Bronco Forum - Full Size Ford Bronco Forum banner
1 - 18 of 18 Posts

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #1 · (Edited)
Update below


Looks like my loss in power in the Bronco back before the house fire was a head gasket on its way out. It still ran fine at idle and cruise speed but as soon as I got on the gas I could faintly hear a miss and the normal power just wasn't there. Nothing major but I could tell it was going down hill(performance wise) over the course of a week. Well, after sitting for a few months now and replacing a lot of parts and tools that were lost in the fire I put the new timing chain on today and adjusted the valve lash so I could do a compression test. The numbers really surprised me. I've never seen numbers this high and remember this was done cold(sitting for months).

compression test results

cyl #
1- 185 psi
2- 200 psi
3- 190 psi
4- 205 psi
5- 155 psi **
6- 195 psi
7- 190 psi
8- 200 psi

I only have appox 9.25:1 - 9.3:1 compression and I never expected numbers this high. I was pleasantly surprised. The 155 psi seems like a pretty good number for every other engine I've done but it is 50 psi lower than the highest cylinder which is 25%. I'm actually kind of glad I got one cylinder low otherwise I still wouldn't have an explanation for why I was losing power. $100 for the high performance head gaskets and $40 for stock. I think stock would be pretty stupid considering the compression I'm running and the engine I built. It kinda ticks me off because I only have 12,000 miles on this engine since I built it but at least it's nothing major mechanically wrong. I sure am missing my air conditioned garage right about now.
OK I'm done complaining now, you can rejoin your life already in progress.:toothless
 

·
Satyr of the Midwest
Joined
·
17,738 Posts
Well, it's a great thing you found it now instead of somewhere out in BFE, right? You're pretty sure it's a gasket and not a valve hanging open? I was thinking you could mebbe run the valves pretty loose, ~0.030-inch, and try it again just to be sure. I know you know what you're doing Bob, just hate to see ya have to pull the heads off if it's something easy. 'specially in this heat!

I'm going to be busy replacing my distributor today. Seems the Michigan salt on the steel screws holding the distributor cap adapter onto the body didn't like life. Damn ears fell right the feck off. :banghead
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #3 ·
Well, I adjusted all the valves(push rods) to zero valve lash then went 3/4 of a turn farther and locked them down. That's not a bad idea. I could re-do the lash on #5 cyl and just go 1/2 turn past zero lash and re-check compression on that cylinder just for the hell of it. It'll only take a couple minutes. I'm sure that's not the problem since I did them all in sequence and did them all the same way but it's worth a check while it's already set up to do. I doubt there's anything wrong with the heads since they were brand new out of the box when I got them and they now only have 12K miles on them. Maybe I'll have the machine shop check them out also while I have them off.
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #4 ·
Well I readjusted the valve lash on #5 to 1/2 turn past zero lash and no change. I'm picking up the head gaskets in a little while. Hopefully I'll have them on soon. I'm working noon to midnight the rest of the week so I'll only have a couple hours a day to work on it. I'm really anxious to get this thing back on the road.
 

·
Satyr of the Midwest
Joined
·
17,738 Posts
I bet. It KILLED me yesterday to have my rig not running, especially with all the people out on the streets and at the beach. Sucks that you have to redo the head gaskets and all, but you're pretty dang close to having 'er road-ready after that, right?


Got-dang AZ... Yesterday is the LAST DAY of my life I'm ever even entering one of those (*#%ing stores. I went through THREE distributors trying to get one that worked; had to go to Sylvania, Byrne, then Reynolds road stores. FYI for everyone else, we're talking probably about 8 hours of dickin' around travelling and troubleshooting (supposedly) brand new parts. I got sick of it, went to ABC NAPA down in Toledo, picked one up, and she fired right up and ran perfectly. So yeah, yesterday was a wash.

EDIT: oh, the problem in the AZ distributors is the method in which they are remanufactured. The hall-effect switch wiring is too small of a gauge. They thought they'd save some $$$ (or something) and just double-up the wiring, obviously being completely ignorant of the kinds of signals that the PIP is sending. Like I said, spending hours chasing down erratic PIP signals due to shit reman'd parts sucks.

Got your PM Bob, thanks for the offer. :thumbup :beer I busted the old distributor body pretty darn good, btw, and the hall-effect switch was toastie.
 

·
Registered
Joined
·
694 Posts
Sorry to hear about the house fire. I haven't been around here all that much recently and hadn't heard of that.



Those are some decent compression numbers.

What cam are you running again???? That is likely the main cause of the high numbers I'm going to guess. Less overlap, has a massive affect on cranking compression numbers.

I have yet to check my fresh bullet, well I think of it as fresh since its still under 6k.

I had a very stout 340 Mopar about 15/16 years ago that mathmatically was 10.5 and thats what the pistons were designed to be at. Yet it only cranking compression tested at 185/195 lbs. All plugs out and carb wide open. But, I was running a 292/509 old school Direct Connection purple shaft cam that actually had @ .050 lift duration numbers up more inline with as advertised 300+ duration cams. The @ .050 on that little valve tickler was 242 deg, which is a heck of a lot of duration (hence overlap, and compression bleed off) for a 345" motor with a short stroke in a daily driven street 4spd Duster.

Again, what cam are you running?
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #7 ·
I had Edelbrock's SD friendly cam before I took it all apart. Now I have Comp Cam's SD cam. I found out that the spring pressure on these TFS heads was higher than the recommended pressure for the Edelbrock cam but was right on the money for the Comp Cam. Yeah I know I should've noticed that when I built the engine last year but somehow I guess I overlooked the Edelbrock cam specs. Probably because it wasn't listed in any of the cam paperwork I had, I found it looking on line after after trying to diagnose a problem(that looks like it was this one weaker cylinder all along). The cam and lifters look fine, no damage which is good so I'm glad I caught it before I ate a few cam lobes and sent metal throughout my whole engine. Also glad I caught the compression problem now and not after I put it all back together.
 

·
Registered
Joined
·
694 Posts
Since you have good aftermarket heads I am compelled to say or type two words ROLLER CAM. With even just decent heads the combo could really really be surpriseing, with more valve lift to take advantage of the already available/capable head flow numbers. My lill 357 has impressed/surprised everyone I know, and considering I've got stock duration numbers and my friends are all used to my past very serious strip/street muscle cars.......well the crowd I hang with is hard to impress at this point.

Not to toot my own horn, but as further peer pressure on ya. The midrange and low end is insane out of my lill 357" engine, insane. I've smoked cars and given cars a run that would never ever have guessed a Bronco could run this strong. I'm talking old muscle, ie; a buddies 454 Chevelle with serious traction issues down low, a 70 very stock appearing Cobra Torino with a 4spd and what sounded like the SCJ not just CJ as I heard solid lifters a ticking away. I have yet to time it against the clocks or have it tuned on a dyno, but I fully intend and honestly need to. I'll be happy to be out of the 15's, but she's running like she could show me a much better time than that.

Before you put that thing back together, do yourself a huge favor and slide a roller cam in there. Keep the duration mellow, and shoot for lift. Compare your head flow numbers and go from there. Thats my huge recomendation to you or anyone that it sounds like could make that decision if they simply wanted to at this point.
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #9 ·
Didn't want to spend the extra $700 - $800 to convert to a roller cam(over $400 just for the conversion roller lifters). I will be building a 393 later this year early next year and converting to MAF though and I do plan on putting a roller cam in that. This thing already screams as it is, I am very pleased and impressed with it and so is every body that I've taken for a ride or raced.
 

·
Registered
Joined
·
694 Posts
Thats cool, and I certainly understand. Money is money after all. Hard to come by and hard to part with.

In my case when I broke the skirt off the number 8 piston and ripped the rod with wrist pin out of it and bent the rod on the original engine I just fairly quickly chose to find an F4TE roller cam capable block for the rebuild. I could have saved my original block, but for 350 bucks more I hoped it would be worth it. Already needed new lifters, just got low mileage used 5.0 ones for 50 bucks there. Already needed new pushrods, so once I mocked it up there was no difference in cost there, just picked the appropriate pn for my +.100' longer valves. And, I already intended to run roller rockers so not biggie. When ordering my PTL heads it was likewise no additional cost for the springs good for a roller cam up to .600" lift.

In my case I got the Comp 258HR cam at a price that it was the same as a flat tappet grind, so non issue. So, I spent 350 for the block, another 50 bucks for the hold down spider and dog bones, and I'd imagine I got the low mileage used roller lifters for possibly less than new aftermarket nice flat tappets.

It doesn't have to cost 700/800 bucks like everyone likes to think, but ......it does cost more one way or another. Way way worth it in the end what with profiles you just can't have any other way.

Sounds good though, and glad to hear your only dealing with the headgasket and it didn't warp the head yet.
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #11 ·
Update 7/25/06


Well I just got the heads back from the machine shop and I had an exhaust valve that was leaking by pretty bad. Definitely glad I took them to the shop to have them checked out and didn't just assume the head gasket was the problem. All the valve guides were good, had them resurface them and hot tank and they re-gound the one valve and seat and I'm good to go now(hopefully). $124 total, I'm happy with that.

There was quite a bit of burnt oil in the combustion chambers and the exhaust ports. I had a problem with a LOT of oil in my upper intake before I took it all apart. Probably due to a bad pcv valve. I'm assuming all that oil getting sucked into the intake and burnt is what fouled the exhaust valve.

I also noticed that I didn't put the high performance head gaskets on when I built it. The street gaskets are $20 per side and the high perf gaskets are $50 per side. I couldn't remember for sure. I probably figured since they said street and strip that the street gaskets would be good enough since it's not a drag strip vehicle. Well now that I know that I'm running some pretty hefty compression numbers I'm going with the HP head gaskets and now maybe she'll be running for a long time to come.

Hope to have it back together by the weekend and hopefully everything's as good as new again. Keep your fingers crossed for me.
 

·
Satyr of the Midwest
Joined
·
17,738 Posts
Great to hear, Bob! Hopefully you'll be tooling around Monroe county PDQ. You got it taken care of for relatively cheap, so that's another case of beer you can get. :D
 

·
Registered
Joined
·
694 Posts
The oil in the upper intake is a common problem even with a new PCV valve. Fairly extensively discussed in the Corral.

You may want to look into air oil seperators.

I looked into ones available on the market, but after some lengthy discussions with a few different people I decided I could make my own that would be much much more effective. I probably spent 10 or 15 bucks and made one thats much bigger, and much more efficient than what the aftermarket has to offer. Mine also didn't cost a bill plus.

Another trick to limit this is to restrict the airflow on the vent side which not only restricts the air going through the PCV to the intake, but if you hook up a vac gauge and adjust the restriction accordingly you can have the crankcase under a tiny bit of vacuum instead of pressure which helps seat the rings a touch better.

Previous to these above little tricks I had a puddle of oil always sitting right behind my throttle body in the intake upper. Now I have no puddleing, and a nearly 98/99% dry intake upper. Just the way you want it. Oil in the combustion chamber is just takeing up space that should be filled by air/fuel mixture so there is power to be had with this as well. Not to mention my oil consumption is now nonexistent.
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #14 ·
Yeah, I plan on using an air line water separator in line between my pcv valve and the intake. I'll be using a Motorcraft pcv valve but just in case it lets any oil by again I'll see it in the separator first.
 

·
Charlie don't surf..
'92 Ford Bronco XLT
Joined
·
16,204 Posts
Bob, was just checking out this thread, sorry to hear about the problems with your engine, I know how you feel. Correct me if I'm wrong, but you did replace the entire valve train on this motor didn't you? I mean rockers, rods, springs and so forth? How many miles did you have on it before the problem showed up? When you did the initial compression check and found the 155 on the one cylinder, was the 155 holding steady or was it dropping. I'm trying to see if there are any similarities to my situation that might offer me some alternatives.

Keep us posted after you get it put back together since you had the work done on the valve.
 

·
Ex Navy Nuke
Joined
·
5,421 Posts
Discussion Starter · #16 ·
Everything was new. New Trick Flow heads with new roller rockers, push rods, cam lifters. The only thing that wasn't brand spanking new was the block. Had 12,000 miles on it when this started(appox 6 or 7 months of driving). I didn't do a leak down test, just a compression test so I don't know if it was holding there or dropping. The gage for a compression test holds the highest pressure on the gage with a check valve until you press the little release valve. Between having the heads taken care of and putting in another new cam(because my Trick Flow springs are too strong for the Edelbrock cam I had) I'm thinking/hoping I should be in pretty good shape when I get it running. I got the heads bolted back on and torqued down today before the rain started. The valve train is the next thing on the list. I'm gonna get the rockers and push rods installed and valve lash adjusted then do a compression check before I go any farther so I have a base line.
 
1 - 18 of 18 Posts
Top