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Modification advice for 331 Ford

General engine tech -- Drag Racing to Circle Track

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blackford
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Modification advice for 331 Ford

Post by blackford » Tue Jun 16, 2020 2:02 pm

I have a 331 ford in my car that has been unchanged since 2006. The engine only has about 10,000 miles on it. It's primarily a street car, but after my upcoming retirement, I may return to the track and make some trips down the 1/4 mile.

I had the car dyno'd years ago and it was making 370 RWHP @ 6500 and HP was still at 340 RWHP @ 7000. I figure the crank HP in in the 430 HP range. The current engine specs are as follows:

'68 302 block .030 over
'70 iron 351W heads fully ported by myself (160cc intake and 60cc exhaust and approx 225 cfm@.500 intake and 180cfm@.500 exhaust)
1.94 intake valves / 1.60 exhaust valves
Single plane vic jr port matched and runner dividers cleaned up
750 HP Holley 4 BBL carb
Comp Cams 282S SFT 236@.050 .528 lift run with tight lash
Probe 1.7 shaft rockers
Stepped Dougs tri-y headers (port matched to exhaust ports)
Magnaflow 2.5" dual exhaust
KB322 Hyper pistons with reduced ring tension (designed originally for 383 Windsor)
9.7:1 compression
289 length H beam rods
Scat 9000 High nodular crank
Windage tray
9 quart road race pan.
5 speed manual w/overdrive
9" ford rear w/3.89 gearing

The engine was designed by me years ago using 289 length H beam rods and a 1.4 Comp Height 383 Windsor piston. The engine has exceeded my expectations especially given the heads that I am using. It loves to scream and has run great for years, but I was thinking about some mods as follows:

185 AFR Renegade heads milled to produce 10.5:1 to 11:1 compression (I will be using 91 octane pump gas)
Re-use existing single plane if possible or new single plane or dual plane port matched to heads
New SFT cam if it makes sense which it probably does

I'm looking for an additional 50 crank HP and to get RWHP above 400. I want to have similar peak HP characteristics and to retain 7000-7200 RPM shift points. If a dual plane can do that then I would be open to going to a dual plane.

I would appreciate any and all comments or recommendations. Thanks
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported DOOEs, T5z, 9" 3.89 gears. 430HP@6500

2013 Corvette 427 Convertible daily driver

frnkeore
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Re: Modification advice for 331 Ford

Post by frnkeore » Tue Jun 16, 2020 3:05 pm

I think you can pick up some real HP, by decreasing your deck clearance. I doubt that you actually have more than 9.2 CR if they are FT pistons, with your 60cc heads. Unless you've deck the block to some other spec, you have .026 deck clearance. A set of SBC 1.425 CH pistons (3.75stroke x 5.7 rod) will decrease it to .001 and give you 5.2cc less chamber, plus much better quench. You could also go to a 4.03 x .027 head gasket. That would help some (2.7cc).

I'm building something similar but, with 5.315 rods and 1.265 SBC pistons (KB9908, 3.48 stroke x 6.0 rod), same .001 deck clearance. 254/258 x .581/.593 (1.6) net lift CC on 106 LSA SFT and Vic Jr intake. My CC is a .875 lifter cam but, you can pick up .200 and above lift and duration, with a Howard .875 cam. I would stay in the low 240's with it.

With your lift, or increased lift, you may have to cut the valve relief. It will have to be checked, for sure!

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Re: Modification advice for 331 Ford

Post by frnkeore » Tue Jun 16, 2020 4:20 pm

I miss worded the above reply.

It should have said:

OR, you could use a 4.03 x .027 head gasket. The .027 gasket and .001 DC is to little piston to head clearance.

I ran what I think your combo is on Diamonds CR site. if you use that .027 gasket, it will raise the CR to 9.55 from these figures.

BTW, I'm originally from the City of Orange, I grew up there and did a lot of street racing in the OC/South LA area.
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blackford
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Re: Modification advice for 331 Ford

Post by blackford » Tue Jun 16, 2020 5:37 pm

Gasket Compression thickness is .039. Deck height is .005 in the hole. Quench is .044 static. piston has 6.5 cc valve reliefs. Been using Performance Trends Engine Analyzer for years and calculated compression is 9.8:1 with 61cc chambers. Intake valves were unshrouded so compression is probably more like 9.7 or 9.6.

Really hoping for some feedback on proposed Heads, Intake and Cam. Thanks
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported DOOEs, T5z, 9" 3.89 gears. 430HP@6500

2013 Corvette 427 Convertible daily driver

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Re: Modification advice for 331 Ford

Post by BobbyB » Tue Jun 16, 2020 6:12 pm

How does the performance of your mustang compare to your corvette? Which one would you rather drive for thrills? Sounds like two really neat cars to have.

It seems the afr 185s Are pretty well known to produce great results. Mike Jones should be able to get you a cam that will do what you want. However, do you think you might be pushing the limits of the stock block? I guess it depends on how often you will “ really push it” and how long you need it to last. Good luck!

frnkeore
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Re: Modification advice for 331 Ford

Post by frnkeore » Tue Jun 16, 2020 8:51 pm

Your rpm is going to go up with both a head cfm increase and cam duration increase.you can use a Super Vic or TF R manifold but the low end might suffer. Your Vic Jr might be the best all round. The Air Gap might help the low end.

There are a lot of manifolds to try, such as the original Torker and the Holley and Wieand versions of it but the dyno will give the answers.

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Re: Modification advice for 331 Ford

Post by Walter R. Malik » Tue Jun 16, 2020 10:58 pm

blackford wrote:
Tue Jun 16, 2020 2:02 pm
I have a 331 ford in my car that has been unchanged since 2006. The engine only has about 10,000 miles on it. It's primarily a street car, but after my upcoming retirement, I may return to the track and make some trips down the 1/4 mile.

I had the car dyno'd years ago and it was making 370 RWHP @ 6500 and HP was still at 340 RWHP @ 7000. I figure the crank HP in in the 430 HP range. The current engine specs are as follows:

'68 302 block .030 over
'70 iron 351W heads fully ported by myself (160cc intake and 60cc exhaust and approx 225 cfm@.500 intake and 180cfm@.500 exhaust)
1.94 intake valves / 1.60 exhaust valves
Single plane vic jr port matched and runner dividers cleaned up
750 HP Holley 4 BBL carb
Comp Cams 282S SFT 236@.050 .528 lift run with tight lash
Probe 1.7 shaft rockers
Stepped Dougs tri-y headers (port matched to exhaust ports)
Magnaflow 2.5" dual exhaust
KB322 Hyper pistons with reduced ring tension (designed originally for 383 Windsor)
9.7:1 compression
289 length H beam rods
Scat 9000 High nodular crank
Windage tray
9 quart road race pan.
5 speed manual w/overdrive
9" ford rear w/3.89 gearing

The engine was designed by me years ago using 289 length H beam rods and a 1.4 Comp Height 383 Windsor piston. The engine has exceeded my expectations especially given the heads that I am using. It loves to scream and has run great for years, but I was thinking about some mods as follows:

185 AFR Renegade heads milled to produce 10.5:1 to 11:1 compression (I will be using 91 octane pump gas)
Re-use existing single plane if possible or new single plane or dual plane port matched to heads
New SFT cam if it makes sense which it probably does

I'm looking for an additional 50 crank HP and to get RWHP above 400. I want to have similar peak HP characteristics and to retain 7000-7200 RPM shift points. If a dual plane can do that then I would be open to going to a dual plane.

I would appreciate any and all comments or recommendations. Thanks
The cylinder head change, (I'd go to the 195's), and a "custom" solid lifter camshaft with about .100" more valve lift would certainly wake it up more than it is.
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Re: Modification advice for 331 Ford

Post by Joe-71 » Tue Jun 16, 2020 11:03 pm

At 331 cubic inches, you will be better off with the AFR 165 CNC Renegade heads on the street and occasional drag strip trip. The 185 heads will make more horsepower if you change camshafts and take advantage of the increase in flow above your current camshaft. A good beehive spring, titanium retainer, and .600-625" valve lift will definitely get you an additional 50 hp you are wanting. Joe-71
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Re: Modification advice for 331 Ford

Post by Mark O'Neal » Tue Jun 16, 2020 11:26 pm

The looks like it has two different goals.

Tri-Y headers better match a dual plane, with nets you better average horsepower and lower peak. Compression is low,and I have no idea why anyone would grind the crank counterweights for a rod that short when 5.315 and 5.400 rod were readily available. You need more head, more cam, more exhaust, more compression.....and like that.

But.....all roads lead to Rome.......

blackford
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Re: Modification advice for 331 Ford

Post by blackford » Wed Jun 17, 2020 1:29 am

Thanks for the recommendations all. Mark, you're right about the grinding. Had to take about .150 off the counterweights. Interesting thing was that when it was balanced they had to barely touch the crank...any more grinding and it would have taken heavy metal to balance it.

I went this route because in '03 when I started looking into 331 and 347 stroker kits there was a lot of buzz about oil consumption and wrist pin intersecting the oil ring and the short compression height resulting in piston instability. I consulted an old time engine builder about my combo (289 length rod and 383W piston) and he gave me the green light and that was that. I actually built 2 of these bottom ends. The engine has been so reliable I often wonder if I should even mess with it...this thread will help me to decide.
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported DOOEs, T5z, 9" 3.89 gears. 430HP@6500

2013 Corvette 427 Convertible daily driver

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Re: Modification advice for 331 Ford

Post by F-BIRD'88 » Wed Jun 17, 2020 3:06 am

Supercharge it with a TorQStorm blower.

blackford
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Re: Modification advice for 331 Ford

Post by blackford » Wed Jun 17, 2020 1:50 pm

F-BIRD'88 wrote:
Wed Jun 17, 2020 3:06 am
Supercharge it with a TorQStorm blower.
Oh My! It would be close to 600 HP with 6-8 lbs of boost! I don't know if my block would handle that. Looks like a nice system though. My ring gap would probably need to be opened up also before boosting it. I wonder if I could have the boost dialed back to 3 lbs or something. That would put the power at around 510...still pretty high for a stock block. I wonder if i'd have to open up the ring gap with 3 lbs of boost.
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported DOOEs, T5z, 9" 3.89 gears. 430HP@6500

2013 Corvette 427 Convertible daily driver

mt-engines
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Re: Modification advice for 331 Ford

Post by mt-engines » Wed Jun 17, 2020 2:44 pm

add some 200cc heads
get the compression close to 11:1
add 10 degrees of duration @.050 and .050" lift 106 lobe sep +4
howards has a 246/252 106lsa 102 icl that i had run in a street strip 331" with canfield 192cc ported were 205cc went 10.40s in a fox

frnkeore
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Re: Modification advice for 331 Ford

Post by frnkeore » Wed Jun 17, 2020 2:50 pm

mt-engines wrote:
Wed Jun 17, 2020 2:44 pm
add some 200cc heads
get the compression close to 11:1
add 10 degrees of duration @.050 and .050" lift 106 lobe sep +4
howards has a 246/252 106lsa 102 icl that i had run in a street strip 331" with canfield 192cc ported were 205cc went 10.40s in a fox
Was that your daily driver? :?

As I said, the Howards .875 lifter cams, have more lift and duration than the CC .875 cams but, I wouldn't go over about 240/246, 110 to 108 LSA, with it, for the street. Howards sells their custom cams for the same price as their stocked cams. Great people to work with also and you can spend as much time as you want, on the phone designing the cam.
Last edited by frnkeore on Wed Jun 17, 2020 3:01 pm, edited 2 times in total.

ustahava67
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Re: Modification advice for 331 Ford

Post by ustahava67 » Wed Jun 17, 2020 2:53 pm

It isn't a HP number that will kill a stock block necessarily.... It could be RPM or a bad tune.... I have built a few turbo SBF, 302's with 500 RWHP. They have been alive for years. My personal 347 NA I have 10 plus years bracket racing it. It still has the same head gaskets from when I put it together. My own self imposed limits are 6500 rpm and a well balanced assembly. My engine will make power to 7400 but I don't take it that high. I bracket race.... a few hundredth's ain't worth it
My Dyno is 1320 ft long. Romans 12:2

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