celine

Howdy,

I’m after some advice. I recently bought a xd 302, heads flowed 400hp for a 351, stock converter, exhaust and inlet manifold, 2.92 diff. 600 vac sec Holley. Don’t know compression or cam specs, but it idles at 1200 with 8 inches of vacuum.

Its acceleration and mileage are garbage.

I’ve put in a 3000 stall. A dual plane highrise manifold, extractors and 3.9 9” is coming.

The question is what to replace that huge cam with. And do I need to change any of the valve train components besides lifters?

Any suggestions or horsepower estimates for when it’s all put together appreciated.

brenx

A single plan manifold would suit it better not a dual plane. Although it would still work.

I wouldn't change the cam till you've changed everything else. As the current camshaft may suit the setup your about to fit. A smaller cam would need less valvespring pressure and thats about it.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

TruBlu351

Hope you aren't wanting to improve mileage with the 3.9's

Low gearing allows some motors to rev fast and "come alive".

Any vacuum leaks? Gaskits, bolts tight, hoses cracked etc?

Finish your mods and get it dyno tuned. This would be your best option. This would ensure all aspects of tuning are looked at.........timing/carb/spark etc.

Poorly tuned motors can become freaks when tuned right.

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XE Falcon
393 Tremec TKO 9"

Falcon67

Without knowing the compression, you could look at a 214/224 (@.050) cam or something in that area. In a 302, that should pull about 12 in/hg at idle. Works decent with that converter and gear. A dual plane is just fine with that carb or even with a 750. When you change the cam, you'll need to change the lifters. And check the chain - if it's got slack, it goes too. Likely you won;t have to change anything else. Take a look at the valve stem tops and make sure the rockers are working the middle of the stem - shows proper geometry is present.

Also, it could just be the timing is off and you could very well have a bad air leak somewhere. Better to check the easy stuff before tearing the motor apart.

brenx

That bits fun. A mate and I spent the best part of 2 hours sorting it. If it's not in the centre and the mark is closer to the exhaust? You need shorter pushrods.

If it's closer to the manifold side? You need longer pushrods.

I had when stuff like that delays getting an engine going again.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

Racer

actually its the opposite...

Racer

Will all due respects, that is one on the worst matched combos i've heard of! You're doing a good job fixing it up though, and headed in the right direction.

1200rpm idle suggests a tuning issue, as my 302 with 3 inches of mercury would idle at 850-900. I'd sort the tune up out first before moving on.

brenx

Didn't work that way for me. I went longer and the roller mark moved out-ward to the exhaust edge. I tested 60thou shorter/stock and 60 thou longer pushrods. I found the 60thou shorter were damn close to perfect.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

xdclevo

Yeah i found the longer the pushrod i went the roller moved to the exhaust edge of the valve more. I think this would only happen untill you reach a fair bit past the correct geometry on the long side, or 90 degrees to the valvetip, then the opposite WOULD occur.
I run 8.65 inch long, or 250 thou longer pushrods than standard!!

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10.70 @ 125.00 on the black fun top
408 Cube Cleveland.

RevHeadRon

what spec cam does the Phase 3 have does anybody know?

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"Buy a holden and be a morjority or buy a ford and be quick"