[xj220]

My car is in the shop right now getting a full rebuild and while they were turning the motor through they noticed the valves were contacting the pistons. The block is coded D4DE ('74 Mav 302), the crank is a 1M, the connecting rods are C3OE (faily certain that's what I saw), and I'm pretty sure the pistons are stock. Before the rebuild, it had 65 coded 289 heads but don't have the cam specs (assuming stock). Motor ran fine with no issues. The new cam and top end is this: https://www.summitracing.com/parts/edl-2027/

Cam specs: Intake duration: 204 Degrees • Exhaust duration: 214 Degrees • Intake lift: .448” • Exhaust lift: .472” • Lobe separation: 112 Degree • Intake Center Line: 107 Degree • Vacuum: 16”

The kit is designed to be bolted directly to a stock pre-roller 289-302 short block. Any thoughts on what the issue may be? I'll get more specs from the shop as to what exactly is going on and they're going to dig in a bit more, but wanted to see what some possiblities may be. Thanks for the help.

 

[Redneckgearhead]

Cam timing off? Who rebuilt it?

 

[LSG]

Xj, what makes you think the valves are hitting the pistons ? has the engine been disassembled again ? what pistons were used ? what timing set was used ? As ******* asked, are we sure cam timing was correct ? That cam is not large by any description, which would make me think either the wrong pistons were chosen, the wrong crank was used, or the timing chain is a tooth off. LSG

 

[my289]

Hmm, pretty sure some one more knowledgeable then me will speak up. But I thought the 302 needed the 2M crank. So when you say the pistons are stock, is that stock 302 pistons or stock 289 pistons? Since it sounds like you are using 289 Crank and 289 rods in a 302 block and not sure on pistons?

 

[xj220]

Well to be honest, this was the brief discussion I had with the shop today and haven't had a chance to follow up. This is what they told me and I know I'm missing some of the details from the conversation (I should've taken notes). It all comes as one top-end kit and I'm assuming my pistons are stock (didn't see any codes on them as the motor was only taken to a short block). The kit is designed for a 289-302 and I have a pretty much stock 289 setup. My estimate is that there was an issue with the original block and all the contents were moved to this newer, later block.

 

[1965GTFB]

Check it with a borescope. How many miles on it since the engine was put together. Don't think it would last too long if they are. If they really are hitting, rocker arm ratio off?

 

[Aussie67]

Check the push rod length if they were replaced, as there were a few different options used over the years.

 

[MrFlash]

What heads are you using and what are the valve sizes?

 

[JW67Conv]

A 74 block shoud have about 0.022 more deck height than earlier ones. I think this lasted from 74-77. So if valves are hitting some thing is way wrong.

 

[dobrostang]

SO many variables, deck height, head thickness, head gasket thickness, piston type, pushrod length, valve timing, valves themselves. SOmeone needs to go back to basic principles. These motors and cars are like archeological digs. Its hard to know what someone else did in the past. Heads get milled to raise Compression Ratio, deck blocks, decide to use chevy valves to increase what ever and I even met a machinest that offset grinds a stock crank when he rebuilds it to get a tiny stroke advantage - people do lots of interesting things and the wrong combination... Personally, if there is an impact issue, head removal and clay is the only way I would feel comfortable solvign the problem.

 

[cheapbastard]

SO many variables, deck height, head thickness, head gasket thickness, piston type, pushrod length, valve timing, valves themselves. SOmeone needs to go back to basic principles. These motors and cars are like archeological digs. Its hard to know what someone else did in the past. Heads get milled to raise Compression Ratio, deck blocks, decide to use chevy valves to increase what ever and I even met a machinest that offset grinds a stock crank when he rebuilds it to get a tiny stroke advantage - people do lots of interesting things and the wrong combination... Personally, if there is an impact issue, head removal and clay is the only way I would feel comfortable solvign the problem.

Exactly.

 

[myfirstcar66]

Were the push rods or rockets substituted or replaced?

I typed that last night but it just posted. Oh well.

 

[LSG]

Xj, several questions. What happened to your iron 65 289 heads ? Those are sought after by folks looking to build higher compression small blocks, guys like me. If the shop didn't give them them back to you, they owe you some serious money. Ford hasn't made that casting for more than 50 years, and it would be a serious mistake to let them disappear. Do you know if you came in with a D4 block ?

Heres an idea. Maybe your valves aren't hitting the pistons at all. Maybe you have a bad combination of parts. If your valves were hitting the pistons, it would NOT run fine. But suppose your guys lost or damaged your crank, or unintentionally mixed it up with a 302 crank ? If one used a 2M 302 crank, with a 1.500 throw, and the common rebuilder shorty flattops at 1.585 tall, and your C3 289 rods @ 5.155 long, you'd have an assembly height of 8.240, and your D4 block is 8.224 tall. You still have the gaskets @ 0.035 ish, but as the pistons rock aT TDC, they can lightly tap against the heads. Seen it happen to folks who weren't aware of the finer points of the baby Windsors. I'd be pulling the heads and checking for witness marks. LSG

 

[xj220]

I'll remember to grab those heads, thanks for the info on that. The entire short block remained untouched during the rebuild (the motor was actually really clean and ran really well), so the only thing really modified has been the top end and cam. I've been visiting the shop about once a week to see how things are going, too.

I don't know if the block has been decked at all, but the heads are brand new Edelbrock E-street #5023, the pushrods are 6.805" long, the pistons are stock, head gaskets are 0.045" thick, and the valves are 1.900" intake and 1.600" exhaust.

We suspect it's an issue with the cam, in that the wrong cam was sent in the kit but we won't know until pulling it back out and looking at numbers. We'll contact Edelbrock after Christmas to see what other things could be going on before pulling it.

As a note, I looked over my old cam and was wondering if you guys could help identify it. The only things I see on it are CWC 1206, on the end it has 910914 stamped, D3 C3 between the distributor gearing and lobe, and a D1 and 4 on the other end. I measured the lobes to have .245 and .260 of lift, too. Thanks again for all the help.

 

[Woodchuck]

The CWC stands for Campbell, Wyant & Cannon (a company that casts camshafts and is a subsidiary of the Textron Company). Hard to say who ground it, but with lift numbers like that it was probably a generic replacement cam for the '74 motor.

 

[LSG]

Xj, if your shortblock is untouched, your engine is not rebuilt. But keep in mind that valve & piston collisions usually mean an engine that runs badly, if at all. You'll want to look for witness marks. And you'll want to pick up your original 65 289 heads, put them in a box, and ship them to me ! LSG

 

[xj220]

Since I’m impatient and I can’t let things wait until after the holidays, I was looking pics of the assembly and wanted to throw things by the more knowledgeable here. The first pic shows the top of the more minus the intake manifold. Looking closely, you see the #1 exhaust valve is open, the #3 intake valve slightly open, and the #7 intake valve full open. Now, I could be way off on this but wouldn’t that mean it’s a 351 cam with that firing order? Also, the second pic shows the cam being installed and I know it’s hard to tell just looking at pics but it looks pretty big in terms of lobes. Maybe I’m grasping at straws here but just thinking of possibilities. Thanks for the help and Happy Holidays.

 

[awhtx]

The change in the firing order didn't cause your problem. The pistons are still going up and down in the same sequence they went up and down previously but now instead of specific pistons going up on the compression stroke they are going up on the exhaust stroke and vice versa.

 

[2nd 66]

I can't tell open from closed in your pic ,but i had Jegs house brand of the 448/472 cam with the 351W firing order in my old 289 so that alone isn't an issue it would of course need to be wired as such

 

[xj220]

The change in the firing order didn't cause your problem. The pistons are still going up and down in the same sequence they went up and down previously but now instead of specific pistons going up on the compression stroke they are going up on the exhaust stroke and vice versa.

But if the timing is off then wouldn’t that be an issue in terms of cam and crank? Maybe I’m just grasping at straws.