Mustang II V6 conversion to V8 HO and T5 problems and solutions

greenflash79 · Jul 6, 2025

Hello
I'm hoping to find solutions here that will help me convert my Mustang II 2.8 V6 to a V8 with a 5.0 HO and T5 transmission.
I'm currently having a huge problem with the exhaust manifold. I ordered the Hedman ones from the USA, but unfortunately, they don't fit at all.
The spark plug caps are touching the manifold and will burn up. One of the manifold pipes is directly touching the clutch cable holder, and I can't install the cable.
The manifolds were hitting everything, but I was able to fix this.
Okay, I want to get rid of this Hedman and am looking for cast manifolds. Unfortunately, I can't find any original Mustang II V8s in Germany.
I read here that someone from the '66 Mustang I installed the manifolds on their II, and I could get one like that in Germany.
We have a whatsapp group about Mustang IIs, and everyone tells me Mustang I manifolds won't fit.
Does anyone have experience with the '66 Mustang I manifold?
Dirk

LILCBRA · Jul 7, 2025

I believe this is what you're looking for. Maybe @extra_stout can offer more assistance if needed.

extra_stout said:
I used stock 66 Mustang exhaust manifolds because I had them already from a previous car (they are available as new part). I also used a 66 mustang downpipe from pypes and modified them:

Progress Thread Post in thread '74 Mustang II - Build as semi-daily driver'

Jun 14, 2020

The pypes downpipe for 66 mustang which i started as an basis is now modified. I wanted to have some flex pipe just in front of the transmission crossmember and the exhaust hangers will be mounted to the crossmember. This takes movment from the rest of the exhaust...
I had to cut up the driverside downpipe because of my hydraulic clutch setup. If it was a cabel clutch the downpipe could have fit without modification.
I tacked it with my stick welder in my garage, then at a friends place we (mainly ma friend) weldet it up with his TIG.

extra_stout

The manifolds fit even with a T5 bellhousing and T5 transmission (but with custom hydraulic clutch). The car pulls strong, but its for sure restrictive at high RPM compared to a shorty header.
What I like is that you can use the stock securing sheet metal from the 66 manifolds, so the exhaust manifold bolts don't come loose. Beside that they are durable and quite down surface radiated noise in the engine compartment.

I have a stock 2001 explorer 5.0 as basis. If i would step up from the stock cam, i would buy or build shorty headers or log manifolds.

One shorty header that could work is this one (because it is made specific for 66 mustang):

https://www.summitracing.com/int/parts/jba-1650s-2
I live oversees... so I have no option to return them if they do not convince me with their fitment...

greenflash79 · Jul 14, 2025

I got '66 headers to test and installed them. They look great and promise to fit.

I've now ordered these new '66 headers, complete with gaskets, downpipes, and new bolts.

I'll post pictures of the installation once I get the headers.

I'm glad I removed the Hedman.

greenflash79 · Jul 14, 2025

Problem 2 has already been solved.
The new bridge under the transmission is great, but it's advisable to buy new transmission mounts.
Used bearings are already too compressed, even if they still look good.
They will cause noise and rattling.
Solution: Install new bearings and two washers underneath the bearings, which will create enough space.

greenflash79 · Jul 14, 2025

One problem I still have:
In most forums, you can read that the original Mustang II Bowden cable is still used with the T5 transmission.
This end piece of the Mustang II Bowden cable is very small and doesn't fit with the large hole in the T5 lever.
How did you solve it?

LILCBRA · Jul 14, 2025

greenflash79 said:
One problem I still have:
In most forums, you can read that the original Mustang II Bowden cable is still used with the T5 transmission.
This end piece of the Mustang II Bowden cable is very small and doesn't fit with the large hole in the T5 lever.
How did you solve it?

I still use the MII bell housing and clutch setup, but I'd take a stab at finding a washer that is large enough to close the hole yet small enough to engage the ball of the cable. If you're able to find something like that, use a grinder with a cut off wheel and cut a slot into it. Then you could weld it in place on the clutch fork before installing the cable. Imagine something like this:

greenflash79 · Oct 26, 2025

Hello everyone.
I bought an electric cooling fan from CJ-Pony Parts.
So far, so good. I found a connector with "12 Volt Low Amp Source" in the description. Unfortunately, we can't find anything comparable with this phrase in Germany.
I imagine it's 12 volts plus from the ignition?
I hope you can help me.
Best regards,
Dirk

Noobz347 · Oct 26, 2025

greenflash79 said:
Hello everyone.
I bought an electric cooling fan from CJ-Pony Parts.
So far, so good. I found a connector with "12 Volt Low Amp Source" in the description. Unfortunately, we can't find anything comparable with this phrase in Germany.
I imagine it's 12 volts plus from the ignition?
I hope you can help me.
Best regards,
Dirk

That would be correct. You are looking for a "trigger" power source and not one that powers the fan motors themselves.

Often, you can use the one that feeds the radio and is off when the ignition switch is off.

greenflash79 · Oct 27, 2025

Which one could I use in the engine compartment near the fan? I found a solid yellow one.
Thanks for the answer.

Noobz347 · Oct 27, 2025

greenflash79 said:
Which one could I use in the engine compartment near the fan? I found a solid yellow one.
Thanks for the answer.

The yellow one should work just fine. Double check that you have power with the key in the [on] position and no power when it is [off]... Just to eliminate any previous owner monkey business.

Solder and heat-shrink your connections. If you are using a wire tap, fill the connector with dielectric grease and cover with heat-shrink.

greenflash79 · Nov 23, 2025

Could a sensor for the radiator fan be installed here in the thermostat housing? Is the thread 3/8 inch? Does anyone know?

welder4956 · Nov 23, 2025

I think mine is 1/2" NPT threads. But, you can get a brass 1/2 x 3/8 reducing bushing at most hardware stores if it needs to be 3/8".

LILCBRA · Nov 23, 2025

It could be installed there. I have the sensor for my gauge in the front left of the intake, the sensor for my fuel injection, which controls my fan, is in the heater tube from a later model that I installed.

greenflash79 · Dec 27, 2025

Hey everyone,

Does anyone have timing cover plates from the 5.0 HO and older 5.0 V8 engines for comparison?

I've heard the 5.0 HO has a different water pump rotation direction, and the timing cover has different water flow directions.

For my Mustang II conversion, I was specifically recommended an older timing cover because of the oil dipstick, The older ones have a precisely cut hole for the dipstick.

I'm not entirely sure if my cooling system is working correctly and would like to confirm that the control caps for the water channels inside are identical.

Does anyone happen to have pictures or experience with these different caps?

Noobz347 · Dec 27, 2025

greenflash79 said:
I've heard the 5.0 HO has a different water pump rotation direction, and the timing cover has different water flow directions.

Correct

greenflash79 said:
Does anyone happen to have pictures or experience with these different caps?

I do not have parts to provide side-by-side images.

I have installed a positive rotation water pump on an HO before. It was due to how the belt routed when I put it together. This one did not have all of the normal accessory drive.

The location of the oil dipstick is irrelevant. There are timing covers for FI, and covers for carb, and covers with provisions for a fuel pump eccentric, etc...

Are you building a carb'd or FI engine for this car? Do you plan to use a mechanical fuel pump?

Noobz347 · Dec 27, 2025

This might help:

Timing cover “type” (what you’ll see)	Typical 302 Windsor application	Water pump / belt setup	Oil dipstick provision	Fuel pump boss	Timing pointer / damper mark alignment	Notes / examples
Early SBF cover (early-style water pump pattern)	Early small-block Ford 221/260/289/302 era (commonly described as the early cover family)	Standard-rotation V-belt style; uses the early water-pump bolt pattern (commonly referenced as “3-bolt”)	Varies by specific casting and pan setup	Often present on carb-era setups	Pointer location depends on the cover/tab style; must match damper mark position (Summit Racing)	If you’re mixing parts, match the pump backing-plate passages to the cover passages; Ford used multiple hole shapes/orientations (hotrod.com)
1970-up style cover (traditional long/standard front dress family)	Very common “1970 and up” style used across many 302/5.0 builds (carb or EFI conversions depending on provisions)	Can be used with standard-rotation or reverse-rotation pumps depending on cover/pump backing plate details (hotrod.com)	Many versions have a timing-cover dipstick hole (front-sump style)	Many versions have a mechanical fuel pump boss	Pointer location varies; you must match the pointer location (A/B/C positions) to the harmonic balancer timing marks (Summit Racing)	Ford Performance M-6059-D351 is a modern “production-style” aluminum cover in this family and is explicitly listed for standard or reverse rotation pumps, and includes dipstick hole + fuel pump boss (Ford Performance Parts)
Fox-body serpentine / reverse-rotation cover (carb-to-EFI era)	1979–1985 Mustang 5.0 (serpentine + reverse-rotation pump per typical Fox accessories)	Reverse-rotation water pump with serpentine belt (LMR.com)	Typically not a “front dipstick” solution in the same way as early front-sump setups (depends on exact cover/casting)	Usually not used for mechanical pump in factory EFI contexts	Pointer location still must match damper marks (A/B/C) (Summit Racing)	Aftermarket direct-replacement style example: LMR lists a carb 79–85 replacement cover intended for serpentine & reverse-rotation pump (LMR.com)
“Short” serpentine cover (SN95 5.0)	1994–1995 Mustang GT 5.0	Reverse-rotation water pump; short-front accessory packaging (Ford Performance Parts)	No provision (per Ford Performance listing) (Ford Performance Parts)	No fuel pump boss (electric pump required) (Ford Performance Parts)	Pointer/damper still must be matched correctly (Summit Racing)	Ford Performance M-6059-A50 is called out as OE on 1994–1995 Mustang GT and explicitly notes “no fuel pump boss” and “no provision for dipstick” (Ford Performance Parts)
Explorer/Mountaineer 5.0 “short” cover (with crank sensor packaging)	1996–2001 Ford Explorer / Mercury Mountaineer 5.0 (popular swap front dress)	Reverse-rotation water pump; Explorer serpentine front dress	Typically not set up for a classic timing-cover dipstick (swap-dependent)	Not intended for mechanical pump in stock form	Pointer mounting can conflict with the Explorer crank sensor arrangement (swap builders run into pointer/bracket differences) (Ford Explorer Forums)	Example swap reference notes using the Explorer short timing cover + water pump + balancer/pulley as a package (Classic Broncos)
“Universal / combo” aftermarket cover (designed to accept both pump rotations)	Aftermarket replacement for mixed builds (hot rod, crate, swaps) when you want flexibility	Explicitly designed to accept both standard and reverse rotation pumps (per manufacturer) (BluePrint Engines)	Typically retains dipstick capability depending on model	Often retains a fuel pump boss for carb use (per manufacturer) (BluePrint Engines)	Still must match pointer location to damper marks (Summit Racing)	Example: BluePrint Engines cover states it accepts both pump rotations and retains a fuel pump mounting boss (BluePrint Engines)
Ford Performance “production-style” aluminum cover with boss + dipstick hole	General 289/302/351W builds (including Boss blocks) where you want the classic provisions available	Listed for standard-rotation pump or reverse-rotation pump (Ford Performance Parts)	Includes dipstick tube hole (front-sump style) (Ford Performance Parts)	Includes fuel pump boss (Ford Performance Parts)	Pointer location must match damper marks (Summit Racing)	Ford Performance M-6059-D351; also noted by retailers that EFI/rear-sump usage may require plugging provisions (levittownfordparts.com)
Aftermarket aluminum “reverse-rotation” covers sold by speed retailers (feature-based category)	Performance/dress-up replacements for 302/5.0 where you’re running a reverse-rotation pump	Reverse-rotation water pump compatible (explicitly stated on listings) (Summit Racing)	Varies by model	Varies by model	Pointer/damper matching still applies (Summit Racing)	Example: Edelbrock timing cover listing explicitly says “for use with reverse rotation water pump” (one of many similar aftermarket options) (Summit Racing)
Timing-pointer position families (not a separate cover, but a required “application match”)	Applies to all 302 timing covers when mixing dampers/covers	N/A	N/A	N/A	Pointer locations are commonly referenced as A (2 o’clock), B (11 o’clock), C (10 o’clock); must match the damper timing marks (Summit Racing)	If your cover/tab position doesn’t match your balancer marks, you’ll never set timing correctly (even if the engine runs) (Summit Racing)

Note: Call out table errors if any. I may use this again as it has come up before.

greenflash79 · Dec 27, 2025

The fuel pump is mechanical, on the engine, and that's how it's going to stay.

Oh no, now I need a different timing case again, everything has to come apart again. ;-(
The dipstick has to go at the front of the case, since I have to use the Mustang II oil pan. The carburetor stays too; it's a 1985 Vox engine.

greenflash79 · Dec 27, 2025

Couldn't I drill a hole for the dipstick?

Now I need to find a suitable timing cover.

GOvert · Dec 27, 2025

I'm a little late for the party. If you want to go to standard rotation water pump, forgive me if this has already been covered, you need a mid to late 1970's timing cover. It has the spot for the mechanical fuel pump. You will need an eccentric (a disc or wheel mounted eccentrically on a revolving shaft in order to transform rotation into backward-and-forward motion) fastened to the front of the camshaft gear to pump the pump.
I have drilled a hole in a 5.0 timing cover up front below the alternator. There was a "blank" spot to drill the hole.
Did you work out your exhaust manifold situation? Here is an Ebay link to a pair of manifolds, stateside.
1975 to 1978 V-8 302 exhaust manifolds USED

Good luck with your project. FoMoCo has made several variations of the small block engine. There are several different sets of pulleys and brackets.

greenflash79 · Dec 27, 2025

https://lmr.com/item/LRS-6019D/79-85-Mustang-50l-58l-302-Carbureted-Timing-Cover?utm_source=chatgpt.com

I ordered this housing; I had to drill a hole and fabricate a cover plate for the electric pump.

I opted for the exhaust manifolds from the 1968 model, with downpipes. This was a very good decision, and I was able to install them quickly.

Until suitable headers become available, I'll leave it as is.

It looks very good.

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