| Author | Message | ||
| Paul Newman (Newman)
Member Username: Newman Post Number: 997 Registered: 12-2001 |
Also when doing a copression test, the engine must be warm and throttle plate wide open. I did a comp test on my fresh engine and found a 50psi difference between closed and open throttles. | ||
| Paul Newman (Newman)
Member Username: Newman Post Number: 996 Registered: 12-2001 |
It is possible to get air leaking past the valves when closed. The condition of the seats determines that, not to mention carbon and a cold compression test. If the valve clearances between the lobe and shim are near spec rather than a 1/4" gap then they are not bent. Thats a vague statement but if the valves hit the pistons (all 32 like you suggest) then they would stay open and the air would blow out the port and take the baseball cap off your head. WD40 means nothing and if you pour fluid into a port of a used but good head, the fluid will seap or leak past the seat and run fine. Who knows, maybe you dropped a valve or a valve head fell off. If so, cha-ching! It just doesnt make sense what really happened but be sure to post pics. | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 40 Registered: 8-2002 |
OK here goes......how do I know the valves are bad.....cam cover off.....intake manifold off. (both cams are still in time....no signs that they have jumped a tooth or anything) I hooked my air compressor up to the cylinder via the spark plug hole...shot a little WD-40 on the intake side of the valve...and I can see/hear the air escaping past it (at 100 psi). This is while visually verifying that the cam lobe is no where near the follower. Thus my loss of compression.....Motor spins over fine. This will be a complete rebuild (might as well while I have it out...) yes the knock scares the daylights out of me...yes I'm sure it will be expensive. But i love my car...it will drive again. Now.....with all that said...the sudden (literally overnight) appearance of a knock, as well as valves that are not sealing properly even though their timing marks indicate that they are fine.....has you baffelled and wonder why 1 + 1 does not = 2.....well....me too! Car was running fine...was a daily driver....and had 2 year/15k miles on the timing belts. I just built a house this year...so funds are a little low....this will be a long process.....I'll keep you all updated...and I thank you very much for all your help. PS...yes it had oil in it. | ||
| Paul Newman (Newman)
Member Username: Newman Post Number: 993 Registered: 12-2001 |
I wouldnt worry Jeff, change the belts and tensioners, do it right and no problems. Its the hard way but you should pull the cam covers to verify the marks all line up rather than marking the cam gears. If the PO installed the belts and one cam is off 1 tooth, you may not notice having nothing to compare it to. So you would be repeating the PO's error again. Also, you can verify the cams are degreed or phased correctly if all the lines are dead on with the new belts and if not, adjust as needed. | ||
| jeff ryerson (Atheyg)
Junior Member Username: Atheyg Post Number: 140 Registered: 8-2002 |
After reading this I will be very apprehensive to touch my belts or tensioners What could have caused this if timing was correct? Tensioner not adjusted properly and belt skipped? Belt failure? Any Ideas? | ||
| Paul Newman (Newman)
Member Username: Newman Post Number: 992 Registered: 12-2001 |
Maybe the daig is a little off regarding valves but he did mention its rebuild time for the engine. I agree, probably bottom end damage by the description and it wont be cheap to fix. | ||
| PSk (Psk)
New member Username: Psk Post Number: 11 Registered: 11-2002 |
Okay, question time. You stated that you lost oil pressure and a load knock started ... this sounds like a crankshaft bearing has failed. Why were you even thinking valves? You do a compression test and you have low compressions, or NO compressions?. If the engine will not spin fast enough then your compression test will be inaccurate. If you have run a bearing then the engine might not spin on the starter well enough to do a compression test. Thus how do you know you have bent valves? Are the valves stuck open? ... have you removed the cam covers to see?, or heads? Doesn't look like it to me ??? Has the camshaft timing altered? If a valve hit a piston or was bent and thus stuck open and is interfering with a piston I would expect the cambelts to have jumped a tooth or got damaged ... due to a seized camshaft. They are strong but will not stop a revving motors momentum ... Assuming an oil line has not fallen off, and the engine has oil  and pump was still working ... I would be REAL worried, as the only place left that will noticeably affect oil pressure is your crank bearings .... oops. This does not sound like a replace valves and drive to me, but a full and expensive engine rebuild, involving crank grinding, balancing, re-hardening, etc. Then your new valves (which should have new springs) assuming they are bent, plus guides (?) and seats (?) ... Again the loss of oil pressure would have my attention more than anything else ... major drama. Pete | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 36 Registered: 8-2002 |
FYI contacted SI valves and they're price was $23 per valve (both intake and exhaust) so thank you for the link!!! | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 35 Registered: 8-2002 |
let me go take out a second mortgage on my home as well | ||
| billy bob (Fatbillybob)
Junior Member Username: Fatbillybob Post Number: 128 Registered: 8-2002 |
Forensically, if your belts are intact and the marks lineup and you have no compression in some lungs you may only have a problem in a few valves. This can save you $ if the other valves are o.k. and in spec. But what the heck up the ante and add in some 10:1 wiseco pistons. If you dropped a valve you may haev chewed a cylinder. Maybe you can do an 020 overbore. Those mods should be good for a few percent. You may have scored the cams with immoveable valve stem ends. Weld up the cams and regrind for more lift! | ||
| Ric Rainbolt (Ricrain)
Member Username: Ricrain Post Number: 346 Registered: 2-2002 |
"If you're in the US try these guys for Valves.... http://www.sivalves.com/index.html" I bought my TR valve guides from SI Valves (50 pcs). Better material than stock and cheaper. I would be interested in knowing what their prices are like for valves. I had custom made exhaust valves for one of my 308 motors for about $40 a valve, but at the moment, I can't remember who I used. | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 34 Registered: 8-2002 |
As far as my experience with Ferrari's is concerned...this is my first f-car (I'm only 30) I've had the clutch out of it and done some other minnor work....but this will be my first MAJOR work. It was a daunting thought at first....then got to thinking you know...it's just a motor....and its not rocket science. Slow and easy with lots of questions and I should be fine. I've built several high perf. sbc's before...so this just has a fancier head design. Thanks you all for the additional valve sources...I'll keep everyone informed as I go. | ||
| Paul Sloan (Sloan83qv)
Member Username: Sloan83qv Post Number: 438 Registered: 3-2001 |
I just bought 32 valves from Nick at Nicks Forza Ferrari (click on ad banner up top). Change all 64 valve springs why your at it. | ||
| fabri (Fabrizio_trunzo)
New member Username: Fabrizio_trunzo Post Number: 3 Registered: 12-2002 |
Myles whats your experience level with working on ferrari's. Will you be doing the work yourself??? | ||
| JRV (Jrvall)
Member Username: Jrvall Post Number: 460 Registered: 11-2002 |
If you're in the US try these guys for Valves.... http://www.sivalves.com/index.html | ||
| Tim Hogan (Tojo)
Junior Member Username: Tojo Post Number: 80 Registered: 4-2002 |
I think www.owners.ferrari.com is the owners web site | ||
| Tim Hogan (Tojo)
Junior Member Username: Tojo Post Number: 79 Registered: 4-2002 |
Myles, you possibly have the sodium filled exhaust valves which are a known weak point. Whack the end of one with a hammer and see if it's hollow on the inside. Better to find out this way than to be going at 7000rpm and have the valve drop and cause major damage. Peter, I'm waiting on valves from superformance, and was told by my parts supplier that he is waiting on a shipment of 308 valves from cosworth, maybe that's where the other info about the Ford valves came from | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 32 Registered: 8-2002 |
what's the address for the Ferrari Owners Site? | ||
| '75 308 GT4 (Peter)
Intermediate Member Username: Peter Post Number: 2328 Registered: 12-2000 |
Superformance has the best prices for valves (at least for two-valve 308 engines. I didn't know he supplied for four-valves...). Nonetheless, check the Ferrari Owner's Site - another UK based parts supplier. After that, don't know. If you have the ability to check, see if the valves from another four-valve car will work. I've never proved it, but a member here (whom I haven't seen post in a LONG time) said the valves from some Euro Ford worked in his two-valve 308. Just needed to trim it and cut a new keeper groove, which he did on his lathe. | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 31 Registered: 8-2002 |
I have absolutely no idea....car went from fine...to a loud knock (overnight)with a loss of oil pressure....sat for a while and had a no start condition...upon doing a compression check...no compression and bent valves. Anyone have a source that can beat Superperformance on valve prices? I'm going to need 32! Sigh....this is going to be a long project. I'm taking this pic in and putting it on my boss' desk with a note attached saying "need a raise!" | ||
| fabri (Fabrizio_trunzo)
New member Username: Fabrizio_trunzo Post Number: 1 Registered: 12-2002 |
Wow, I guess you started your new years resolution early. Keep us updated with pics.. I am sure things will go fine.. Have you purchased any manuals?. | ||
| jeff ryerson (Atheyg)
Junior Member Username: Atheyg Post Number: 132 Registered: 8-2002 |
Sorry to hear that,for you and especially the Ferrari What do you think went wrong? | ||
| myles kleinfelter (Gonzo350)
New member Username: Gonzo350 Post Number: 30 Registered: 8-2002 |
Well after much thought, debate, and reading...I've decided to take the plunge. Somehow I have bent valves (yes the cams were in alignment) and it's rebuild time.....dear lord am I scared! But I'm sure with the help of all of you....my car will live again! 1984 308QV Euro.  |