhaust and plan on not putting the air pump back on, does the ECM have to be redone then? Have the stock lockup 350, can I put a higher stall in and just not hook the wire up for the lock-up or would I have to get a new trans. Tall order I know but any help would be great. Oh ya then there's money, I keep forgeting to water that tree out back.

 

[LannyL81]

Hi,

I am in the process of re-assembling my stock 81 engine. Sure wish I had gone teh 383 route though....started to several times, but final factor was that the block is a 2 bolt main and I did not have a good feelin' about putting a 383 stroker in a 2 bolt main block.
If you do not care about any kind of orginalty, then get a TPI engine...say a L98 or if you have lots of money an LT4 and put in there. Probably cheaper would be to get a GM crate engine though...like a ZZ4...but then you have to contend with emission regulations.
I have seen an 81 with an L98 in it....looked great...and since you have to redo the wiring anyway if you go with a stock rebuild...you might as well get the most bang for all your work.

Lanny
Tucson, AZ

 

[smooth-rider]

Yes Lanny now that you mention it I to have a two bolt main, and no it does'nt sound strong enough, will keep the block though and maybe rebuilt it at a latter date. No emissions to worry about here in MN. Going to look into the zz4 but would still need to add the cost of new alt. carb. manifold, distibutor ect. if the ecm can't be used.

One more thing has anyone got a good way to seperate the a-arms without lossing a part of your body.

 

[smooth-rider]

Another question if I could can one use the 81 th350 on the newer tpi engines.

 

[MoeJr]

Smooth pull that original motor and tuck it away. Buy your self either the GM 350-290HP engine or the 350-330HP engine. That is the way to go IMHO.

 

[dk1977]

Has anyone used this company before? http://www.blueprintengines.com/
They list some pretty impressive engines at reasonable prices... They claim around 400 hp & torque for $3000.

 

[smooth-rider]

A balanced engine for around 3k looking into it further now

 

[Glensgages]

Yes Lanny now that you mention it I to have a two bolt main, and no it does'nt sound strong enough.....

I'd guess if you DO build a 383-stroker, and keep the RPMs below 5000/5500, the 2-bolt block will survive fairly-well:
if you have the extra scheckels, why-not set-up that 2-bolt block for 4-bolt/splayed caps, and it'd be good for 500+ HP in the future?
:confused

 

[smooth-rider]

I'd guess if you DO build a 383-stroker, and keep the RPMs below 5000/5500, the 2-bolt block will survive fairly-well:
if you have the extra scheckels, why-not set-up that 2-bolt block for 4-bolt/splayed caps, and it'd be good for 500+ HP in the future?
:confused

Didn't know you could do that with a 2-bolt set up, were do you get the splayed caps and are there new holes to drill, also have decided to try to find a comparible engine to drop in for the time being to work at my own pace to the orginal motor.

 

[smooth-rider]

http://www.edelbrock.com/automotive/mpfi_sbchevy.html
Saw this last night, might go with this when I rebuild the engine, around 1k for the whole thing.

 

[Glensgages]

Didn't know you could do that with a 2-bolt set up, were do you get the splayed caps and are there new holes to drill, also have decided to try to find a comparible engine to drop in for the time being to work at my own pace to the orginal motor.

Yes, that is how you MAKE a splayed-cap block, and why 2-bolt 400" blocks (which have more 'meat' in that area) are much-preffered over 4-bolt 400" blocks.


A competent machine-shop, that handles race-motors, can probably drill the angled (splayed) outer bolt-holes, and get the matching caps, which provide a better clamping surface, and keep the caps 'in-register'.....

 

[smooth-rider]

Now that sounds very intresting

 

[Glensgages]

Now that sounds very intresting

+ tax;
with the 4 cap-bolts threading into the block at 3 different angles, the cap almost CAN'T pull itself off the block.

Most 'serious' circle-burners and drag-racers run this set-up, and if you'd keep the 3.750"-stroke cast-crank below 5500 RPM, it'll make tons o' torque!

 

[bobherr46]

Hey Smooth rider - If you are interested I have a fresh 406(400 bored .030 over) that is ready for asssembly. It is a splayed 4 bolt main block,400 crank,h-beam rods,hypereutectic pistons and includes rings,bearings,oil pump and pan and good heads. It has been balanced. I will take $2400.00 for the parts. I put one of these in my 79 2 years ago and it is really stout. I went through the same thought process that you are having and it finally dawned on me that the cost for parts and machine work is the same for a 350 or 400 block so your only cost difference is the extra price of a 400 block. Those extra cubes only cost a couple of hundred bucks and they are well worth it. Another comment. If you are going the 383 route,I bet with some shopping you can find a finished 4 bolt main 350 block to start with that will be plenty strong for a street motor that will be a lot cheaper than having the splayed caps put on a 2 bolt main block. Bob 618 237 7101

 

[dfw81shark]

Another question if I could can one use the 81 th350 on the newer tpi engines.

I'm running an L98 block with a carb in my 81. You have to use the flexplate from the L98 (1 piece rear main, something about externally balanced crank) with your TH350.

 

[KANE]

Another question if I could can one use the 81 th350 on the newer tpi engines.

You can use the old style block with TPI (86 iron heads TPI set up). Or even an LT1 manifold (with some work... look at LT1intake.com).

If your block is OK... and you can make out cheaper on the project... go for it... use the block.

 

[smooth-rider]

You can use the old style block with TPI (86 iron heads TPI set up). Or even an LT1 manifold (with some work... look at LT1intake.com).

If your block is OK... and you can make out cheaper on the project... go for it... use the block.

Say Dark is this what your talking about? Is 86 the only year that works for this.
http://cgi.ebay.com/ebaymotors/MODIFIED-LT1-INTAKE-AND-LT1-HEADS-TO-FIT-A-L98-ENGINE_W0QQitemZ7990411606QQcategoryZ33617QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[Jack]

First ask & answer a few questions:
Foremost; What is your budget?
Who will do the assembly; you or a shop?
What level of auto mech skill & exp do you possess?
Do you have the time, shop & tools to do the work?

In general ... for MANY folks ... a nice, new crate motor from GM will do a great job for small$.
JACK:gap

 

[KANE]

Say Dark is this what your talking about? Is 86 the only year that works for this.
http://cgi.ebay.com/ebaymotors/MODIFIED-LT1-INTAKE-AND-LT1-HEADS-TO-FIT-A-L98-ENGINE_W0QQitemZ7990411606QQcategoryZ33617QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The intake looks right- but ask the seller to be sure about the heads. I didn't see the center/side manifold bolts machined...

Of course- YOU WILL NEED TO BUILD a TPI system- harness, ECM, fuel system, etc to get it to work. You will need a custom PROM (or go DFI and do it yourself!).

I'd buy a manifold from John Millican versus some unknown guy. John has A LOT of experience with making the changes and giving people a good product.

I have an LT1 intake awaiting the needed machine work to fit a GEN I. I am also waiting until I get back to the states before I get another Vette to put it on!