New engine issues

[digitech]

Thanks for the interest and suggestions. I am not nearly the accomplished engine tuner that some of you are so I appreciate the insight; I foolishly listened to the guys at Paeco and accepted their recomendations regarding cams and compression ratios.
I am not too sure what ratio I bought - I was told it would be around 10:1 and would make the car a lot of fun. The pistons I got were Venolia brand with a slight, maybe 2mm, dome. The head has been surfaced at least twice.

The cams I bought were Alquati (I know that spelling is not correct) from Bayless a few years ago. They are not regrinds and the clearance is .016 on both intake and exhaust. If I don't need them for my engine, I wouldn't be opposed to putting the original cams back in. I feel certain my ticking/clacking or whatever is coming from the valves and it may be because of not enough clearance for the lift I have. My 2L engine has 84.4 pistons, 1800 single plane intake and a 34ADF carb, rejetted. I also just fitted the earlier version 4-2-1 exhaust manifold and downpipe.

I remember reading something about those cambox gaskets now that you mention them - I had forgotton all about them. I will try to get a pair from Guy if I can. I have been cleaning the surfaces each time but maybe not well enough. I guess each time they leaked, I tended to put more and more sealer on them in an effort to stop it.

I may have figured out the belt walking issue but I'll wait until I try it before saying anything. The belt goes straight to the rear and stays there - the only thing that keeps the belt from running off is the block so I'm not at all comfortable with that.

Thanks again for the help and observations.

[ventura ace]

Did the Paeco fellows measure the volume in the combustion chambers? Did they check the height of the piston crown (not the dome) in relation to the block? Do you know the dome volume (the dome height is not that helpful -- you need to know the volume that they displace)? Are there cutouts for the valves that go below the crown, and if yes, what is the volume of the cutouts? What is the thickness of the head gasket? All of the above, and more, make up the compression ratio. It takes making thorough measurements of all these parameters (and more) to know your engine, that is if you are intending to build it properly. It's not something that can be covered in a few sentences or paragraphs, so I won't attempt to try. Maybe the Paeco folks went through all this for you, and if they did, then that's good. A 10.1:1 compression ratio should give you much higher than 135 psi compression, though.

Alquati makes a lot of different cams, so you'll need to know what their profile and the recommended clearance. It may change from one one Alquati spec cam to another. The only Alquati cams that I have been exposed to had a recommended clearance of .3mm (.012"). If that's true for yours, then running them at .016" may make them clattery.

If you buy your cam gaskets from Guy Croft, I'd recommend that you get more than a couple, to have spares. Shipping from the UK is a killer, so you might as well get more.

Alvon

[131]

The auxilary gear you have is the wrong one, it should have the flange at the rear, that will solve your belt walking problem. It could also mean the auxilary shaft is not timed correctly, possibly causing a slight collision with your bigend. That would be a noise I wouldn't want to hear! The exhaust cam gear also appears to be at least 5mm further forward than the intake cam gear, when viewed side on. I'd be starting from scratch on this one. Checking correct cam gears are correctly fitted to appropriate cams ie: inlet gear not fitted to exhaust cam etc. Gear properly fitted on locating pin and correctly torqued. Food for thought!

[Daniel]

I'd be starting from scratch on this one. Checking correct cam gears are correctly fitted to appropriate cams ie: inlet gear not fitted to exhaust cam etc. Gear properly fitted on locating pin and correctly torqued. Food for thought!

I would also replace all the pulleys just to save time and be on the safe side ! Have you measured the clearance between
the cam pulleys and the cam tower is one farther out then the other as Jason mentioned ? would be nice to know why this
is happening though what a weird problem good luck with fixing it ...

[ventura ace]

The auxilary gear you have is the wrong one, it should have the flange at the rear, that will solve your belt walking problem. It could also mean the auxilary shaft is not timed correctly, possibly causing a slight collision with your bigend. That would be a noise I wouldn't want to hear! . . .

131, Please check your sources on that one. All the info that I have shows that the Aux shaft pulley is correct (flange on the front -- same as the exhaust pulley).

The exhaust cam gear also appears to be at least 5mm further forward than the intake cam gear, when viewed side on. I'd be starting from scratch on this one. Checking correct cam gears are correctly fitted to appropriate cams ie: inlet gear not fitted to exhaust cam etc. Gear properly fitted on locating pin and correctly torqued. Food for thought!

Digtech pointed out that the exhaust gear is .25" wider than the intake gear, giving it the appearance that it is more forward. He measured the spacing between the rear of the gears and the cam boxes and found them to be almost equal. I agree with your suggestion to double check all the timing gears for proper mounting, not swapped, etc., but I believe he has been through this fairly thoroughly. I don't recall torque being mentioned previously though. The bolts for these gears should be torqued to 87 ft-lbs.

Alvon

[digitech]

Thanks Alvon, I have been through all of those checks (but they're good ideas). I have torqued the bolts to 87 ft.lbs per the suggestions. Also, .016" was the spec provided on the paper with the cams (in Italian, of course). These are all the same gears that were on the car when I got it in 2003, except I put a new crank gear on in 2004 and another crank pulley I just got from Mike Bouse. I drove the car without any major issues for about a year. Took it down for about another year and a half for "a refresh" at which time I removed the engine, replaced the block, got a valve job, replaced all the ancillary components, etc. It was then a daily driver for about 9 months until a oil galley plug blew because the one that came with the new block was the wrong type. Guy supplied me with the correct one and I took advantage of the downtime to pull the engine again and haul it over to Alabama to Paeco for some "performance" work. A BIG mistake! However, Jon Logan wasn't as far along in his business yet and I didn't want to ship it to Texas to Vicks. Really wished I had. But, all this time, no issues with the belt tracking, valve train noise or any other major issue - it's a Fiat, there's always something minor.

When I got the engine back (in boxes), I washed it, inside/out, lubed it, wrapped it up and it sat for a while. Finally began to put it together and during my dry fit, I discovered two of the pistons (don't remember which two) were contacting the combustion chamber and preventing rotation! I wasn't able to find anyone in my area that could machine the pistons so I dremeled some material from the head - it wasn't much, a slight enlargement of the chamber as I recall. I'm sorry I can't answer your questions regarding piston height, cutout vol., etc. There were cutouts for the valves. Based on what WAS done, I'd say very little, if any, was done to the correct standard.

Used modeling clay and measured valve clearances as best as I could - all seemed to be okay and I had a smooth rotation during the subsequent dry fit, without any undue effort. Next, I trucked the entire engine to a local machine shop know to do pretty fair work and had him recheck the engine for fit, balance (which was way off) and examine my dremel work. I'm fairly sure the bottom end is good; I'm not hearing any knocks and there's no blue smoke during startup or running. I will say the engine appears to rotate a lot slower on the starter than it used to.

I then began cleaning, lubing and assembling the engine, put it back into the car and here's where I'm at. So, I'll leave it running long enough to check my idea on the timing belt issue, back the car out and turn it around, putting it back into the garage front first, remove the head assembly and see if anything is amiss there and try to get these leaks solved.

[131]

131, Please check your sources on that one. All the info that I have shows that the Aux shaft pulley is correct (flange on the front -- same as the exhaust pulley).

I've never seen an auxiliary pulley on an engine with the flange on the front. The 3 blocks I looked at last night all have it at the rear.

[FiatMac]

Based on looking at engines I have, I believe the flange was moved to the back of the auxillary pulley after the 79 or 80 model year. My '76 and '78 engines have flanges on the front of the exhaust and Auxilliary pulleys and on the rear of the intake pulley. I have a '79 with the same set-up. I have an '80 with the same except with a flangeless exhaust pulley. My '82 has flangelss on both intake and exhaust with a flange on the back of the auxillary pulley. I believe Fiat's change must have corresponded with going flangeless on both cam pulleys (to keep the belt from walking back). Unfortunately, it appears that many of the vendors are selling the exhaust pulley from the early cars as an auxillary pulley because the locating pin and timing marks for the exhaust and auxillary is the same. However, for the later 2 liter engines (or those with flangeless cam pulleys)the locating flange is on the wrong side.

For the performance engine I am building, I have modified the auxillary shaft to remove the fuel pump lobe. Therefore, an intake pulley with the flange on the rear can be used.

Stan McConnell

[ventura ace]

Stan,
Thanks for the feedback about the evolution of timing pulley designs, and I apologize to 131 for questioning his reply (all my experienced is based on engines earlier than the 2L engine).

Can we safely say the following applies to the timing pulley design for all years 67-85 Fiat 124 spider DOHC engine designs:
1) As far as timing marks go, the exhaust pulley and the auxilliary shaft pulley are the same. If you hold the pulley so that the dowel pin locating hole is at the 12:00 o'clock position (viewed from the front of the engine), then the timing mark is a few degrees to the RIGHT.
2) For the intake pulley, if you hold the pulley so that the dowel pin locating hole is at the 12:00 o'clock position (viewed from the front of the engine), then the timing mark is a few degrees to the LEFT.

Can we also state that the flanges on these pulleys are not needed?? As Stan pointed out, in some years the flange was omitted from the intake and exhaust pulleys, and the flange has possibly moved from the front to the rear of the auxilliary shaft pulley. It seems that the belt is guarded from walking forward and backward by the way that it is retained at the small drive pulley on the crankshaft, and that is good enough????? Just asking.

Alvon

[FiatMac]

Alvon,
I think if both the cam pulleys are flangeless, then an auxillary pulley with a rear flange is needed. The crank gear has the pulley to prevent walking forward, but at the rear there is nothing to keep the belt from walking back into the crank seal housing. The housing is stationary and would give a rubbing contact which would damage the belt.

Stan

[Daniel]

Flange front or rear this doesnt matter ! a waste of time to make this a point of interest ...........

[digitech]

In regards to my own issues, I'd have to agree. As I've said, I've owned the car for several years, put several thousand miles on it and never had an issue with the belt not staying centered on the pulleys -ever. But my problems run so much deeper than cam pulleys - that's what I'm looking for advice/observations on. Thanks!