Ford 351C engine rebuild

This winters project was to rebuild the engine to fix the problem with plug #7 fouling once and for all.


I had done several compression tests, without finding anything alarming.

Hooking up a vacuum gauge to the PCV-fitting in the intake proved that there definitely is a problem. Less than 0.4bar (12in hg) vacuum on a stock 2V engine. The needle would also start to jump if I increased the idle rpms and it would take a few seconds to settle once it returned to normal idle.

To be able to better test the condition of the piston rings and valves I built a simple leak down tester.

I tested the left bank, which was the one having the greatest problem with plug fouling, and the result showed that the engine definitely needed a rebuild.

One cylinder leaked around 14%. Amazingly this was cylinder #7!

Two cylinders leaked 24%, and one cylinder leaked 30%.

I could hear one cylinder hissing through the exhaust, which indicates a leaking valve. I could also hear air hissing past the rings when I removed the oil cap, which indicates leaking rings.

An engine on good shape should leak no more than around 5%, and to verify that the tester was OK I tested one cylinder in a VW Golf with around 180kkm, and it leaked around 4%.

Engine removal and dismantling

I borrowed a 2 ton engine hoist with a long arm and extendable legs, and Master Mechanic Tomas Gunnarsson helped me get it out.

A sloppy timing chain.

Someone has apparently been here before.


My machinist checked out the block and crank, and he said that the bores were glazed, but that there weren't much taper. They were within specs and I figured that a gentle honing would clear the glazing and allow the new rings to seat properly.


Bore after honing.

Cam restrictors Oil restrictors 2

Installing a Moroso cam restrictor kit. The procedure includes threading the oil feed holes. As I'm using hydraulic lifters, I only installed the small restrictors in mains 2 - 5.

Here you also see the ARP main studs I installed.

Rods & Pistons

The old pistons were a bit uneven in size and not particularly round. They are also dished, which lowers the compression and inhibits the "quench" effect of the new heads I use.

I used forged standard sized Speed-Pro pistons, and I would have used 0.010" oversize if that had been available. Unfortunately the first oversize is 0.030", which is the maximum recommended for a 351C. I didn't want to use all the meat,  so I decided to go with stock size pistons, Total Seal rings and only hone the bores slightly.

Pistons and rods

The rods were cleaned up and fitted with new ARP bolts and then fitted to the pistons


This is what an Australian crank look like.

The machinist wanted to clean up and polish the journals and also index the rod journals. It was ground to the first under-dimension, 0.010".

Oil pan

One of the things I had planned was to install a windage tray and oil pan baffles. This proved unnecessary as the engine already had a windage tray installed and the large oil pan was already baffled.

Oilpan 1

Oilpan 2

This shows the trap door in the pan, as well as some of the less than stellar welding job.

Oilpan 3

There has been an oil leak somewhere and I have had to keep an old newspaper under the oil pan. I have wiped the oil pan clean before and it appears that the leaks were actually some pin hole in the welding. To find the leaks I filled the pan with water plus some detergent.

After sand blasting and fixing some of the holes the pan now appears tight. I haven't torqued the plug fully which is the reason that there's some sweat around it.

Factory windage tray and extended pickup.


I planned to replace the low compression open chamber 2V heads with a pair of closed chamber Australian 302C heads. I found a guy in Australia that frequently auctions these on Ebay, and he made me a really good offer on 12 pairs.

As these are heavy he sent them by boat, which took around 8 weeks.

The crate as it arrived from Australia.

I have some port matching to do to make a smooth transition from the modified 351W intake (square ports) to the 2V Cleveland (rounded) ports. A good quality carbide bit in the Dremel works fine for this.

Head surfacing

Surfacing one of the heads.

Valves Chamber through bore

Left: The finished combustion chamber, with titanium valves, 2.18" intake and 1.60" exhaust.
Right: The chamber seen through the bore. The bronze valve guide inserts can barely be seen with the copper like finish.


This what the port mismatch looked like before attacking it with the Dremel.


I chose a Crane Energizer cam, 133052, which is a non staggered cam, that I figured would be fine with the 2V heads I'm using.

Cam degreeing

Degreeing the cam.

It was during this session I noticed that the wrist pin offset makes the cam about 1.5 degree early. Timing chain slop will easily accommodate this.

Water pump

I have heard that the standard impeller "leaks", which can cause cavitation and less efficient cooling.

Summit carries the "FlowKooler" disc, which is a simple sheet metal disc that is riveted to the back of the impeller.

Waterpump 1Waterpump 2


I noticed that the clutch disc had cracked in one placed, but this was fixed by TIG-welding it.


Last year, when I was mounting the HEGO bungs to the headers, I noticed that the headers had several cracks, and I had those fixed at the time. The right header is very tight at the collector, and we couldn't see all the joints.

Tomas Gunnarsson came by and borrowed one head to use as a fixture when he was welding up his headers. He had opened them drastically to be able to reach the leaks.

I filled the headers with water to check for leaks, and the left header was relatively OK. Only a few drops per second. The right header was another story. There was a substantial leak between the tubes that was not visible from the outside.

Well, what leaks from the inside must also leak from the outside. I filled the bathtub, grabbed a flashlight and the camera:

The left picture shows water flowing into the right tubes.

The right picture shows quite a large hole.


While I had everything out, I figured it would be a good time to safety wire the ring gear.

The left picture shows what the leaking oil pan does to cleanliness and the right after some washing.

The drilling setup. I used 1.5mm titanium nitride drill bits, which worked pretty well. I used up 5 bits on the 10 bolts.

Special tool fabricated to allow proper torquing of the bolts. The torque set on the wrench has to be lowered to compensate for the extra torque that the tool adds:

Ms = (M * lm) / (lm + lv)


Ms = Torque set on torque wrench
M = Desired torque at bolt, 8-9 kpm, ~80-90Nm
lm = length between head and handle of torque wrench (where the force is applied)
lv = length of tool, between center of bolt and socket

If you (like I did) believe that the distance between the head of the torque wrench and where the force is applied is irrelevant, then you need to think again.

The end result.


I had figured that I should be using standard sized rings as I had standard sized pistons.

Checking the ring gap, I quickly realized that I was bordering on the wear limit with the honed bores.

I returned the ring set and ordered an oversize set, 4.005", file-to-fit Total Seal gapless rings. This unfortunately took a few weeks as this was an item that Summit normally does  not stock.

Once I got the rings, the engine came together in a few evenings.


The short block.

Notice the Summit timing tape on the damper. The marks are very easy to see, even with my simple and dim timing lamp. I timed the tape with  dial gauge directly on top of #1 piston. I also marked the damper so that slippage will be easily visible.


I assembled the heads with only the outer spring, figuring that this would be gentle to the cam during break-in.

You may be able to see that I have valve stem seals only on the intake valves. The machinist recommended this, at least initially.

I used a Crane rocker shim kit to shim the rockers to about 1/2 a turn of lifter preload.

I will probably install roller rockers at the same time as i install the inner spring.

Complete engine

The finished engine.


Tomas Gunnarsson was kind enough to help me get the engine back in.

Install 1 Install 2
Install 3 Install 4
Install 5 Install 6
Install 7 Install 8
Install 9 Install 10
Install 11

If you have comments or suggestions, email me at thomas@Hax.SE

Last update: 2002-12-04