69 mach 351w engine rebuild question
#31
(02-12-2015, 10:54 AM)rindel Wrote: hey guys,

i am planning on getting my 351w 4barrel rebuilt. It is #s matching stock but burning smoke. I mentioned this on another thread and after replacing valve seals and deep creep in combustion chamber, it still smokes. You can see black oil specs on rear of car.

My question is, the restoration place said they can bring the 351w to 400HP but they also quoted adding shift kit to my FMX trans. FMX trans is #s matching as well and in good shape. Do you think I need to do this?

Should I also add headers and replace original exchaust maniforld?

400 hp is easy to obtain with a 351W. Especially is you stay with the original compression ratio of 10.7:1 that was standard on the 4 barrel, M-code version.

The biggest drawback is the factory cylinder heads. The 69 casting 351W cylinder was the best small block Ford OEM cylinder head until the GT40. But they still have some drawbacks that need to be addressed to obtain 400 hp. In addition to standard cylinder head rebuilding the following areas need to be addressed.

1) The exhaust ports are very small and have a big casting bump in the roof of the port, thus they are very restrictive. Port work needs to be performed to improve the exhaust flow rates.

2) The rocker arms are not adjustable. So new rocker arms and studs (see item 3) will be needed. Likely roller rocker arms to get your 400 hp goal. Be careful of rocker arm selection if you want to install stock height valve covers. Most roller rocker arms require tall valve covers for clearance.

3) The press in rocker arm studs do not permit rocker arm adjustment and will pull out with the higher rate valve spring needed for a camshaft that will get you to 400 hp. The heads will need to be machined for screw in rocker arm studs and guide plates.

4) In addition to routine valve guide work, valve guide machining will likely be needed to fit the higher rate stronger valve springs.

5) Hardened exhaust seats will need to be installed for unleaded fuel. Machine work is required for that.

6) Larger intake and exhaust will likely be needed.

I spent a lot of time porting my cylinder heads with the guidance of the machine shop. Then had them machined for screw in rocker arm studs and guide plates, larger valves, and on and on... I reworked mine a lot. Most people buy aftermarket cylinder heads instead on all the work to the stock head.

Headers, yes. Short type like what JBA offers if you don't want to possibly fight fitment issues associated with long tube headers in these cars. Avoid inexpensive headers or you will constantly fight exhaust leaks. The stock manifolds on the 351W are too restrictive to get to 400 hp.

** 400 hp is not hard to obtain. But it is definitely more than a stock rebuild with a camshaft upgrade. I didn't mention, but an intake and carb upgrade would be in order as well.

As far as shift kits. In my opinion every stock automatic trans will benefit from one. It doesn't need to be aggressive. I have one in all my vehicles with an auto trans. Shift kits eliminate most of the clutch slippage that occurs during shifting. Thus, reducing wear and heat. The factory engineers soft imperceptible shifts (more on newer vehicles) into transmissions because most people don't want to feel the shift. Then they wonder why the transmission in their car is worn out at 100K miles. An auxiliary trans cooler is also beneficial. High temps are another life killer for automatic transmissions.

Best Regards,
Mike
Reply
#32
More sensible stuff. On the matter of valve seats, one school of thought concluded that the standard seat will withstand many years of 'week-end warrior' use. The valve seat recession thing was found on engines running flat out in both rpm and load for EXTENDED periods (k's of miles). I shall hunt out the book and quote the title so you can all LOL at the findings.....
Reply
#33
You are correct. A friend of mine I grew up with and have known about 45 years owns a machine shop, and also says it takes thousands of miles ( 15K or so) for a standard seat to be damaged from unleaded fuel. Occasionally, he doesn't install hardened seats when it's for a restoration project that will see very little driving. As long as the customer is aware of the long term aspects.

On the other side. Since you have to perform so much work on stock small block Ford Stock heads for performance supplications, including installing larger exhaust valves. Why not also add hardened exhaust seats. Regardless, I would always use hardened exhaust seats.

Most people buy aftermarket heads, like AFR's, and save their originals. AFR's were very expensive when I rebuilt mine. If I did it again I would consider that option as well. It is not uncommon for cylinder head machine work to be the most costly part of a rebuild.

I'm not trying to discourage the engine build. A 400 hp 351W is easy to attain. But there are issues that need to be addressed. Such as the cylinder heads and also pistons to fit the shorter deck height of a 1969 and 1970 351W block, 9.480 vs. 9.503 for 1971 and later. Regarding the pistons I am only aware of a stock cast aluminum replacement piston, a Ross Racing forged piston, and I think now Probe Industries has forged pistons as well that are off-the-shelf and fit the 69 and 70 block. All other pistons are made to fit the taller deck height of the 1971 and later 351W blocks. Installing those in the earlier blocks will cause them to stick out of the deck 0.020" or so depending on final deck height after surfacing. I wanted something little better than the cast aluminum and at the time my only option for an off-the-shelf piston was the Ross Racing forged pistons.

Best Regards,
Mike
Reply


Possibly Related Threads…
Thread Author Replies Views Last Post
  1970 351C 4V engine, Shaker, AC, Dist-o-vac, FMX Tim 0 1,227 01-14-2022, 08:57 AM
Last Post: Tim
  Best radiator for my 69 Mach 1 NoOnesHero 2 4,914 11-04-2020, 05:21 AM
Last Post: Mach1 Driver
  "70 Mach 1 Fuel Line Routing 70MACH427 1 6,462 12-28-2018, 06:07 AM
Last Post: 1969_Mach1
  69 Mach 1 SCJ Vakue My Mach 1 20 26,905 09-01-2018, 03:33 PM
Last Post: Steven Harris
  427 in a 69 Mach 1 My Mach 1 3 8,159 08-28-2018, 01:59 PM
Last Post: My Mach 1
  Hurst Shifter Rebuild 1969_Mach1 25 47,772 06-19-2017, 06:48 AM
Last Post: Mustangmike
  Toploader Input Shaft Question 1969_Mach1 2 9,271 05-15-2017, 02:49 AM
Last Post: 1969_Mach1
  Stock Cam Specs - 69 351w 4v ? rindel 57 139,833 05-03-2016, 03:14 AM
Last Post: 1969_Mach1
  magnaflow vs flowmaster for 1969 mach 1 351w rindel 7 22,642 08-25-2015, 01:12 PM
Last Post: JTS71 Mach1
  Headers for 1969 mach 1 351w 4brrl? rindel 38 73,290 07-29-2015, 08:12 AM
Last Post: 1969_Mach1

Forum Jump:


Users browsing this thread: 2 Guest(s)
[-]
Latest Threads
What's One More Iron In The Fire!
Last Post: fram lee666
03-18-2024 06:21 PM
» Replies: 125
» Views: 238140
"Jacobra"
Last Post: JTS71 Mach1
06-30-2023 11:13 PM
» Replies: 86
» Views: 150925
My old Queensland Ambulance
Last Post: JTS71 Mach1
06-30-2023 11:08 PM
» Replies: 5
» Views: 1703
New member from San Jose, CA
Last Post: JTS71 Mach1
05-09-2023 08:39 AM
» Replies: 12
» Views: 3964
Saving Seatbelts
Last Post: Jim
02-19-2023 10:23 PM
» Replies: 2
» Views: 9113
Sourcing new wheels
Last Post: JTS71 Mach1
01-25-2023 02:34 PM
» Replies: 1
» Views: 2003
Shaker Air Filter
Last Post: JTS71 Mach1
01-08-2023 02:24 AM
» Replies: 3
» Views: 1467
1971 Mach 1 parting out interior parts -...
Last Post: ylwhrse
12-22-2022 01:38 PM
» Replies: 0
» Views: 640
Painting
Last Post: Rare Pony
12-14-2022 06:24 PM
» Replies: 2
» Views: 1971
WELCOME ALL NEW MEMBERS INTRODUCE YOURSE...
Last Post: JTS71 Mach1
08-31-2022 01:36 PM
» Replies: 82
» Views: 157068
1970 mach 1 matching numbers
Last Post: Kstweeter
08-31-2022 10:31 AM
» Replies: 1
» Views: 1087
Brake booster/servo hose length
Last Post: JTS71 Mach1
08-23-2022 09:40 AM
» Replies: 7
» Views: 3005
New Member
Last Post: JTS71 Mach1
08-20-2022 11:18 AM
» Replies: 2
» Views: 1501
smooth window operation on 70 Mach
Last Post: CUSTOMMISER
08-15-2022 12:10 PM
» Replies: 2
» Views: 1482
Blinkers on solid
Last Post: busted21
08-09-2022 03:58 AM
» Replies: 14
» Views: 8728
Blinkers on solid when lights on.
Last Post: JTS71 Mach1
08-08-2022 12:06 PM
» Replies: 1
» Views: 1720
351 cj running hot
Last Post: busted21
08-08-2022 12:13 AM
» Replies: 5
» Views: 3410
Major Winter projects
Last Post: JTS71 Mach1
07-09-2022 05:12 AM
» Replies: 49
» Views: 21299
Happy Fathers Day!!!
Last Post: JTS71 Mach1
06-20-2022 02:34 AM
» Replies: 0
» Views: 1686
1969 Raven Black 390 Looking For
Last Post: mason1958
06-11-2022 09:48 AM
» Replies: 10
» Views: 15088

>