View Full Version : GM 260 horse engine?


76z28
11-10-2010, 06:37:16 PM
What pistons does it have in it? im guessing dished? I have a set of pretty good heads only problem is they are 76cc chambers...Anyone know?
thanks

CorkyE
11-10-2010, 07:21:26 PM
Cast dished. What are you good heads? Here's specs on that engine, Google is your friend.

http://www.jegs.com/i/GM+Performance/809/10067353/10002/-1

76z28
11-10-2010, 07:23:15 PM
i went to jegs but it wouldn't load... i need to get the casting number off the head, they were in my old 330 horse 360 torque motor

CorkyE
11-10-2010, 07:44:31 PM
If they are old GM cast 76cc heads, it doesn't matter... The bang for the buck seems to be with the vortec heads. I know you'll have to buy a new intake but it's still a better deal in the long run. Depending on how strong the wallet is, you can step up to modern aluminum designs for not a lot more. IMHO

badazz81z28
11-10-2010, 07:54:35 PM
Can't beat modern technology. I can vouch Vortecs are a good budget head. I have ported vortecs on my 350 and has enough power for a street go getter.

BondoSpecial
11-10-2010, 08:04:29 PM
They are not only dished, they are dished pistons that are 100+g heavier than even the normal 1970's stock 350 dished pistons. I had to have a lot of metal taken off my crank to balance my 260 hp crate motor when I put normal cheap pistons back in it, we couldn't believe how heavy the hecho en mexico crate motor slugs were. It's something like a 16cc dish.

76cc pistons on the 260 hp crate motor is going to be very low compression. Even with 64cc heads it will only be around 9:1, which is why I pulled them for some flat tops.

76z28
11-10-2010, 09:05:56 PM
Yea, that is why i was asking...I was afraid but make for a good blower motor untill the bottom end goes. I already have the heads and intake is why i was asking.
Im just in speculation right now, this is for my dads 68 bel air(has the original 307)

Damon
11-10-2010, 09:46:50 PM
ANY 350 will feel like you strapped a second engine under the hood compared to a stock 307!

It's really a shame that GM doesn't offer any inexpensive 350 short blocks with flattop pistons (the ZZ4 bottom end which uses flattops is $2500). Or ANYTHING with forged pistons in it (they're all cast or hypereutectic).

An observation I made recently.... the 260HP 350 LONG BLOCK is less money than just buying the SHORT BLOCK. Sounds crazy, I know, but that's what I found the last time I looked. Buy the complete engine and put your existing heads back on the shelf. Plus you get a cam, lifters, timing chain and the bottom end tin along with it. Saves money plus a bunch of work- just put on your intake and drop it in the car.

z28rod
11-10-2010, 09:51:48 PM
and it a reliable 350 to boot.....

Todd80Z28
11-10-2010, 10:24:42 PM
An observation I made recently.... the 260HP 350 LONG BLOCK is less money than just buying the SHORT BLOCK. Sounds crazy, I know, but that's what I found the last time I looked. Buy the complete engine and put your existing heads back on the shelf. Plus you get a cam, lifters, timing chain and the bottom end tin along with it. Saves money plus a bunch of work- just put on your intake and drop it in the car.Kinda, sorta. You can get the L31 (Vortec) 350 short block with similar-looking dished pistons for $11xx on the web, and my local dealer offered me $12xx. I've contemplated it for a new, budget solution. It's a one-piece rear seal, though.
Like you said, though- it's a shame you can't get a budget flat-top setup from them.

Twisted_Metal
11-10-2010, 10:42:38 PM
I followed Damon's plan when I swapped out a 305.
It's been completely trouble free for 20k miles so far.
You get a three year warrantee too.

night rider
11-11-2010, 04:17:39 AM
Cast Aluminum dish with four valve reliefs Pistons-#12514101

Its the same piston used in the 260, 300 and 330 HP crate engines.

I can't find the CC spec listed anywhere but based on listed bore, stroke, head cc, gaskets (4.100" x.028", deck height I come up with 8.343cc pistons to get 8.5:1 compression.

Which that piston CC don't sound right for a dish 4vr piston. That sounds more like a flat top 4vr

Engine consists of the following parts:
Block -part # 10066034, casting # 10066036
2 piece rear main seal 4 bolt main
Crankshaft- # 3932444
Nodular Iron 1985 and older flywheel bolt pattern.
Powdered Metal Connecting rods- # 10108688
Cast Aluminum Pistons-#12514101
G.M. High Volume Pump Oil Pump- part # 12555284
Hydralic Flat tappet Camshaft- #14088839
Intake Lift-.383" Exhaust Lift-.401"
Intake Duration @ .050"- 194 Exhaust Duration @.050"- 202
Lobe Seperation-112
This cam Has a mechanical Fuel Pump Lobe.
This is a low end Torque oriented camshaft.
Cylinder Heads- part # 14034808, casting #33417369, 1.94" Intake valve, 1.50" Exhaust Valve, 76cc Combustion Chamber, 7 Bolt style Exhaust Flange Standard, 85' and prior intake manifold bolt pattern. Perimeter bolt style Valve Covers. This head is very similar to the old #882castings from the 1970's

z28rod
11-11-2010, 04:32:56 AM
dosnt the 260 hp goodwrench motor have 380 ft lbs of tq. also ?? thats not bad amount of tq. for 1600 bucks with a warr...... for a driver it should cruise very nice and still give some nice pull to her...

DesmoEd
11-11-2010, 08:26:07 AM
dosnt the 260 hp goodwrench motor have 380 ft lbs of tq. also ?? thats not bad amount of tq. for 1600 bucks with a warr...... for a driver it should cruise very nice and still give some nice pull to her...


you need 300+ hp to make 380tq

260hp should be in the 290tq range......enough to get the job done but don't be surprised if you get smoked by some dude in a turtleneck driving a 535Beemer:)

76z28
11-11-2010, 10:56:16 AM
you need 300+ hp to make 380tq

260hp should be in the 290tq range......enough to get the job done but don't be surprised if you get smoked by some dude in a turtleneck driving a 535Beemer:)

thats what my camaros for =)
but he is unsure what he wants to do, it seems like a good buy for an engine that just needs an intake and carb
He may want to do a big block. He is up in the air i just wanted more info about it.
And the 307 is pretty surprising in how much tq it makes lol idk what gears are in the car though

DesmoEd
11-11-2010, 11:12:21 AM
thats what my camaros for =)
it seems like a good buy for an engine that just needs an intake and carb
He may want to do a big block.



It is a decent buy for the price - 64cc vortecs would do wonders on that fresh bottom end and with a 9-1 CR and a 264`ish cam you are in the 300hp range easily

A BB is gonna require a whole bunch of different accessories

76z28
11-11-2010, 06:49:19 PM
It is a decent buy for the price - 64cc vortecs would do wonders on that fresh bottom end and with a 9-1 CR and a 264`ish cam you are in the 300hp range easily

A BB is gonna require a whole bunch of different accessories

Yea, he knows, its a project car.
The BB is also use able with basically any gear combo also(as in like 3.08s or something)

trroscoe
11-28-2010, 12:11:27 AM
You can make over 300 hp with that GM crate 260 just by changing out the cam. The only difference in the 260/290 hp versions is the camshaft. Slap a good cam and some good flowing 64cc heads and your getting close to 375hp easy. The pistons in these crate engines are the -12cc 4VR dished versions.

I have the 290hp version in my chevelle that has a stock bottom end that has held together for 15,000 miles with all kinds of mods to the top end.

z28rod
11-28-2010, 12:50:01 AM
You can make over 300 hp with that GM crate 260 just by changing out the cam. The only difference in the 260/290 hp versions is the camshaft. Slap a good cam and some good flowing 64cc heads and your getting close to 375hp easy. The pistons in these crate engines are the -12cc 4VR dished versions.this is true, hotrod did a big build on one of these got her past 400 hp.

76 camaro car 1
11-28-2010, 09:28:54 AM
Cast Aluminum dish with four valve reliefs Pistons-#12514101

Its the same piston used in the 260, 300 and 330 HP crate engines.

I can't find the CC spec listed anywhere but based on listed bore, stroke, head cc, gaskets (4.100" x.028", deck height I come up with 8.343cc pistons to get 8.5:1 compression.

Which that piston CC don't sound right for a dish 4vr piston. That sounds more like a flat top 4vr

Engine consists of the following parts:
Block -part # 10066034, casting # 10066036
2 piece rear main seal 4 bolt main
Crankshaft- # 3932444
Nodular Iron 1985 and older flywheel bolt pattern.
Powdered Metal Connecting rods- # 10108688
Cast Aluminum Pistons-#12514101
G.M. High Volume Pump Oil Pump- part # 12555284
Hydralic Flat tappet Camshaft- #14088839
Intake Lift-.383" Exhaust Lift-.401"
Intake Duration @ .050"- 194 Exhaust Duration @.050"- 202
Lobe Seperation-112
This cam Has a mechanical Fuel Pump Lobe.
This is a low end Torque oriented camshaft.
Cylinder Heads- part # 14034808, casting #33417369, 1.94" Intake valve, 1.50" Exhaust Valve, 76cc Combustion Chamber, 7 Bolt style Exhaust Flange Standard, 85' and prior intake manifold bolt pattern. Perimeter bolt style Valve Covers. This head is very similar to the old #882castings from the 1970's
I think my targetmaster has 993 heads from what I remember?

THOMAS81Z
11-28-2010, 09:42:51 AM
I followed Damon's plan when I swapped out a 305.
It's been completely trouble free for 20k miles so far.
You get a three year warrantee too.
i have the same motor , i will pick up a set of vortec heads but what cam did u use with the vortec heads ??

Twisted_Metal
11-28-2010, 10:20:58 AM
I haven't swapped to Vortecs.... My three year warranty hasn't expired yet. ;)

z28rod
11-28-2010, 01:00:46 PM
read that hotrod article they used a couple of cams.

AJ_72
11-28-2010, 04:18:57 PM
Here are the Goodwrench Quest series of articles which Chevy High Performance (under the guidance of Jeff Smith) did a write up on starting with that same crate engine and building it up, progressively, to make more HP on a budget.

They started by a simple cam swap, some head modifications, then eventually switched to the Vortec heads. It's a good read.

When you click on the second part of the series, you'll read that in retrospect, they found out the true compression ratio of the engine is 7.8:1. Pathetic, to say the least.

http://www.chevyhiperformance.com/techarticles/46320_gm_350_crate_engine_build/index.html

http://www.chevyhiperformance.com/techarticles/46326_gm_350_crate_engine_build_ii/index.html

http://www.chevyhiperformance.com/techarticles/46359_gm_350_crate_engine_build_iii/index.html

http://www.chevyhiperformance.com/techarticles/46364_gm_350_crate_engine_build_iv/index.html

http://www.chevyhiperformance.com/techarticles/46370_gm_350_crate_engine_build_v/index.html

Jim Mac
11-28-2010, 11:23:17 PM
I was talking to a guy with a street rod, he's got the old target master motor, he just bolted a underdriven 6-71 on top of it. with a pair of eddy carbs and he says it runs great, no loping, no over heating, starts and idles smoothly. jim

z28rod
11-29-2010, 12:09:01 AM
I was talking to a guy with a street rod, he's got the old target master motor, he just bolted a underdriven 6-71 on top of it. with a pair of eddy carbs and he says it runs great, no loping, no over heating, starts and idles smoothly. jimyou put this in a t-bucket and there is not much on the street you can't dust....

76z28
11-29-2010, 12:46:34 AM
you put this in a t-bucket and there is not much on the street you can't dust....

seriously.....

z28rod
11-29-2010, 01:25:41 AM
Those Target 350's Are One Rock Solid 350 Engine That Can Take Some Abuse For Sure, I Had One In My 77 K5 Blazer And It Climbed Mount Beacon Here In The Hudson Valley, A Good Climb Around Here, And With A Half Keg Of Cold Bud In The Back Mind You..... Spent The Night Cause No Way To Drive Her Back Down, Was Cool Had Bags And Tents With Chicks :)

Penskr2
11-29-2010, 02:16:17 AM
i just recently installed a 260hp crate motor in mine also, still has the 76cc heads on it, slapped a cam in it, put my intake and carb on it and went to the track. Ran a 13.38 @ 102 in a 3,400lb <me in it> 72 camaro

Im guessing some where around 400hp ?

z28rod
11-29-2010, 06:14:48 AM
Penskr2, Are You Sure It Was A 260 Hp Targetmaster Motor ? Did You Buy It New And What Cam Did You Install ?

Penskr2
11-29-2010, 09:30:44 AM
Yep, 260hp made in Mexico, Target master. i even pulled the pan off when I got it and found it is a 4 bolt main with smooth rod caps. I'm guessing late model rods, but for cheap insurance I installed a rubber pan gasket from a '75 Chevy, that I picked up at kragens ($35). But before that I done some talking to a good friend of mine and went to power house and bought an E1067P cam. Great cam and ran it in a few motors, no problems.

trroscoe
11-29-2010, 02:20:48 PM
No way your anywhere close to 400 Hp with just a cam change. With those 74cc heads 300hp is probably more like it. Still good ET and MPH with that motor. I have the 290 hp version of that motor in my Chevelle. To make 400hp you will have to change your heads and raise the compression. With the stock heads they are only listed at having 8.5 to 1 compression. I swapped the heads and cam and a bunch of other stuff and should be right at 400 HP. They are good engines to modify and can make some great HP.

Penskr2
11-29-2010, 03:31:39 PM
I have a set of 64cc heads that I'm goin to throw on before march meets, see how she is with the new heads. Oh yea and the T-Ram.

76z28
11-29-2010, 03:38:48 PM
I have a set of 64cc heads that I'm goin to throw on before march meets, see how she is with the new heads. Oh yea and the T-Ram.

Hey, you part of the bakersfield camaro club?
i just saw you are from bakersfield

Penskr2
11-29-2010, 05:34:35 PM
No, me myself and I.. I'm not currently in any group.

wild84
11-29-2010, 07:22:18 PM
This is the same motor we had in my ex's 77 camaro. Had about 20,xxx miles on it when we got it. Long tubes, performer manifold, msd ignition, speed demond vac secondaries, stock converter, 3.08, and a small comp nitrous cam (.462/.480 218/230 113lsa) ran 15.0@ 93 on the piston. 64mm turbo w/8psi (pump gas tune) on a 3000 converter ran 12.2@110, and 17psi ran 11.89 on a 800' pass (went lean in 3rd gear and got out of it) also, on 17psi, it was blowin threw the converter pretty bad. Managed a 7.3 1/8th at 94mph though. Tough motor for bein built in mexico. I expected to be pickin parts off the track at 6psi. I think with a better converter, and some work in the carb (really needed boost refranced powervalves) it would have gone 11.3's in Vegas.

76z28
11-29-2010, 09:53:57 PM
No, me myself and I.. I'm not currently in any group.

Oh, we dont do much any more thoug, quiet sad. I think ive seen your car around town...not sure