Hey guys

Ive got a 460 with DOVE 3 heads. I rebuilt it before Top Truck and it ran great! The last time I had it out it seemed to not have much power so I did a compression check on it. They are all about 90 to 95

Shouldnt a new motor with DOVE heads be somewhere in 150 to 175 range?

I thought it was weird that they were all similar. Maybe my tester is bad.


I did smash my oil pump and it ran for maybe 5 minutes without oil. It also got really hot a few times. I looked at the bearings when I changed the pump. They were scored but not spun or ruined. It has had pressure since.

What do you guys think?

Flame on :D

How hot and what kind of rings did you use? Rings can collapse after you get motor really, really hot. However cast rings are pretty good. Some of my derby motors will run 20 minutes at a time with not much water and survive. That compression is no where near acceptiable. Try a leakdown test to make sure you didn't eat the head gaskets or something.

its funny that they are so evenly low though. id put that tester on another engine of known quantity first before i started tearing it apart to find broken rings, etc. i hope it got new bearings now. if you had no oil pressure and lost power i would tend to think maybe you wiped the cam and or fawked over the lifters if they are hydro. oil starvation will take a while to hurt the cylinders, alot longer than it takes to wreck all the bearings and valvetrain. I cant see it shitting 8 cylinders at the same time.

its funny that they are so evenly low though.

Maybe the timing chain jumped a tooth?

id check the tester first, you can do it with a tire gauge and a compressor - or just borrow one - ive seen a good motor lose a lot of compression due to heat, and low / no oil at idle

Good ideas! I didnt think of the timing chain jumping a tooth.


First off I will check my tester. If its working right I will have to do the leakdown test next.

I would say it hit 220 several times and the worst it got was about 245.

It did run really good after the damage and it seems like its getting worse the more it runs.

I will keep you guys updated

DOVE 3 heads? Never heard of them. You mean D3VE heads? Other than that, the only D0VE heads I know of are the D0VE-A, B and C.

D0VE heads have a combustion chamber of ~72cc, whereas the D3's chambers are ~95cc's. That will definately be a determining factor in compression.

I have a '69 block (C9VE), with D0VE-A heads and before I rebuilt it, I got readings anywhere from 150psi to 175psi (and 0psi on the problem cylinder).

DOVE 3 heads? Never heard of them. You mean D3VE heads? Other than that, the only D0VE heads I know of are the D0VE-A, B and C.

D0VE heads have a combustion chamber of ~72cc, whereas the D3's chambers are ~95cc's. That will definately be a determining factor in compression.

I have a '69 block (C9VE), with D0VE-A heads and before I rebuilt it, I got readings anywhere from 150psi to 175psi (and 0psi on the problem cylinder).

WOW cant believe I didnt catch that. I was kind of tired this morning.


They are DOVE C. I didnt have time to play tonight. Hopefully tomorrow


Thanks for catching my stupid :grinpimp:

My '89 EFI 460 motor read 118-125 before I pulled it apart. Very consistent, but very low power and a lot of oil consumption. I found the oil control rings completely coked to where they wouldn't move. The compression rings were all installed with the gaps lined up too. :shaking:

I think as a minimum, you've bought yourself a ring & bearing job. Probably a cam and lifters too. Sorry for the bad news...

If you run one out of water, or lose a belt and the guage goes past 260, you can rest assured the rings will be toast sooner rather than later. Squirt a little oil in the cylinder, any light oil will work. If it goes up, rings are shot. If not, suspect no air getting into the cylinder or burnt valves.

Usually when you cook one, it acts just like you describe. Runs o.k. for awhile then gets worse and worse, eventually they quit starting without ether. By then you are down to 75 lbs or less compression. They will still run, but you're better off starting over again.

If you want a FI 460 brand new rebuilt, PM me.

If you run one out of water, or lose a belt and the guage goes past 260, you can rest assured the rings will be toast sooner rather than later. Squirt a little oil in the cylinder, any light oil will work. If it goes up, rings are shot. If not, suspect no air getting into the cylinder or burnt valves.

Usually when you cook one, it acts just like you describe. Runs o.k. for awhile then gets worse and worse, eventually they quit starting without ether. By then you are down to 75 lbs or less compression. They will still run, but you're better off starting over again.

If you want a FI 460 brand new rebuilt, PM me.



Your not making me feel any better :D

I think you are right though. My tester seems to be working right with the air compressor.

Im running propane so I dont need FI. I also have a newly rebuilt 460 sitting in my garage that was for my Mustang. I might just throw it in the Scout. It has flat tops and a HUGE cam. I think I will have to swap the cam out though.

Thanks for all the advice everyone!

I don't think the oil control ring plays that big of a role in the compression test, but putting the light oil in each cylinder will tell you if the compression rings are bad if the pressure rises significantly. That should have been your next move once the suspected low readings were observed. Somehow I missed the no oil for 5 minutes and scored bearings. regardless of how the rings are, I think you are only running on borrowed time if you keep using it. Its best to bite the bullet now and take it down rather than just keep chewing metal up till something big happens.

I don't think the oil control ring plays that big of a role in the compression test, but putting the light oil in each cylinder will tell you if the compression rings are bad if the pressure rises significantly. That should have been your next move once the suspected low readings were observed. Somehow I missed the no oil for 5 minutes and scored bearings. regardless of how the rings are, I think you are only running on borrowed time if you keep using it. Its best to bite the bullet now and take it down rather than just keep chewing metal up till something big happens.



For sure! I put the stupid motor in so I could have more power. TTC was awesome but now it feels just like I stil have my anemic 345 in there. :eek:


Its got to be fixed. Can barely spin the 44s and thats with the Black Box engaged

Im on my way out to play with the motor a bit.


Correct me if Im wrong but if it was the rings that were bad....bad enough to lose half their compression.....shouldnt it be burning a butt load of oil??

Like I said....no smoke and perfect plugs.

Im still suspecting heads.


I will let you guys know what I find today

Im on my way out to play with the motor a bit.


Correct me if Im wrong but if it was the rings that were bad....bad enough to lose half their compression.....shouldnt it be burning a butt load of oil??

Like I said....no smoke and perfect plugs.

Im still suspecting heads.


I will let you guys know what I find today

Checking compression with oil is just part of the process of elimination if you have low readings. You are probably right though. Bad rings should burn oil. I guess the most logical oil related across the board failure would have to be worn cam lobes. If you had valve or head problems, I think your readings would still have been spread out instead of consistant.

Checking compression with oil is just part of the process of elimination if you have low readings. You are probably right though. Bad rings should burn oil. I guess the most logical oil related across the board failure would have to be worn cam lobes. If you had valve or head problems, I think your readings would still have been spread out instead of consistant.

Well I did the oil test. The reading jumped to 120. I even used 2 different testers and they were the same.


I guess I will start tearing it down to see what shape the cam is in. The guy I bought it from said it was a stock cam that he had reground. Made me a little nervous from the get go.

Well I did the oil test. The reading jumped to 120. I even used 2 different testers and they were the same.


I guess I will start tearing it down to see what shape the cam is in. The guy I bought it from said it was a stock cam that he had reground. Made me a little nervous from the get go.

I know very little about the actual engineering of cam fabrication, but if they are surface hardened, and it was ground, it probably lost that hardness and just naturally wore itself down. Maybe it was just weakened enough that it would have been fine had it not lost oil. I've never heard of anyone custom grinding a camshaft other than the factory, but if its common practice then this is probably not an issue. I just can't see something like that having a consistent hardness all the way through.

P.S. The oil boosting the compression is telling you the rings are part of the problem, at least as far as holding compression, but maybe not completely wiped out yet.

JMHO but I think the rings are your problem. I dont know how you think the oil boosting your compression leads to a bad cam but.......

JMHO but I think the rings are your problem. I dont know how you think the oil boosting your compression leads to a bad cam but.......



I have come to the conclusion that the whole motor is bad. The oil test made me know the rings were bad......I was just wondering if the cam was bad as well. Thats why I was going to start tearing it down.


I think instead I am just going to throw the Mustangs 460 in (with a different cam) and go play. It does need heads tho. I will go through the one in the Scout now and stroke it to a 514 for the Mustang.

The only other option Im thinking about is finding a running 460 for a couple hundred bucks and throwing it in for awhile. Money is real tight right now so that would be the cheapest option. Im planning on going to Moab in October so I need it up and running by then

JMHO but I think the rings are your problem. I dont know how you think the oil boosting your compression leads to a bad cam but.......

Not trying to argue, just asking your opinion, but don't you think 120 is still a little on the low side for a 460. Assuming the oil sealed the rings completely, I was thinking 150-170 maybe. That makes me think its not bumpin' the intakes open long enough. Who knows. With this custom ground cam, maybe it never had that much static compression anyway.

Not trying to argue, just asking your opinion, but don't you think 120 is still a little on the low side for a 460. Assuming the oil sealed the rings completely, I was thinking 150-170 maybe. That makes me think its not bumpin' the intakes open long enough. Who knows. With this custom ground cam, maybe it never had that much static compression anyway.

It does still sound a bit low, but we dont know what the cam specs are or anything like that. I think mine was around 150 IIRC.

I'm just about done doing a bone stock rebuild on my '89 460. I'll compression test it after I get done and let everybody know what a fresh stock 460 pushes. BTW, I like your idea of a 514 in the Mustang!

I'm just about done doing a bone stock rebuild on my '89 460. I'll compression test it after I get done and let everybody know what a fresh stock 460 pushes. BTW, I like your idea of a 514 in the Mustang!

Don't test it till you've got the rings seated good, maybe around 500 miles at least. I wouldn't crank it for that till everything is broke in properly.

I'm just about done doing a bone stock rebuild on my '89 460. I'll compression test it after I get done and let everybody know what a fresh stock 460 pushes. BTW, I like your idea of a 514 in the Mustang!

screw that. 514 the scout :smokin:

screw that. 514 the scout :smokin:

he he he :eek:



Someday maybe. I dont know how my one ton axles would appreciate that though

Just another question for ya, how bad was it blowing by?? usually a real good indicator of bad rings is alot of blowby from the crankcase. FYI flat tappet cams are not through hardened, hence the need for break in, also why they get wiped real quick when there is no oil, especially in a low mile motor.

Started tearing down the motor saturday. There are no visual signs of problems. Cylinder walls look good, there are a couple marks on them but you can still see the hone marks. Heads look good, I havent pulled the cam yet but from what I can see of it doesnt look like anything but normal. I took the heads in to get checked..........Im starting to wonder what the hell


Is it possible the timing chain skipped a tooth???

hopefully I will get the front end torn down tonight

Well........

Just pulled the front end apart.

The dbl roller timing chain is super loose. About 3/4" of play and the gears are 2 teeth off!

I think I found my problem.

Im gonna get a new chain and slap it back together and go wheel.


Thanks for all the input.

BTW

Look for me on the cover of this months Fourwheeler mag