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Discussion Starter #1
Hey everybody I have a question or two.. Well probably more than two.:dontknow: My brother and I are attempting to swap the motor out of our 78 Caballero. I've swapped identical motors before , but not upgraded like this. The replacement engine is in question here. We purchased a 78 Monte with a Frankenstiend 350, and Turbo 350 transmission.
1.) The Engine code or ID number stamped on the plate behind the alternator is "V0119800". There is no suffix code like I've seen on other GM motors.
(This appears to be a 1979 crate motor from GM Targetmaster 9800=1979)

2.) The Cast number on the back of the block "39-GM 14016379"
(This appears to be a 1978-85 -350 block)

3.) The cast number(14014416) and design(Saddle and Vertical Bar) on the heads appear to be from a 305
("Late-model 305, conventional valve covers, intake port not restricted; lightweight; 57cc chamb")

4.) The V6 bracketry and pulleys don't seem to be swappable. The existing pulleys on this V8 Frankenstien are a hybrid flat serpentine belt from Crank->Alt-->Water Pump, and tensioned by alternator. The other is a vbelt off the back of the hybrid 2 groove crank, running the power steering pump. They even look a little out of
allignment. I believe the old bracketry from 79 was used, just with new pulleys. As this motor was changed from it's 79' crate arrangement. Looking into aftermarket pulley systems at this point.

5.) My questions are:
Does any one have any advice as to what I have going on for an engine here, or what else I need to investigate to figure out what we have.
What show stoppers might we run into doing this swap. Motor mounts, exhaust mainfold/headers, throttle cable from pedal?

Cheers, and thanks for your help in advance!!!:beer:
 

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I guess I'm wondering why they put 305 heads on a 350 block. Should I look at casting numbers on the crankshaft for more information??

Radiator, and cowl need to be replaced too??
 

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I can't help you on the numbers, but I can offer a few bits of info. My 87 has the same belt setup with a flat ribbed belt for the alternator and water pump and separate v-belts for the A/C and P/S pump. It was the OEM setup. As far as the heads, a low-buck swap years ago was to use 305 heads on a 350. Valve sizes were 1.72 intake vs the 1.94 intake on a 350, but the smaller 305 combustion chambers upped the compression from the pitiful large chamber (76cc IIRC) 350 heads of the 70's and 80's, boosting low and midrange power. If your original engine was a Buick 231 V6 (front-mounted distributor), none of the brackets will interchange. If it was a Chevy 229 V6, most everything will bolt onto a 305 or 350. Some of the newer exhaust manifolds won't be a direct bolt to older heads, as the rearmost hole on the right side head is in a different position, but that shouldn't be an issue on a 305 head. I ran into that problem when I was swapping a '73 400 in place of my '78 305, but I just used red silicone on the rear port and went without the rear bolt. It sealed fine for as long as I had it.

Bill
 

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Thanks Bill!! Yeah I'm definitely a weekend mechanic.. Never done a V6 to V8 swap like this.. Yeah the engine is the original GMC 231 V6 and the dist. is front mounted.. On quick inspection the brackets didn't look like they'd fit. I am looking at March Performance pulley systems, or get a used set off a truck. I'm pulling the pan off today, and I'll get more casting numbers as I go, to help ID this beast.. It has a 750cfm edelbrock carb.. Thinking it's too much sauce for this baby, but not sure. Was thinking a 600 would be a better fit. Thanks for the response!! :You_Rock:
 

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I guess I'm wondering why they put 305 heads on a 350 block. Should I look at casting numbers on the crankshaft for more information??

Radiator, and cowl need to be replaced too??
If the block casting number says it's a 350, it cannot be a 305 since the 350 bore is 4.00" and the 305 is 3.375". The cranks are both 3.48" stroke, though.

It's a 350. It just has 305 heads. NBD.

Jack
 

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Discussion Starter #6
Thanks again for the help!! Figure they beefed up the cam and put 305 heads on it, and put a 750cfm on it to dump gas in it. I'm accumulating pictures as I go, so I'll start posting progress on here soon. Still stuck on the brackets for this beast.. The 305 head (passanger side) only has one accessory hole in the top corner. I've looked on multiple sites, and with the amount of options I'm lost.

March has a 22082 setup that will bolt on, but the problem is really cost. I'd be looking at $700 for the pulley/bracket kit, and another $200-250 to replace the R4 A/C pump with a Sanden 508. Expensive, but will keep the orientation of my accessories correct with the ALT/A/C on the passanger side, and look pretty sick. The other question is the radiator clearance, it does state on March's site to check clearance between the long water pump, and radiator. Problem is the motor is still out of the car.. Guess I'd want to wait to put the motor in and mock up the radiator before I ordered such an expensive kit. Also wanted to run a clutch fan, so the clearance is crucial!!

I would like to find a stock set of brackets that keep the vbelt config with existing compressor, and just upgrade the pulleys.. Anyone have pics of a stock 350 bracket setup on a 78 gbody with A/C??

Lastly, pulled the V6 (231) out last weekend, and went to pull the motor mounts., and check allignment for 350 mounts. However it appears the only way to get access to the bolts is to remove or bottom control arm, shock/spring to gain access to the hole into the crossmember. I do see a few service holes in the crossmember, but I don't see any other way to get at them besides dissassembling. Problem is we bolted up a hotchkis TVS kit already, and now are looking at taking it back apart. :let_it_all_out: Really the only thing that pisses me off is compressing the $%! springs, always scares me. Any help or advice geared toward my tribulations, is greatly I mean greatly appreciated!
 

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Hey Jack,, the bore for a 305 is 3.736,, the 305 heads on a 350 is fairly common, just have to watch the compression ratio,, you can swap out the motor mounts that bolt to the frame,, I had to "smoke bend a wrench" so I could get to the bolt heads on the inside of the frame,, but it is easier with the control arms out of the way,, clean and paint the frame while everything is out,,,, Matty man
 

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Discussion Starter #9
Figured I'd start adding some pic's for ya'll.. :smileyb:


Header Panel off, Radiator bracket removed, 231-V6 getting pulled, and put in storage.



Heart transplant, Step 1 remove the heart. :beer:




Prep the TM V8-350


Little paint here, little paint there


Should be bead blasting the intake this week.. I pulled a EB 750cfm carburator off the engine when I got it.. Figure that was overkill for a 350, even with the 305 heads, and the possible cam upgrade. My buddy has a 600cfm carb, and told me that would be good to go.. Any advice on the carb size?? Using a performer series intake from Edelbrock. Thanks guys!!
 
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