field report: 264/274 *12 cam installation

[falcon fanatic]

When I last left you, I had the powerband right where I wanted it, peaking a few hundred revs past 5,000 and coming on early. However, I couldn't get a decent idle and I seemed to have a miss. Use of an infrared thermometer on the header revealed that #2 and #5 where running as much as 30% colder than the other cylinders. AFter exhausting all my standard tuning practices I gave up and took it to an old british car mechanic. He turned it around same day, performance much improved. His solution? Set the TIMING AT 50*BTDC!! Car runs great, but still idles a bit weak when in D and tends to load up a bit. Exhaust temps a the head are much more even (although 3 & 4 sure are hotter than the rest).

My conclusions: Don't put this cam in an engine with relatively low compression. Although several people have described it as a "girly cam", tame, street, etc, it just won't pull enough vacuum to run decently on my engine which I calculate at 8.5: static compression.

The lesson: don't screw around. If you want a performance engine, just build the whole darn engine. I've spent enough money trying to do this piecemeal to have had a super nice, balanced performance engine built by an experienced professional, but what I have instead is a dog that won't idle and is still slower than a Nissan Sentra. Yay! Now I get to pull the engine anyways and have it rebuilt at a total of twice the cost, if I can give a damn anymore because frankly a 280Z or a turbo Supra with t-tops is starting to look pretty nice right about now...

 

[JackFish]

Umm, so you have a "high-performance" cam in a stock low compression engine? Is the head modified at all?

Why did you not bump up the compression a bit?
Perhaps a smaller, 1bbl carb might help.

 

[rbohm]

8) i would say get the compression up to 9.5:1, and add a second carb to the mix to balance your fuel mixtures cylinder to cylinder.

 

[Gene Fiore]

Did you degree the camshaft when it was installed?

 

[jamyers]

Is that considered a 'performance cam'? From the ClassicInlines tech page...
That'd be a Class II cam, should be good on a stock engine...or am I missing something?

Listed below is a general group classification for aftermarket cam profiles. The durations shown are based on .050 cam lift with a 112° lobe center. The descriptions within each group show the characteristics of the cams in that group as well as any recommended modifications to the car or engine that will help get the desired performance.

•Class I (200° - 215°)
Good idle quality. Low rpm torque and mid range performance.Will work with
stock or slightly modified engine. Manual or auto transmission.
•Class II (215° - 230°)
Fair idle quality. Good low to mid range torque and horsepower. Will work with
stock or modified engine. For use with manual or automatic transmission with mild stall converter. Lower vacuum than stock.
•Class III (230° - 245°)
Rough idle quality. Good mid to high rpm torque and horsepower. For use with manual transmission or high stall automatic. Requires improved induction, exhaust system, and ignition system. Combination street and drag. Will have low vacuum.
•Class IV (245° - UP)
Rough idle quality. Mid to high rpm torque and horsepower. For serious racing.
Need proper selection of rear axle ratio and improvements in carburetion and exhaust systems. For use with manual transmission or automatic with very high
stall converter. Will not have enough vacuum for power accessories.

 

[falcon fanatic]

I have a mod-log head which is ported with big valves and 51.5cc chambers (stock where 56cc) and I have a .044 crush thickness head gasket in place of the old .056 Fel-Pro, so a noticeable bump up in compression from stock. My conclusion was the same as Jamyers that it should be good on a stock engine. Mike agreed. It does run awesome and makes good power, but it idles quite poorly, that's all.

Being able to run 50* of timing implies that I could be using a heck of a lot more compression. Of course I'd like to up my compression, but that involves pulling the engine and replacing the pistons at least. At that point it just makes sense to get a complete rebuild since this engine isn't especially well balanced. Plan B would be to step down to a tamer cam. Maybe a Comp Cams 260??? Plan C would be to light my car on fire and get something that actually works right out of the box

Yes Gene, I degreed the cam, incorrectly. So, that was no help at all unless I wanted an engine that revved to 6500 (which was pretty cool, actually). I then I guestimated a new advance for the cam based on where the powerband was and where I wanted it to be. Ended up at the +4 mark on the adjustable gear, so +4 give or take whatever slop is manufactured into the engine. Cam timing is good now as the power comes on immediately and pulls to about 5200 rpm or so.

 

[falcon fanatic]

It wouldl actually work pretty well with a manual, but since it only pulls 10" of mercury at idle once you put it in Drive i start to bog down kinda bad.

 

[rbohm]

8) why not just shave the head .050" to get the higher compression?

 

[Broncitis]

This is a tough one to comment on, without just throwing something out there, I'm assuming from your comments that the idle advance is 50 degrees, so that would be total timing is around 70 degrees, I just don't think that can be correct if all else is correct, dampner, cam, timing chain etc, most dampners don't even have that many marks, I don't think it is as serious as you think, it could be as easy as a badly stabbed distributor, just get back to basics and I think you will find it.

 

[Ronbo]

Normally I would agree with Broncitis however comma, I have personally experienced the same phenomena (sp) on my stock rebuild when I first installed it. My problem was a MASSIVE vacuum leak around the throttle shafts on the carb (H/W5200) AND a small perforation in the CLIFFORD piece of work (POW) adapter. Once I replaced the carb with a DGES 38/38, much like F/F, I was having a heck of a time tuning the beotch. I pulled the carb for a rebuild (bought new in the box but hey, you never know) and discovered that hole. JB weld and bam! Tuned the carb in, brought the timing down and voila! Nice running vehicle, sorta. The DGES can be finicky in hot/cold humid weather. I KNOW F/F has been all over that engine numerous times both awake and in his sleep but look again. If you have a direct mount carb start where the adapter is mounted to the log and go from there. The vacuum/idle problem coupled with the timing issue indicates you may have the same problems I did. DO NOT forget those end caps on the log either. That is a spot most forget.

Much like F/F, I was ready to throw the whole thing away (along with money invested) because of frustration. I'm sure many of you, like myself, have scored awesome vehicles because of things like this. I had a 62 P-50 moped for free because of debris in the gas tank. A 65 Honda Dream for $125 (same owner as the moped now suspicious of this 14 year old's capabilities) with a plugged fuel filter ($1.65) and so on.

F/F, where are you jetted at? I was up to, I think, 70s? Before I went for the rebuild and found the hole. Dropped me back down to 55s. I think it was Jamyers that I asked what he was running and that got me to thinking something was still wrong. Check it out buddy! Looks like you have a lot of nice items on the car and a lot of hard work into it. If nothing else, this time throw in a professionaly built 289 capable of twisting 6K rpms and call it a day! 8) Oh, and STILL get the Supra/280Z and have that on the side. Anyone looking for a Porsche 280S? One of 200 built. Lady is asking $12 Gs for it with extra parts and the coveted "special" tools to go with. I popped the hood and....too much for this old dog. :roll:


Ron (I think the coffee is kicking in.)

 

[Lazy JW]

....... I'm assuming from your comments that the idle advance is 50 degrees, so that would be total timing is around 70 degrees, I just don't think that can be correct if all else is correct, dampner, cam, timing chain etc......

That's my thinking too. This type engine requiring 50º of initial timing truly is an indication of something very fundamental that is haywire.
Joe

 

[aahsac]

If the timing is that fast (50 degrees) then I doubt your could get the starter to spin the motor enough to start. If the timing mark hasn't been accurately verified against TDC then you have to assume the balancer has spun.

 

[falcon fanatic]

The timing mark was cut by me using a magnetic dial guage on the top of the #1 cylinder when I ha the head off for the cam swap. I'll check it again, of course. The mechanic who did the tune thought this was not so unusual in a cam with long duration. I've certainly never heard of such a thing, though. total advance is now 76* since my dizzy has 26* with the current weights and springs. Seems impossible, but there it is.

 

[Ronbo]

I guess I'm just a crack monster Army vet so I didn't see what I mentioned above.

Falcon Fanatic, seen it myself and I have a post on it somewhere in this muck.

Ron

 

[Ronbo]

Not to hijack or anything, but we are in the same boat. By going back and forth between idle and checking timing I was able to get mine to run smooth at idle but forget driving it, same symptoms. When I crank it up to around 20 degrees initial I can drive it but that is NOT normal. I have a newer distributor with Pertronix and the H/W 5200. I'm really thinking vacuum leak somewhere :roll: Idle screw is almost all the way backed out too. Not sure why the timing would have to be so high. I checked the h-balancer during reassembly and it was good.

Ron

Here is a part of one of the posts. It actually was way more than 20* but I was too embarassed to say.

Just check it out...my problem was a vacuum leak. Best of luck!

Ron

 

[Broncitis]

There is a huge difference between 20 degrees and 50 degrees initial timing at idle, huge, there is somthing very fundamental wrong here, I'm just going to say whats on my mind and that is that if everything is timed correctly this motor could not run with 50 degrees btdc initial timing, there is something wrong with the timing events here and I don't know which it is, I still think its something very smple or at worst a redegree of this cam, 8.5 static compression will not cause this with this cam, granted you will not have the same power as someone with 9.5 and I'm not trying to flame anyone here. Also granted here is if you have a very bad air leaking carb and bad vacuum lines causing you to run high idle, you could possibly see 20 degrees initial timing, but not 50 degrees.

 

[AzCoupe]

You definitley have something else going on, as that cam should be pulling 16-20" of vacuum. I'd also guess a vacuum leak, but it could be a few other things (faulty head gasket, burned or bent valves, improper valve lash, etc). Did you do a wet-n-dry compression test? If so, what were the results?

I calculate your C/R to be 8.7 to 8.8 depending on bore size. And while I don't agree that this is your proplem, I'd would certainly bump it up to 9.4-9.5, simply to enhance the throttle response and over-all performance. Especially if you wind up pulling the head. This can be done by using a Felpro gasket (.038 crush) and milling the head .030-035 thousands. This would put the Dynamic C/R at 7.8-8.0, which still lets you use pump gas.

 

[falcon fanatic]

Dry compression test was 145 155 155 145 150 155. Wet was pretty much exactly 15 psi more for each.

I can't mill any more off the head. the guy did a sonic test before milling and this was what he was comfortable with. 51.5cc is pretty small, anyhow. Since they also had several full race engiens in there, including a 3000hp drag monster, I'll have to trust them.

Yep, I agree with all of you. When the mechanic told me what he had done I just had to say "that ain't right." And he said "well, all engines are different. this one likes a lot of timing." Then he took my money.

The problem is, I can't figure out what's wrong and I can't find a mechanic who knows squat. I was actually turned away from three shops one day. First one said "we don't know how to work on cars with carburettors." Second one said "we only work on cars that nobody else has ever worked on." Third one said "that car is too old, we can't get parts for it" I said "It's a Ford, have you heard of AutoZone?"

Well, back to the drawing board. It really might just be easiest to yank this sucker and take it to my machine shop and have them freshen up the bottom end, mill the deck, and assemble it *correctly*. Then I'd have what I've been after from the beginning...

 

[Broncitis]

FFthis has got to be a hair yanker for ya, I feel the pain after just having to rebuild my 200 after 500 miles on a 10k build, just don't give up, you will find the answer, at least you don't live in no mans land like myself, I wish you well.

 

[A CALT Morris]

Try using a propane torch to find a vacumn leak. Remove the tip, slide a piece of rubber tubing on the outlet tubing and then put an old carbuertor jet in the end of the tubing. then you can direct a small stream of propane all around any suspected vacumn leak area. Any change in rpm will indicate a leak.