Can someone measure from the flat surface the intake manifold seals to (ya know, the one you have to put a bead of silicone on, lightly bolt up the manifold, let it set, then torque it down only to have it leak anyways) to the underside of the engine lid?

I need to make some intake manifold mods for my LT1. There was a rumor that the intake would just flip around, putting the trottle body at the rear and less in the way. I have just confirmed that it won't flip around. It's VERY close though. ports line up, holes line up, but those two horizontal sealing surfaces are different from front to back.

I now have two options:

1. Modify those sealing surfaces

2. Mount the throttle body elsewhere on the manifold

I'm leaning towards #1 because it looks easier. If I don't have room to mount the throttle body on the top of the manifold then that will force me to option #1.. which is why I need the measurement.

Ok, hold on

Not an easy thing to measure. Somewhere around 9" for an SBC.

Here's the intake on forwards, from the top:

Here it is on backwards:

The last pic doesn't show much.. here's a closeup of the sealing area I'm talking about, at the rear:

Here's the best pic, it clearly shows the ends of the lifter valley are not the same:

QUOTE (914GT @ Feb 2 2005, 09:09 PM)

Not an easy thing to measure. Somewhere around 9" for an SBC.

Oof, that's not much. I assume that's with no rain tray?

Royce, that's correct. And thats at the rear. Might be a little more at the front.

any desent machine shop could tig on an extention and mill it flat, i would not think it should be more than 150 bucks

QUOTE (914GT @ Feb 2 2005, 09:18 PM)

Royce, that's correct. And thats at the rear. Might be a little more at the front.

Cool, thanks. The manifold is already 6" high.. looks like option #1.

QUOTE (scott thacher @ Feb 2 2005, 09:22 PM)

any desent machine shop could tig on an extention and mill it flat, i would not think it should be more than 150 bucks

Hehe, that's exactly what I was thinking of doing. Fortunately I have access to a TIG and a mill, so it'll be much less than $150

just get a Victor JR and run a four barrel style throttle body. That should be plenty low profile.

my picture is too big and I am too lazy to resize it.

That's made for a carb, right? Where would I put the injectors?

QUOTE (bondo @ Feb 2 2005, 10:03 PM)

That's made for a carb, right? Where would I put the injectors?

Hahaha, He means go with a carb instead of the FI silly. Looks like you are making some progress on it. Did you ever post pictures of the car you are going to put this all in? If not, now is a good time.

Ya, this is MPFI not TBI where talking about here.

You COULD always put the injectors in the runners (like the RPM MPFI manifold is.... I was considering it....)

OH ya, What about the dizzy???

wouldnt the piping hit the dizzy???

I REAALLLY want to run a tuned port injectoin like this setup... buuuut the obvious arises...

No I am talking about the carb intake manifold with a FI throttle body on it. You just drill the bungs for the fuel injectors and mount them at the head like the LT1 manifold. You cuold probably use the fuel rail from the LT1 as well as the fuel injectors.


Andrew
The dizzy is driven off the front of the motor by the cam. LT1s and LT4s did away with ole HEI and went to a front mounted setup.

QUOTE (skline @ Feb 2 2005, 11:13 PM)

Did you ever post pictures of the car you are going to put this all in? If not, now is a good time.

Yup, sure did. You can find them here.

Changing manifolds is way too much work. This manifold is pretty complicated. EGR and PCV are incorporated into it. I also really liked the way this engine performed in the Firebird before I pulled it. I don't want to mess with it too much. The distributor is on the front of the engine, so that won't be a problem.

I think option #1 is the way to go.

Oh thats right, I forgot we where talking about the lt1...

phoey...

Royce:

I believe we discussed this a little earlier since I am doing a similar, Chev LT1 from
a 1995 Camaro in my 914 project car. Here are some of my thoughts and comments:

- My plan currently is to make use of the GM motorsports manifold designed for a
carburetor and also allows me to located the "regular old style distributor" in
the rear for ignition system. (or Electronic distributor)

- Future plans will be to make use of the complete GM fuel injection system, manifold
and megasquirt or aftermarket programmable FI system. At that time I will also be
modifying my FI manifold to re-install my distributor/electronic spark controls.
Check out this link and look it over which should help you out
http://www.lt1intake.com/swapping.htm

- In addition to modiflying my manilfold as outlined above, I also did some research
on a donor car which indicated to me that I would likely need to "re-locate" the
throttle body by fabricating a special adaptor and thus that is my plan to take once
to move ahead with installation of the complete FI. Side mounted is my plan.

- In the short term I am more interested in getting the conversion done and upgrading
the car along with getting some driving time before I spend all the extra engineering
time to source, set-up and fine tune a FI system and the associated "extra" electronics

- In regards to the COOLING SYSTEM, how is that going with your plans of front
mounting the water pump ? Does everything look workable or any problems do you
foresee. See below photo of my "water adapters" for external water pump.

- Getting back to your manifold, for some reason when I was considering mine in
a reversed mode I thought there were other issues WHY it could not be also just
turned around and run that way. But the above mentioned comment regarding
welding and then just machine/mill flat would work fine, otherwise check with a
well known engine builder to confirm Why you could not just use RTV sealant in
excess around the areas of concern. When teh engine is fully assembled and the
intake gaskets are properly sealed, there should be little if any pressure at the
front and rear manifold sealing points other than some loose oil (not under pressure)
from the lifter gallery below. Just my thoughts but could be worth consideration.

Must go for now getting too long winded, but an interesting project. Best of luck
with your LT1 conversion, keep in touch.

Allan

Allan: Nice water adapters! It still looks like I'll be able to do the front mount water pump. Not ideal but I think it'll work. The whole reason for choosing the LT1 is I like the FI-system, going to carb would be a step backwards to me.

I am tempted to just add RTV. It's a really close fit, I can just barely see a gap. I could probably get away with it, but it's so easy to do it right now vs. having to go do it right later (manifold is off and stripped).

Royce:

What are your plans regarding the Ignition System ? Trust the Opti-Spark gets removed
because of space and that since you are planning to go FI, you will not likely be using a
rear standard mounted distributor ? Thus the only other option I can think of would be
some type of aftermarket "crank mounted" trigger electronic type system ?
Appreciate your reply and thoughts.

Allan

All my rough measurements have shown that the optispark won't be in the way. If it gets in the way... I'll cross that bridge when I get to it

(I have cut off the engine shelf, it may get in the way with the engine shelf in place)