C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

350 Crate engine and TPI

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Old Apr 11, 2012 | 07:54 PM
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Default 350 Crate engine and TPI

I'm wondering...anyone know whether a TPI intake manifold will bolt on to this 350 GM engine? http://www.jegs.com/i/GM+Performance...67353/10002/-1
Thanks
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Old Apr 11, 2012 | 08:59 PM
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Should bolt right up. You would end up with a motor very close to what an 85 came with.
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Old Apr 11, 2012 | 09:39 PM
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I thought the early TPI's had the 4 center bolt holes on the manifold base going straight down instead of at the same angle as all the other manifold bolts. If that is the case you'd have to oval those holes or get a later base to make it a bolt-on. Not a lot of work, just something to be aware of.
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Old Apr 11, 2012 | 09:55 PM
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Originally Posted by mcm95403
I thought the early TPI's had the 4 center bolt holes on the manifold base going straight down instead of at the same angle as all the other manifold bolts. .
Back to front

All Vette TPI and 85/86 F-Body TPI heads retained the old school SBC intake bolt angle

Only '87+ cast iron ( centerbolt ) heads have the revised bolt angle on the center 4 bolts
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Old Apr 11, 2012 | 10:08 PM
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Originally Posted by rodj
Back to front

All Vette TPI and 85/86 F-Body TPI heads retained the old school SBC intake bolt angle

Only '87+ cast iron ( centerbolt ) heads have the revised bolt angle on the center 4 bolts
The C4s kept the old angled bolt pattern. Even thats not a big deal. My Ebdelbrock base was made to go either way.
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Old Apr 11, 2012 | 10:20 PM
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I'm thinking that I read or heard somewhere that there was a passage hole for the EGR system that needed to match between the manifold and the block but having not worked on a lot of these - I don't know if this is an issue or not.
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Old Apr 11, 2012 | 10:42 PM
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Originally Posted by pletzvet
I'm thinking that I read or heard somewhere that there was a passage hole for the EGR .
If requiring EGR functional

Vette intake base can be used on any heads
F-Body intake can't be used on Vette alum heads because they have no exh riser from head ; used a tube from pass side exh manifold as supply
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Old Apr 12, 2012 | 12:47 PM
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Originally Posted by pletzvet
I'm wondering...anyone know whether a TPI intake manifold will bolt on to this 350 GM engine? http://www.jegs.com/i/GM+Performance...67353/10002/-1
Thanks
I looked into this engine a couple of years ago for a replacement in my 85 and I was told the engine was not designed for fuel injection, although I am sure the TPI setup would bolt on directly. I was also told the cam would need to be swapped out too. Still, $1500 with free shipping is a great price.
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Old Apr 12, 2012 | 06:59 PM
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Originally Posted by ejscarfo
I looked into this engine a couple of years ago for a replacement in my 85 and I was told the engine was not designed for fuel injection, although I am sure the TPI setup would bolt on directly. I was also told the cam would need to be swapped out too. Still, $1500 with free shipping is a great price.
Worked fine with mine back in 2002. Even seemed better, probably because the old one had around 180K on it before letting go. Great engine for a stand in while you build your dream engine. GM performance parts website lists a 290 hp version of their bread and butter engine but for 700-800 dollars more, not sure it's worth it.
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Old Apr 12, 2012 | 07:07 PM
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Originally Posted by ejscarfo
I was also told the cam would need to be swapped out too. Still, $1500 with free shipping is a great price.


2pc rms, 4 bolt, flat tappet, I didnt know GM still made them.
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Old Apr 12, 2012 | 07:46 PM
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Originally Posted by 1985 Corvette
GM performance parts website lists a 290 hp version of their bread and butter engine but for 700-800 dollars more, not sure it's worth it.
Major difference is the cam ( and springs to suit presumably )
260Hp engine
194 deg / 202 deg.383” Intake / .401”

290Hp engine
222 / 222 .450” Intake / .460”

better to buy the base engine and swap in a cam more suited to TPI

Last edited by rodj; Apr 12, 2012 at 07:48 PM.
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Old Apr 12, 2012 | 11:57 PM
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Can you help me understand the cam issue a little more clearly? I honestly never even thought about cam compatibility and the TPI system. What are the specs for a stock L98 cam? I'll see if I can get comparison specs on what comes with the crate engine. Not to sound glib, but would one notice if the cam specs weren't right on par with what the stock TPI came with?
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Old Apr 13, 2012 | 12:56 PM
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The cam falls a little short of the stock cam. At 112 degrees LSA, the computer should handle it just fine. Stock is 114.5. (I am running a 112 LSA cam). The compression at 8.5:1 is pretty weak, this is due to the dished pistons. The stock 85 has forged flat tops, with compression around 9:1 I believe. Both engines have 76 cc chambered heads. This is just a slightly weaker version of your stock engine, but I bet it would run just fine. You could put thinner head gaskets on it and change out the cam for less than 200 bucks.
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Old Apr 13, 2012 | 02:52 PM
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knowing what I know today, this is the route I should have taken and pocket the difference.
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Old Apr 13, 2012 | 09:36 PM
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Originally Posted by powerpigz-51
This is just a slightly weaker version of your stock engine, but I bet it would run just fine.
You could put thinner head gaskets on it and change out the cam for less than 200 bucks.
Good writeup series of what is required to make power from the 290Hp engine
http://www.chevyhiperformance.com/te...iii/index.html

Last edited by rodj; Apr 13, 2012 at 09:40 PM.
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Old Mar 4, 2013 | 11:54 PM
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A little curious how this build turned out. I just bought a 1985 Corvette, with a spun main bearing (I am pretty sure that is what it is, I am pulling the oil pan just to confirm what the guy I bought it from told me he thought it was). I want to replace the motor (maybe the tranny too) and I am not looking for a ton of HP, maybe a little more then the stock 230 HP 330 Ft lbs. If this motor worked with the TPI then I think I will use it....unless anyone else has any other suggestions.
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Old Mar 5, 2013 | 08:47 PM
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Is that a ZZ4 crate motor ?
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To 350 Crate engine and TPI

Old Mar 8, 2013 | 10:26 PM
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I am not sure.

Im still looking around for a replacement for my L98 (1985 Corvette). I want to keep the TPI. The motor will be out within the next few days, any suggestions ideas???
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Old Jan 27, 2015 | 12:53 PM
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Originally Posted by strotter13
I am not sure.

Im still looking around for a replacement for my L98 (1985 Corvette). I want to keep the TPI. The motor will be out within the next few days, any suggestions ideas???

My son has a 1985 corvette that the engine had a valve that was stuck. Was told that it was a hand grenade waiting to blow.

He only paid 2700 for the car and was very disappointed that after 2 months is went to crap.

We ordered the GM 350/360hp engine from Jegs. Took a couple of days to remove it. A day to move the parts from the old engine to the new engine. A few more days to install it and put back all the TPI stuff.

We did not add anything different except that engine as it arrived from jegs.

We are very pleased with how it turned out. Everything fit perfectly. Started right up and this car is much better that is was the day he purchased it.

Costs

Engine - $1500 on sale at jegs
Gaskets - Intake (about 40)
Gaskets Exhaust Manifold (about 27)
Oil 10 qts with an oil change right after the install 40
Harmonic balancer 70
Balancer bolt 25
balancer installer / Puller 27
Happy Hooker 79
We also changed the IAC, Knock Sensor, oxy sensor, oil pressure just because we were in there.
I had about all the other tools.

All in all it was about $2000 to have a new engine in that car. Eismann's Corvette center in Jupiter said it would run between 6 and 8K to have them do it. After completing the job and counting the hours, I think that their estimate was about right on. So by working with my son and taking about 4 weekends we saved quite a bit.

We put the car on jackstands and began following the engine removal steps in the manual. This forum and google in general were very helpful.

I found that when looking for torque specs it was easier to google it than to dig thru the manual.

While I cannot point to specific posts, this forum was extremely useful.

The coolest thing was that he got another car after the vette went down. We worked together on it and I suggested that he could sell the vette for now, since he is moving to denver and could use the money. His reply was really cool. "I don't know, since we built this car together, I am not sure that I want to get rid of it ever!"

Ken
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Old Jan 27, 2015 | 05:29 PM
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