Intake mismatch?

[Steve.k]

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As you can see mismatch on intake. We flowed intake and head and no drop on bench. Would we see gains by filling intake to match. The head and intake are a3 ford however head was filled to c3 size. Not sure its worth spending time on filling or is it a crap shoot at best. Thanks Steve

[Walter R. Malik]

IMG_2571.JPG As you can see mismatch on intake. We flowed intake and head and no drop on bench. Would we see gains by filling intake to match. The head and intake are a3 ford however head was filled to c3 size. Not sure its worth spending time on filling or is it a crap shoot at best. Thanks Steve

Years ago we tested a Ford Marine 460 engine on the dyno for a HP Books article. It had regular passenger car size intake ports with a much larger port Cobra Jet intake manifold ... GIANT mismatch so, we port matched the heads and lost torque & horsepower.

[Steve.k]

Thanks Walter this is exactly what we wondering also. The labour involved likely not worth gains and even worse losses.

[cjperformance]

That mismatch is 'possibly' costing you a few hp right up top but is also likely helping around the shift recovery rpm. I'll say that if you matched it up your timeslip would not change for the better.
Unless csa at that mismatch is getting small for your application it will not hurt one bit.

[cjperformance]

IMG_2571.JPG As you can see mismatch on intake. We flowed intake and head and no drop on bench. Would we see gains by filling intake to match. The head and intake are a3 ford however head was filled to c3 size. Not sure its worth spending time on filling or is it a crap shoot at best. Thanks Steve

Years ago we tested a Ford Marine 460 engine on the dyno for a HP Books article. It had regular passenger car size intake ports with a much larger port Cobra Jet intake manifold ... GIANT mismatch so, we port matched the heads and lost torque & horsepower.

Yes Walter the 385 has a huge mismatch from passenger car to SCJ. Leaving the mismatch from either scj head and passenger intake or passenger head and scj intake is always better than matching them up. That funneled out area in either the intake or the port to match them just kills hp & tq. Learned that the long hard hours of grinding cast iron and feeling so good just to see a loss way!

[Steve.k]

Ford used to say the cleveland 4v intake on 2v cleveland was a big gain with 780 reguardless of mismatch. Never tried that but spose it was. I have gone the other way, small intake runner to big iron 4v. Same thing very little difference?

[cjperformance]

Ford used to say the cleveland 4v intake on 2v cleveland was a big gain with 780 reguardless of mismatch. Never tried that but spose it was. I have gone the other way, small intake runner to big iron 4v. Same thing very little difference?

Yes the 4v intake on 2v heads is a boost in power BUT when Ford said that what were they comparing it to? Ford USA only had a 2 barrel intake for the 2v heads.Did they compare to anything aftermarket, i doubt it.
Ford Australia had a 4 barrel intake with 2v port sizes which is better everywhere on the 2v heads than a 4v intake when talking factory type cammed or mild engines so nothing big HP.
Up to around 370hp the Aussie 4bl 2v intake with some plenum mods will outshine a stock Airgap intake for midrange but over that hp level the Aussie intake becomes time consuming for small gains so is not worth it.
I did digress there! But also yes a 2v port Performer or any single plane variant etc on the 4v heads will pick up midrange and not hurt Hp.
I think the fact that these huge mismatches show gains in midrange either way you swap them and help or at least not hurt Hp just shows how poorly matched these heads are for the HP level being asked of them along with the known downfalls of stock Clevo ports.
Also remember that Fords factory stock and mild/CJ cams were wide LSA, low lift and very short intake duration, then anything with some CR got crazy long seat duration still with low lift unless you purchased an OHO grind that yes had lift but seat duration was insanely long.
All that aside I find that unless CSA is on the very small side that a mismatch wont hurt anything, and if correcting the mismatch involves only opening up the last inch or 2 of the intake runner and not correcting the entire runner that at least midrange will suffer.

[Steve.k]

Craig so the Holley street domminator intake would've been way ahead of factory cast 4v on 2v head?

[cjperformance]

Craig so the Holley street domminator intake would've been way ahead of factory cast 4v on 2v head?

With 351 ci 2400+ stall and 220*+@.050 yes!
The 4v dual plane was still happier at car park rpms.

With 400 ci (on a 400c) 2800 stall, 224/234@.050 iron 4v intake using adaptor plates with factory .5" pcv spacer and 780vs compared to a 351m/400c street dominator, same spacer and carb = 1.4 tenths over 1/4 mile.

[peejay]

IMG_2571.JPG As you can see mismatch on intake. We flowed intake and head and no drop on bench. Would we see gains by filling intake to match. The head and intake are a3 ford however head was filled to c3 size. Not sure its worth spending time on filling or is it a crap shoot at best. Thanks Steve

Years ago we tested a Ford Marine 460 engine on the dyno for a HP Books article. It had regular passenger car size intake ports with a much larger port Cobra Jet intake manifold ... GIANT mismatch so, we port matched the heads and lost torque & horsepower.

Y'know, I'd read the a similar thing in (Pat Ganahl's?) book on Ford engines. Put a 429CJ intake on an engine with passcar 429 heads, make X power (25hp? more than stock manifold) despite huge mismatch. Port match heads to the intake, no additional power found.

[Steve.k]

Well we leave for now see how she works. Thanks guys.

[GARY C]

filling the floor would probably show a gain on the bench but might do nothing on the engine, several people have claimed good success with a square port BBC intake on a oval port head, testing one vs the other would be the only way to know for sure.

[cjperformance]

Yep at the end of the day there's nothing like an A/B test.
Get it consistent on the track first then match it and run again!

[Scotthatch]

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I did this on a engine .... on the dyno run the peak torque was just as expected in both rpm and level .....the HP though was just a little low and like 1200 rpm lower then expected but carried at that level to where peak should be so it flattened the peak curve .... made it nice to drive so I left it ...