Temptation to do a swap

Topic: Temptation to do a swap (Read 5182 times) previous topic - next topic

Temptation to do a swap

July 04, 2011, 10:55:23 AM

I'm sitting in my barn drinking a beer and looking at the 5.8L motor from my truck sitting on the stand. I pulled it to remove the pan and other sheet metal and clean out 145k of sludge. (The motor runs strong but has lost oil pressure lately in a way that tells me the pan is full of ). And I start thinking, why not just drop the truck motor into the T-Bird? It might be a good match for the 2.73 gears... more torque than the 5.0L. Eventually I might steal the 3.55 gears from the truck, too. It is the same locking 8.8in. diff in both. What I will actually do for now is just weigh the 5.8L while it is out so that when I do have occasion to pull the T-Bird motor (soon, because the rear seal leaks like the Exxon Valdez) I can compare the weight and get an idea of how my front springs will take the new motor. Here in the hills I really need a 4wd truck anyway, and my old F-150 would not be worth much as a used truck. Maybe it will end up sitting on cinder blocks behind the barn. The T-Bird radiator has been leaking lately, and I happen to have a 4-row NIB, so a bigger motor is no problem. That may be

an omen!

Temptation to do a swap

Reply #1 – July 04, 2011, 11:28:21 AM

Is the Bird a 5.0 car? If so, the springs will be fine. Start gathering the parts you need and drop that 5.8 in there. I wanted to do that as well, but ended up finding the GT40-P score of a lifetime, so, I took it.

Temptation to do a swap

Reply #2 – July 15, 2011, 09:20:16 AM

5L springs will be fine. I did this swap years ago.
This would be a good time to build that 351

And then, reality set in...

Reply #3 – July 29, 2011, 09:50:47 AM

OK, an update is in order. The 5.8L is almost built. It is going back into the truck because it is a flat tappet block. Not suitable for high revs or radical cam. Is there a 5.8L block with rollers for the police pursuit cars? That would be cool for the T-Bird. If I had the 5.0L apart at the same time I would see how the long stroke crank fits in the 5 liter...must be clearance issues. Anyway, I went .040" over for 355.4cid (an honest 5.8L now), with a CompCams RV grind. It has about .020" more lobe lift than stock, with what appears to my eye to be less duration than stock (anybody know specs for a stock 5.8L truck motor cam?). They say it provides "noticeably improved performance" while being compatible with EFI. Chamber volume is now 94-96cc for a mathematical compression ratio of about 8.5:1. It should run on regular with no ping, but I expect to see a drop in fuel economy because the only tuning option I currently have is turning up the FPressure and throwing more gas down the hole. A heavy Duty upgraded torque converter from torqueconverter1.com is on the way. It is supposed to have stock stall speed with beefed up internals. I hope I am not building a herky jerky hotrod that squeals the tires every time. D**n it's hot in the barn. I should be out there turning wrenches instead of sitting here staring at the glowing screen of this time-wasting machine.

Temptation to do a swap

Reply #4 – July 31, 2011, 11:34:27 AM

Can you explain why a flat tappet block isn't good for high rpm?????? I'm baffled! When I was 20something, I had a 69 stang fastback with a 351w that would turn 8500 rpm at the strip. And it did it without a complaint what-so-ever. Oh ya, it also idled at 1200 rpm. Yes I drove it on the street, but back then I was never concerned about fuel mileage. Back to the original point, I'm still very baffled as to why you would say that.

Temptation to do a swap

Reply #5 – August 02, 2011, 10:52:55 AM

Yeah, flat tappets can work, but the reason for rollers is to reduce friction and allow for greater valvelift and faster opening. With moderate cam profiles it is not really an issue, but I notice Ford's engineers selected rollers for the 5.0 Mustang block. Reckon they are onto something? My stock 5.8L cam had several lobes rubbing away at only 106k miles.

Temptation to do a swap

Reply #6 – August 02, 2011, 09:51:07 PM

I know why they went to rollers, the reduced friction helped with mileage. But for greater lift?? I had a .788 lift, solid lifters, roller rockers, gear drive timing set. Stock cams do tend to go flat when not properly maintained or many other causes, but we're not talking stock items here are we. I had a stock 2.3 lobes go flat too, but that was caused by a plugged oil passage.
Point of what I'm saying is this, You shouldn't go around saying "It's not a Roller block so it's junk or not worth building".
Yes we are in agreement that reduced friction is always better because you do get less parasitic loss which helps with the HP or mileage.

Temptation to do a swap

Reply #7 – August 07, 2011, 01:06:32 PM

Do it..............

I did.

The Result

Reply #8 – August 08, 2011, 10:38:55 PM

I fired up the new motor Sunday. Ran it at 2000rpm per the cam mfr. instructions but I did stop after a minute or so and look for leaks. All was well and soon I felt confident enough to put the pedal depressor on it and get out. I kept it at 1800-2000 for about twenty minutes, then set the timing and drove the wife around the neighborhood. Today I put about 30 miles on it. The TC feels just like the OEM as far as normal driving. Have not given it much throttle, but the motor seems to "come onto the cam" at just about 2800rpm. The guy at the machine shop told me the cam they sold me is a "flat tappet version of the 303 mustang cam". Well, it is .303 lift on the ex lobes. That is .020 more than stock, similar increase on the in lobes. But the lobes are much "pointier" than the OEM cam. I see that the idea is to have more lift for less duration to give it some more top end without screwing up the low and mid range calibration of the EFI. Very limited range to play with there. If I wasn't such a tightwad I might buy a programmable ECM. I had the SnapOn Scanner hooked up today as I drove, and the STFT varied from 0 to 16 or so. It never went negative, even though the O2 sensor was switching just fine. It is running lean. I think I will need to increase the fuel pressure just enough until I see the STFT drift into negative numbers occasionally. Hopefully the system will be able to keep the idle mixture in range.
Now, if I had a wet manifold and a carburetor, I could open the valves a lot earlier and hold them open longer. This would require a more abrupt cam profile, and the forces applied to the surface of the cam lobe would be too great at high rpm if it was in contact with a flat tappet. blah, blah, long section edited out here.
So anyway, yes, one can do great things without roller lifters. For a while. Roller tappets are all about durability, but they only become necessary when you try to do more than flat lifters can handle. Car motor= high rpm oversquare design; Truck motor = low rpm high torque undersquare design. I think I am going to like my new truck motor and I have lots of data for the next one I build (??? to relieve the long suffering original motor in the T-Bird Sport?)

Temptation to do a swap

Reply #9 – August 08, 2011, 10:57:49 PM

What do you consider "for a while"?? Does 5+ yrs (regrettably sold the car) qualify?? Glad ur happy with it anyway. I'll shut up now.

Temptation to do a swap

Reply #10 – September 04, 2011, 05:48:44 PM

Quote from: Stealth;364815

Car motor= high rpm oversquare design; Truck motor = low rpm high torque undersquare design. I think I am going to like my new truck motor and I have lots of data for the next one I build (??? to relieve the long suffering original motor in the T-Bird Sport?)

The last under square engines in any Ford vehicle were flatheads that were discontinued after '53...

Temptation to do a swap

Reply #11 – September 04, 2011, 06:57:08 PM

Lol, I was wondering how exactly a 4" bore/3.5" stroke was undersquare. Glad I wasn't the only one.

Temptation to do a swap

Reply #12 – September 04, 2011, 10:38:22 PM

Well that could be said 2 ways. With over-square being the 4" bore being bigger than the 3.5" stroke or with under-square being the 3.5" stroke smaller than the 4" bore. I would guess it's all in how you look at it.

Temptation to do a swap

Reply #13 – September 04, 2011, 11:45:35 PM

Not really. Undersquare isn't a word that's open to interpretation. The definition of undersquare is simply an engine with a greater stroke length than bore diameter.

Temptation to do a swap

Reply #14 – September 05, 2011, 07:29:27 AM

Nascar uses flat tappets still, in a block based off the 351 and they turn upwards of 9000+ for hours on end.