How much power is too much - spec for new crate engine? (1 Viewer)

[tdskip]

First of all - I hope everyone is doing well and staying safe. Boat loads of great people here that I hope are taking care of themselves and family...

My '68 rig needs an engine refresh, and after doing all of the math on it with needing/wanting some professional help on it I've realized that simply buying a new GM Performance crate engine is the right way for me to go at this point. That leads to the question of what spec crate engine I should buy.

The rig has a 350 SBC with Edelbrock carb in it now, 1990 crate engine from what I can tell, and it's a mild build. On the AZ/UT adventure honestly I never felt like it was lacking in power, it was fine on the road and ate up any obstacle we put in front of it.

The '68 is running a TH350 with an NP203 doubler and also a FJ40 transfer case (as a reminder it came like this, not my handywork, although it is fun to climb straight up trees with everything in low).

I'm leaning towards another mild 190 hp / ~250 ft pounds torque (both likely a bit understated as GM crate engines are usually stronger than advertised), but it isn't much more money for a 250hp / 300 ft pounds torque engine or even a 290 hp / 340 ft pounds torque engine. All things equal more power is usually more fun but not sure if the bigger engine hp / torque is going to break things like driveshaft bolts or the transfer case internals etc...

So - the question I was hoping to get some feedback on is this - stay with the lower hp engine as it will likely be more capable than what it is replacing or sell some parts to fund buying the 250hp or 290 hp engine?

Thoughts? Thanks!

 

[SNLC]

Depends how you drive it.

I built a 40 a couple years ago with a 400. The engine was somewhat built so I guess around 400hp. It was/is fast enough to scare you, easily enough power to brake things.

I used to have an FJ60 with a ramjet, thats 350hp. It was just about right and very fun to drive plus very basic.

I personally would not mess with a TBI engine. The 5.7 vortec is great in a 40 if you still want a distributor. Myself though I would go to an LS for the fuel injection, coil packs and aftermarket support.

Cheers

 

[workingdog]

I agree with @SNLC about going straight to LS and skipping the distributor.

For me, power is really about freeway performance. With all that gearing you'll never notice it crawling.

If all your axles and knuckles are stock, they are the things you might break. But, I agree with SNLC again - it depends how you drive it. I've got a 6.0 in my 40, I broke a birf on the Rubicon because I tried to power through an obstacle and came down on a spinning tire. Totally my mistake and I probably could have done the same with a 2F.

Can you share more details about teh engines? 5.3's? 6.0's? 6.2's?

What are you going to do about the trans. Keep the 350? Go to a 4l60?

 

[tdskip]

Good morning. I was actually planning on just swapping everything over from the existing low-tech (carb and HEI) set up, leaving the TH350 as well for now.

The plan, which I can revised as makes sense based on your coaching (and budget allowing), was to sort the engine out and enjoy this year's offroading season and then see if a more modern automatic transmission was calling to me. That would a chance to simplify the NP203 and FJ40 transfer case set up as I don't think I am really going to need both going forward...

 

[Downey]

If your's is a daily/freeway driver, then I guess you should build for best milage. Horse power is better milage, Touque is not. The mistake some guys make is they mis-match the way they equip their engines, they will install an aftermarket "horse power" intake manifold, then a "torquer" cam. If you are using a carbureted engine, then all add-on equipment should be geared towards building best horse power or best torque.
The best operating FJ40 I ever had was equipped with a brand new 300 horse power 327, bought new in the crate from Chevy, try getting one of those now days.

 

[pjohnson]

What's wrong with the current engine that you feel the need to replace it?

If it is not burning oil from worn rings or has a spun bearing or bad wrist pin, etc. Why not just refresh it?

And put a sniper on it

 

[SNLC]

Sounds like as a long term project you can better budget it. That’s how I usually do things on my own Cruisers as well. Get a game plan on, spend six to twelve months getting all the gear together and then go for it. Makes for the least amount of downtime and allows you to spread the expense out.

I would really go for the LS if I was you. Couple that to a 4L60 and run an FJ60 split case behind that. There is a number of guys you can get a freshly rebuilt 5.3 from that take good low mile engines and make them like new, cost is $4500-5500 and they are about 425hp.

Cheers

 

[Downey]

Plus keep in mind, if you are going late model LS that was used in front of a 4L60E automatic trans, keep them together. The engine computer keeps this engine married to this tranny. For starters the engine controls shift points, the tranny sends VSS signals, etc.. You have a lot of re-programming to do if you don't keep them together.

 

[tdskip]

What's wrong with the current engine that you feel the need to replace it?

If it is not burning oil from worn rings or has a spun bearing or bad wrist pin, etc. Why not just refresh it?

And put a sniper on it

@pjohnson - hi there, and thanks for all of the responses gentlemen.

Current engine has marginal oil pressure when hot and will oil foul her plugs.

 

[65swb45]

One of the signs of middle age is when you become more interested in how long something will last, instead of how fast it will go.

My F135 is not in danger of breaking anything...except the minimum speed law!

 

[tdskip]

Just for grins I’m going to get the engine on a stand and partially disassemble it to see exactly what is going on with the engine. If it’s just rings and bearings then I may simply refresh it and put it back in.

If not I will follow the advice here and put as big and modern of an engine in as possible and just not go crazy with my right foot.



Hope everybody’s doing well and taking good care of themselves and family.

 

[matzell]

I recently pulled my TBI 350 out of one of my projects and installed a 6.0/4L80 combo in it. I have not hooked anything up yet and after pricing out most of everything I will need to complete the swap, I have decided that the 350 fits in the engine bay sooo much better and will not cost the 2-3k to make work for another 50 hp or so. My 350 has 500 miles on it since I rebuilt it and never lacked power, even with 4:10's and 37's.

You could buy a EFI kit, Sniper, TBI etc for ~$1000 and spend another $600-1000 to rebuild the 350 and bolt it all back in.

I really like the LS engines and drive a 6.0 Yukon daily and have a 6.2 in my race car. I just think they do not fit in a 40 very well without a ton of work and money. Look at the LS swaps and the 350 swaps and see how much more room you have with a 350.

 

[tdskip]

Thanks @matzell , appreciate the feedback. Hope you all are doing well.

 

[pjohnson]

just not go crazy with my right foot.

Haha, good luck with that I know I couldn't do it. I love videos of 40s burning rubber

 

[pjohnson]

I'll just leave this right here:

Pacific Fabrication

Pacific Fabrication Swap xmember Crossmember LSx

pacificfabrication.com

 

[BrianSanDiego]

Hi TDSKIP. Just wanted to say I have exhaust system envy, yours looks great. I may hit you up for details on it sometime.
Stay safe bro.

 

[tdskip]

Good morning and happy Sunday all. Hope everyone is doing OK and safe.

@Lil'John - have been thinking about that but concerned about what I’d actually be getting/buying, a bit put off by the unknows.

@BrianSanDiego - custom exhaust by local shop, will need tweaking as I’m going with a different set of headers (existing ones are funky and prevent mounting power steering pump). Happy to take more pictures and post if helpful.

 

[Downey]

I guess when I read your original post #1 above I skipped over the TH350 auto tranny. Now that I looked at your photo in post #14 above, I see you are running an automatic, soooo I wouldn't be overly concerned about doing drivetrain damage since that big blue torque converter is "drivetrain cushioning" at it's finest (fluid drive).
What has my curiosity though is the motor mount pads in the photo, they look rectangular, and laying perfectly horizontal (for SBC ???). The other thing that has my curiosity is the red thing shown below the exhaust pipe, what is it ???.

 

[bikersmurf]

Back to the original question. The stock motor always got me there... even got me home with a spun bearing... and it died a slow death initiated by PO neglect.

My first 350, a Sept '69 Bel Aire motor, had flattop pistons, 10.25:1 compression, 250 hp stock, +/- 300 hp as I ran it... more than enough power, and good low end.

My current 350, '72 Fleet-side 4-bolt main, 165 hp stock... with an RV Cam, SP2P manifold, and a 1406 Edelbrock carb... feels like more power, even better low end, pulls from about 400 rpm.

The bottom line is, as mentioned previously, it that having power where you need it is what matters.

 

[tdskip]

Thanks for the discussion gentlemen.

Did some more digging on this crate engine and It like a pretty typical replacement ~250 HP and 300 foot points torque 350 replacement crate engine. Should have a 4-bolt main block, cast crank and pretty generic heads.

I’m going to open it up tomorrow and see how it looks.

In any case this spec was fine, even tired, in the rig.

I didn’t install the engine mounts etc but I am pretty sure they are BTB Prooduct mounts