Ford 1700 X/Flow Valve Adjustment

[Steve in Lititz PA]

Hello all,

 

I'm a relatively new owner of a 1985 Caterham Super Sprint and have a question about valve adjustment.  I'm not new to adjusting valves, just new to what I'm seeing.  Engines in my experience have a jam nut which is loosened, then one adjusts the valve with a screwdriver, then tightens the jam nut.  Naturally, some trial and error is always needed since the jam nut changes the clearance slightly.

What I'm seeing, however, appears to be similar to a tube nut which bears on the pushrod, but with no lock nut.  Is this correct?  After adjusting clearance with nut part of the tube nut, what maintains the clearance? Picture attached. 

Thanks in advance.

Steve

[anduril3019]

You have the uprated friction fit adjusters, no lock nuts required. You should have significant resistance to turning them with your wrench, but they will turn. Typically I like to adjust them clockwise, reducing the clearance. If your clearances are already too tight, open them up slightly, then tighten in to your desired clearance.

 

As an aside, you also have aftermarket steel rocker stands. The stock aluminum pedestals are known to flex under high stress.

[MV8]

Also, the shaft spacers to replace springs do a much better job at reducing oil leaks so more oil gets to where it can do the most good.

[Steve in Lititz PA]

Thanks, MV8, 

 

I noticed them, but wasn't aware they were also a valve train mod.  

 

Someone in the past put some thought into it.  This morning I had time to adjust the valves with #1 at TDC:

1  I & E

2 E

3 I

I'll rotate to #4 TDC and get the others in a bit.  None of the first group are off more than 0.001, but this is much easier than the old "lock nut and screwdriver" method.

 

Steve Rineer

Lititz, PA

[IamScotticus]

You also have the hot adjustment. Where are getting your gap numbers from?

 

[Steve in Lititz PA]

Well, there's a question which I suspect a lot of folks have opinions on:

prev owner's notes say intake 0.020, exhaust 0.022 (didn't say hot or cold, I assume cold

OTOH, Caterham's specs say 0.022/0.024 cold, (which seems to be what was used...a few clearances, particularly exhaust, were a little tight, but not 0.022 tight. 

Ivey says 0.010/0.020 HOT,

Lamont says 0.010/0.018 HOT.

 

Seems to be a Burton A2 cam, 40/76/76/40 = 296, I haven't confirmed that (and have no intentions to dive that deep into it, it is what it is).  But I have no reason to disprove of it, either.

 

So 0.022/0.024 seems safe since I'm not searching for the last bit of HP.

 

[IamScotticus]

Cold gap is a starting point to get you close so you are less likely to do any damage.  Hot gap is the fine tune. The thing about Caterham's gaps is that the early Sprint builds were A2s but they later went to GT cam on the Sprints.  My '95 manual does not specify but I suspect by '95 they were GTs, with the 1700s getting the 234 profile.

Do different cam lifts require different gaps? I don't know.  Assuming your pistons are pocketed correctly,  maybe not.  But since your head is built, your springs should be checked for binding and breaks at the least.

[Steve in Lititz PA]

I doubt the engine has been apart since its 1985 build date.  The previous owner ordered it from Caterham with the 1700 Super Sprint engine; he contracted out the build.  It has about 20,000 miles on it, runs very well, engine feels strong.  Caterham claimed 135 bhp, and I can believe it.

At some point it was fitted with an Electromotive ignition; I was concerned about lack of information and support since they've been out of business for years.  I'm installing a 123Ignition Tune+ distributor (it clears the intake manifold) with a Bosch Blue coil.  While turning the engine to #1 TDC figured I should check clearances.

 

Which bring me to the original reason for the post.

 

[IamScotticus]

Its a really good question 

[Steve in Lititz PA]

Here's what Burton says in their catalog regarding the A2 camshaft:

Well proven fast road/rally type camshaft with good mid range to top end power. No modifications are normally required but piston to valve clearance must be checked when fitting in X/flow engines.

 

Valve Clearances: .020" inlet/.022" exhaust

 

The original owner told me 0.020/0.022, and if you recall he contracted  the build out.  My guess is that the engine builder got it from the Burton website, or Caterham, which suggests the piston clearance was checked at that time.  So I could go as tight as 0.020/0.022.  I am at 0.022/0.024.  I don't compete or do track days, so it's good enough for me.

[EdWills]

Hey Steve.

 

According to Tony Weale in his book "Lotus Seven - Restoration - Preparation - Maintenance" the 1600 Caterham Sprint version was fitted with the A2 camshaft with clearances of 0.020/0.022 inches as standard.  The h.p. rating for that car was only given as 110 @6000 rpm with 2 Weber 40 DCOE carbs.  Weale included a note that the 1600 Sprint engine up to chassis CS3 4099 had clearances of 0.012/0.014 inches.

[Steve in Lititz PA]

ara Thank, Tony, but mine is a 1700 Supersprint, not a 1600.  According to "Lotus/Caterham Seven Model Statistics" (I can't recall where I got it, but it's three pages and lists every Seven from the Series 1 through the Caterham 7 1.8 K-Series Supersport Roadsport), mine is listed as a Caterham 1700 Supersprint 1982-1999, Caterham Mod Ford Cross Flow, 135 bhp (101kw) 6000 rpm, along with other pertinent information.  

I downloaded it from either USA7s, or the UK Club, Caterham and Lotus Seven Club        www.caterhamlotus7.club   

 

The staytistics doesn't include clearance information, but I've seen 0.022/0.024 elsewhere; if I was competing or tracking the car I might be inclined to use the clearances from race engine builder Ivey at 0.010/0.020, but I don't.  Just for fun, and looking at only the intake clearance difference, 0.022 minus 0.012 = 0.010; that's a really small difference, and the exhaust is practically identical  So I'm not too concerned that I'm losing much hp...and hp isn't what I bought a Caterham for, anyway.

But thanks for you comment!

steve rineer

freezing in Lititz PA (16 degrees tonight)

 

[Steve in Lititz PA]

Tony, Lotus7Stats (2).xlsxLotus7Stats (2).xlsxHere's the spreadsheet

 

[Steve in Lititz PA]

Oops...sorry Ed, got confused between you and the author you mentioned.

[jbcollier]

Clearance specs are based on camshaft design and are specified by the cam maker.  If you set them too wide, then the cam may not properly use its opening and closing ramps leading to rapid cam/follower wear.

 

"Generally" with a cast-iron, push-rod, engine, you can set the clearances hot or cold.  If there is an aluminium head, then you set them cold.

[Steve in Lititz PA]

Hi, John

 

So glad to hear from you on this forum in addition to the Europa forum.  You have been a HUGE help to me many times with my S2.  

As you have undoubtedly gathered, in addition to the S2/843/395, I've acquired a 1985 1700 Super Sprint...GREAT FUN! 

 

The madness continues! 

 

Steve Rineer

Lititz, PA

[EdWills]

Hi Steve.

 

According to the Tony Weale book, the 1700 Supersprint (my apologies, I thought that you had the 'Sprint' model with the A2) was fitted with the 'Caterham BCD' camshaft.  Years ago I inquired with Caterham and the parts manger advised that the BCD cam was actually a 234 camshaft (Kent Cams product possibly?) with 1300 c.c. pistons fitted to the engine for higher compression ratio and Weale puts this at 9.75:1.  The 234 cam is 280 degree inlet and exhaust with valve clearances cold at inlet: 0.022 inches, exhaust: 0.024 inches.  The engine capacity is listed as 1690 c.c., and the bhp rpm is as you note, 135 @ 6000 rpm..  Kent describe the 234 as a 'superb sports road cam, flexible enough for use in a lightweight se7en, good for track day use'.  Timing 37/63 73/27.   Plug type NGK B8ECS.  Just an fyi, James Whiting in the U.K. is a great source for NGK plugs for the Seven range.  I tried my local auto parts shop, and they couldn't find some of the plugs listed for the original Lotus Seven or the Caterham variants in their NGK booklets.  Maybe NAPA or similar can order them?  Hope that this helps? Ed.

[Steve in Lititz PA]

Hi, Ed

 

No apologies needed, and thanks for all the additional information.  It caused me to go back to my purchase notes, and notes from the original owner who spec'd the engine build.  FWIW, at that point it became a custom build, and reading through his communications with Caterham, the US dealer, and the shop which performed the engine mods, here is what I have determined, all of it shrouded in uncertainty, ie,  I don't really know:  The 1600 crossflow was overbored to (possibly) 1760, and has the A2 Burton camshaft.  The builder specified clearances at 0.020/0.022, which, coincidently, is the same as Burton cites for the A2 in its catalog.  The builder claimed 150 hp, which, of course, makes all of the above suspect, because most of us know that the builder's quoted hp, and the dyno hp, are two different numbers.  I subtracted 10% from the builder's number and arrive at (!) 135 hp, exactly what Caterham states in its specification sheet.  Imaging that!  ha ha.

 

I included you very helpful information in my "engine" folder, it adds to the body of knowledge.

 

steve rineer

lititz, pa