Can anyone confirm if a LT4 intake will bolt up and have the proper port alignment with the GM fastburn heads ?

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No, it won't.

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

I'll let you know once I have both in my possesion. I've been planning this job for a while now. Sometime early next week the new motor will arrive. Scoggin Dickey is sending it with the Fast Burn heads not bolted down. I've also ordered an LT4 intake manifold along with it. From what I've gathered, the ports will be off up to .100" so some port matching may be necessary and I'm prepared to do this if needed. Since the Fast Burns have both the Vortec and standard bolt pattern drilled, getting them bolted on shouldn't be anything more involved than bolting an LT1 intake to standard heads. I'll keep you posted on my progress.

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1991 Z28 - 350 TPI, T56, McLeod street clutch, LT4 pressure plate, Pro 5.0 shifter, ported plenum & runners, AFPR, Hooker shorty headers w/o AIR, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Kenny Brown STB, Global West steering box brace, Steve Spohn adjustable torque arm and T56 crossmember

 

The only problem is that the LT1 or LT4 intake has yet another bolt pattern to it that is neither a standard pre-86 pattern, a 87-up non LT1 pattern, or a Vortec pattern. The LT1 pattern is it's own. Now, that is not to say that some work cannot be done to it to get the bolt holes to work, but you are talking about a decent amount of filling and drilling - along with a bunch of port-matching filling and grinding. So the intake will most assuredly not bolt up to anything other than an LT1 style head, but I guess anything is possible....

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

Not bolt up to anything but a LT1 head? You hav't seen my tech article on LT1 intake to regular SBC?


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86 Camaro Sport
LT1 Induction
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project
Moderator at SE ThirdGen

 

My statement is 100% correct since the intake will not directly bolt up to anything other than an LT1 style head. That is not to say that some modifications cannot be done to it to allow it to bolt up to any other style head, but I am talking without any mods. I even say that in my reply. So at-ease there, nitro . I'm not hate'in !!

But the two styles we are talking about here are the Vortec head and an LT1/LT4 manifold which have more than just bolt pattern problems - the intake ports themselves will be off a bit and I am not really sure if there is enough material on that manifold to get it to match up to the head. But don't let me stop ya, Steve!! I'm just trying to help and let you know about some of the pitfalls that you will come across. In fact, I would like to hear some concrete evidence on what kind of work is needed to get them to work - kind of like John's 'break-through' work on the LT1 manifold to Gen-1 SBC heads. I would read up on John's article as you will need to do all of the things that he did along with getting the intake ports to match up.

And FYI John, I have a lead on an LT1 intake to play with myself .

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

Don't worry, I've visited John's website many, many times. Without him, I would never even think of attempting something like this. You're right though, I'm not even sure it will be able to work but from what I've gathered, there is enough material on the LT4 intake to be able to make it match up. I'll know in about a week.

 

I stand corrected, sorry.


I have compared the LT1 intake to Vortec heads. I don't see how it's possible. The LT1 intake bolts are where nothing is on the Vortec heads.
It would be QUITE a challange.


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86 Camaro Sport
LT1 Induction
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project
Moderator at SE ThirdGen

 

You probably know this already John but just to clarify: There is no way the LT1/4 intake will bolt to the cast iron Vortecs like you said unless the heads are drilled and tapped with the standard bolt pattern. The Fast Burns, however, are drilled for both the Vortec and standard bolt patterns from GM so it is definitely possible to bolt on the LT1/4 manifold to these heads. Just making sure the distinction was made.

 

Steve let me know how it works out for you.

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The LT4 has a different angle on the ports. It has to be milled to fit standard LT1 heads, so they will need this on the standard SBC as well. They have enough material to do so as well.

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91 Z28
Best Time Slip:
60' - 2.098
1/8 - 9.137 , MPH - 76.21
1/4 - 14.213, MPH - 97.55
Performace Mods: SLP Catback
Appearance Mods: SS wheels, 2.5" Cowl Hood (not on at the moment), Clear Side Marker Lights
ICQ: 1437212
AOL: normalmatt9

More Pictures are Here

 

If you're referring to the angle of the mouting surfaces of the intake and heads, I've heard from many different sources that they are the same angle for LT1 and LT4 which would make them the same as the Gen I SBC. I know that the ports will not line up and their shapes may not even be exactly the same (LT4 ports are slightly trapezoidal from what I've seen/heard).

 

Or maybe you mean the angle of the runners. If this is what you're talking about then I'm pretty sure you're correct there. As long as the intake mates flat with the heads, then it will be able to work.

[This message has been edited by Steve91Z28 L98 (edited December 12, 2001).]

 

Well, I meant the angle of the runners, however, the LT4 will not bolt up to a standard head. or a LT1 standard head for that matter. It will have to be milled. This I'm almost sure on, but I do not have them in my hand, so cannot be positive.

 

I can tell you from FIRST hand experience that an LT4 manifold WILL bolt to LT1 heads.. but the port is slightly different and the intake runners are a tenth of an inch higher.. I had vacuum leaks all over.

But it did bolt right up.




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Kelly 'GhoSSt' Rosato
1996 Impala SS, 383 LT4 (14.65 up here, 13.24 lower)
1984 Firebird, +.060 350 (Vortech Heads, HOT Cam, and schtuff)
1993 Caprice, 5.7 TBI (stock . . . FOR NOW)

"And if you wrong us, shall we not revenge? Revenge. The villany you
teach me, I will execute, and it shall go hard but I will better the
instruction."

Shylock in Act III, Scene I of 'Merchant of Venice' by William Shakespeare

 

I forget where I saw it, but they had an lt4 intake that was made to be a direct bolt on to the lt1's. Someone posted a link to it on one of the threads. I dont know if it was aftermarket or just a company selling ones that they had changed to work. Maybe someone else knows.

Ben

 

GhoSSt. Thankyou for posting. I had heard all laong that it did bolt up but there were always those few people who said it wouldn't. Your first hand experience puts that to rest.

 

Well, back when I first got my Impala SS I just HAD to have a LT4 red intake.. So when i put ported iron LT1 heads on, I swapped to the LT4 intake at the same time. Because of the way that the iron LT1 heads are machined, I had to grind a bit on the top edge of the runners and it bolted on after that. I had a LOT of drivability problems that never went away until I went to a 383 LT4. In retrospect, I'm 110% sure that they were vacuum related due to 1) slight head gasket sealing issue and 2) vacuum leaks, I spent the $$$ to have the codes pulled one time and it was all excessive lean conditions.

But from a strictly performance standpoint the 1992/3 Y-body or 1993 F-body LT1 intake is the one you want.. They're rare, but they have no crossover tube in the front and have a slightly greater plenum volume than the 1994 - 1997 F/Y/B intakes. The LT4 intake is actually a really rough casting inside because it was rushed to production. Just a tidbit for you.

Kelly Rosato

 

I think there is a communication issue here on what people's definition of 'bolt-up' is. I am inclined to think that 'bolt-up' means everything will line up and you can 'bolt it up' and be done with it - everything will work. So even if all that is needed is a small bit of grinding to get it to fit, it doesn't really 'bolt-up'.

But it seems to me that some people think of only the bolt holes when they hear the term 'bolt-up'. I guess that would be the more accurate usage of the term.... but it is a bit misleading in the way it comes across... to me anyways.

Anyways, I am just trying to clear things up a bit....

So GhoSSt, what kind of a difference is there between the 93 and older LT1 manifolds and the newer ones? As in, what exactly are the measurements and dimension differences? How about the LT4 manifolds, how do they measure up? And by no cross over tube I assume you are talking about the coolant crossover passage in the front of the manifold casting? I'm not all that up on my LT1-tech and I am about to get a '93 LT1 manifold, for a decent price, to mod and put on my GTA's engine.... So the more I know about them the better . Thanks,

Laterzzzzzzz

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

No flames please, but I have a dumb question. What are you retrofitting LT-1 intake guys going to do for an ignition solution being's LT-1's do not have distributors? Isnt this why the Mini-ram was invented by TPIS? Well I hope you guys doing the LT-1 intake conversion do NOT use the factory LT-1 opti-spark, as it is JUNK!! And if you do use the the opti-spark, dont get it wet when it comes time to wash the car! This is how many LT-1 guys trash there ignition systems.

 

What are we using for a distributer? Not to flame but duh!
Have you even looked at the tech article? We drill a hole for the old small base distributer and run the existing ignition system. That's why this is a cheap mod.

 

Check this site for the difference between the LT1 & LT4 http://www.lapracing.com/lt1-vs-lt4_intake.htm