Any small block Ford gurus here?

[Dave_L]

I'm building a motor for my Mustang and ran into some clearance issues. Exhaust valves are hitting the pistons. I think I may have just been a dummy and over tightened the rocker arms down but wanted to see if there are any experts that can help me decide if that's what I did or not? I know the right answer is put some putty in there, slap it back together, spin it and then pull it back apart but I have hydraulic lifters and I don't really want to order solid lifters just to test it.

First question, whats the stock pushrod length on Ford 289s? I seem to get mixed answers when I google it. The length I have in there is 6.805".

Motor is a 289 block with a 331 stroker kit. Flat top pistons with 5 cc valve reliefs. Cam is pretty mild at .500 lift for int/exh. Nothing "crazy". Lifters are the matching set that came with the cam, hydraulic. .040 thickness headgasket and I had the block decked down to .005 to help me get some compression with the 60 cc heads and the flat tops. I know clearance is tight with the decking so I think its a combo of over tightening and maybe slightly too long of push rods? I couldn't use a push rod length checker because the guide plates got in the way of the adjustment nut. I put sharpie on the stem and the rocker was rubbing on the outside third of the stem so again, slightly too long if I understand it correctly. I was a bit anxious to get this thing started as it's been a long process. I figured get it fired up and then I could swap the push rods out after the test fire before they wore the stem in a funky way. Lesson learned.

I pulled the heads and pistons are in good shape. Valves seem to be fine but I'm going to have them checked while it's all apart anyways. Push rods seem to have took the beating.

My thoughts at this point are to put a thicker headgasket in to get some extra space. I'll lose a little compression but I'll still sit at 9.6 if I jump up to a .080 HG. It's just a street motor so no biggie really. The extra insurance room is worth it at this point, in my opinion. Also going to get the shorter push rods like I should have done to begin with.

Any other thoughts by someone that has more experience on this sort of thing? Any glaring issues that I did wrong? The exhaust valves are the ones that hit. The intakes seem to have been fine.

I'm sticking to Chevy's from now on.

[Great-Kazoo]

Zteknik / BobbyZ is the guy. I'm unable to reach my ford builder till later today.

[zteknik]

Geez it's been ages since I toyed around with any performance stuff
But have you checked the exhaust valve springs? I did an engine once with a similar issue and found the springs to be to weak- wound up doing a double spring set up- but then again it was in a Mopar440
Now I just fix stock Ford stuff. I don't remember all the little tricks anymore.

[Dave_L]

Geez it's been ages since I toyed around with any performance stuff
But have you checked the exhaust valve springs? I did an engine once with a similar issue and found the springs to be to weak- wound up doing a double spring set up- but then again it was in a Mopar440
Now I just fix stock Ford stuff. I don't remember all the little tricks anymore.

I had the matching springs for the cam installed on the heads.

[jmg8550]

I didn't think a 289 could be bored and punched to a 331. If I remember right, the 289 has a shorter deck height than a 302W. Do your pistons have any valve reliefs cut? What size combustion chamber size? Rocker ratio? Total cam lift? Is this a high compression engine?

Also, why not build a 5.0 roller motor? Better valve train, more parts, probably easier/cheaper to stroke...

[jmg8550]

Might call AMS (Automotive Machine Shop) in Fort Collins, they are very good with Ford engines.

[Dave_L]

I didn't think a 289 could be bored and punched to a 331. If I remember right, the 289 has a shorter deck height than a 302W. Do your pistons have any valve reliefs cut? What size combustion chamber size? Rocker ratio? Total cam lift? Is this a high compression engine?

Also, why not build a 5.0 roller motor? Better valve train, more parts, probably easier/cheaper to stroke...

Some say the cylinder walls are shorter in 289 blocks but it's one of those "Internet mysteries". Only thing I saw consistently was 347 strokers "push" it so that's why I went 331. Also the stroke ratio is better on the 331 for quicker revs. Bore is the exact same on either block, 4.00. Bor on mine is 4.030, stroke is 3.25. 5 cc valve reliefs, 60 cc chamber, 1.6 ratio, .500 lift, 10.1 compression.

[jmg8550]

That combination is for stroking a 302 to a 331. A 347 has a stroke of 3.4. With a 4.030 bore. I'm pretty sure the 289 has a shorter cylinder wall now that you mention it. Not internet lore.

[jmg8550]

Ok so doing research, we are both right and wrong. The 289 block had a few different wall heights. The C5 block was the shortest, the C6 and C8 blocks had longer cylinder heights. It's not that the 289 can't be stroked to a 331, it's about cylinder wall integrity. The pistons tend to side load in the cylinders. And I misspoke about the stroke measurement. Being that the 289 has a 4" bore, a 3.25 crank will give you 331CI. Sorry, it's been awhile since I was really into small block ford performance.

As far as your pushrod length, you may need to get an adjustable pushrod and order custom length ones. I don't think one solid tapped lifter costs very much.

[Dave_L]

Both blocks are a 4" bore. It was said 302 blocks had .019" longer skirts but lots of people report measuring the blocks and seeing no difference consistent enough to confirm. I've read that some 289 blocks were longer than some 302 blocks. "officially" yes they had slightly longer but in the real world, machinists couldn't see it consistently. Either way, I spun the assembly while on the stand and the 289 skirt was long enough to handle the 3.25" stroke.

Eta: you posted again before I posted but didn't see it. Haha. Gonna do a thicker head gasket by .04 to help with clearance too. It'll drop my comp down to 9.6 but still good enough for a fun street car.