Performance Cams and Valves

[yap123]

I have an 82 and runs pretty well with 54,000 miles. Last year, I had a mechanic install Mark's front big brakes. The braking power is quite noticeable. I am very pleased with it.

This year, I would like to get more pep and power. So, I was looking at Mark's header. However, after having the Fiat sit a few days, I get white smoke from the exhaust. I asked Mark for his recommendations with a budget of $1,500. He said it's probably worn valve guides and he would port the head and put in oversize valves along with mild cams. Cost would be $2,000+

I have the following questions:

1) At what RPM do most drivers typically shift gears?

2) For those who have installed performance cams and valves, is there a big noticeable difference in torque and power?

3) To have a good idea on the top end of costs, while replacing the cams and valves, what other items may need or should be replaced?

4) How bad is it for the engine to have worn guide valves?

I thank you in advance for your advice and comments

[engineerted]

I would guess that your valve stem seals are hard and possibly cracked, not that your guides are worn. Upgrading to cams and headers without bumping the compression is just wasting money. I would pull the head, clean and inspect replace as needed. new seals, gaskets at min.

[PatTroy]

I was shifting my car on the track, just a bit above 7K (this is a bone-stock 1608). Performance cams and a valve job should yield improved VE and a noticeable improvement in power. Cams and valves means re-sizing the shim stack to correct valve lash. I'm not familiar with whether or not the manuals recommend new locks or retainers. you'll also need some gaskets (head, cam covers, rear covers etc.) timing belt is a good move too. Worn valve guides are bad, and will result in all sorts of issues (misfire, low power, high EGT, noise, etc.) but it does sound more like valve seals. These are not bronze guides in the head, so it's totally possible that all these engines get sloppy valve guides too based on the age and materials. Mark knows better than I and I suspect your post is an abridged form of the conversation you had with him (so we might not have all the details).

[md88plt]

I upgraded my 1979 with 8mm domed Mahle pistons, balanced the lower end added 34 ADF with 1800 manifold and and a mild performance intake cam. Car runs great but the performance is not staggering. Maybe back in 1979 I would have more appreciation, but when my 2014 4 cylinder 2.0L BMW produces 250bhp its hard to appreciate the few extra horses that my FIAT makes. That being said I am excited about doing some cylinder headwork and exhaust upgrade to get some more horses out of my Spider.

[joelittel]

I shift around 7k on spirited drives. My car really comes alive as the rpms climb.

Over the past few years I've done just about every mod that's available. One of the first big ones was a hi performance head with Mark's 285 cams on both the intake and exhaust. This required adjustable cam pulleys to take full advantage of the upgrade.

The head alone wasn't a huge gain, but a noticeable one. Adding the free flowing exhaust, header and higher compression to the mix made a very enjoyable difference.

[yap123]

Joel,

I'm from Homewood and my wife is from Skokie now living in Southern CA. Back in the early 80's, I use to drive my brother's 81 Spider along Lake Shore Drive. That's the reason I purchased my 82 Spider 11 years ago.

I wonder how well is the Spider engineered to accept high performance modifications? The added stresses on the frame, differential, clutch etc.

[So Cal Mark]

I was asked for worst case scenario, that's why I mentioned valve guides in the discussion. Since I haven't seen the car yet I was only prepping the owner for what might be required. My suggestion was for mild cams since compression is not getting raised at this time. The reason for porting and oversize valves is to be ready for the next step.
I've built many of these packages with stock compression and the cars are MUCH quicker afterwards. $2k does not allow a lot of room for upgrades when you first have to repair an issue.
If there was any extra $ I'd recommend the lightweight flywheel, the bang for the buck is excellent.
And yes, the Spider will hold up to more power and like any car will have various failures if abused

[chrisg]

many years ago (like, nearly 20), I got a '79 spider 2K from a guy who for some reason had bought a set of IAP street performance (?) cams and had them installed. The rest of the motor was stock '79 complete with the full array of crappy carb and a million and a half vacuum hookups for smog. The driving impression of that car was that at lower RPM it felt about like any other 8:1 2L carburated twin cam...maybe even on the puny side. I don't know if it was wishful thinking, but it did feel like above 5500 RPM rather than flat lining, there was some more power coming in line. After some test drives, the '79 intake & smog kit was removed & I put a '74 intake & carburetor on it (34 DMSA). With that setup, it clearly breathed better throughout the spectrum and without any hard numbers to back it up, it was clearly making more power and even felt pretty nice in the 5K-up range. It still was not remarkable at the 3k-down range. (around the same time as the intake change, I put the rear axle/diff from the '74 on it, so seat-of-the-pants analysis was quickly skewed). A few years later, those cams came out of that engine and went into a FrankenTwinCam 1.8 head on a '79 Lancia 2L block first with the same type of (or maybe same actual?) '74 intake & carb & then with 40 IDFs and a PBS style intake...so, basically a 2L twin cam that would be around 9:1 CR, fresh head work, but stock - no special porting, none of the stuff that's all but "par" for a build up these days. That set up felt very lively...it was able to idle well, but did not have any low RPM deep holes in the power band and (especially with the IDFs) pulled until even driving a Fiat you felt like you needed to shift! Since then, I've never really considered it made much sense to do too much without at least bumping the compression some. I rather liked (in part because of my budget at the time) the 1.8/2L on a good low mileage bottom end vs. rebuilding w/ new pistons, but the plentitude of good low mileage 2L blocks may have passed by now anyway. 1.8 heads...well, that's easy. I'm assuming Mark sells an array of flywheels lighter than stock...I like that idea, in terms of the feel of the engine, at least a bit of lightening.

[joelittel]

Yap123, if you drove Lake Shore I'm sure you know about Sheridan Rd. I spend a lot of time running up and down the lake between Lake Forest and 35th Street.

As far as the added stress goes, I have broken quite a few of the original bits, but always replace them with the best I can afford. Knock on wood but it's been a few years since I've suffered a serious failure.

I try to do all my own maintainance these days but once a year I have a real mechanic look at the car to make sure that I haven't overlooked anything.

Other than a broken "spider" gear (the one in the middle of the rear axle ) there have been no issues, and I drive my car like Bo & Luke Duke drove the General Lee. Just last week after my drive my wife could still smell the burning rubber even after the car had been parked for a minute.

It's an old car and I know that I'm pushing my luck but I am committed to upgrading everything I replace and so far I could not be happier.

I also modified my car with an end goal in mind. Doing it this way isn't ideal, Ie spending a year or two with high lift cams and stock compression wasn't the most impressive setup... but the end result has been so worth it for me.

Joe

[calvinconrad]

I had marks cams with stage 1 grind and bigger valves installed recently. it has the big header, full 2.25 exhaust system and the 32/36 empi carb which was installed prior to this. its a 1800 cc with stock compression. I am really happy with the Cam and valve mods. much more power.

[chrisg]

what kind of range of shim thicknesses did you end up with? I'm assuming you also needed adjustable cam gears?

[joelittel]

I bought a shim kit and it seems that I've used quite a few, ranging more than I would have thought.

Adjustable cam pulleys make a difference. In my opinion it would be silly not to dial in your new cams perfectly.

[chrisg]

right on...well, with regrinds and (I presume?) milled cam towers, you would have to be able to adjust the gears, right?

thanks

[MIGHTY 8]

I have an 82 and runs pretty well with 54,000 miles. Last year, I had a mechanic install Mark's front big brakes. The braking power is quite noticeable. I am very pleased with it.

This year, I would like to get more pep and power. So, I was looking at Mark's header. However, after having the Fiat sit a few days, I get white smoke from the exhaust. I asked Mark for his recommendations with a budget of $1,500. He said it's probably worn valve guides and he would port the head and put in oversize valves along with mild cams. Cost would be $2,000+

I have the following questions:

1) At what RPM do most drivers typically shift gears?

2) For those who have installed performance cams and valves, is there a big noticeable difference in torque and power?

3) To have a good idea on the top end of costs, while replacing the cams and valves, what other items may need or should be replaced?

4) How bad is it for the engine to have worn guide valves?

I thank you in advance for your advice and comments

Close to 154,000 miles on original engine and it has lived at idle, 4K while highway cruising, or 6,500rpm red line sprints in the twisties! These cars were meant to rev and she has never skipped a beat! Now granted, although it may sound like a "thrashing" but in reality, you DO need to baby them and give them some TLC probably more so then a modern car.
If I'm not mistaken, think of those performance cams alone (and they're added overlap) while still maintaining a stock piston set up, and it will result in over-all lowering your already low stock compression ratio. (Not good!)

[So Cal Mark]

we have a grind designed for stock FI and compression that has reduced overlap. Great midrange power from them