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-   -   TPI 305 need rebuild.... time for 350? (http://www.hotrodders.com/forum/tpi-305-need-rebuild-time-350-a-219458.html)

zildjian4life218 05-16-2012 07:01 AM

TPI 305 need rebuild.... time for 350?
 
Okay... I have a friend that wants me to rebuild the motor out of his 86 f-body. Its a 305 TPI with an automatic transmission. He was having issues with it over heating and drove it anyways and now the engine runs pretty rough...

Im thinking instead of rebuilding the 305 why not swap in a rebuilt 350... stock rotating assembly just new rings and bearings maybe a small cam and try to find a set of those 305HO 416 heads and rebuild those for him. Of course I will need to burn a new chip for the ecu and add some larger injectors..

What would you guys do if you had a 305 that needed rebuilding. My vote is swap a 350 into its place. His budget is between 1000-1200 and I think I can make it work once I get the quote back from the machine shop.

123pugsy 05-16-2012 08:10 AM

I'd go 350 but not sure about the small heads.

zildjian4life218 05-16-2012 08:47 AM

Quote:

Originally Posted by 123pugsy
I'd go 350 but not sure about the small heads.

I have heard quite a few good things about these heads with some minimal port work done to them... plus with the tpi intake this is gonna be built for low end torque, those intakes aren't really known for their high rpm breathing abilities.

123pugsy 05-16-2012 09:23 AM

TPI is no good after 4800 rpm's but I found restrictions can really choke it off.

Intake and exhaust on my truck TPI were restricted and robbing a bunch of torque and HP.

Just seems smaller valves would do the same.

Second entry down shows the difference in dyno pulls after removing restrictions. Maybe these heads are a totally different deal, but in theory restrictions cost torque and HP.

TPI DYNO PULLS

my87Z 05-16-2012 10:58 AM

personally i would find a complete vortec 350, inspect it, and then change it to a carb set up, ditch the ECU. he should have a 700R4 trans which can easily be adapted to a carb set up with the detent (TV) cable.

zildjian4life218 05-17-2012 09:28 AM

Quote:

Originally Posted by my87Z
personally i would find a complete vortec 350, inspect it, and then change it to a carb set up, ditch the ECU. he should have a 700R4 trans which can easily be adapted to a carb set up with the detent (TV) cable.

This will definitely be a consideration but I think he wanted to keep it efi.

zildjian4life218 05-17-2012 09:33 AM

Quote:

Originally Posted by 123pugsy
TPI is no good after 4800 rpm's but I found restrictions can really choke it off.

Intake and exhaust on my truck TPI were restricted and robbing a bunch of torque and HP.

Just seems smaller valves would do the same.

Second entry down shows the difference in dyno pulls after removing restrictions. Maybe these heads are a totally different deal, but in theory restrictions cost torque and HP.

TPI DYNO PULLS

I think the posts I have seen on these heads involved installing 1.94" intake valves

S10 Racer 05-17-2012 10:08 AM

You will have to change the ecu if you change to a 350.

zildjian4life218 05-17-2012 10:21 AM

Quote:

Originally Posted by S10 Racer
You will have to change the ecu if you change to a 350.

Not just reprogram it for the larger injectors and displacement but actually physically change it?

S10 Racer 05-17-2012 10:26 AM

Quote:

Originally Posted by zildjian4life218
Not just reprogram it for the larger injectors and displacement but actually physically change it?

Either or. It may be cheaper to find one in a junk yard and just replace it as opposed to reflashing it.

zildjian4life218 05-17-2012 10:27 AM

http://tpiparts.net/305_tpi_to_350_tpi_conversion

says just gotta change the prom, knock sensor, esc module and injectors so the efi wont be bad to do. I have been looking for an excuse to buy an emulator and chip burner for awhile so now I have that excuse

123pugsy 05-17-2012 01:59 PM

Quote:

Originally Posted by zildjian4life218
I think the posts I have seen on these heads involved installing 1.94" intake valves


Bigger valves would help for sure.

Rhansen 05-18-2012 05:23 AM

You won't necessarily even have to change the ECU/Prom or injectors. I swapped in a 350 (crate motor for an 87 pickup) into my 87 IROC back in 1991. This was a MAF setup not speed density and all I did was use an adjustable fuel pressure regulator to bump up the pressure to 50 psi. Only other mods were edelbrock headers, 3" single exhaust, and a homemade ram air setup.
It worked flawlessly until I swapped cams. IIRC the new cam was a Blue Racer dual pattern with 112 lsa, 204/214 duration and .435/.465 lift. After the cam swap the car would surge a bit at idle and sometimes stall sitting at lights. Had a custom PROM burned at Arizona Speed and Marine which cured the idle problem but made the mpg nosedive and made no improvement in ET/mph at the strip.
I would think with the right cam and an adjustable regulator on a mass air motor you could do the swap without new injectors or a prom.

AutoGear 05-18-2012 07:13 AM

If he wants to invest some money into it and youre going to try your hand at burning, you might want to see how he feels about picking up a different manifold and heads. Over on thirdgen.org, you can always find someone doing a LS1 swap, and there usually a few minirams, ported OEM intakes, worked iron heads, 58cc aluminum heads etc on the for sale boards. Also, there are some racing circles that need date coded 305 blocks, so it should be worth more than scrap.

zildjian4life218 05-18-2012 08:11 AM

Quote:

Originally Posted by AutoGear
If he wants to invest some money into it and youre going to try your hand at burning, you might want to see how he feels about picking up a different manifold and heads. Over on thirdgen.org, you can always find someone doing a LS1 swap, and there usually a few minirams, ported OEM intakes, worked iron heads, 58cc aluminum heads etc on the for sale boards. Also, there are some racing circles that need date coded 305 blocks, so it should be worth more than scrap.

awesome thanks for that advice. Ill definitely take a look. I just figured with the way I wanted to build the engine his transmission and rearend should last longer lol.


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