Engine Suggestions on an engine rebuild. Stock cam/GT40Ps or aftermarket on both for a fun weekend driver?

[MadSquirrelTech]

I am going to try to keep this short, but there’s a lot of info behind the question.

TLDR; I’m looking at suggestions for engine rebuilding options when an engine and getting my foxbody on the road.

The car is an 87 GT with the standard T5 5spd. I want something that’s a fun weekend ride and can do some trips to local shows and meetups, so not too crazy. I have a Terminator X setup for it and an On3 Turbo kit along with the associated fuel system upgrades, etc.

Over the last few years I have ended up with 3 engines (a 1991 that was horribly overheated after a blown head gasket and I’m not sure I trust, a 1995 of unknown history, and a past rebuilt one that was in the 87 when I got it and ran sort of OK. I also have some GT40P heads and a spring kit (and yes, the exhaust clears the plugs).

I will probably keep the one I heard running that was in it even though the pistons are cast. Heads are off and it looks fair, I don’t remember any knocking noises before, it just ran rough, but the whole car had been sitting for a while. These pistons are cast and .040 over from the past rebuilder (Jasper I think) and I have no idea how many miles are on the rebuild. I think I’m just going to send it with this block and rotating goodies and if it decides to go pear shaped, then I’ll do something else with one of the other blocks.

This is where I’m having trouble deciding. I am strongly debating the following and would welcome suggestions on both aspects. My budget is variable, but I'm not going down the route of a new Summit block and rotating assembly or anything like that... yet:

• Stick with the stock cam or do something aftermarket that will work well with the turbo. I do like some chop.
• Finish the refresh on the GT40P’s or grab some cheap aluminum heads

Thoughts on sticking stockish vs the heads and cam? Would I see much difference with the turbo already stuffing air in the thing? I’m not going for huge horsepower. Thanks

 

[86HO5.0]

Since you're not going for maximum power, I'd stick with the 'P' heads. They'll be more reliable and less issues than a cheap aftermarket aluminum IMO.

Get some forged slugs just to be safe.

 

[AeroCoupe]

Stock cam will work really well with boost and at the level that short block can handle it would be wasted money on another cam.

 

[JD1964]

I’m running the stock HO roller cam along with Crane 1.7 full roller rockers. No regrets whatsoever. It has very good low end manners and easily pulls to the rev limiter (6200rpm)

 

[2000xp8]

If i'm reading this right, you do not currently have a running engine or one that is known to be 100%?

 

[MadSquirrelTech]

If i'm reading this right, you do not currently have a running engine or one that is known to be 100%?

Correct. I have an engine I heard run (in the pictures), and while it didn't run well, I did not hear any concerning noises. I drove it onto my lift under it's own power. I am looking to use that short block as I have actually heard it run

 

[nickyb]

If I'm in your shoes I am going to take anyone of those blocks to a machine shop, have them clean it up ,bore it ,line hone ,new cam bearings,ect. Then new forged pistons and rings gapped for boost. Then you can use whatever heads and cam you have and have some fun.

 

[AeroCoupe]

Why not tear down the best short block and inspect the bearings, check the cylinder walls for any heavy wear, regap existing rings for boost, reassemble (assuming everything looks good) and check the bearings for proper tolerance (plastigage). Put a new oil pump and good timing gear & chain on it and send that mofo.

I mean if you just want to save some money and see what it will do and you don’t care if it lives 1,000 miles or 50,000 miles who cares. Sometimes it’s just fun seeing what you can get out of what’s available. Get the turbo kit sorted and then start building a nice long block to put in it or don’t.

 

[MadSquirrelTech]

Why not tear down the best short block and inspect the bearings, check the cylinder walls for any heavy wear, regap existing rings for boost, reassemble (assuming everything looks good) and check the bearings for proper tolerance (plastigage). Put a new oil pump and good timing gear & chain on it and send that mofo.

Thanks.

I've got that short block torn down a bit (it's in the images), and the cylinders don't look bad, so I'm not worried about that. The pistons need some cleaning up as it looks like it was running pretty rich. I will check the bearings and see how they are looking before buttoning it back up. I will also do an oil pump while it's apart as well, but I wasn't really planning on the timing chain. Do these stretch that often? It look a lot more beefy than the SBC's I've worked on in the past.

 

[AeroCoupe]

Depends on what the rebuilder used. I would not trust a auto parts store one with boost but that is just me. See if there are any identifying marks on the gears and if its a quality timing chain and gears then bolt it back up.

 

[Noobz347]

When you can get a new one for less than a $100 and have no history on the old one, it's a no-brainer.

 

[MadSquirrelTech]

When you can get a new one for less than a $100 and have no history on the old one, it's a no-brainer.

Do you mean the oil pump?

 

[AeroCoupe]

Timing chain I am pretty sure.

 

[Noobz347]

Yes, the timing chain.

 

[2000xp8]

With costs these days, i struggle with idea of doing anything and not being as close to100% sure as possible about how it's done, for me it has to be as if the first time is the last time.
I'm also no fan of pulling engines out, especially after just putting it in.

A turbo is pretty much the most problematic modification you can make to one of these cars and boost exploits every weakness. My faith in running one on an unknown engine, is not great. The jackstand jokes aren't just funny, they are real.

If it were mine, it would goto the machine shop or i'd buy a built short/long block. If that's not going to be done in this case (i get it, we aren't all made of money), i'd get the engine 100% before messing with anything. I'd run the stock computer, harness and long block and drive it that way for a while.
Then if it's all good, i'd consider modifying it.
You have to know where it stands before introducing more problems.

As for the P's, other than on a replacement engine from a junkyard explorer (which might even be a better idea in this case), I see them as boat anchors.

 

[Noobz347]

I second the machine shop. Wish I had a dollar for all the blown head gasket threads I've seen over the years.

 

[AeroCoupe]

@2000xp8 - you are right on all accounts. I think the idea of putting it all together and driving it naturally aspirated is spot on.

I am thinking of this a junk yard wars. You have what you have and have to make it work. Get it good and broke in and a solid driver. Then introduce yourself to the world of boost and jack stands.

 

[NXcoupe]

I am going to try to keep this short, but there’s a lot of info behind the question.

TLDR; I’m looking at suggestions for engine rebuilding options when an engine and getting my foxbody on the road.

The car is an 87 GT with the standard T5 5spd. I want something that’s a fun weekend ride and can do some trips to local shows and meetups, so not too crazy. I have a Terminator X setup for it and an On3 Turbo kit along with the associated fuel system upgrades, etc.

Over the last few years I have ended up with 3 engines (a 1991 that was horribly overheated after a blown head gasket and I’m not sure I trust, a 1995 of unknown history, and a past rebuilt one that was in the 87 when I got it and ran sort of OK. I also have some GT40P heads and a spring kit (and yes, the exhaust clears the plugs).

I will probably keep the one I heard running that was in it even though the pistons are cast. Heads are off and it looks fair, I don’t remember any knocking noises before, it just ran rough, but the whole car had been sitting for a while. These pistons are cast and .040 over from the past rebuilder (Jasper I think) and I have no idea how many miles are on the rebuild. I think I’m just going to send it with this block and rotating goodies and if it decides to go pear shaped, then I’ll do something else with one of the other blocks.

This is where I’m having trouble deciding. I am strongly debating the following and would welcome suggestions on both aspects. My budget is variable, but I'm not going down the route of a new Summit block and rotating assembly or anything like that... yet:

• Stick with the stock cam or do something aftermarket that will work well with the turbo. I do like some chop.
• Finish the refresh on the GT40P’s or grab some cheap aluminum heads

Thoughts on sticking stockish vs the heads and cam? Would I see much difference with the turbo already stuffing air in the thing? I’m not going for huge horsepower. Thanks

First, a cam is subdued a bit by the turbo, but a good turbo cam will still sound nice. Aluminum heads hands down. You are running a turbo and cast iron heads hold heat, too much heat in the combustion chamber and you get preignition. Aluminum heads and a good custom turbo cam, and it'll perform very well.
For an fyi, I tuned a completely stock engine with a turbo kit through dual exhaust and it made 425 with around 10 psi on a VERY conservative tune. Very respectable and fun cruiser.

 

[90trunk]

An issue to keep in mind is not to have so much money stuck into a set of GT40 iron or "P" heads that you could have moved into a new budget aluminum or better level of used aluminum heads. It used to be easy to find a set of newish take-off GT40's as an inexpensive upgrade, but that ship has sailed.

I had great results with take-off GT40 irons and the stock cam w/1.7's. They were a 3 mph and .3 gain at the track over E7's, apples to apples. It now has AFR Renegades 165's (with the same stock cam/1.7's) and the car picked up roughly 25 hp on the Dynojet (over 4500 rpm) above the GT40 irons.

Let your wallet be your guide...

 

[MadSquirrelTech]

An issue to keep in mind is not to have so much money stuck into a set of GT40 iron or "P" heads that you could have moved into a new budget aluminum or better level of used aluminum heads. It used to be easy to find a set of newish take-off GT40's as an inexpensive upgrade, but that ship has sailed.

I had great results with take-off GT40 irons and the stock cam w/1.7's. They were a 3 mph and .3 gain at the track over E7's, apples to apples. It now has AFR Renegades 165's (with the same stock cam/1.7's) and the car picked up roughly 25 hp on the Dynojet (over 4500 rpm) above the GT40 irons.

Let your wallet be your guide...

I appreciate all of the feedback.

I picked up the pair of GT40p's for $100 then added the spring kit, so there isn't much invested. The valve job and cleanup was pretty easy as well with only 1 valve needing replacement. They weren't even very dirty. The 1.7s are a serious consideration.

I simply don't want to sink a lot into this engine until I figure out if I like it as much as I hope to. I daily drive a C7 Grand Sport, so I'm not even worried too much about reliability with this one, I just want a manual transmission car to rip around in and I always liked Foxbodies.

I'll certainly replace the oil pump and timing chain as those are cheap. I have head studs and ARP main cap bolts for it already as well as a new clutch assembly and a ton of spare and new parts (I bought a parts car that came with a mountain of brand new parts from Rock Auto that they tossed in). As I said, I will probably grab the 1.7s as well as some new pushrods once I know the length (I already have the solid lifter/adjustable PR to size it). I've build a number of engines over the years, Chevy, Mopar, even an Oldsmobile for a boat, but this is my first SBF and I don't know the platform the way I do the chevy's. I've also had some turbo cars before and even doen some minor tuning on them, so I'm not that intimidated by the boost side of things. I tend to start conservative.

I've also got a 4-post lift (I despise jack stands anymore) and I'm kitted out with tools and a 30x60 workshop as well, so an engine swap isn't really a huge problem if I want to go that way. The bigger time eater I think will be getting the Terminator X all wired up and working, and getting the turbo stuff fitted. That's easy to pull off later and swap on to a new long block. I really don't want to try to start up a brand new $$ build and have trouble getting it all working right, so I'd rather start that route with a used engine that I won't feel bad cranking over with little/no oil pressure 100 times before it starts.

If I find that this doesn't make me smile enough and I like the car, I'll probably build something from the ground up using either 1 of the 2 other shortblocks I have and replacing all of the internals with a new rotating assembly, or starting with a brand new Summit block and new rotating assembly. With that I would certainly do aluminum heads. This isn't meant to be a race car, it will probably hit the road 1 or 2 days a month (assuming my wife doesn't take it over )

This is what it's going in BTW